feat: Update activity transitions, prepare for predictive-back (#650)

Previous code used a single animation type (slide) when transitioning,
the transition was quite slow, and didn't behave appropriately if the
device was set to a RTL writing system.

In addition, handling the back affordance didn't work well with the new
"Predictive Back" feature in Android 14

(https://developer.android.com/guide/navigation/custom-back/predictive-back-gesture).

Fix this.

## Transitions

To update the transitions the `startActivityWithSlideInAnimation()`
implementation (and associated `finishWithoutSlideOutAnimation()`) have
been replaced.

There are three transitions; `default`, `slide`, and `explode`,
represented as an enum passed to the activity intent.

The `default` transition is the activity transition from Android 14,
from the Android open source project

(https://cs.android.com/android/platform/superproject/+/android-14.0.0_r18:frameworks/base/core/res/res/anim/;bpv=1).
This is used for most transitions.

The `slide` transition is the pre-existing slide transition, with a
shorter transition time so it feels more responsive, and an RTL
implementation. This is used when there is a strong spatial component to
the navigation, for example, when going from:

- a status to its thread
- a preference menu item to its subscreen
- a filter in a list to the "edit filter" screen
- viewing your profile to editing your profile

The `explode` transition is used when the state of the app changes
significantly, such as when switching accounts.

Activities are now started with `startActivityWithTransition()` which
sets the intent and prepares the transition. `BaseActivity` checks the
intent for the transition type and makes further changes to the
transition as necessary.

## Predictive back

"Predictive back" needs to know what the back button would do before the
user interacts with it with an `onBackPressedCallback` that is either
enabled or disabled. This required refactoring some code (particularly
in `ComposeActivity`) to gather data ahead of time and enable/disable
the callback appropriately.

## Fixed bugs

- Back button wasn't stepping back through the tabs in AccountActivity
- Modifying a filter and pressing back without saving wasn't prompting
the user to save the changes
- Writing a content warning and then hiding it would still count the
text of the content warning toward's the post's length

## Other cleanups

- Use `ViewCompat.setTransitionName()` instead of setting the
`transitionName` property
- Delete the unused `fade_in` and `fade_out` animations.
- Use androidx-activity 1.9.0 to get the latest predictive back support
library code
- Show validation errors when creating / editing filters

app/lint-baseline.xml

@@ -54,7 +54,7 @@
     <issue
         id="UnusedAttribute"
         message="Attribute `networkSecurityConfig` is only used in API level 24 and higher (current min is 23)"
-        errorLine1="        android:networkSecurityConfig=&quot;@xml/network_security_config&quot;>"
+        errorLine1="        android:networkSecurityConfig=&quot;@xml/network_security_config&quot;"
         errorLine2="        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/AndroidManifest.xml"
@@ -62,6 +62,17 @@
             column="9"/>
     </issue>
 
+    <issue
+        id="UnusedAttribute"
+        message="Attribute `enableOnBackInvokedCallback` is only used in API level 33 and higher (current min is 23)"
+        errorLine1="        android:enableOnBackInvokedCallback=&quot;true&quot;>"
+        errorLine2="        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
+        <location
+            file="src/main/AndroidManifest.xml"
+            line="26"
+            column="9"/>
+    </issue>
+
     <issue
         id="SelectedPhotoAccess"
         message="Your app is currently not handling Selected Photos Access introduced in Android 14+"
@@ -883,7 +894,7 @@
         errorLine2="        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/java/app/pachli/components/account/AccountActivity.kt"
-            line="493"
+            line="515"
             column="9"/>
     </issue>
 
@@ -905,7 +916,7 @@
         errorLine2="        ~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/java/app/pachli/adapter/AccountFieldEditAdapter.kt"
-            line="44"
+            line="49"
             column="9"/>
     </issue>
 
@@ -916,7 +927,7 @@
         errorLine2="        ~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/java/app/pachli/adapter/AccountFieldEditAdapter.kt"
-            line="50"
+            line="55"
             column="9"/>
     </issue>
 

app/src/main/AndroidManifest.xml

@@ -22,7 +22,8 @@
         android:theme="@style/AppTheme"
         android:usesCleartextTraffic="false"
         android:localeConfig="@xml/locales_config"
-        android:networkSecurityConfig="@xml/network_security_config">
+        android:networkSecurityConfig="@xml/network_security_config"
+        android:enableOnBackInvokedCallback="true">
 
         <activity
             android:name=".SplashActivity"

app/src/main/java/app/pachli/EditProfileActivity.kt

@@ -30,6 +30,7 @@ import androidx.activity.OnBackPressedCallback
 import androidx.activity.viewModels
 import androidx.appcompat.app.AlertDialog
 import androidx.core.view.isVisible
+import androidx.core.widget.doAfterTextChanged
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.lifecycleScope
 import androidx.recyclerview.widget.LinearLayoutManager
@@ -59,6 +60,7 @@ import com.mikepenz.iconics.typeface.library.googlematerial.GoogleMaterial
 import com.mikepenz.iconics.utils.colorInt
 import com.mikepenz.iconics.utils.sizeDp
 import dagger.hilt.android.AndroidEntryPoint
+import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.launch
 import timber.log.Timber
 
@@ -75,7 +77,9 @@ class EditProfileActivity : BaseActivity() {
 
     private val binding by viewBinding(ActivityEditProfileBinding::inflate)
 
-    private val accountFieldEditAdapter = AccountFieldEditAdapter()
+    private val accountFieldEditAdapter: AccountFieldEditAdapter = AccountFieldEditAdapter {
+        viewModel.onChange(currentProfileData)
+    }
 
     private var maxAccountFields = InstanceInfoRepository.DEFAULT_MAX_ACCOUNT_FIELDS
 
@@ -108,6 +112,12 @@ class EditProfileActivity : BaseActivity() {
             fields = accountFieldEditAdapter.getFieldData(),
         )
 
+    private val onBackPressedCallback = object : OnBackPressedCallback(false) {
+        override fun handleOnBackPressed() {
+            showUnsavedChangesDialog()
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
@@ -216,19 +226,19 @@ class EditProfileActivity : BaseActivity() {
             }
         }
 
-        val onBackCallback = object : OnBackPressedCallback(enabled = true) {
+        lifecycleScope.launch {
-            override fun handleOnBackPressed() = checkForUnsavedChanges()
+            viewModel.isDirty.collectLatest { onBackPressedCallback.isEnabled = it }
         }
 
-        onBackPressedDispatcher.addCallback(this, onBackCallback)
+        binding.displayNameEditText.doAfterTextChanged {
-    }
+            viewModel.onChange(currentProfileData)
-
-    fun checkForUnsavedChanges() {
-        if (viewModel.hasUnsavedChanges(currentProfileData)) {
-            showUnsavedChangesDialog()
-        } else {
-            finish()
         }
+
+        binding.lockedCheckBox.setOnCheckedChangeListener { _, _ ->
+            viewModel.onChange(currentProfileData)
+        }
+
+        onBackPressedDispatcher.addCallback(this, onBackPressedCallback)
     }
 
     override fun onStop() {

app/src/main/java/app/pachli/MainActivity.kt

@@ -53,6 +53,7 @@ import androidx.core.view.GravityCompat
 import androidx.core.view.MenuProvider
 import androidx.core.view.forEach
 import androidx.core.view.isVisible
+import androidx.drawerlayout.widget.DrawerLayout.DrawerListener
 import androidx.lifecycle.lifecycleScope
 import androidx.viewpager2.widget.MarginPageTransformer
 import app.pachli.appstore.AnnouncementReadEvent
@@ -70,6 +71,9 @@ import app.pachli.core.activity.AccountSelectionListener
 import app.pachli.core.activity.BottomSheetActivity
 import app.pachli.core.activity.PostLookupFallbackBehavior
 import app.pachli.core.activity.emojify
+import app.pachli.core.activity.extensions.TransitionKind
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
+import app.pachli.core.activity.extensions.startActivityWithTransition
 import app.pachli.core.common.di.ApplicationScope
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
@@ -215,6 +219,15 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
     /** Adapter for the different timeline tabs */
     private lateinit var tabAdapter: MainPagerAdapter
 
+    private val onBackPressedCallback = object : OnBackPressedCallback(false) {
+        override fun handleOnBackPressed() {
+            when {
+                binding.mainDrawerLayout.isOpen -> binding.mainDrawerLayout.close()
+                binding.viewPager.currentItem != 0 -> binding.viewPager.currentItem = 0
+            }
+        }
+    }
+
     @SuppressLint("RestrictedApi")
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -284,7 +297,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                 // otherwise show notification tab
                 if (MainActivityIntent.getNotificationType(intent) == Notification.Type.FOLLOW_REQUEST) {
                     val intent = AccountListActivityIntent(this, AccountListActivityIntent.Kind.FOLLOW_REQUESTS)
-                    startActivityWithSlideInAnimation(intent)
+                    startActivityWithDefaultTransition(intent)
                 } else {
                     showNotificationTab = true
                 }
@@ -379,24 +392,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
 
         selectedEmojiPack = sharedPreferencesRepository.getString(EMOJI_PREFERENCE, "")
 
-        onBackPressedDispatcher.addCallback(
+        onBackPressedDispatcher.addCallback(this, onBackPressedCallback)
-            this,
-            object : OnBackPressedCallback(true) {
-                override fun handleOnBackPressed() {
-                    when {
-                        binding.mainDrawerLayout.isOpen -> {
-                            binding.mainDrawerLayout.close()
-                        }
-                        binding.viewPager.currentItem != 0 -> {
-                            binding.viewPager.currentItem = 0
-                        }
-                        else -> {
-                            finish()
-                        }
-                    }
-                }
-            },
-        )
 
         if (Build.VERSION.SDK_INT >= TIRAMISU && ActivityCompat.checkSelfPermission(this, POST_NOTIFICATIONS) != PERMISSION_GRANTED) {
             ActivityCompat.requestPermissions(this, arrayOf(POST_NOTIFICATIONS), 1)
@@ -500,7 +496,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                 return true
             }
             KeyEvent.KEYCODE_SEARCH -> {
-                startActivityWithSlideInAnimation(SearchActivityIntent(this))
+                startActivityWithDefaultTransition(SearchActivityIntent(this))
                 return true
             }
         }
@@ -603,6 +599,20 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
             refreshMainDrawerItems(addSearchButton)
             setSavedInstance(savedInstanceState)
         }
+
+        binding.mainDrawerLayout.addDrawerListener(object : DrawerListener {
+            override fun onDrawerSlide(drawerView: View, slideOffset: Float) { }
+
+            override fun onDrawerOpened(drawerView: View) {
+                onBackPressedCallback.isEnabled = true
+            }
+
+            override fun onDrawerClosed(drawerView: View) {
+                onBackPressedCallback.isEnabled = binding.tabLayout.selectedTabPosition > 0
+            }
+
+            override fun onDrawerStateChanged(newState: Int) { }
+        })
     }
 
     private fun refreshMainDrawerItems(addSearchButton: Boolean) {
@@ -616,7 +626,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                                 nameText = list.title
                                 iconicsIcon = GoogleMaterial.Icon.gmd_list
                                 onClick = {
-                                    startActivityWithSlideInAnimation(
+                                    startActivityWithDefaultTransition(
                                         TimelineActivityIntent.list(this@MainActivity, list.id, list.title),
                                     )
                                 }
@@ -635,7 +645,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     nameRes = R.string.title_notifications
                     iconicsIcon = GoogleMaterial.Icon.gmd_notifications
                     onClick = {
-                        startActivityWithSlideInAnimation(
+                        startActivityWithDefaultTransition(
                             TimelineActivityIntent.notifications(context),
                         )
                     }
@@ -644,7 +654,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     nameRes = R.string.title_public_local
                     iconRes = R.drawable.ic_local_24dp
                     onClick = {
-                        startActivityWithSlideInAnimation(
+                        startActivityWithDefaultTransition(
                             TimelineActivityIntent.publicLocal(context),
                         )
                     }
@@ -653,7 +663,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     nameRes = R.string.title_public_federated
                     iconRes = R.drawable.ic_public_24dp
                     onClick = {
-                        startActivityWithSlideInAnimation(
+                        startActivityWithDefaultTransition(
                             TimelineActivityIntent.publicFederated(context),
                         )
                     }
@@ -662,7 +672,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     nameRes = R.string.title_direct_messages
                     iconRes = R.drawable.ic_reblog_direct_24dp
                     onClick = {
-                        startActivityWithSlideInAnimation(
+                        startActivityWithDefaultTransition(
                             TimelineActivityIntent.conversations(context),
                         )
                     }
@@ -672,7 +682,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     iconicsIcon = GoogleMaterial.Icon.gmd_bookmark
                     onClick = {
                         val intent = TimelineActivityIntent.bookmarks(context)
-                        startActivityWithSlideInAnimation(intent)
+                        startActivityWithDefaultTransition(intent)
                     }
                 },
                 primaryDrawerItem {
@@ -681,21 +691,21 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     iconicsIcon = GoogleMaterial.Icon.gmd_star
                     onClick = {
                         val intent = TimelineActivityIntent.favourites(context)
-                        startActivityWithSlideInAnimation(intent)
+                        startActivityWithDefaultTransition(intent)
                     }
                 },
                 primaryDrawerItem {
                     nameRes = R.string.title_public_trending
                     iconicsIcon = GoogleMaterial.Icon.gmd_trending_up
                     onClick = {
-                        startActivityWithSlideInAnimation(TrendingActivityIntent(context))
+                        startActivityWithDefaultTransition(TrendingActivityIntent(context))
                     }
                 },
                 primaryDrawerItem {
                     nameRes = R.string.title_followed_hashtags
                     iconRes = R.drawable.ic_hashtag
                     onClick = {
-                        startActivityWithSlideInAnimation(FollowedTagsActivityIntent(context))
+                        startActivityWithDefaultTransition(FollowedTagsActivityIntent(context))
                     }
                 },
                 primaryDrawerItem {
@@ -703,7 +713,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     iconicsIcon = GoogleMaterial.Icon.gmd_person_add
                     onClick = {
                         val intent = AccountListActivityIntent(context, AccountListActivityIntent.Kind.FOLLOW_REQUESTS)
-                        startActivityWithSlideInAnimation(intent)
+                        startActivityWithDefaultTransition(intent)
                     }
                 },
                 SectionDrawerItem().apply {
@@ -714,7 +724,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     nameRes = R.string.manage_lists
                     iconicsIcon = GoogleMaterial.Icon.gmd_settings
                     onClick = {
-                        startActivityWithSlideInAnimation(ListActivityIntent(context))
+                        startActivityWithDefaultTransition(ListActivityIntent(context))
                     }
                 },
                 DividerDrawerItem(),
@@ -723,14 +733,14 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     iconRes = R.drawable.ic_notebook
                     onClick = {
                         val intent = DraftsActivityIntent(context)
-                        startActivityWithSlideInAnimation(intent)
+                        startActivityWithDefaultTransition(intent)
                     }
                 },
                 primaryDrawerItem {
                     nameRes = R.string.action_access_scheduled_posts
                     iconRes = R.drawable.ic_access_time
                     onClick = {
-                        startActivityWithSlideInAnimation(ScheduledStatusActivityIntent(context))
+                        startActivityWithDefaultTransition(ScheduledStatusActivityIntent(context))
                     }
                 },
                 primaryDrawerItem {
@@ -738,7 +748,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     nameRes = R.string.title_announcements
                     iconRes = R.drawable.ic_bullhorn_24dp
                     onClick = {
-                        startActivityWithSlideInAnimation(AnnouncementsActivityIntent(context))
+                        startActivityWithDefaultTransition(AnnouncementsActivityIntent(context))
                     }
                     badgeStyle = BadgeStyle().apply {
                         textColor = ColorHolder.fromColor(MaterialColors.getColor(binding.mainDrawer, com.google.android.material.R.attr.colorOnPrimary))
@@ -751,7 +761,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     iconRes = R.drawable.ic_account_settings
                     onClick = {
                         val intent = PreferencesActivityIntent(context, PreferenceScreen.ACCOUNT)
-                        startActivityWithSlideInAnimation(intent)
+                        startActivityWithDefaultTransition(intent)
                     }
                 },
                 secondaryDrawerItem {
@@ -759,7 +769,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     iconicsIcon = GoogleMaterial.Icon.gmd_settings
                     onClick = {
                         val intent = PreferencesActivityIntent(context, PreferenceScreen.GENERAL)
-                        startActivityWithSlideInAnimation(intent)
+                        startActivityWithDefaultTransition(intent)
                     }
                 },
                 primaryDrawerItem {
@@ -767,7 +777,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     iconicsIcon = GoogleMaterial.Icon.gmd_person
                     onClick = {
                         val intent = EditProfileActivityIntent(context)
-                        startActivityWithSlideInAnimation(intent)
+                        startActivityWithDefaultTransition(intent)
                     }
                 },
                 secondaryDrawerItem {
@@ -775,7 +785,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                     iconicsIcon = GoogleMaterial.Icon.gmd_info
                     onClick = {
                         val intent = AboutActivityIntent(context)
-                        startActivityWithSlideInAnimation(intent)
+                        startActivityWithDefaultTransition(intent)
                     }
                 },
                 secondaryDrawerItem {
@@ -792,7 +802,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                         nameRes = R.string.action_search
                         iconicsIcon = GoogleMaterial.Icon.gmd_search
                         onClick = {
-                            startActivityWithSlideInAnimation(SearchActivityIntent(context))
+                            startActivityWithDefaultTransition(SearchActivityIntent(context))
                         }
                     },
                 )
@@ -943,6 +953,8 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
 
         onTabSelectedListener = object : OnTabSelectedListener {
             override fun onTabSelected(tab: TabLayout.Tab) {
+                onBackPressedCallback.isEnabled = tab.position > 0 || binding.mainDrawerLayout.isOpen
+
                 supportActionBar?.title = tabs[tab.position].title(this@MainActivity)
 
                 refreshComposeButtonState(tabs[tab.position])
@@ -952,9 +964,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
 
             override fun onTabReselected(tab: TabLayout.Tab) {
                 val fragment = tabAdapter.getFragment(tab.position)
-                if (fragment is ReselectableFragment) {
+                (fragment as? ReselectableFragment)?.onReselect()
-                    (fragment as ReselectableFragment).onReselect()
-                }
 
                 refreshComposeButtonState(tabs[tab.position])
             }
@@ -987,12 +997,12 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
         // open profile when active image was clicked
         if (current && activeAccount != null) {
             val intent = AccountActivityIntent(this, activeAccount.accountId)
-            startActivityWithSlideInAnimation(intent)
+            startActivityWithDefaultTransition(intent)
             return
         }
         // open LoginActivity to add new account
         if (profile.identifier == DRAWER_ITEM_ADD_ACCOUNT) {
-            startActivityWithSlideInAnimation(
+            startActivityWithDefaultTransition(
                 LoginActivityIntent(this, LoginMode.ADDITIONAL_LOGIN),
             )
             return
@@ -1012,12 +1022,8 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
             intent.action = forward.action
             intent.putExtras(forward)
         }
-        startActivity(intent)
+        startActivityWithTransition(intent, TransitionKind.EXPLODE)
-        finishWithoutSlideOutAnimation()
+        finish()
-        overridePendingTransition(
-            DR.anim.explode,
-            DR.anim.explode,
-        )
     }
 
     private fun logout() {
@@ -1040,7 +1046,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
                             LoginActivityIntent(this@MainActivity, LoginMode.DEFAULT)
                         }
                         startActivity(intent)
-                        finishWithoutSlideOutAnimation()
+                        finish()
                     }
                 }
                 .setNegativeButton(android.R.string.cancel, null)

app/src/main/java/app/pachli/ViewMediaActivity.kt

@@ -46,6 +46,7 @@ import androidx.viewpager2.adapter.FragmentStateAdapter
 import androidx.viewpager2.widget.ViewPager2
 import app.pachli.BuildConfig.APPLICATION_ID
 import app.pachli.core.activity.BaseActivity
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
@@ -250,7 +251,7 @@ class ViewMediaActivity : BaseActivity(), MediaActionsListener {
 
     private fun onOpenStatus() {
         val attach = attachmentViewData!![binding.viewPager.currentItem]
-        startActivityWithSlideInAnimation(ViewThreadActivityIntent(this, attach.statusId, attach.statusUrl))
+        startActivityWithDefaultTransition(ViewThreadActivityIntent(this, attach.statusId, attach.statusUrl))
     }
 
     private fun copyLink() {

app/src/main/java/app/pachli/adapter/AccountFieldEditAdapter.kt

@@ -25,7 +25,12 @@ import app.pachli.core.ui.BindingHolder
 import app.pachli.databinding.ItemEditFieldBinding
 import app.pachli.util.fixTextSelection
 
-class AccountFieldEditAdapter : RecyclerView.Adapter<BindingHolder<ItemEditFieldBinding>>() {
+/**
+ * @property onChange Call this whenever data in the UI fields changes
+ */
+class AccountFieldEditAdapter(
+    val onChange: () -> Unit,
+) : RecyclerView.Adapter<BindingHolder<ItemEditFieldBinding>>() {
 
     private val fieldData = mutableListOf<MutableStringPair>()
     private var maxNameLength: Int? = null
@@ -84,10 +89,12 @@ class AccountFieldEditAdapter : RecyclerView.Adapter<BindingHolder<ItemEditField
 
         holder.binding.accountFieldNameText.doAfterTextChanged { newText ->
             fieldData.getOrNull(holder.bindingAdapterPosition)?.first = newText.toString()
+            onChange()
         }
 
         holder.binding.accountFieldValueText.doAfterTextChanged { newText ->
             fieldData.getOrNull(holder.bindingAdapterPosition)?.second = newText.toString()
+            onChange()
         }
 
         // Ensure the textview contents are selectable

app/src/main/java/app/pachli/components/account/AccountActivity.kt

@@ -36,6 +36,7 @@ import android.view.MenuItem
 import android.view.View
 import android.view.ViewGroup
 import android.view.ViewGroup.MarginLayoutParams
+import androidx.activity.OnBackPressedCallback
 import androidx.activity.viewModels
 import androidx.annotation.ColorInt
 import androidx.annotation.DrawableRes
@@ -58,6 +59,9 @@ import app.pachli.R
 import app.pachli.core.activity.AccountSelectionListener
 import app.pachli.core.activity.BottomSheetActivity
 import app.pachli.core.activity.emojify
+import app.pachli.core.activity.extensions.TransitionKind
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
+import app.pachli.core.activity.extensions.startActivityWithTransition
 import app.pachli.core.activity.loadAvatar
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
@@ -180,6 +184,12 @@ class AccountActivity :
 
     private var noteWatcher: TextWatcher? = null
 
+    private val onBackPressedCallback = object : OnBackPressedCallback(false) {
+        override fun handleOnBackPressed() {
+            binding.accountFragmentViewPager.currentItem = 0
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         loadResources()
@@ -207,6 +217,8 @@ class AccountActivity :
         } else {
             binding.saveNoteInfo.visibility = View.INVISIBLE
         }
+
+        onBackPressedDispatcher.addCallback(onBackPressedCallback)
     }
 
     /**
@@ -243,7 +255,7 @@ class AccountActivity :
                 else -> throw AssertionError()
             }
             val accountListIntent = AccountListActivityIntent(this, kind, viewModel.accountId)
-            startActivityWithSlideInAnimation(accountListIntent)
+            startActivityWithDefaultTransition(accountListIntent)
         }
         binding.accountFollowers.setOnClickListener(accountListClickListener)
         binding.accountFollowing.setOnClickListener(accountListClickListener)
@@ -299,7 +311,10 @@ class AccountActivity :
 
                 override fun onTabUnselected(tab: TabLayout.Tab?) {}
 
-                override fun onTabSelected(tab: TabLayout.Tab?) {}
+                override fun onTabSelected(tab: TabLayout.Tab?) {
+                    tab?.position ?: return
+                    onBackPressedCallback.isEnabled = tab.position > 0
+                }
             },
         )
     }
@@ -561,7 +576,7 @@ class AccountActivity :
     }
 
     private fun viewImage(view: View, uri: String) {
-        view.transitionName = uri
+        ViewCompat.setTransitionName(view, uri)
         startActivity(
             ViewMediaActivityIntent(view.context, uri),
             ActivityOptionsCompat.makeSceneTransitionAnimation(this, view, uri).toBundle(),
@@ -630,7 +645,7 @@ class AccountActivity :
             binding.accountFollowButton.setOnClickListener {
                 if (viewModel.isSelf) {
                     val intent = EditProfileActivityIntent(this@AccountActivity)
-                    startActivity(intent)
+                    startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
                     return@setOnClickListener
                 }
 
@@ -959,12 +974,12 @@ class AccountActivity :
 
     override fun onViewTag(tag: String) {
         val intent = TimelineActivityIntent.hashtag(this, tag)
-        startActivityWithSlideInAnimation(intent)
+        startActivityWithDefaultTransition(intent)
     }
 
     override fun onViewAccount(id: String) {
         val intent = AccountActivityIntent(this, id)
-        startActivityWithSlideInAnimation(intent)
+        startActivityWithDefaultTransition(intent)
     }
 
     override fun onViewUrl(url: String) {

app/src/main/java/app/pachli/components/accountlist/AccountListFragment.kt

@@ -32,9 +32,9 @@ import app.pachli.components.accountlist.adapter.FollowRequestsAdapter
 import app.pachli.components.accountlist.adapter.FollowRequestsHeaderAdapter
 import app.pachli.components.accountlist.adapter.MutesAdapter
 import app.pachli.core.accounts.AccountManager
-import app.pachli.core.activity.BaseActivity
 import app.pachli.core.activity.BottomSheetActivity
 import app.pachli.core.activity.PostLookupFallbackBehavior
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
@@ -158,19 +158,15 @@ class AccountListFragment :
     }
 
     override fun onViewTag(tag: String) {
-        (activity as BaseActivity?)
+        activity?.startActivityWithDefaultTransition(TimelineActivityIntent.hashtag(requireContext(), tag))
-            ?.startActivityWithSlideInAnimation(TimelineActivityIntent.hashtag(requireContext(), tag))
     }
 
     override fun onViewAccount(id: String) {
-        (activity as BaseActivity?)?.let {
+        activity?.startActivityWithDefaultTransition(AccountActivityIntent(requireContext(), id))
-            val intent = AccountActivityIntent(it, id)
-            it.startActivityWithSlideInAnimation(intent)
-        }
     }
 
     override fun onViewUrl(url: String) {
-        (activity as BottomSheetActivity?)?.viewUrl(url, PostLookupFallbackBehavior.OPEN_IN_BROWSER)
+        (activity as? BottomSheetActivity)?.viewUrl(url, PostLookupFallbackBehavior.OPEN_IN_BROWSER)
     }
 
     override fun onMute(mute: Boolean, id: String, position: Int, notifications: Boolean) {

app/src/main/java/app/pachli/components/announcements/AnnouncementsActivity.kt

@@ -29,6 +29,7 @@ import app.pachli.R
 import app.pachli.adapter.EmojiAdapter
 import app.pachli.adapter.OnEmojiSelectedListener
 import app.pachli.core.activity.BottomSheetActivity
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
@@ -187,7 +188,7 @@ class AnnouncementsActivity :
 
     override fun onViewTag(tag: String) {
         val intent = TimelineActivityIntent.hashtag(this, tag)
-        startActivityWithSlideInAnimation(intent)
+        startActivityWithDefaultTransition(intent)
     }
 
     override fun onViewAccount(id: String) {

app/src/main/java/app/pachli/components/compose/ComposeActivity.kt

@@ -17,6 +17,7 @@
 package app.pachli.components.compose
 
 import android.Manifest
+import android.annotation.SuppressLint
 import android.app.ProgressDialog
 import android.content.ClipData
 import android.content.Intent
@@ -30,7 +31,6 @@ import android.os.Bundle
 import android.provider.MediaStore
 import android.text.InputFilter
 import android.text.Spanned
-import android.text.style.URLSpan
 import android.view.KeyEvent
 import android.view.MenuItem
 import android.view.View
@@ -94,7 +94,6 @@ import app.pachli.core.network.model.Status
 import app.pachli.core.preferences.AppTheme
 import app.pachli.core.preferences.PrefKeys
 import app.pachli.core.preferences.SharedPreferencesRepository
-import app.pachli.core.ui.MentionSpan
 import app.pachli.databinding.ActivityComposeBinding
 import app.pachli.util.PickMediaFiles
 import app.pachli.util.getInitialLanguages
@@ -155,9 +154,9 @@ class ComposeActivity :
 
     @VisibleForTesting
     var maximumTootCharacters = InstanceInfoRepository.DEFAULT_CHARACTER_LIMIT
-    var charactersReservedPerUrl = InstanceInfoRepository.DEFAULT_CHARACTERS_RESERVED_PER_URL
 
-    private val viewModel: ComposeViewModel by viewModels()
+    @VisibleForTesting
+    val viewModel: ComposeViewModel by viewModels()
 
     private val binding by viewBinding(ActivityComposeBinding::inflate)
 
@@ -206,6 +205,28 @@ class ComposeActivity :
         viewModel.cropImageItemOld = null
     }
 
+    /**
+     * Pressing back either (a) closes an open bottom sheet, or (b) goes
+     * back, if no bottom sheets are open.
+     */
+    private val onBackPressedCallback = object : OnBackPressedCallback(false) {
+        override fun handleOnBackPressed() {
+            if (composeOptionsBehavior.state == BottomSheetBehavior.STATE_EXPANDED ||
+                addMediaBehavior.state == BottomSheetBehavior.STATE_EXPANDED ||
+                emojiBehavior.state == BottomSheetBehavior.STATE_EXPANDED ||
+                scheduleBehavior.state == BottomSheetBehavior.STATE_EXPANDED
+            ) {
+                composeOptionsBehavior.state = BottomSheetBehavior.STATE_HIDDEN
+                addMediaBehavior.state = BottomSheetBehavior.STATE_HIDDEN
+                emojiBehavior.state = BottomSheetBehavior.STATE_HIDDEN
+                scheduleBehavior.state = BottomSheetBehavior.STATE_HIDDEN
+                return
+            }
+
+            handleCloseButton()
+        }
+    }
+
     public override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
@@ -268,7 +289,7 @@ class ComposeActivity :
         }
 
         setupLanguageSpinner(getInitialLanguages(composeOptions?.language, activeAccount))
-        setupComposeField(sharedPreferencesRepository, viewModel.startingText, composeOptions)
+        setupComposeField(sharedPreferencesRepository, viewModel.initialContent, composeOptions)
         setupContentWarningField(composeOptions?.contentWarning)
         setupPollView()
         applyShareIntent(intent, savedInstanceState)
@@ -282,7 +303,7 @@ class ComposeActivity :
             }
 
             it.getBoolean(CONTENT_WARNING_VISIBLE_KEY).apply {
-                viewModel.contentWarningChanged(this)
+                viewModel.showContentWarningChanged(this)
             }
 
             it.getString(SCHEDULED_TIME_KEY)?.let { time ->
@@ -369,7 +390,9 @@ class ComposeActivity :
         if (startingContentWarning != null) {
             binding.composeContentWarningField.setText(startingContentWarning)
         }
-        binding.composeContentWarningField.doOnTextChanged { _, _, _, _ -> updateVisibleCharactersLeft() }
+        binding.composeContentWarningField.doOnTextChanged { newContentWarning, _, _, _ ->
+            viewModel.onContentWarningChanged(newContentWarning?.toString() ?: "")
+        }
     }
 
     private fun setupComposeField(
@@ -404,7 +427,7 @@ class ComposeActivity :
         highlightSpans(binding.composeEditField.text, mentionColour)
         binding.composeEditField.doAfterTextChanged { editable ->
             highlightSpans(editable!!, mentionColour)
-            updateVisibleCharactersLeft()
+            viewModel.onContentChanged(editable)
         }
 
         // work around Android platform bug -> https://issuetracker.google.com/issues/67102093
@@ -419,12 +442,19 @@ class ComposeActivity :
         lifecycleScope.launch {
             viewModel.instanceInfo.collect { instanceData ->
                 maximumTootCharacters = instanceData.maxChars
-                charactersReservedPerUrl = instanceData.charactersReservedPerUrl
                 maxUploadMediaNumber = instanceData.maxMediaAttachments
-                updateVisibleCharactersLeft()
+                updateVisibleCharactersLeft(viewModel.statusLength.value)
             }
         }
 
+        lifecycleScope.launch {
+            viewModel.statusLength.collect { updateVisibleCharactersLeft(it) }
+        }
+
+        lifecycleScope.launch {
+            viewModel.closeConfirmation.collect { updateOnBackPressedCallbackState(it, bottomSheetStates()) }
+        }
+
         lifecycleScope.launch {
             viewModel.emoji.collect(::setEmojiList)
         }
@@ -493,6 +523,23 @@ class ComposeActivity :
         }
     }
 
+    /** @return List of states of the different bottomsheets */
+    private fun bottomSheetStates() = listOf(
+        composeOptionsBehavior.state,
+        addMediaBehavior.state,
+        emojiBehavior.state,
+        scheduleBehavior.state,
+    )
+
+    /**
+     * Enables [onBackPressedCallback] if a confirmation is required, or any botttom sheet is
+     * open. Otherwise disables.
+     */
+    private fun updateOnBackPressedCallbackState(confirmationKind: ConfirmationKind, bottomSheetStates: List<Int>) {
+        onBackPressedCallback.isEnabled = confirmationKind != ConfirmationKind.NONE ||
+            bottomSheetStates.any { it != BottomSheetBehavior.STATE_HIDDEN }
+    }
+
     private fun setupButtons() {
         binding.composeOptionsBottomSheet.listener = this
 
@@ -501,6 +548,17 @@ class ComposeActivity :
         scheduleBehavior = BottomSheetBehavior.from(binding.composeScheduleView)
         emojiBehavior = BottomSheetBehavior.from(binding.emojiView)
 
+        val bottomSheetCallback = object : BottomSheetBehavior.BottomSheetCallback() {
+            override fun onStateChanged(bottomSheet: View, newState: Int) {
+                updateOnBackPressedCallbackState(viewModel.closeConfirmation.value, bottomSheetStates())
+            }
+            override fun onSlide(bottomSheet: View, slideOffset: Float) { }
+        }
+        composeOptionsBehavior.addBottomSheetCallback(bottomSheetCallback)
+        addMediaBehavior.addBottomSheetCallback(bottomSheetCallback)
+        scheduleBehavior.addBottomSheetCallback(bottomSheetCallback)
+        emojiBehavior.addBottomSheetCallback(bottomSheetCallback)
+
         enableButton(binding.composeEmojiButton, clickable = false, colorActive = false)
 
         // Setup the interface buttons.
@@ -534,26 +592,7 @@ class ComposeActivity :
         binding.actionPhotoPick.setOnClickListener { onMediaPick() }
         binding.addPollTextActionTextView.setOnClickListener { openPollDialog() }
 
-        onBackPressedDispatcher.addCallback(
+        onBackPressedDispatcher.addCallback(this, onBackPressedCallback)
-            this,
-            object : OnBackPressedCallback(true) {
-                override fun handleOnBackPressed() {
-                    if (composeOptionsBehavior.state == BottomSheetBehavior.STATE_EXPANDED ||
-                        addMediaBehavior.state == BottomSheetBehavior.STATE_EXPANDED ||
-                        emojiBehavior.state == BottomSheetBehavior.STATE_EXPANDED ||
-                        scheduleBehavior.state == BottomSheetBehavior.STATE_EXPANDED
-                    ) {
-                        composeOptionsBehavior.state = BottomSheetBehavior.STATE_HIDDEN
-                        addMediaBehavior.state = BottomSheetBehavior.STATE_HIDDEN
-                        emojiBehavior.state = BottomSheetBehavior.STATE_HIDDEN
-                        scheduleBehavior.state = BottomSheetBehavior.STATE_HIDDEN
-                        return
-                    }
-
-                    handleCloseButton()
-                }
-            },
-        )
     }
 
     private fun setupLanguageSpinner(initialLanguages: List<String>) {
@@ -851,7 +890,7 @@ class ComposeActivity :
             maxOptionLength = instanceParams.pollMaxLength,
             minDuration = instanceParams.pollMinDuration,
             maxDuration = instanceParams.pollMaxDuration,
-            onUpdatePoll = viewModel::updatePoll,
+            onUpdatePoll = viewModel::onPollChanged,
         )
     }
 
@@ -881,30 +920,21 @@ class ComposeActivity :
     }
 
     private fun removePoll() {
-        viewModel.poll.value = null
+        viewModel.onPollChanged(null)
         binding.pollPreview.hide()
     }
 
     override fun onVisibilityChanged(visibility: Status.Visibility) {
+        viewModel.onStatusVisibilityChanged(visibility)
         composeOptionsBehavior.state = BottomSheetBehavior.STATE_COLLAPSED
-        viewModel.statusVisibility.value = visibility
-    }
-
-    @VisibleForTesting
-    fun calculateTextLength(): Int {
-        return statusLength(
-            binding.composeEditField.text,
-            binding.composeContentWarningField.text,
-            charactersReservedPerUrl,
-        )
     }
 
     @VisibleForTesting
     val selectedLanguage: String?
         get() = viewModel.postLanguage
 
-    private fun updateVisibleCharactersLeft() {
+    private fun updateVisibleCharactersLeft(textLength: Int) {
-        val remainingLength = maximumTootCharacters - calculateTextLength()
+        val remainingLength = maximumTootCharacters - textLength
         binding.composeCharactersLeftView.text = String.format(Locale.getDefault(), "%d", remainingLength)
 
         val textColor = if (remainingLength < 0) {
@@ -917,8 +947,7 @@ class ComposeActivity :
 
     private fun onContentWarningChanged() {
         val showWarning = binding.composeContentWarningBar.isGone
-        viewModel.contentWarningChanged(showWarning)
+        viewModel.showContentWarningChanged(showWarning)
-        updateVisibleCharactersLeft()
     }
 
     private fun verifyScheduledTime(): Boolean {
@@ -957,11 +986,11 @@ class ComposeActivity :
         if (viewModel.showContentWarning.value) {
             spoilerText = binding.composeContentWarningField.text.toString()
         }
-        val characterCount = calculateTextLength()
+        val statusLength = viewModel.statusLength.value
-        if ((characterCount <= 0 || contentText.isBlank()) && viewModel.media.value.isEmpty()) {
+        if ((statusLength <= 0 || contentText.isBlank()) && viewModel.media.value.isEmpty()) {
             binding.composeEditField.error = getString(R.string.error_empty)
             enableButtons(true, viewModel.editing)
-        } else if (characterCount <= maximumTootCharacters) {
+        } else if (statusLength <= maximumTootCharacters) {
             lifecycleScope.launch {
                 viewModel.sendStatus(contentText, spoilerText, activeAccount.id)
                 deleteDraftAndFinish()
@@ -1008,8 +1037,9 @@ class ComposeActivity :
             this,
             BuildConfig.APPLICATION_ID + ".fileprovider",
             photoFile,
-        )
+        )?.also {
-        takePicture.launch(photoUploadUri)
+            takePicture.launch(it)
+        }
     }
 
     private fun enableButton(button: ImageButton, clickable: Boolean, colorActive: Boolean) {
@@ -1105,6 +1135,7 @@ class ComposeActivity :
         return super.onOptionsItemSelected(item)
     }
 
+    @SuppressLint("GestureBackNavigation")
     override fun onKeyDown(keyCode: Int, event: KeyEvent): Boolean {
         if (event.action == KeyEvent.ACTION_DOWN) {
             if (event.isCtrlPressed) {
@@ -1126,10 +1157,10 @@ class ComposeActivity :
     private fun handleCloseButton() {
         val contentText = binding.composeEditField.text.toString()
         val contentWarning = binding.composeContentWarningField.text.toString()
-        when (viewModel.handleCloseButton(contentText, contentWarning)) {
+        when (viewModel.closeConfirmation.value) {
             ConfirmationKind.NONE -> {
                 viewModel.stopUploads()
-                finishWithoutSlideOutAnimation()
+                finish()
             }
             ConfirmationKind.SAVE_OR_DISCARD ->
                 getSaveAsDraftOrDiscardDialog(contentText, contentWarning).show()
@@ -1183,7 +1214,7 @@ class ComposeActivity :
             }
             .setNegativeButton(R.string.action_discard) { _, _ ->
                 viewModel.stopUploads()
-                finishWithoutSlideOutAnimation()
+                finish()
             }
     }
 
@@ -1193,13 +1224,13 @@ class ComposeActivity :
      */
     private fun getContinueEditingOrDiscardDialog(): AlertDialog.Builder {
         return AlertDialog.Builder(this)
-            .setMessage(R.string.compose_unsaved_changes)
+            .setMessage(R.string.unsaved_changes)
             .setPositiveButton(R.string.action_continue_edit) { _, _ ->
                 // Do nothing, dialog will dismiss, user can continue editing
             }
             .setNegativeButton(R.string.action_discard) { _, _ ->
                 viewModel.stopUploads()
-                finishWithoutSlideOutAnimation()
+                finish()
             }
     }
 
@@ -1213,7 +1244,7 @@ class ComposeActivity :
             .setPositiveButton(R.string.action_delete) { _, _ ->
                 viewModel.deleteDraft()
                 viewModel.stopUploads()
-                finishWithoutSlideOutAnimation()
+                finish()
             }
             .setNegativeButton(R.string.action_continue_edit) { _, _ ->
                 // Do nothing, dialog will dismiss, user can continue editing
@@ -1222,7 +1253,7 @@ class ComposeActivity :
 
     private fun deleteDraftAndFinish() {
         viewModel.deleteDraft()
-        finishWithoutSlideOutAnimation()
+        finish()
     }
 
     private fun saveDraftAndFinish(contentText: String, contentWarning: String) {
@@ -1240,7 +1271,7 @@ class ComposeActivity :
             }
             viewModel.saveDraft(contentText, contentWarning)
             dialog?.cancel()
-            finishWithoutSlideOutAnimation()
+            finish()
         }
     }
 
@@ -1315,54 +1346,6 @@ class ComposeActivity :
             return mimeType != null && (mimeType.startsWith("image/") || mimeType.startsWith("video/") || mimeType.startsWith("audio/") || mimeType == "text/plain")
         }
 
-        /**
-         * Calculate the effective status length.
-         *
-         * Some text is counted differently:
-         *
-         * In the status body:
-         *
-         * - URLs always count for [urlLength] characters irrespective of their actual length
-         *   (https://docs.joinmastodon.org/user/posting/#links)
-         * - Mentions ("@user@some.instance") only count the "@user" part
-         *   (https://docs.joinmastodon.org/user/posting/#mentions)
-         * - Hashtags are always treated as their actual length, including the "#"
-         *   (https://docs.joinmastodon.org/user/posting/#hashtags)
-         * - Emojis are treated as a single character
-         *
-         * Content warning text is always treated as its full length, URLs and other entities
-         * are not treated differently.
-         *
-         * @param body status body text
-         * @param contentWarning optional content warning text
-         * @param urlLength the number of characters attributed to URLs
-         * @return the effective status length
-         */
-        fun statusLength(body: Spanned, contentWarning: Spanned?, urlLength: Int): Int {
-            var length = body.toString().mastodonLength() - body.getSpans(0, body.length, URLSpan::class.java)
-                .fold(0) { acc, span ->
-                    // Accumulate a count of characters to be *ignored* in the final length
-                    acc + when (span) {
-                        is MentionSpan -> {
-                            // Ignore everything from the second "@" (if present)
-                            span.url.length - (
-                                span.url.indexOf("@", 1).takeIf { it >= 0 }
-                                    ?: span.url.length
-                                )
-                        }
-                        else -> {
-                            // Expected to be negative if the URL length < maxUrlLength
-                            span.url.mastodonLength() - urlLength
-                        }
-                    }
-                }
-
-            // Content warning text is treated as is, URLs or mentions there are not special
-            contentWarning?.let { length += it.toString().mastodonLength() }
-
-            return length
-        }
-
         /**
          * [InputFilter] that uses the "Mastodon" length of a string, where emojis always
          * count as a single character.

app/src/main/java/app/pachli/components/compose/ComposeViewModel.kt

@@ -17,6 +17,10 @@
 package app.pachli.components.compose
 
 import android.net.Uri
+import android.text.Editable
+import android.text.Spanned
+import android.text.style.URLSpan
+import androidx.annotation.VisibleForTesting
 import androidx.core.net.toUri
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
@@ -25,6 +29,7 @@ import app.pachli.components.compose.ComposeAutoCompleteAdapter.AutocompleteResu
 import app.pachli.components.drafts.DraftHelper
 import app.pachli.components.search.SearchType
 import app.pachli.core.accounts.AccountManager
+import app.pachli.core.common.string.mastodonLength
 import app.pachli.core.common.string.randomAlphanumericString
 import app.pachli.core.data.model.InstanceInfo
 import app.pachli.core.data.repository.InstanceInfoRepository
@@ -35,6 +40,7 @@ import app.pachli.core.network.model.Emoji
 import app.pachli.core.network.model.NewPoll
 import app.pachli.core.network.model.Status
 import app.pachli.core.network.retrofit.MastodonApi
+import app.pachli.core.ui.MentionSpan
 import app.pachli.service.MediaToSend
 import app.pachli.service.ServiceClient
 import app.pachli.service.StatusToSend
@@ -49,6 +55,8 @@ import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharedFlow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.asFlow
+import kotlinx.coroutines.flow.asSharedFlow
+import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.shareIn
 import kotlinx.coroutines.flow.update
@@ -66,20 +74,40 @@ class ComposeViewModel @Inject constructor(
     instanceInfoRepo: InstanceInfoRepository,
 ) : ViewModel() {
 
+    /** The current content */
+    private var content: Editable = Editable.Factory.getInstance().newEditable("")
+
+    /** The current content warning */
+    private var contentWarning: String = ""
+
+    /**
+     * The effective content warning. Either the real content warning, or the empty string
+     * if the content warning has been hidden
+     */
+    private val effectiveContentWarning
+        get() = if (showContentWarning.value) contentWarning else ""
+
     private var replyingStatusAuthor: String? = null
     private var replyingStatusContent: String? = null
-    internal var startingText: String? = null
+
+    /** The initial content for this status, before any edits */
+    internal var initialContent: String = ""
+
+    /** The initial content warning for this status, before any edits */
+    private var initialContentWarning: String = ""
+
     internal var postLanguage: String? = null
+
+    /** If editing a draft then the ID of the draft, otherwise 0 */
     private var draftId: Int = 0
     private var scheduledTootId: String? = null
-    private var startingContentWarning: String = ""
     private var inReplyToId: String? = null
     private var originalStatusId: String? = null
     private var startingVisibility: Status.Visibility = Status.Visibility.UNKNOWN
 
     private var contentWarningStateChanged: Boolean = false
     private var modifiedInitialState: Boolean = false
-    private var hasScheduledTimeChanged: Boolean = false
+    private var scheduledTimeChanged: Boolean = false
 
     val instanceInfo: SharedFlow<InstanceInfo> = instanceInfoRepo::getInstanceInfo.asFlow()
         .shareIn(viewModelScope, SharingStarted.Eagerly, replay = 1)
@@ -87,16 +115,27 @@ class ComposeViewModel @Inject constructor(
     val emoji: SharedFlow<List<Emoji>> = instanceInfoRepo::getEmojis.asFlow()
         .shareIn(viewModelScope, SharingStarted.Eagerly, replay = 1)
 
-    val markMediaAsSensitive: MutableStateFlow<Boolean> =
+    private val _markMediaAsSensitive: MutableStateFlow<Boolean> =
         MutableStateFlow(accountManager.activeAccount?.defaultMediaSensitivity ?: false)
+    val markMediaAsSensitive = _markMediaAsSensitive.asStateFlow()
 
-    val statusVisibility: MutableStateFlow<Status.Visibility> = MutableStateFlow(Status.Visibility.UNKNOWN)
+    private val _statusVisibility: MutableStateFlow<Status.Visibility> = MutableStateFlow(Status.Visibility.UNKNOWN)
-    val showContentWarning: MutableStateFlow<Boolean> = MutableStateFlow(false)
+    val statusVisibility = _statusVisibility.asStateFlow()
-    val poll: MutableStateFlow<NewPoll?> = MutableStateFlow(null)
+    private val _showContentWarning: MutableStateFlow<Boolean> = MutableStateFlow(false)
-    val scheduledAt: MutableStateFlow<String?> = MutableStateFlow(null)
+    val showContentWarning = _showContentWarning.asStateFlow()
+    private val _poll: MutableStateFlow<NewPoll?> = MutableStateFlow(null)
+    val poll = _poll.asStateFlow()
+    private val _scheduledAt: MutableStateFlow<String?> = MutableStateFlow(null)
+    val scheduledAt = _scheduledAt.asStateFlow()
 
-    val media: MutableStateFlow<List<QueuedMedia>> = MutableStateFlow(emptyList())
+    private val _media: MutableStateFlow<List<QueuedMedia>> = MutableStateFlow(emptyList())
-    val uploadError = MutableSharedFlow<Throwable>(replay = 0, extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST)
+    val media = _media.asStateFlow()
+    private val _uploadError = MutableSharedFlow<Throwable>(replay = 0, extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST)
+    val uploadError = _uploadError.asSharedFlow()
+    private val _closeConfirmation = MutableStateFlow(ConfirmationKind.NONE)
+    val closeConfirmation = _closeConfirmation.asStateFlow()
+    private val _statusLength = MutableStateFlow(0)
+    val statusLength = _statusLength.asStateFlow()
 
     private lateinit var composeKind: ComposeKind
 
@@ -133,7 +172,7 @@ class ComposeViewModel @Inject constructor(
     ): QueuedMedia {
         var stashMediaItem: QueuedMedia? = null
 
-        media.update { mediaList ->
+        _media.update { mediaList ->
             val mediaItem = QueuedMedia(
                 localId = mediaUploader.getNewLocalMediaId(),
                 uri = uri,
@@ -176,12 +215,12 @@ class ComposeViewModel @Inject constructor(
                                 },
                             )
                         is UploadEvent.ErrorEvent -> {
-                            media.update { mediaList -> mediaList.filter { it.localId != mediaItem.localId } }
+                            _media.update { mediaList -> mediaList.filter { it.localId != mediaItem.localId } }
-                            uploadError.emit(event.error)
+                            _uploadError.emit(event.error)
                             return@collect
                         }
                     }
-                    media.update { mediaList ->
+                    _media.update { mediaList ->
                         mediaList.map { mediaItem ->
                             if (mediaItem.localId == newMediaItem.localId) {
                                 newMediaItem
@@ -192,11 +231,13 @@ class ComposeViewModel @Inject constructor(
                     }
                 }
         }
+
+        updateCloseConfirmation()
         return mediaItem
     }
 
     private fun addUploadedMedia(id: String, type: QueuedMedia.Type, uri: Uri, description: String?, focus: Attachment.Focus?) {
-        media.update { mediaList ->
+        _media.update { mediaList ->
             val mediaItem = QueuedMedia(
                 localId = mediaUploader.getNewLocalMediaId(),
                 uri = uri,
@@ -214,22 +255,53 @@ class ComposeViewModel @Inject constructor(
 
     fun removeMediaFromQueue(item: QueuedMedia) {
         mediaUploader.cancelUploadScope(item.localId)
-        media.update { mediaList -> mediaList.filter { it.localId != item.localId } }
+        _media.update { mediaList -> mediaList.filter { it.localId != item.localId } }
+        updateCloseConfirmation()
     }
 
     fun toggleMarkSensitive() {
-        this.markMediaAsSensitive.value = this.markMediaAsSensitive.value != true
+        this._markMediaAsSensitive.value = this._markMediaAsSensitive.value != true
     }
 
-    fun handleCloseButton(contentText: String?, contentWarning: String?): ConfirmationKind {
+    /** Call this when the status' primary content changes */
-        return if (didChange(contentText, contentWarning)) {
+    fun onContentChanged(newContent: Editable) {
+        content = newContent
+        updateStatusLength()
+        updateCloseConfirmation()
+    }
+
+    /** Call this when the status' content warning changes */
+    fun onContentWarningChanged(newContentWarning: String) {
+        contentWarning = newContentWarning
+        updateStatusLength()
+        updateCloseConfirmation()
+    }
+
+    /** Call this to attach or clear the status' poll */
+    fun onPollChanged(newPoll: NewPoll?) {
+        _poll.value = newPoll
+        updateCloseConfirmation()
+    }
+
+    /** Call this to change the status' visibility */
+    fun onStatusVisibilityChanged(newVisibility: Status.Visibility) {
+        _statusVisibility.value = newVisibility
+    }
+
+    @VisibleForTesting
+    fun updateStatusLength() {
+        _statusLength.value = statusLength(content, effectiveContentWarning, instanceInfo.replayCache.last().charactersReservedPerUrl)
+    }
+
+    private fun updateCloseConfirmation() {
+        _closeConfirmation.value = if (isDirty()) {
             when (composeKind) {
-                ComposeKind.NEW -> if (isEmpty(contentText, contentWarning)) {
+                ComposeKind.NEW -> if (isEmpty(content, effectiveContentWarning)) {
                     ConfirmationKind.NONE
                 } else {
                     ConfirmationKind.SAVE_OR_DISCARD
                 }
-                ComposeKind.EDIT_DRAFT -> if (isEmpty(contentText, contentWarning)) {
+                ComposeKind.EDIT_DRAFT -> if (isEmpty(content, effectiveContentWarning)) {
                     ConfirmationKind.CONTINUE_EDITING_OR_DISCARD_DRAFT
                 } else {
                     ConfirmationKind.UPDATE_OR_DISCARD
@@ -242,23 +314,30 @@ class ComposeViewModel @Inject constructor(
         }
     }
 
-    private fun didChange(content: String?, contentWarning: String?): Boolean {
+    /**
-        val textChanged = content.orEmpty() != startingText.orEmpty()
+     * @return True if content of this status is "dirty", meaning one or more of the
-        val contentWarningChanged = contentWarning.orEmpty() != startingContentWarning
+     *   following have changed since the compose session started: content,
+     *   content warning and content warning visibility, media, polls, or the
+     *   scheduled time to send.
+     */
+    private fun isDirty(): Boolean {
+        val contentChanged = !content.contentEquals(initialContent)
+
+        val contentWarningChanged = effectiveContentWarning != initialContentWarning
         val mediaChanged = media.value.isNotEmpty()
         val pollChanged = poll.value != null
-        val didScheduledTimeChange = hasScheduledTimeChanged
 
-        return modifiedInitialState || textChanged || contentWarningChanged || mediaChanged || pollChanged || didScheduledTimeChange
+        return modifiedInitialState || contentChanged || contentWarningChanged || mediaChanged || pollChanged || scheduledTimeChanged
     }
 
-    private fun isEmpty(content: String?, contentWarning: String?): Boolean {
+    private fun isEmpty(content: CharSequence, contentWarning: CharSequence): Boolean {
-        return !modifiedInitialState && (content.isNullOrBlank() && contentWarning.isNullOrBlank() && media.value.isEmpty() && poll.value == null)
+        return !modifiedInitialState && (content.isBlank() && contentWarning.isBlank() && media.value.isEmpty() && poll.value == null)
     }
 
-    fun contentWarningChanged(value: Boolean) {
+    fun showContentWarningChanged(value: Boolean) {
-        showContentWarning.value = value
+        _showContentWarning.value = value
         contentWarningStateChanged = true
+        updateStatusLength()
     }
 
     fun deleteDraft() {
@@ -296,7 +375,7 @@ class ComposeViewModel @Inject constructor(
             inReplyToId = inReplyToId,
             content = content,
             contentWarning = contentWarning,
-            sensitive = markMediaAsSensitive.value,
+            sensitive = _markMediaAsSensitive.value,
             visibility = statusVisibility.value,
             mediaUris = mediaUris,
             mediaDescriptions = mediaDescriptions,
@@ -337,7 +416,7 @@ class ComposeViewModel @Inject constructor(
             text = content,
             warningText = spoilerText,
             visibility = statusVisibility.value.serverString(),
-            sensitive = attachedMedia.isNotEmpty() && (markMediaAsSensitive.value || showContentWarning.value),
+            sensitive = attachedMedia.isNotEmpty() && (_markMediaAsSensitive.value || showContentWarning.value),
             media = attachedMedia,
             scheduledAt = scheduledAt.value,
             inReplyToId = inReplyToId,
@@ -356,7 +435,7 @@ class ComposeViewModel @Inject constructor(
     }
 
     private fun updateMediaItem(localId: Int, mutator: (QueuedMedia) -> QueuedMedia) {
-        media.update { mediaList ->
+        _media.update { mediaList ->
             mediaList.map { mediaItem ->
                 if (mediaItem.localId == localId) {
                     mutator(mediaItem)
@@ -438,10 +517,10 @@ class ComposeViewModel @Inject constructor(
 
         val contentWarning = composeOptions?.contentWarning
         if (contentWarning != null) {
-            startingContentWarning = contentWarning
+            initialContentWarning = contentWarning
         }
         if (!contentWarningStateChanged) {
-            showContentWarning.value = !contentWarning.isNullOrBlank()
+            _showContentWarning.value = !contentWarning.isNullOrBlank()
         }
 
         // recreate media list
@@ -468,14 +547,14 @@ class ComposeViewModel @Inject constructor(
         draftId = composeOptions?.draftId ?: 0
         scheduledTootId = composeOptions?.scheduledTootId
         originalStatusId = composeOptions?.statusId
-        startingText = composeOptions?.content
+        initialContent = composeOptions?.content ?: ""
         postLanguage = composeOptions?.language
 
         val tootVisibility = composeOptions?.visibility ?: Status.Visibility.UNKNOWN
         if (tootVisibility != Status.Visibility.UNKNOWN) {
             startingVisibility = tootVisibility
         }
-        statusVisibility.value = startingVisibility
+        _statusVisibility.value = startingVisibility
         val mentionedUsernames = composeOptions?.mentionedUsernames
         if (mentionedUsernames != null) {
             val builder = StringBuilder()
@@ -484,44 +563,101 @@ class ComposeViewModel @Inject constructor(
                 builder.append(name)
                 builder.append(' ')
             }
-            startingText = builder.toString()
+            initialContent = builder.toString()
         }
 
-        scheduledAt.value = composeOptions?.scheduledAt
+        _scheduledAt.value = composeOptions?.scheduledAt
 
-        composeOptions?.sensitive?.let { markMediaAsSensitive.value = it }
+        composeOptions?.sensitive?.let { _markMediaAsSensitive.value = it }
 
         val poll = composeOptions?.poll
         if (poll != null && composeOptions.mediaAttachments.isNullOrEmpty()) {
-            this.poll.value = poll
+            _poll.value = poll
         }
         replyingStatusContent = composeOptions?.replyingStatusContent
         replyingStatusAuthor = composeOptions?.replyingStatusAuthor
 
+        updateCloseConfirmation()
         setupComplete = true
     }
 
-    fun updatePoll(newPoll: NewPoll) {
-        poll.value = newPoll
-    }
-
     fun updateScheduledAt(newScheduledAt: String?) {
         if (newScheduledAt != scheduledAt.value) {
-            hasScheduledTimeChanged = true
+            scheduledTimeChanged = true
         }
 
-        scheduledAt.value = newScheduledAt
+        _scheduledAt.value = newScheduledAt
+        updateCloseConfirmation()
     }
 
     val editing: Boolean
         get() = !originalStatusId.isNullOrEmpty()
 
     enum class ConfirmationKind {
-        NONE, // just close
+        /** No confirmation, finish */
+        NONE,
+
+        /** Content has changed and it's an un-posted status, show "save or discard" */
         SAVE_OR_DISCARD,
+
+        /** Content has changed when editing a draft, show "update draft or discard changes" */
         UPDATE_OR_DISCARD,
-        CONTINUE_EDITING_OR_DISCARD_CHANGES, // editing post
+
-        CONTINUE_EDITING_OR_DISCARD_DRAFT, // edit draft
+        /** Content has changed when editing a posted status or scheduled status */
+        CONTINUE_EDITING_OR_DISCARD_CHANGES,
+
+        /** Content has been cleared when editing a draft */
+        CONTINUE_EDITING_OR_DISCARD_DRAFT,
+    }
+
+    companion object {
+        /**
+         * Calculate the effective status length.
+         *
+         * Some text is counted differently:
+         *
+         * In the status body:
+         *
+         * - URLs always count for [urlLength] characters irrespective of their actual length
+         *   (https://docs.joinmastodon.org/user/posting/#links)
+         * - Mentions ("@user@some.instance") only count the "@user" part
+         *   (https://docs.joinmastodon.org/user/posting/#mentions)
+         * - Hashtags are always treated as their actual length, including the "#"
+         *   (https://docs.joinmastodon.org/user/posting/#hashtags)
+         * - Emojis are treated as a single character
+         *
+         * Content warning text is always treated as its full length, URLs and other entities
+         * are not treated differently.
+         *
+         * @param body status body text
+         * @param contentWarning optional content warning text
+         * @param urlLength the number of characters attributed to URLs
+         * @return the effective status length
+         */
+        fun statusLength(body: Spanned, contentWarning: String, urlLength: Int): Int {
+            var length = body.toString().mastodonLength() - body.getSpans(0, body.length, URLSpan::class.java)
+                .fold(0) { acc, span ->
+                    // Accumulate a count of characters to be *ignored* in the final length
+                    acc + when (span) {
+                        is MentionSpan -> {
+                            // Ignore everything from the second "@" (if present)
+                            span.url.length - (
+                                span.url.indexOf("@", 1).takeIf { it >= 0 }
+                                    ?: span.url.length
+                                )
+                        }
+                        else -> {
+                            // Expected to be negative if the URL length < maxUrlLength
+                            span.url.mastodonLength() - urlLength
+                        }
+                    }
+                }
+
+            // Content warning text is treated as is, URLs or mentions there are not special
+            length += contentWarning.mastodonLength()
+
+            return length
+        }
     }
 }
 

app/src/main/java/app/pachli/components/filters/EditFilterActivity.kt

@@ -1,13 +1,15 @@
 package app.pachli.components.filters
 
-import android.content.Context
+import android.content.DialogInterface.BUTTON_NEGATIVE
 import android.content.DialogInterface.BUTTON_POSITIVE
 import android.os.Bundle
 import android.view.View
 import android.widget.AdapterView
 import android.widget.ArrayAdapter
+import androidx.activity.OnBackPressedCallback
 import androidx.activity.viewModels
 import androidx.appcompat.app.AlertDialog
+import androidx.core.view.isVisible
 import androidx.core.view.size
 import androidx.core.widget.doAfterTextChanged
 import androidx.lifecycle.lifecycleScope
@@ -21,6 +23,7 @@ import app.pachli.core.network.model.Filter
 import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.FilterKeyword
 import app.pachli.core.network.retrofit.MastodonApi
+import app.pachli.core.ui.extensions.await
 import app.pachli.databinding.ActivityEditFilterBinding
 import app.pachli.databinding.DialogFilterBinding
 import at.connyduck.calladapter.networkresult.fold
@@ -28,8 +31,8 @@ import com.google.android.material.chip.Chip
 import com.google.android.material.snackbar.Snackbar
 import com.google.android.material.switchmaterial.SwitchMaterial
 import dagger.hilt.android.AndroidEntryPoint
-import java.util.Date
 import javax.inject.Inject
+import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.launch
 import retrofit2.HttpException
 
@@ -51,11 +54,20 @@ class EditFilterActivity : BaseActivity() {
     private var originalFilter: Filter? = null
     private lateinit var filterContextSwitches: Map<SwitchMaterial, FilterContext>
 
+    private val onBackPressedCallback = object : OnBackPressedCallback(true) {
+        override fun handleOnBackPressed() {
+            lifecycleScope.launch {
+                if (showUnsavedChangesFilterDialog() == BUTTON_NEGATIVE) finish()
+            }
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
+        onBackPressedDispatcher.addCallback(onBackPressedCallback)
 
         originalFilter = EditFilterActivityIntent.getFilter(intent)
-        filter = originalFilter ?: Filter("", "", listOf(), null, Filter.Action.WARN, listOf())
+        filter = originalFilter ?: Filter()
         binding.apply {
             filterContextSwitches = mapOf(
                 filterContextHome to FilterContext.HOME,
@@ -69,7 +81,6 @@ class EditFilterActivity : BaseActivity() {
         setContentView(binding.root)
         setSupportActionBar(binding.includedToolbar.toolbar)
         supportActionBar?.run {
-            // Back button
             setDisplayHomeAsUpEnabled(true)
             setDisplayShowHomeEnabled(true)
         }
@@ -99,12 +110,10 @@ class EditFilterActivity : BaseActivity() {
                 } else {
                     viewModel.removeContext(context)
                 }
-                validateSaveButton()
             }
         }
         binding.filterTitle.doAfterTextChanged { editable ->
             viewModel.setTitle(editable.toString())
-            validateSaveButton()
         }
         binding.filterActionWarn.setOnCheckedChangeListener { _, checked ->
             viewModel.setAction(
@@ -130,13 +139,8 @@ class EditFilterActivity : BaseActivity() {
                 viewModel.setDuration(0)
             }
         }
-        validateSaveButton()
 
-        if (originalFilter == null) {
+        loadFilter()
-            binding.filterActionWarn.isChecked = true
-        } else {
-            loadFilter()
-        }
         observeModel()
     }
 
@@ -170,6 +174,25 @@ class EditFilterActivity : BaseActivity() {
                 }
             }
         }
+
+        lifecycleScope.launch {
+            viewModel.isDirty.collectLatest { onBackPressedCallback.isEnabled = it }
+        }
+
+        lifecycleScope.launch {
+            viewModel.validationErrors.collectLatest { errors ->
+                binding.filterSaveButton.isEnabled = errors.isEmpty()
+
+                binding.filterTitleWrapper.error = if (errors.contains(FilterValidationError.NO_TITLE)) {
+                    getString(R.string.error_filter_missing_title)
+                } else {
+                    null
+                }
+
+                binding.keywordChipsError.isVisible = errors.contains(FilterValidationError.NO_KEYWORDS)
+                binding.filterContextError.isVisible = errors.contains(FilterValidationError.NO_CONTEXT)
+            }
+        }
     }
 
     // Populate the UI from the filter's members
@@ -213,7 +236,6 @@ class EditFilterActivity : BaseActivity() {
         }
 
         filter = filter.copy(keywords = newKeywords)
-        validateSaveButton()
     }
 
     private fun showAddKeywordDialog() {
@@ -256,9 +278,18 @@ class EditFilterActivity : BaseActivity() {
             .show()
     }
 
-    private fun validateSaveButton() {
+    /**
-        binding.filterSaveButton.isEnabled = viewModel.validate()
+     * Dialog that warns the user they have unsaved changes, and prompts
-    }
+     * to continue editing or discard the changes.
+     *
+     * @return [BUTTON_NEGATIVE] if the user chose to discard the changes,
+     *   [BUTTON_POSITIVE] if the user chose to continue editing.
+     */
+    suspend fun showUnsavedChangesFilterDialog() = AlertDialog.Builder(this)
+        .setMessage(R.string.unsaved_changes)
+        .setCancelable(true)
+        .create()
+        .await(R.string.action_continue_edit, R.string.action_discard)
 
     private fun saveChanges() {
         // TODO use a progress bar here (see EditProfileActivity/activity_edit_profile.xml for example)?
@@ -297,16 +328,4 @@ class EditFilterActivity : BaseActivity() {
             }
         }
     }
-
-    companion object {
-        // Mastodon *stores* the absolute date in the filter,
-        // but create/edit take a number of seconds (relative to the time the operation is posted)
-        fun getSecondsForDurationIndex(index: Int, context: Context?, default: Date? = null): String? {
-            return when (index) {
-                -1 -> default?.let { ((default.time - System.currentTimeMillis()) / 1000).toString() }
-                0 -> ""
-                else -> context?.resources?.getStringArray(R.array.filter_duration_values)?.get(index)
-            }
-        }
-    }
 }

app/src/main/java/app/pachli/components/filters/EditFilterViewModel.kt

@@ -3,6 +3,7 @@ package app.pachli.components.filters
 import android.content.Context
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import app.pachli.R
 import app.pachli.appstore.EventHub
 import app.pachli.appstore.FilterChangedEvent
 import app.pachli.core.network.model.Filter
@@ -11,20 +12,38 @@ import app.pachli.core.network.model.FilterKeyword
 import app.pachli.core.network.retrofit.MastodonApi
 import at.connyduck.calladapter.networkresult.fold
 import dagger.hilt.android.lifecycle.HiltViewModel
+import java.util.Date
 import javax.inject.Inject
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.withContext
 import retrofit2.HttpException
 
 @HiltViewModel
 class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub: EventHub) : ViewModel() {
-    private var originalFilter: Filter? = null
+    private lateinit var originalFilter: Filter
     val title = MutableStateFlow("")
     val keywords = MutableStateFlow(listOf<FilterKeyword>())
     val action = MutableStateFlow(Filter.Action.WARN)
     val duration = MutableStateFlow(0)
     val contexts = MutableStateFlow(listOf<FilterContext>())
 
+    /** Track whether the duration has been modified, for use in [onChange] */
+    // TODO: Rethink how duration is shown in the UI.
+    // Could show the actual end time with the date/time widget to set the duration,
+    // along with dropdown for quick settings (1h, etc).
+    private var durationIsDirty = false
+
+    private val _isDirty = MutableStateFlow(false)
+
+    /** True if the user has made unsaved changes to the filter */
+    val isDirty = _isDirty.asStateFlow()
+
+    private val _validationErrors = MutableStateFlow(emptySet<FilterValidationError>())
+
+    /** True if the filter is valid and can be saved */
+    val validationErrors = _validationErrors.asStateFlow()
+
     fun load(filter: Filter) {
         originalFilter = filter
         title.value = filter.title
@@ -40,10 +59,12 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
 
     fun addKeyword(keyword: FilterKeyword) {
         keywords.value += keyword
+        onChange()
     }
 
     fun deleteKeyword(keyword: FilterKeyword) {
         keywords.value = keywords.value.filterNot { it == keyword }
+        onChange()
     }
 
     fun modifyKeyword(original: FilterKeyword, updated: FilterKeyword) {
@@ -52,35 +73,66 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
             keywords.value = keywords.value.toMutableList().apply {
                 set(index, updated)
             }
+            onChange()
         }
     }
 
     fun setTitle(title: String) {
         this.title.value = title
+        onChange()
     }
 
     fun setDuration(index: Int) {
+        if (!durationIsDirty && duration.value != index) durationIsDirty = true
+
         duration.value = index
+        onChange()
     }
 
     fun setAction(action: Filter.Action) {
         this.action.value = action
+        onChange()
     }
 
     fun addContext(filterContext: FilterContext) {
         if (!contexts.value.contains(filterContext)) {
             contexts.value += filterContext
+            onChange()
         }
     }
 
     fun removeContext(filterContext: FilterContext) {
         contexts.value = contexts.value.filter { it != filterContext }
+        onChange()
     }
 
-    fun validate(): Boolean {
+    private fun validate() {
-        return title.value.isNotBlank() &&
+        _validationErrors.value = buildSet {
-            keywords.value.isNotEmpty() &&
+            if (title.value.isBlank()) add(FilterValidationError.NO_TITLE)
-            contexts.value.isNotEmpty()
+            if (keywords.value.isEmpty()) add(FilterValidationError.NO_KEYWORDS)
+            if (contexts.value.isEmpty()) add(FilterValidationError.NO_CONTEXT)
+        }
+    }
+
+    /**
+     * Call when the contents of the filter change; recalculates validity
+     * and dirty state.
+     */
+    private fun onChange() {
+        validate()
+
+        if (durationIsDirty) {
+            _isDirty.value = true
+            return
+        }
+
+        _isDirty.value = when {
+            originalFilter.title != title.value -> true
+            originalFilter.contexts != contexts.value -> true
+            originalFilter.action != action.value -> true
+            originalFilter.keywords.toSet() != keywords.value.toSet() -> true
+            else -> false
+        }
     }
 
     suspend fun saveChanges(context: Context): Boolean {
@@ -90,15 +142,17 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
         val action = action.value
 
         return withContext(viewModelScope.coroutineContext) {
-            val success = originalFilter?.let { filter ->
+            val success = if (originalFilter.id == "") {
-                updateFilter(filter, title, contexts, action, durationIndex, context)
+                createFilter(title, contexts, action, durationIndex, context)
-            } ?: createFilter(title, contexts, action, durationIndex, context)
+            } else {
+                updateFilter(originalFilter, title, contexts, action, durationIndex, context)
+            }
 
             // Send FilterChangedEvent for old and new contexts, to ensure that
             // e.g., removing a filter from "home" still notifies anything showing
             // the home timeline, so the timeline can be refreshed.
             if (success) {
-                val originalContexts = originalFilter?.contexts ?: emptyList()
+                val originalContexts = originalFilter.contexts
                 val newFilterContexts = contexts
                 (originalContexts + newFilterContexts).distinct().forEach {
                     eventHub.dispatch(FilterChangedEvent(it))
@@ -109,7 +163,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
     }
 
     private suspend fun createFilter(title: String, contexts: List<FilterContext>, action: Filter.Action, durationIndex: Int, context: Context): Boolean {
-        val expiresInSeconds = EditFilterActivity.getSecondsForDurationIndex(durationIndex, context)
+        val expiresInSeconds = getSecondsForDurationIndex(durationIndex, context)
         api.createFilter(
             title = title,
             context = contexts,
@@ -133,7 +187,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
     }
 
     private suspend fun updateFilter(originalFilter: Filter, title: String, contexts: List<FilterContext>, action: Filter.Action, durationIndex: Int, context: Context): Boolean {
-        val expiresInSeconds = EditFilterActivity.getSecondsForDurationIndex(durationIndex, context)
+        val expiresInSeconds = getSecondsForDurationIndex(durationIndex, context)
         api.updateFilter(
             id = originalFilter.id,
             title = title,
@@ -176,7 +230,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
 
     private suspend fun updateFilterV1(contexts: List<FilterContext>, expiresInSeconds: String?): Boolean {
         val results = keywords.value.map { keyword ->
-            if (originalFilter == null) {
+            if (originalFilter.id == "") {
                 api.createFilterV1(
                     phrase = keyword.keyword,
                     context = contexts,
@@ -186,7 +240,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
                 )
             } else {
                 api.updateFilterV1(
-                    id = originalFilter!!.id,
+                    id = originalFilter.id,
                     phrase = keyword.keyword,
                     context = contexts,
                     irreversible = false,
@@ -199,4 +253,18 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
 
         return results.none { it.isFailure }
     }
+
+    companion object {
+        /**
+         * Mastodon *stores* the absolute date in the filter,
+         * but create/edit take a number of seconds (relative to the time the operation is posted)
+         */
+        fun getSecondsForDurationIndex(index: Int, context: Context?, default: Date? = null): String? {
+            return when (index) {
+                -1 -> default?.let { ((default.time - System.currentTimeMillis()) / 1000).toString() }
+                0 -> ""
+                else -> context?.resources?.getStringArray(R.array.filter_duration_values)?.get(index)
+            }
+        }
+    }
 }

app/src/main/java/app/pachli/components/filters/FilterExtensions.kt

@@ -18,8 +18,10 @@
 package app.pachli.components.filters
 
 import android.app.Activity
+import androidx.annotation.StringRes
 import androidx.appcompat.app.AlertDialog
 import app.pachli.R
+import app.pachli.core.network.model.Filter
 import app.pachli.core.ui.extensions.await
 
 internal suspend fun Activity.showDeleteFilterDialog(filterTitle: String) = AlertDialog.Builder(this)
@@ -27,3 +29,36 @@ internal suspend fun Activity.showDeleteFilterDialog(filterTitle: String) = Aler
     .setCancelable(true)
     .create()
     .await(R.string.dialog_delete_filter_positive_action, android.R.string.cancel)
+
+/** Reasons why a filter might be invalid */
+enum class FilterValidationError {
+    /** Filter title is empty or blank */
+    NO_TITLE,
+
+    /** Filter has no keywords */
+    NO_KEYWORDS,
+
+    /** Filter has no contexts */
+    NO_CONTEXT,
+}
+
+/**
+ * @return Set of validation errors for this filter, empty set if there
+ *   are no errors.
+ */
+fun Filter.validate() = buildSet {
+    if (title.isBlank()) add(FilterValidationError.NO_TITLE)
+    if (keywords.isEmpty()) add(FilterValidationError.NO_KEYWORDS)
+    if (contexts.isEmpty()) add(FilterValidationError.NO_CONTEXT)
+}
+
+/**
+ * @return String resource containing an error message for this
+ *   validation error.
+ */
+@StringRes
+fun FilterValidationError.stringResource() = when (this) {
+    FilterValidationError.NO_TITLE -> R.string.error_filter_missing_title
+    FilterValidationError.NO_KEYWORDS -> R.string.error_filter_missing_keyword
+    FilterValidationError.NO_CONTEXT -> R.string.error_filter_missing_context
+}

app/src/main/java/app/pachli/components/filters/FiltersActivity.kt

@@ -6,11 +6,12 @@ import androidx.activity.viewModels
 import androidx.lifecycle.lifecycleScope
 import app.pachli.R
 import app.pachli.core.activity.BaseActivity
+import app.pachli.core.activity.extensions.TransitionKind
+import app.pachli.core.activity.extensions.startActivityWithTransition
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.common.extensions.visible
-import app.pachli.core.designsystem.R as DR
 import app.pachli.core.navigation.EditFilterActivityIntent
 import app.pachli.core.network.model.Filter
 import app.pachli.core.ui.BackgroundMessage
@@ -94,8 +95,7 @@ class FiltersActivity : BaseActivity(), FiltersListener {
 
     private fun launchEditFilterActivity(filter: Filter? = null) {
         val intent = EditFilterActivityIntent(this, filter)
-        startActivity(intent)
+        startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
-        overridePendingTransition(DR.anim.slide_from_right, DR.anim.slide_to_left)
     }
 
     override fun deleteFilter(filter: Filter) {

app/src/main/java/app/pachli/components/filters/FiltersAdapter.kt

@@ -8,6 +8,7 @@ import app.pachli.core.network.model.Filter
 import app.pachli.core.ui.BindingHolder
 import app.pachli.databinding.ItemRemovableBinding
 import app.pachli.util.getRelativeTimeSpanString
+import com.google.android.material.color.MaterialColors
 
 class FiltersAdapter(val listener: FiltersListener, val filters: List<Filter>) :
     RecyclerView.Adapter<BindingHolder<ItemRemovableBinding>>() {
@@ -34,11 +35,25 @@ class FiltersAdapter(val listener: FiltersListener, val filters: List<Filter>) :
             )
         } ?: filter.title
 
-        binding.textSecondary.text = context.getString(
+        // Secondary row shows filter actions and contexts, or errors if the filter is invalid
-            R.string.filter_description_format,
+        val errors = filter.validate()
-            actions.getOrNull(filter.action.ordinal - 1),
+        val secondaryText: String
-            filter.contexts.map { filterContextNames.getOrNull(it.ordinal) }.joinToString("/"),
+        val secondaryTextColor: Int
-        )
+
+        if (errors.isEmpty()) {
+            secondaryText = context.getString(
+                R.string.filter_description_format,
+                actions.getOrNull(filter.action.ordinal - 1),
+                filter.contexts.map { filterContextNames.getOrNull(it.ordinal) }.joinToString("/"),
+            )
+            secondaryTextColor = android.R.attr.textColorTertiary
+        } else {
+            secondaryText = context.getString(errors.first().stringResource())
+            secondaryTextColor = androidx.appcompat.R.attr.colorError
+        }
+
+        binding.textSecondary.text = secondaryText
+        binding.textSecondary.setTextColor(MaterialColors.getColor(binding.textSecondary, secondaryTextColor))
 
         binding.delete.setOnClickListener {
             listener.deleteFilter(filter)

app/src/main/java/app/pachli/components/followedtags/FollowedTagsActivity.kt

@@ -16,6 +16,7 @@ import androidx.recyclerview.widget.SimpleItemAnimator
 import app.pachli.R
 import app.pachli.components.compose.ComposeAutoCompleteAdapter
 import app.pachli.core.activity.BaseActivity
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
@@ -172,7 +173,7 @@ class FollowedTagsActivity :
     }
 
     override fun onViewTag(tag: String) {
-        startActivityWithSlideInAnimation(TimelineActivityIntent.hashtag(this, tag))
+        startActivityWithDefaultTransition(TimelineActivityIntent.hashtag(this, tag))
     }
 
     override suspend fun search(token: String): List<ComposeAutoCompleteAdapter.AutocompleteResult> {

app/src/main/java/app/pachli/components/preference/AccountPreferencesFragment.kt

@@ -26,7 +26,8 @@ import app.pachli.R
 import app.pachli.appstore.EventHub
 import app.pachli.components.notifications.currentAccountNeedsMigration
 import app.pachli.core.accounts.AccountManager
-import app.pachli.core.activity.BaseActivity
+import app.pachli.core.activity.extensions.TransitionKind
+import app.pachli.core.activity.extensions.startActivityWithTransition
 import app.pachli.core.common.util.unsafeLazy
 import app.pachli.core.designsystem.R as DR
 import app.pachli.core.navigation.AccountListActivityIntent
@@ -104,11 +105,7 @@ class AccountPreferencesFragment : PreferenceFragmentCompat() {
                 setIcon(R.drawable.ic_add_to_tab_24)
                 setOnPreferenceClickListener {
                     val intent = TabPreferenceActivityIntent(context)
-                    activity?.startActivity(intent)
+                    activity?.startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
-                    activity?.overridePendingTransition(
-                        DR.anim.slide_from_right,
-                        DR.anim.slide_to_left,
-                    )
                     true
                 }
             }
@@ -118,11 +115,7 @@ class AccountPreferencesFragment : PreferenceFragmentCompat() {
                 setIcon(R.drawable.ic_hashtag)
                 setOnPreferenceClickListener {
                     val intent = FollowedTagsActivityIntent(context)
-                    activity?.startActivity(intent)
+                    activity?.startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
-                    activity?.overridePendingTransition(
-                        DR.anim.slide_from_right,
-                        DR.anim.slide_to_left,
-                    )
                     true
                 }
             }
@@ -132,11 +125,7 @@ class AccountPreferencesFragment : PreferenceFragmentCompat() {
                 setIcon(R.drawable.ic_mute_24dp)
                 setOnPreferenceClickListener {
                     val intent = AccountListActivityIntent(context, AccountListActivityIntent.Kind.MUTES)
-                    activity?.startActivity(intent)
+                    activity?.startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
-                    activity?.overridePendingTransition(
-                        DR.anim.slide_from_right,
-                        DR.anim.slide_to_left,
-                    )
                     true
                 }
             }
@@ -146,11 +135,7 @@ class AccountPreferencesFragment : PreferenceFragmentCompat() {
                 icon = makeIcon(GoogleMaterial.Icon.gmd_block)
                 setOnPreferenceClickListener {
                     val intent = AccountListActivityIntent(context, AccountListActivityIntent.Kind.BLOCKS)
-                    activity?.startActivity(intent)
+                    activity?.startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
-                    activity?.overridePendingTransition(
-                        DR.anim.slide_from_right,
-                        DR.anim.slide_to_left,
-                    )
                     true
                 }
             }
@@ -160,11 +145,7 @@ class AccountPreferencesFragment : PreferenceFragmentCompat() {
                 setIcon(R.drawable.ic_mute_24dp)
                 setOnPreferenceClickListener {
                     val intent = InstanceListActivityIntent(context)
-                    activity?.startActivity(intent)
+                    activity?.startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
-                    activity?.overridePendingTransition(
-                        DR.anim.slide_from_right,
-                        DR.anim.slide_to_left,
-                    )
                     true
                 }
             }
@@ -175,7 +156,7 @@ class AccountPreferencesFragment : PreferenceFragmentCompat() {
                     setIcon(R.drawable.ic_logout)
                     setOnPreferenceClickListener {
                         val intent = LoginActivityIntent(context, LoginMode.MIGRATION)
-                        (activity as BaseActivity).startActivityWithSlideInAnimation(intent)
+                        activity?.startActivityWithTransition(intent, TransitionKind.EXPLODE)
                         true
                     }
                 }
@@ -185,7 +166,8 @@ class AccountPreferencesFragment : PreferenceFragmentCompat() {
                 setTitle(R.string.pref_title_timeline_filters)
                 setIcon(R.drawable.ic_filter_24dp)
                 setOnPreferenceClickListener {
-                    launchFilterActivity()
+                    val intent = FiltersActivityIntent(requireContext())
+                    activity?.startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
                     true
                 }
                 val server = serverRepository.flow.value.getOrElse { null }
@@ -298,14 +280,10 @@ class AccountPreferencesFragment : PreferenceFragmentCompat() {
             val intent = Intent()
             intent.action = "android.settings.APP_NOTIFICATION_SETTINGS"
             intent.putExtra("android.provider.extra.APP_PACKAGE", BuildConfig.APPLICATION_ID)
-            startActivity(intent)
+            requireActivity().startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
         } else {
-            activity?.let {
+            val intent = PreferencesActivityIntent(requireContext(), PreferenceScreen.NOTIFICATION)
-                val intent =
+            requireActivity().startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
-                    PreferencesActivityIntent(it, PreferenceScreen.NOTIFICATION)
-                it.startActivity(intent)
-                it.overridePendingTransition(DR.anim.slide_from_right, DR.anim.slide_to_left)
-            }
         }
     }
 
@@ -356,12 +334,6 @@ class AccountPreferencesFragment : PreferenceFragmentCompat() {
         }
     }
 
-    private fun launchFilterActivity() {
-        val intent = FiltersActivityIntent(requireContext())
-        activity?.startActivity(intent)
-        activity?.overridePendingTransition(DR.anim.slide_from_right, DR.anim.slide_to_left)
-    }
-
     companion object {
         fun newInstance() = AccountPreferencesFragment()
     }

app/src/main/java/app/pachli/components/preference/PreferencesActivity.kt

@@ -27,7 +27,8 @@ import androidx.preference.PreferenceFragmentCompat
 import app.pachli.R
 import app.pachli.appstore.EventHub
 import app.pachli.core.activity.BaseActivity
-import app.pachli.core.designsystem.R as DR
+import app.pachli.core.activity.extensions.TransitionKind
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.navigation.MainActivityIntent
 import app.pachli.core.navigation.PreferencesActivityIntent
 import app.pachli.core.navigation.PreferencesActivityIntent.PreferenceScreen
@@ -61,7 +62,7 @@ class PreferencesActivity :
              * back stack. */
             val intent = MainActivityIntent(this@PreferencesActivity)
             intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
-            startActivityWithSlideInAnimation(intent)
+            startActivityWithDefaultTransition(intent)
         }
     }
 
@@ -107,11 +108,11 @@ class PreferencesActivity :
                         setAppNightMode(theme)
 
                         restartActivitiesOnBackPressedCallback.isEnabled = true
-                        this@PreferencesActivity.restartCurrentActivity()
+                        this@PreferencesActivity.recreate()
                     }
                     PrefKeys.FONT_FAMILY, PrefKeys.UI_TEXT_SCALE_RATIO -> {
                         restartActivitiesOnBackPressedCallback.isEnabled = true
-                        this@PreferencesActivity.restartCurrentActivity()
+                        this@PreferencesActivity.recreate()
                     }
                     PrefKeys.STATUS_TEXT_SIZE, PrefKeys.ABSOLUTE_TIME_VIEW, PrefKeys.SHOW_BOT_OVERLAY, PrefKeys.ANIMATE_GIF_AVATARS, PrefKeys.USE_BLURHASH,
                     PrefKeys.SHOW_SELF_USERNAME, PrefKeys.SHOW_CARDS_IN_TIMELINES, PrefKeys.CONFIRM_REBLOGS, PrefKeys.CONFIRM_FAVOURITES,
@@ -136,11 +137,13 @@ class PreferencesActivity :
         fragment.arguments = args
         fragment.setTargetFragment(caller, 0)
         supportFragmentManager.commit {
+            // Slide transition, as sub preference screens are "attached" to the
+            // parent screen.
             setCustomAnimations(
-                DR.anim.slide_from_right,
+                TransitionKind.SLIDE_FROM_END.openEnter,
-                DR.anim.slide_to_left,
+                TransitionKind.SLIDE_FROM_END.openExit,
-                DR.anim.slide_from_left,
+                TransitionKind.SLIDE_FROM_END.closeEnter,
-                DR.anim.slide_to_right,
+                TransitionKind.SLIDE_FROM_END.closeExit,
             )
             replace(R.id.fragment_container, fragment)
             addToBackStack(null)
@@ -148,25 +151,11 @@ class PreferencesActivity :
         return true
     }
 
-    private fun saveInstanceState(outState: Bundle) {
-        outState.putBoolean(EXTRA_RESTART_ON_BACK, restartActivitiesOnBackPressedCallback.isEnabled)
-    }
-
     override fun onSaveInstanceState(outState: Bundle) {
         outState.putBoolean(EXTRA_RESTART_ON_BACK, restartActivitiesOnBackPressedCallback.isEnabled)
         super.onSaveInstanceState(outState)
     }
 
-    private fun restartCurrentActivity() {
-        intent.flags = Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_NEW_TASK
-        val savedInstanceState = Bundle()
-        saveInstanceState(savedInstanceState)
-        intent.putExtras(savedInstanceState)
-        startActivityWithSlideInAnimation(intent)
-        finish()
-        overridePendingTransition(DR.anim.fade_in, DR.anim.fade_out)
-    }
-
     companion object {
         private const val EXTRA_RESTART_ON_BACK = "restart"
     }

app/src/main/java/app/pachli/components/search/SearchActivity.kt

@@ -88,10 +88,6 @@ class SearchActivity : BottomSheetActivity(), MenuProvider, SearchView.OnQueryTe
         return false
     }
 
-    override fun finish() {
-        super.finishWithoutSlideOutAnimation()
-    }
-
     private fun getPageTitle(position: Int): CharSequence {
         return when (position) {
             0 -> getString(R.string.title_posts)

app/src/main/java/app/pachli/components/search/fragments/SearchFragment.kt

@@ -19,6 +19,7 @@ import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
 import app.pachli.R
 import app.pachli.components.search.SearchViewModel
 import app.pachli.core.activity.BottomSheetActivity
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.common.extensions.visible
 import app.pachli.core.navigation.AccountActivityIntent
@@ -140,11 +141,11 @@ abstract class SearchFragment<T : Any> :
     }
 
     override fun onViewAccount(id: String) {
-        bottomSheetActivity?.startActivityWithSlideInAnimation(AccountActivityIntent(requireContext(), id))
+        bottomSheetActivity?.startActivityWithDefaultTransition(AccountActivityIntent(requireContext(), id))
     }
 
     override fun onViewTag(tag: String) {
-        bottomSheetActivity?.startActivityWithSlideInAnimation(TimelineActivityIntent.hashtag(requireContext(), tag))
+        bottomSheetActivity?.startActivityWithDefaultTransition(TimelineActivityIntent.hashtag(requireContext(), tag))
     }
 
     override fun onViewUrl(url: String) {

app/src/main/java/app/pachli/components/search/fragments/SearchStatusesFragment.kt

@@ -40,6 +40,7 @@ import app.pachli.R
 import app.pachli.components.search.adapter.SearchStatusesAdapter
 import app.pachli.core.activity.AccountSelectionListener
 import app.pachli.core.activity.BaseActivity
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.activity.openLink
 import app.pachli.core.database.model.AccountEntity
 import app.pachli.core.navigation.AttachmentViewData
@@ -187,7 +188,7 @@ class SearchStatusesFragment : SearchFragment<StatusViewData>(), StatusActionLis
                 kind = ComposeOptions.ComposeKind.NEW,
             ),
         )
-        bottomSheetActivity?.startActivityWithSlideInAnimation(intent)
+        bottomSheetActivity?.startActivityWithDefaultTransition(intent)
     }
 
     private fun more(statusViewData: StatusViewData, view: View) {

app/src/main/java/app/pachli/components/timeline/TimelineFragment.kt

@@ -49,8 +49,8 @@ import app.pachli.components.timeline.viewmodel.StatusAction
 import app.pachli.components.timeline.viewmodel.StatusActionSuccess
 import app.pachli.components.timeline.viewmodel.TimelineViewModel
 import app.pachli.components.timeline.viewmodel.UiSuccess
-import app.pachli.core.activity.BaseActivity
 import app.pachli.core.activity.RefreshableFragment
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
@@ -637,12 +637,12 @@ class TimelineFragment :
 
     override fun onShowReblogs(statusId: String) {
         val intent = AccountListActivityIntent(requireContext(), AccountListActivityIntent.Kind.REBLOGGED, statusId)
-        (activity as BaseActivity).startActivityWithSlideInAnimation(intent)
+        activity?.startActivityWithDefaultTransition(intent)
     }
 
     override fun onShowFavs(statusId: String) {
         val intent = AccountListActivityIntent(requireContext(), AccountListActivityIntent.Kind.FAVOURITED, statusId)
-        (activity as BaseActivity).startActivityWithSlideInAnimation(intent)
+        activity?.startActivityWithDefaultTransition(intent)
     }
 
     override fun onContentCollapsedChange(viewData: StatusViewData, isCollapsed: Boolean) {

app/src/main/java/app/pachli/components/trending/TrendingActivity.kt

@@ -35,8 +35,11 @@ import app.pachli.core.model.Timeline
 import app.pachli.core.ui.extensions.reduceSwipeSensitivity
 import app.pachli.databinding.ActivityTrendingBinding
 import app.pachli.interfaces.AppBarLayoutHost
+import app.pachli.interfaces.ReselectableFragment
 import app.pachli.pager.MainPagerAdapter
 import com.google.android.material.appbar.AppBarLayout
+import com.google.android.material.tabs.TabLayout
+import com.google.android.material.tabs.TabLayout.OnTabSelectedListener
 import com.google.android.material.tabs.TabLayoutMediator
 import dagger.hilt.android.AndroidEntryPoint
 import javax.inject.Inject
@@ -55,6 +58,12 @@ class TrendingActivity : BottomSheetActivity(), AppBarLayoutHost, MenuProvider {
 
     private lateinit var adapter: MainPagerAdapter
 
+    private val onBackPressedCallback = object : OnBackPressedCallback(false) {
+        override fun handleOnBackPressed() {
+            binding.pager.currentItem = 0
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(binding.root)
@@ -90,14 +99,19 @@ class TrendingActivity : BottomSheetActivity(), AppBarLayoutHost, MenuProvider {
             }
         }.attach()
 
-        onBackPressedDispatcher.addCallback(
+        binding.tabLayout.addOnTabSelectedListener(object : OnTabSelectedListener {
-            this,
+            override fun onTabSelected(tab: TabLayout.Tab) {
-            object : OnBackPressedCallback(true) {
+                onBackPressedCallback.isEnabled = tab.position > 0
-                override fun handleOnBackPressed() {
+            }
-                    if (binding.pager.currentItem != 0) binding.pager.currentItem = 0 else finish()
+
-                }
+            override fun onTabUnselected(tab: TabLayout.Tab) {}
-            },
+
-        )
+            override fun onTabReselected(tab: TabLayout.Tab) {
+                (adapter.getFragment(tab.position) as? ReselectableFragment)?.onReselect()
+            }
+        })
+
+        onBackPressedDispatcher.addCallback(this, onBackPressedCallback)
     }
 
     override fun onCreateMenu(menu: Menu, menuInflater: MenuInflater) {

app/src/main/java/app/pachli/components/trending/TrendingTagsFragment.kt

@@ -37,8 +37,8 @@ import androidx.recyclerview.widget.SimpleItemAnimator
 import androidx.swiperefreshlayout.widget.SwipeRefreshLayout.OnRefreshListener
 import app.pachli.R
 import app.pachli.components.trending.viewmodel.TrendingTagsViewModel
-import app.pachli.core.activity.BaseActivity
 import app.pachli.core.activity.RefreshableFragment
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
@@ -173,7 +173,7 @@ class TrendingTagsFragment :
     }
 
     fun onViewTag(tag: String) {
-        (requireActivity() as BaseActivity).startActivityWithSlideInAnimation(
+        activity?.startActivityWithDefaultTransition(
             TimelineActivityIntent.hashtag(
                 requireContext(),
                 tag,

app/src/main/java/app/pachli/components/viewthread/ViewThreadFragment.kt

@@ -33,7 +33,7 @@ import androidx.recyclerview.widget.SimpleItemAnimator
 import androidx.swiperefreshlayout.widget.SwipeRefreshLayout.OnRefreshListener
 import app.pachli.R
 import app.pachli.components.viewthread.edits.ViewEditsFragment
-import app.pachli.core.activity.BaseActivity
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.activity.openLink
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
@@ -337,12 +337,12 @@ class ViewThreadFragment :
 
     override fun onShowReblogs(statusId: String) {
         val intent = AccountListActivityIntent(requireContext(), AccountListActivityIntent.Kind.REBLOGGED, statusId)
-        (requireActivity() as BaseActivity).startActivityWithSlideInAnimation(intent)
+        activity?.startActivityWithDefaultTransition(intent)
     }
 
     override fun onShowFavs(statusId: String) {
         val intent = AccountListActivityIntent(requireContext(), AccountListActivityIntent.Kind.FAVOURITED, statusId)
-        (requireActivity() as BaseActivity).startActivityWithSlideInAnimation(intent)
+        activity?.startActivityWithDefaultTransition(intent)
     }
 
     override fun onContentCollapsedChange(viewData: StatusViewData, isCollapsed: Boolean) {
@@ -374,7 +374,12 @@ class ViewThreadFragment :
         val viewEditsFragment = ViewEditsFragment.newInstance(statusId)
 
         parentFragmentManager.commit {
-            setCustomAnimations(DR.anim.slide_from_right, DR.anim.slide_to_left, DR.anim.slide_from_left, DR.anim.slide_to_right)
+            setCustomAnimations(
+                DR.anim.activity_open_enter,
+                DR.anim.activity_open_exit,
+                DR.anim.activity_close_enter,
+                DR.anim.activity_close_exit,
+            )
             replace(R.id.fragment_container, viewEditsFragment, "ViewEditsFragment_$id")
             addToBackStack(null)
         }

app/src/main/java/app/pachli/components/viewthread/edits/ViewEditsFragment.kt

@@ -32,6 +32,7 @@ import androidx.swiperefreshlayout.widget.SwipeRefreshLayout.OnRefreshListener
 import app.pachli.R
 import app.pachli.core.activity.BottomSheetActivity
 import app.pachli.core.activity.emojify
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.activity.loadAvatar
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
@@ -183,11 +184,11 @@ class ViewEditsFragment :
     }
 
     override fun onViewAccount(id: String) {
-        bottomSheetActivity?.startActivityWithSlideInAnimation(AccountActivityIntent(requireContext(), id))
+        bottomSheetActivity?.startActivityWithDefaultTransition(AccountActivityIntent(requireContext(), id))
     }
 
     override fun onViewTag(tag: String) {
-        bottomSheetActivity?.startActivityWithSlideInAnimation(TimelineActivityIntent.hashtag(requireContext(), tag))
+        bottomSheetActivity?.startActivityWithDefaultTransition(TimelineActivityIntent.hashtag(requireContext(), tag))
     }
 
     override fun onViewUrl(url: String) {

app/src/main/java/app/pachli/fragment/SFragment.kt

@@ -34,6 +34,7 @@ import androidx.annotation.CallSuper
 import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.widget.PopupMenu
 import androidx.core.app.ActivityOptionsCompat
+import androidx.core.view.ViewCompat
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
@@ -44,10 +45,10 @@ import app.pachli.core.activity.AccountSelectionListener
 import app.pachli.core.activity.BaseActivity
 import app.pachli.core.activity.BottomSheetActivity
 import app.pachli.core.activity.PostLookupFallbackBehavior
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.activity.openLink
 import app.pachli.core.database.model.AccountEntity
 import app.pachli.core.database.model.TranslationState
-import app.pachli.core.designsystem.R as DR
 import app.pachli.core.navigation.AttachmentViewData
 import app.pachli.core.navigation.ComposeActivityIntent
 import app.pachli.core.navigation.ComposeActivityIntent.ComposeOptions
@@ -94,8 +95,7 @@ abstract class SFragment<T : IStatusViewData> : Fragment(), StatusActionListener
     private var serverCanTranslate = false
 
     override fun startActivity(intent: Intent) {
-        super.startActivity(intent)
+        requireActivity().startActivityWithDefaultTransition(intent)
-        requireActivity().overridePendingTransition(DR.anim.slide_from_right, DR.anim.slide_to_left)
     }
 
     override fun onAttach(context: Context) {
@@ -400,7 +400,7 @@ abstract class SFragment<T : IStatusViewData> : Fragment(), StatusActionListener
                 val intent = ViewMediaActivityIntent(requireContext(), attachments, urlIndex)
                 if (view != null) {
                     val url = attachment.url
-                    view.transitionName = url
+                    ViewCompat.setTransitionName(view, url)
                     val options = ActivityOptionsCompat.makeSceneTransitionAnimation(
                         requireActivity(),
                         view,

app/src/main/java/app/pachli/fragment/ViewImageFragment.kt

@@ -30,6 +30,7 @@ import android.view.ViewGroup
 import android.widget.ImageView
 import androidx.coordinatorlayout.widget.CoordinatorLayout
 import androidx.core.view.GestureDetectorCompat
+import androidx.core.view.ViewCompat
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
 import androidx.lifecycle.repeatOnLifecycle
@@ -62,7 +63,7 @@ class ViewImageFragment : ViewMediaFragment() {
     private var scheduleToolbarHide = false
 
     override fun setupMediaView(showingDescription: Boolean) {
-        binding.photoView.transitionName = attachment.url
+        ViewCompat.setTransitionName(binding.photoView, attachment.url)
         binding.mediaDescription.text = attachment.description
         binding.captionSheet.visible(showingDescription)
 

app/src/main/java/app/pachli/fragment/ViewVideoFragment.kt

@@ -34,6 +34,7 @@ import android.widget.FrameLayout
 import android.widget.LinearLayout
 import androidx.annotation.OptIn
 import androidx.core.view.GestureDetectorCompat
+import androidx.core.view.ViewCompat
 import androidx.lifecycle.lifecycleScope
 import androidx.media3.common.MediaItem
 import androidx.media3.common.PlaybackException
@@ -359,7 +360,7 @@ class ViewVideoFragment : ViewMediaFragment() {
         // Ensure the description is visible over the video
         binding.mediaDescription.elevation = binding.videoView.elevation + 1
 
-        binding.videoView.transitionName = attachment.url
+        ViewCompat.setTransitionName(binding.videoView, attachment.url)
 
         if (!startedTransition && shouldCallMediaReady) {
             startedTransition = true

app/src/main/java/app/pachli/service/PachliTileService.kt

@@ -16,14 +16,10 @@
 
 package app.pachli.service
 
-import android.annotation.SuppressLint
 import android.annotation.TargetApi
 import android.app.PendingIntent
-import android.content.Context
-import android.content.Intent
 import android.os.Build
 import android.service.quicksettings.TileService
-import app.pachli.components.notifications.pendingIntentFlags
 import app.pachli.core.navigation.ComposeActivityIntent.ComposeOptions
 import app.pachli.core.navigation.MainActivityIntent
 
@@ -33,21 +29,14 @@ import app.pachli.core.navigation.MainActivityIntent
  */
 @TargetApi(24)
 class PachliTileService : TileService() {
-    @SuppressLint("StartActivityAndCollapseDeprecated")
     override fun onClick() {
         val intent = MainActivityIntent.openCompose(this, ComposeOptions())
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE) {
-            startActivityAndCollapse(getActivityPendingIntent(this, 0, intent))
+            val pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_IMMUTABLE)
+            startActivityAndCollapse(pendingIntent)
         } else {
+            @Suppress("DEPRECATION")
             startActivityAndCollapse(intent)
         }
     }
-
-    private fun getActivityPendingIntent(context: Context, requestCode: Int, intent: Intent): PendingIntent {
-        return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-            PendingIntent.getActivity(context, requestCode, intent, pendingIntentFlags(false))
-        } else {
-            PendingIntent.getActivity(context, requestCode, intent, pendingIntentFlags(false))
-        }
-    }
 }

app/src/main/java/app/pachli/viewmodel/EditProfileViewModel.kt

@@ -40,8 +40,10 @@ import dagger.hilt.android.lifecycle.HiltViewModel
 import java.io.File
 import javax.inject.Inject
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.asFlow
+import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.shareIn
 import kotlinx.coroutines.launch
 import okhttp3.MediaType.Companion.toMediaTypeOrNull
@@ -77,6 +79,11 @@ class EditProfileViewModel @Inject constructor(
 
     private var apiProfileAccount: Account? = null
 
+    private val _isDirty = MutableStateFlow(false)
+
+    /** True if the user has made unsaved changes to the profile */
+    val isDirty = _isDirty.asStateFlow()
+
     fun obtainProfile() = viewModelScope.launch {
         if (profileData.value == null || profileData.value is Error) {
             profileData.postValue(Loading())
@@ -170,10 +177,8 @@ class EditProfileViewModel @Inject constructor(
         }
     }
 
-    internal fun hasUnsavedChanges(newProfileData: ProfileDataInUi): Boolean {
+    internal fun onChange(newProfileData: ProfileDataInUi) {
-        val diff = getProfileDiff(apiProfileAccount, newProfileData)
+        _isDirty.value = getProfileDiff(apiProfileAccount, newProfileData).hasChanges()
-
-        return diff.hasChanges()
     }
 
     private fun getProfileDiff(oldProfileAccount: Account?, newProfileData: ProfileDataInUi): DiffProfileData {

app/src/main/res/layout/activity_edit_filter.xml

@@ -27,6 +27,7 @@
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:layout_marginTop="16dp"
+                app:errorEnabled="true"
                 android:hint="@string/label_filter_title">
                 <com.google.android.material.textfield.TextInputEditText
                     android:id="@+id/filterTitle"
@@ -43,6 +44,15 @@
                 style="@style/TextAppearance.Material3.TitleSmall"
                 android:textColor="?attr/colorAccent" />
 
+            <TextView
+                android:id="@+id/keywordChipsError"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="4dp"
+                android:text="@string/error_filter_missing_keyword"
+                style="@style/TextAppearance.Material3.BodySmall"
+                android:textColor="?attr/colorError" />
+
             <com.google.android.material.chip.ChipGroup
                     android:id="@+id/keywordChips"
                     android:layout_width="match_parent"
@@ -100,8 +110,7 @@
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:minHeight="48dp"
-                android:entries="@array/filter_duration_names"
+                android:entries="@array/filter_duration_names" />
-                />
 
             <TextView
                 android:layout_width="match_parent"
@@ -146,6 +155,15 @@
                 android:minHeight="48dp"
                 android:text="@string/pref_title_account_filter_keywords" />
 
+            <TextView
+                android:id="@+id/filterContextError"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="4dp"
+                android:text="@string/error_filter_missing_context"
+                style="@style/TextAppearance.Material3.BodySmall"
+                android:textColor="?attr/colorError" />
+
             <LinearLayout
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"

app/src/main/res/values-ar/strings.xml

@@ -503,7 +503,7 @@
     <string name="notification_report_description">ارسال إشعار عن شكاوى المدراء</string>
     <string name="set_focus_description">اضغط على الدائرة أو اسحبها لاختيار النقطة المحورية التي ستكون مرئية دائمًا في الصور المصغرة.</string>
     <string name="compose_save_draft_loses_media">حفظ المسودة؟ (سيتم رفع المرفقات مرة أخرى عند استعادة المسودة.)</string>
-    <string name="compose_unsaved_changes">لديك تعديلات لم تحفظ.</string>
+    <string name="unsaved_changes">لديك تعديلات لم تحفظ.</string>
     <string name="post_edited">عدَّلَ %s</string>
     <string name="notification_report_format">شكوى جديدة عن %s</string>
     <string name="status_edit_info">%1$s :عدّله</string>

app/src/main/res/values-be/strings.xml

@@ -374,7 +374,7 @@
         <item quantity="many"><b>%s</b> пашыраных</item>
         <item quantity="other"><b>%s</b> пашыраных</item>
     </plurals>
-    <string name="compose_unsaved_changes">У Вас засталіся незахаваныя змены.</string>
+    <string name="unsaved_changes">У Вас засталіся незахаваныя змены.</string>
     <string name="expand_collapse_all_posts">Разгарнуць/згарнуць допісы</string>
     <string name="action_open_post">Адкрыць допіс</string>
     <string name="restart_required">Патрэбна перазапусціць праграму</string>

app/src/main/res/values-ca/strings.xml

@@ -508,7 +508,7 @@
     <string name="pachli_compose_post_quicksetting_label">Redacta la publicació</string>
     <string name="pref_title_confirm_favourites">Mostra el diàleg de confirmació abans de marcar com a preferit</string>
     <string name="action_unfollow_hashtag_format">Deixar de seguir #%s\?</string>
-    <string name="compose_unsaved_changes">Tens canvis no desats.</string>
+    <string name="unsaved_changes">Tens canvis no desats.</string>
     <string name="set_focus_description">Toqueu o arrossegueu el cercle per triar el punt focal que sempre serà visible a les miniatures.</string>
     <string name="url_domain_notifier">\u0020(🔗 %s)</string>
     <string name="pref_title_show_self_username">Mostra el nom d\'usuari a les barres d\'eines</string>

app/src/main/res/values-cy/strings.xml

@@ -563,7 +563,7 @@
     <string name="title_edits">Golygiadau</string>
     <string name="post_media_alt">AMGEN</string>
     <string name="action_discard">Hepgor newidiadau</string>
-    <string name="compose_unsaved_changes">Mae gennych newidiadau heb eu cadw.</string>
+    <string name="unsaved_changes">Mae gennych newidiadau heb eu cadw.</string>
     <string name="mute_notifications_switch">Tewi hysbysiadau</string>
     <string name="a11y_label_loading_thread">Llwytho trywydd</string>
     <string name="action_share_account_link">Rhannu ddolen i gyfrif</string>

app/src/main/res/values-de/strings.xml

@@ -515,7 +515,7 @@
     <string name="pref_summary_http_proxy_disabled">Deaktiviert</string>
     <string name="pref_summary_http_proxy_missing">&lt;nicht gesetzt&gt;</string>
     <string name="pref_summary_http_proxy_invalid">&lt;ungültig&gt;</string>
-    <string name="compose_unsaved_changes">Du hast nicht gespeicherte Änderungen.</string>
+    <string name="unsaved_changes">Du hast nicht gespeicherte Änderungen.</string>
     <string name="pref_title_http_proxy_port_message">Port sollte zwischen %d und %d liegen</string>
     <string name="error_muting_hashtag_format">Fehler beim Stummschalten von #%s</string>
     <string name="action_post_failed">Hochladen fehlgeschlagen</string>

app/src/main/res/values-es/strings.xml

@@ -526,7 +526,7 @@
     <string name="pref_title_notification_filter_reports">Hay una nueva denuncia</string>
     <string name="action_discard">Descartar cambios</string>
     <string name="action_continue_edit">Continuar editando</string>
-    <string name="compose_unsaved_changes">Tienes cambios sin guardar.</string>
+    <string name="unsaved_changes">Tienes cambios sin guardar.</string>
     <string name="title_edits">Ediciones</string>
     <string name="action_post_failed">La subida falló</string>
     <string name="action_post_failed_do_nothing">Descartar</string>
@@ -683,4 +683,4 @@
     <string name="manage_lists">Gestionar listas</string>
     <string name="title_lists_loading">Listas - cargando…</string>
     <string name="title_lists_failed">Listas - falló en cargar</string>
-</resources>
+</resources>

app/src/main/res/values-fa/strings.xml

@@ -534,7 +534,7 @@
     <string name="description_browser_login">ممکن است از روش‌های تأیید خویت اضافی پشتیبانی کند؛ ولی نیازمند مرورگری پشتیبانی شده است.</string>
     <string name="action_discard">دور انداختن تغییرات</string>
     <string name="action_continue_edit">ادامهٔ ویرایش</string>
-    <string name="compose_unsaved_changes">تغییراتی ذخیره نشده دارید.</string>
+    <string name="unsaved_changes">تغییراتی ذخیره نشده دارید.</string>
     <string name="action_share_account_link">هم‌رسانی پیوند به حساب</string>
     <string name="action_share_account_username">هم‌رسانی نام کاربری حساب</string>
     <string name="send_account_link_to">هم‌رسانی نشانی حساب به…</string>

app/src/main/res/values-fi/strings.xml

@@ -376,7 +376,7 @@
     <string name="pref_title_notification_filter_poll">päättyneet äänestykset</string>
     <string name="abbreviated_in_seconds">%ds</string>
     <string name="failed_to_unpin">Irrottaminen epäonnistui</string>
-    <string name="compose_unsaved_changes">Sinulla on tallentamattomia muutoksia.</string>
+    <string name="unsaved_changes">Sinulla on tallentamattomia muutoksia.</string>
     <string name="state_follow_requested">Seuraamista pyydetty</string>
     <string name="compose_delete_draft">Poista luonnos?</string>
     <string name="notification_notification_worker">Ilmoituksia haetaan…</string>

app/src/main/res/values-fr/strings.xml

@@ -568,7 +568,7 @@
     <string name="description_login">Fonctionne dans la plupart des cas. Aucune autre application n\'aura accès à vos données.</string>
     <string name="description_browser_login">Peut permettre des méthodes d\'authentification supplémentaires, mais un navigateur compatible est nécessaire.</string>
     <string name="mute_notifications_switch">Masquer les notifications</string>
-    <string name="compose_unsaved_changes">Il y a des modifications non enregistrées.</string>
+    <string name="unsaved_changes">Il y a des modifications non enregistrées.</string>
     <string name="description_post_edited">Modifié</string>
     <string name="select_list_empty">Vous n\'avez pas encore de liste</string>
     <string name="select_list_manage">Gérer les listes</string>

app/src/main/res/values-gd/strings.xml

@@ -548,7 +548,7 @@
     <string name="notification_summary_report_format">%s · Tha postaichean ris, %d dhiubh</string>
     <string name="action_share_account_link">Co-roinn ceangal dhan chunntas</string>
     <string name="account_username_copied">Chaidh lethbhreac a dhèanamh dhen ainm-chleachdaiche</string>
-    <string name="compose_unsaved_changes">Tha atharraichean gun sàbhaladh agad.</string>
+    <string name="unsaved_changes">Tha atharraichean gun sàbhaladh agad.</string>
     <string name="error_status_source_load">Dh’fhàillig luchdadh bun-tùs a’ phuist on fhrithealaiche.</string>
     <string name="action_post_failed_detail">Dh’fhàillig luchdadh suas a’ phuist agad is chaidh a shàbhaladh ’na dhreachd.
 \n

app/src/main/res/values-gl/strings.xml

@@ -514,7 +514,7 @@
     <string name="status_created_info">Creado por %1$s</string>
     <string name="action_discard">Desbotar cambios</string>
     <string name="action_continue_edit">Continuar a edición</string>
-    <string name="compose_unsaved_changes">Hai cambios non gardados.</string>
+    <string name="unsaved_changes">Hai cambios non gardados.</string>
     <string name="action_share_account_link">Comparte ligazón da conta</string>
     <string name="action_share_account_username">Comparte identificador da conta</string>
     <string name="send_account_link_to">Compartir URL da conta en…</string>

app/src/main/res/values-hu/strings.xml

@@ -524,7 +524,7 @@
     <string name="post_media_alt">ALT</string>
     <string name="action_discard">Változtatások elvetése</string>
     <string name="action_continue_edit">Szerkesztés folytatása</string>
-    <string name="compose_unsaved_changes">Elmentetlen változtatásaid vannak.</string>
+    <string name="unsaved_changes">Elmentetlen változtatásaid vannak.</string>
     <string name="action_share_account_link">Fiókra történő hivatkozás megosztása</string>
     <string name="action_share_account_username">Fiók felhasználói nevének megosztása</string>
     <string name="send_account_link_to">Fiók URL megosztása vele…</string>

app/src/main/res/values-is/strings.xml

@@ -507,7 +507,7 @@
     <string name="pref_title_http_proxy_port_message">Gáttin ætti að vera á milli %d og %d</string>
     <string name="error_status_source_load">Mistókst að hlaða inn uppruna stöðufærslu af netþjóninum.</string>
     <string name="a11y_label_loading_thread">Hleð inn þræði</string>
-    <string name="compose_unsaved_changes">Þú ert með óvistaðar breytingar.</string>
+    <string name="unsaved_changes">Þú ert með óvistaðar breytingar.</string>
     <string name="pref_summary_http_proxy_disabled">Óvirkt</string>
     <string name="pref_summary_http_proxy_missing">&lt;ekki stillt&gt;</string>
     <string name="pref_summary_http_proxy_invalid">&lt;ógilt&gt;</string>

app/src/main/res/values-it/strings.xml

@@ -542,7 +542,7 @@
     <string name="notification_header_report_format">%s ha segnalato %s</string>
     <string name="notification_summary_report_format">%s · %d post allegati</string>
     <string name="action_add_reaction">aggiungi reazione</string>
-    <string name="compose_unsaved_changes">Hai delle modifiche non salvate.</string>
+    <string name="unsaved_changes">Hai delle modifiche non salvate.</string>
     <string name="confirmation_hashtag_unfollowed">Non segui più #%s</string>
     <string name="error_status_source_load">Caricamento dello status della sorgente dal server fallito.</string>
     <string name="post_edited">Modificato %s</string>

app/src/main/res/values-ja/strings.xml

@@ -512,7 +512,7 @@
     <string name="status_created_info">%1$s の投稿</string>
     <string name="follow_requests_info">アカウントがロックされていなかったとしても、%1$s のスタッフは以下のアカウントのフォローリクエストを確認した方がいいと判断しました。</string>
     <string name="action_set_focus">中心点の設定</string>
-    <string name="compose_unsaved_changes">保存していない変更があります。</string>
+    <string name="unsaved_changes">保存していない変更があります。</string>
     <string name="error_status_source_load">サーバーからステータスの元情報を取得できませんでした。</string>
     <string name="pref_summary_http_proxy_disabled">無効</string>
     <string name="pref_summary_http_proxy_missing">&lt;設定なし&gt;</string>

app/src/main/res/values-lv/strings.xml

@@ -331,7 +331,7 @@
     <string name="notification_summary_large">%1$s, %2$s, %3$s un %4$d citi</string>
     <string name="title_media">Multivide</string>
     <string name="pref_title_alway_show_sensitive_media">Vienmēr rādīt sensitīvu saturu</string>
-    <string name="compose_unsaved_changes">Tev ir nesaglabātas izmaiņas.</string>
+    <string name="unsaved_changes">Tev ir nesaglabātas izmaiņas.</string>
     <string name="description_post_media">Multivide: %s</string>
     <string name="description_poll">Aptauja ar izvēlēm: %1$s, %2$s, %3$s, %4$s; %5$s</string>
     <string name="poll_info_format"><!-- 15 balsis • atlikusi 1 stunda -->%1$s • %2$s</string>

app/src/main/res/values-nb-rNO/strings.xml

@@ -554,7 +554,7 @@
     <string name="ui_success_accepted_follow_request">Følgeforespørsel akseptert</string>
     <string name="action_discard">Forkast endringer</string>
     <string name="action_continue_edit">Fortsett endring</string>
-    <string name="compose_unsaved_changes">Du har ulagrede endringer.</string>
+    <string name="unsaved_changes">Du har ulagrede endringer.</string>
     <string name="select_list_empty">Du har ingen lister, enda</string>
     <string name="error_list_load">Feil under lading av lister</string>
     <string name="select_list_manage">Forvalte lister</string>

app/src/main/res/values-nl/strings.xml

@@ -488,7 +488,7 @@
     <string name="delete_scheduled_post_warning">Dit ingeplande bericht verwijderen\?</string>
     <string name="failed_to_pin">Kan niet vastmaken</string>
     <string name="pref_summary_http_proxy_disabled">Uitgeschakeld</string>
-    <string name="compose_unsaved_changes">Er zijn niet opgeslagen wijzigingen.</string>
+    <string name="unsaved_changes">Er zijn niet opgeslagen wijzigingen.</string>
     <string name="mute_notifications_switch">Meldingen negeren</string>
     <string name="title_edits">Bewerkingen</string>
     <string name="pref_default_post_language">Standaardtaal van berichten</string>

app/src/main/res/values-oc/strings.xml

@@ -520,7 +520,7 @@
     <string name="post_media_alt">ALT</string>
     <string name="action_discard">Ignorar las modificacions</string>
     <string name="action_continue_edit">Téner de modificar</string>
-    <string name="compose_unsaved_changes">Avètz de modificacions pas salvadas.</string>
+    <string name="unsaved_changes">Avètz de modificacions pas salvadas.</string>
     <string name="a11y_label_loading_thread">Cargament del fil</string>
     <string name="pref_summary_http_proxy_disabled">Desactivat</string>
     <string name="pref_summary_http_proxy_missing">&lt;pas definit&gt;</string>

app/src/main/res/values-pl/strings.xml

@@ -526,7 +526,7 @@
     <string name="status_edit_info">%1$s edytował</string>
     <string name="status_created_info">%1$s stworzył</string>
     <string name="title_edits">Edycje</string>
-    <string name="compose_unsaved_changes">Masz niezapisane zmiany.</string>
+    <string name="unsaved_changes">Masz niezapisane zmiany.</string>
     <string name="action_post_failed">Błąd wysyłania</string>
     <string name="action_post_failed_show_drafts">Pokaż szkice</string>
     <string name="action_post_failed_do_nothing">Odrzuć</string>

app/src/main/res/values-pt-rBR/strings.xml

@@ -510,7 +510,7 @@
     <string name="description_browser_login">Pode oferecer suporte a métodos de autenticação adicionais, mas requer um navegador compatível.</string>
     <string name="status_edit_info">%1$s editou</string>
     <string name="action_continue_edit">Continuar editando</string>
-    <string name="compose_unsaved_changes">Você tem alterações não salvas.</string>
+    <string name="unsaved_changes">Você tem alterações não salvas.</string>
     <string name="description_post_edited">Editado</string>
     <string name="delete_scheduled_post_warning">Excluir este Toot agendado?</string>
     <string name="action_unfollow_hashtag_format">Deixar de seguir #%s\?</string>

app/src/main/res/values-sa/strings.xml

@@ -481,7 +481,7 @@
     <string name="dialog_follow_hashtag_title">व्यक्तित्वविवरणलेखा अनुसरतु</string>
     <string name="limit_notifications">कालानुक्रमपङ्क्त्याः सूचनाः परिमिताः कुरुताम्</string>
     <string name="notification_report_description">परिमितावेदनानि प्रति ज्ञापनसूचनाः</string>
-    <string name="compose_unsaved_changes">भवतः अरक्षितानि परिवर्तनानि सन्ति।</string>
+    <string name="unsaved_changes">भवतः अरक्षितानि परिवर्तनानि सन्ति।</string>
     <string name="pref_title_notification_filter_reports">नूतनम् आवेदनमस्ति</string>
     <string name="pref_title_wellbeing_mode">सुस्थितिः</string>
     <string name="delete_scheduled_post_warning">इदं कालबद्धदौत्यं विनश्येत् किम् \?</string>

app/src/main/res/values-sv/strings.xml

@@ -532,7 +532,7 @@
     <string name="status_created_info">%1$s skapade</string>
     <string name="action_discard">Förkasta ändringar</string>
     <string name="action_continue_edit">Fortsätt redigera</string>
-    <string name="compose_unsaved_changes">Du har ändringar som inte sparats.</string>
+    <string name="unsaved_changes">Du har ändringar som inte sparats.</string>
     <string name="action_post_failed">Uppladdning misslyckades</string>
     <string name="action_post_failed_detail">Ett fel inträffade när inlägget skulle laddas upp och har sparats till utkast.
 \n

app/src/main/res/values-tr/strings.xml

@@ -524,7 +524,7 @@
     <string name="status_created_info">%1$s oluşturdu</string>
     <string name="dialog_follow_hashtag_title">Etiketi takip et</string>
     <string name="dialog_follow_hashtag_hint">#etiket</string>
-    <string name="compose_unsaved_changes">Kaydedilmemiş değişikliklerin var.</string>
+    <string name="unsaved_changes">Kaydedilmemiş değişikliklerin var.</string>
     <string name="status_edit_info">%1$s düzenledi</string>
     <string name="title_edits">Düzenlemeler</string>
     <string name="hint_description">Açıklama</string>

app/src/main/res/values-uk/strings.xml

@@ -530,7 +530,7 @@
     <string name="error_status_source_load">Не вдалося завантажити джерело стану з сервера.</string>
     <string name="post_media_alt">ALT</string>
     <string name="action_discard">Відкинути зміни</string>
-    <string name="compose_unsaved_changes">У вас є незбережені зміни.</string>
+    <string name="unsaved_changes">У вас є незбережені зміни.</string>
     <string name="action_continue_edit">Продовжити редагування</string>
     <string name="mute_notifications_switch">Беззвучні сповіщення</string>
     <string name="title_edits">Редагування</string>

app/src/main/res/values-vi/strings.xml

@@ -499,7 +499,7 @@
     <string name="post_media_alt">✦</string>
     <string name="action_discard">Hủy bỏ thay đổi</string>
     <string name="action_continue_edit">Tiếp tục sửa</string>
-    <string name="compose_unsaved_changes">Thay đổi chưa được lưu.</string>
+    <string name="unsaved_changes">Thay đổi chưa được lưu.</string>
     <string name="mute_notifications_switch">Ẩn thông báo</string>
     <string name="status_edit_info">Sửa %1$s</string>
     <string name="status_created_info">Đăng %1$s</string>

app/src/main/res/values-zh-rCN/strings.xml

@@ -513,7 +513,7 @@
     <string name="post_media_alt">ALT</string>
     <string name="action_discard">放弃更改</string>
     <string name="action_continue_edit">继续编辑</string>
-    <string name="compose_unsaved_changes">你有未保存的更改。</string>
+    <string name="unsaved_changes">你有未保存的更改。</string>
     <string name="status_created_info">%1$s 创建了</string>
     <string name="mute_notifications_switch">将通知静音</string>
     <string name="title_edits">编辑</string>

app/src/main/res/values/strings.xml

@@ -412,7 +412,7 @@
     <string name="compose_delete_draft">Delete draft?</string>
     <string name="compose_save_draft">Save draft?</string>
     <string name="compose_save_draft_loses_media">Save draft? (Attachments will be uploaded again when you restore the draft.)</string>
-    <string name="compose_unsaved_changes">You have unsaved changes.</string>
+    <string name="unsaved_changes">You have unsaved changes.</string>
     <string name="send_post_notification_title">Sending post…</string>
     <string name="send_post_notification_error_title">Error sending post</string>
     <string name="send_post_notification_channel_name">Sending Posts</string>
@@ -703,5 +703,8 @@
     <string name="action_add_to_tab_success">Added \'%1$s\' to tabs</string>
     <string name="action_remove_tab">Remove tab</string>
     <string name="action_manage_tabs">Manage tabs</string>
+    <string name="error_filter_missing_keyword">At least one keyword or phrase is required</string>
+    <string name="error_filter_missing_context">At least one filter context is required</string>
+    <string name="error_filter_missing_title">Title is required</string>
 
 </resources>

app/src/test/java/app/pachli/FilterV1Test.kt

@@ -18,7 +18,7 @@
 package app.pachli
 
 import androidx.test.ext.junit.runners.AndroidJUnit4
-import app.pachli.components.filters.EditFilterActivity
+import app.pachli.components.filters.EditFilterViewModel.Companion.getSecondsForDurationIndex
 import app.pachli.core.network.model.Attachment
 import app.pachli.core.network.model.Filter
 import app.pachli.core.network.model.FilterContext
@@ -259,7 +259,7 @@ class FilterV1Test {
     fun unchangedExpiration_shouldBeNegative_whenFilterIsExpired() {
         val expiredBySeconds = 3600
         val expiredDate = Date.from(Instant.now().minusSeconds(expiredBySeconds.toLong()))
-        val updatedDuration = EditFilterActivity.getSecondsForDurationIndex(-1, null, expiredDate)
+        val updatedDuration = getSecondsForDurationIndex(-1, null, expiredDate)
         assert(updatedDuration != null && updatedDuration.toInt() <= -expiredBySeconds)
     }
 
@@ -267,7 +267,7 @@ class FilterV1Test {
     fun unchangedExpiration_shouldBePositive_whenFilterIsUnexpired() {
         val expiresInSeconds = 3600
         val expiredDate = Date.from(Instant.now().plusSeconds(expiresInSeconds.toLong()))
-        val updatedDuration = EditFilterActivity.getSecondsForDurationIndex(-1, null, expiredDate)
+        val updatedDuration = getSecondsForDurationIndex(-1, null, expiredDate)
         assert(updatedDuration != null && updatedDuration.toInt() > (expiresInSeconds - 60))
     }
 

app/src/test/java/app/pachli/components/compose/ComposeActivityTest.kt

@@ -239,7 +239,7 @@ class ComposeActivityTest {
         rule.launch()
         rule.getScenario().onActivity {
             insertSomeTextInContent(it, content)
-            assertEquals(content.length, it.calculateTextLength())
+            assertEquals(content.length, it.viewModel.statusLength.value)
         }
     }
 
@@ -249,7 +249,7 @@ class ComposeActivityTest {
         rule.launch()
         rule.getScenario().onActivity {
             insertSomeTextInContent(it, content)
-            assertEquals(6, it.calculateTextLength())
+            assertEquals(6, it.viewModel.statusLength.value)
         }
     }
 
@@ -259,7 +259,7 @@ class ComposeActivityTest {
         rule.launch()
         rule.getScenario().onActivity {
             insertSomeTextInContent(it, content)
-            assertEquals(7, it.calculateTextLength())
+            assertEquals(7, it.viewModel.statusLength.value)
         }
     }
 
@@ -271,7 +271,7 @@ class ComposeActivityTest {
             insertSomeTextInContent(it, content)
             assertEquals(
                 InstanceInfoRepository.DEFAULT_CHARACTERS_RESERVED_PER_URL,
-                it.calculateTextLength(),
+                it.viewModel.statusLength.value,
             )
         }
     }
@@ -282,7 +282,7 @@ class ComposeActivityTest {
         rule.launch()
         rule.getScenario().onActivity {
             insertSomeTextInContent(it, content)
-            assertEquals(21, it.calculateTextLength())
+            assertEquals(21, it.viewModel.statusLength.value)
         }
     }
 
@@ -295,7 +295,7 @@ class ComposeActivityTest {
             insertSomeTextInContent(it, additionalContent + url)
             assertEquals(
                 additionalContent.length + InstanceInfoRepository.DEFAULT_CHARACTERS_RESERVED_PER_URL,
-                it.calculateTextLength(),
+                it.viewModel.statusLength.value,
             )
         }
     }
@@ -310,7 +310,7 @@ class ComposeActivityTest {
             insertSomeTextInContent(it, shortUrl + additionalContent + url)
             assertEquals(
                 additionalContent.length + (InstanceInfoRepository.DEFAULT_CHARACTERS_RESERVED_PER_URL * 2),
-                it.calculateTextLength(),
+                it.viewModel.statusLength.value,
             )
         }
     }
@@ -324,7 +324,7 @@ class ComposeActivityTest {
             insertSomeTextInContent(it, url + additionalContent + url)
             assertEquals(
                 additionalContent.length + (InstanceInfoRepository.DEFAULT_CHARACTERS_RESERVED_PER_URL * 2),
-                it.calculateTextLength(),
+                it.viewModel.statusLength.value,
             )
         }
     }
@@ -340,7 +340,7 @@ class ComposeActivityTest {
             insertSomeTextInContent(it, additionalContent + url)
             assertEquals(
                 additionalContent.length + customUrlLength,
-                it.calculateTextLength(),
+                it.viewModel.statusLength.value,
             )
         }
     }
@@ -357,7 +357,7 @@ class ComposeActivityTest {
             insertSomeTextInContent(it, shortUrl + additionalContent + url)
             assertEquals(
                 additionalContent.length + (customUrlLength * 2),
-                it.calculateTextLength(),
+                it.viewModel.statusLength.value,
             )
         }
     }
@@ -373,7 +373,7 @@ class ComposeActivityTest {
             insertSomeTextInContent(it, url + additionalContent + url)
             assertEquals(
                 additionalContent.length + (customUrlLength * 2),
-                it.calculateTextLength(),
+                it.viewModel.statusLength.value,
             )
         }
     }

app/src/test/java/app/pachli/components/compose/StatusLengthTest.kt

@@ -22,15 +22,15 @@ import app.pachli.util.highlightSpans
 import org.junit.Assert.assertEquals
 import org.junit.Test
 import org.junit.runner.RunWith
-import org.junit.runners.Parameterized
+import org.robolectric.ParameterizedRobolectricTestRunner
 
-@RunWith(Parameterized::class)
+@RunWith(ParameterizedRobolectricTestRunner::class)
 class StatusLengthTest(
     private val text: String,
     private val expectedLength: Int,
 ) {
     companion object {
-        @Parameterized.Parameters(name = "{0}")
+        @ParameterizedRobolectricTestRunner.Parameters(name = "{0}")
         @JvmStatic
         fun data(): Iterable<Any> {
             return listOf(
@@ -61,7 +61,7 @@ class StatusLengthTest(
 
         assertEquals(
             expectedLength,
-            ComposeActivity.statusLength(spannedText, null, 23),
+            ComposeViewModel.statusLength(spannedText, "", 23),
         )
     }
 
@@ -75,7 +75,7 @@ class StatusLengthTest(
         )
         assertEquals(
             expectedLength + cwText.length,
-            ComposeActivity.statusLength(spannedText, cwText, 23),
+            ComposeViewModel.statusLength(spannedText, cwText.toString(), 23),
         )
     }
 }

core/activity/src/main/kotlin/app/pachli/core/activity/BaseActivity.kt

@@ -37,6 +37,9 @@ import androidx.core.app.ActivityCompat
 import androidx.core.content.ContextCompat
 import androidx.core.view.MenuProvider
 import app.pachli.core.accounts.AccountManager
+import app.pachli.core.activity.extensions.canOverrideActivityTransitions
+import app.pachli.core.activity.extensions.getTransitionKind
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.database.model.AccountEntity
 import app.pachli.core.designsystem.EmbeddedFontFamily
 import app.pachli.core.designsystem.R as DR
@@ -82,6 +85,13 @@ abstract class BaseActivity : AppCompatActivity(), MenuProvider {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
+        if (canOverrideActivityTransitions()) {
+            intent.getTransitionKind()?.let {
+                overrideActivityTransition(OVERRIDE_TRANSITION_OPEN, it.openEnter, it.openExit)
+                overrideActivityTransition(OVERRIDE_TRANSITION_CLOSE, it.closeEnter, it.closeExit)
+            }
+        }
+
         // Set the theme from preferences
         val theme = AppTheme.from(sharedPreferencesRepository)
         Timber.d("activeTheme: %s", theme)
@@ -156,11 +166,6 @@ abstract class BaseActivity : AppCompatActivity(), MenuProvider {
         return true
     }
 
-    fun startActivityWithSlideInAnimation(intent: Intent) {
-        super.startActivity(intent)
-        overridePendingTransition(DR.anim.slide_from_right, DR.anim.slide_to_left)
-    }
-
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
         if (item.itemId == android.R.id.home) {
             onBackPressedDispatcher.onBackPressed()
@@ -171,11 +176,13 @@ abstract class BaseActivity : AppCompatActivity(), MenuProvider {
 
     override fun finish() {
         super.finish()
-        overridePendingTransition(DR.anim.slide_from_left, DR.anim.slide_to_right)
-    }
 
-    fun finishWithoutSlideOutAnimation() {
+        if (!canOverrideActivityTransitions()) {
-        super.finish()
+            intent.getTransitionKind()?.let {
+                @Suppress("DEPRECATION")
+                overridePendingTransition(it.closeEnter, it.closeExit)
+            }
+        }
     }
 
     private fun redirectIfNotLoggedIn() {
@@ -183,7 +190,7 @@ abstract class BaseActivity : AppCompatActivity(), MenuProvider {
         if (account == null) {
             val intent = LoginActivityIntent(this)
             intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_NEW_TASK)
-            startActivityWithSlideInAnimation(intent)
+            startActivityWithDefaultTransition(intent)
             finish()
         }
     }
@@ -259,7 +266,7 @@ abstract class BaseActivity : AppCompatActivity(), MenuProvider {
         accountManager.setActiveAccount(account.id)
         val intent = MainActivityIntent.redirect(this, account.id, url)
         startActivity(intent)
-        finishWithoutSlideOutAnimation()
+        finish()
     }
 
     override fun onRequestPermissionsResult(

core/activity/src/main/kotlin/app/pachli/core/activity/BottomSheetActivity.kt

@@ -24,6 +24,9 @@ import android.widget.LinearLayout
 import android.widget.Toast
 import androidx.annotation.VisibleForTesting
 import androidx.lifecycle.lifecycleScope
+import app.pachli.core.activity.extensions.TransitionKind
+import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
+import app.pachli.core.activity.extensions.startActivityWithTransition
 import app.pachli.core.navigation.AccountActivityIntent
 import app.pachli.core.navigation.ViewThreadActivityIntent
 import app.pachli.core.network.retrofit.MastodonApi
@@ -105,13 +108,13 @@ abstract class BottomSheetActivity : BaseActivity() {
     open fun viewThread(statusId: String, url: String?) {
         if (!isSearching()) {
             val intent = ViewThreadActivityIntent(this, statusId, url)
-            startActivityWithSlideInAnimation(intent)
+            startActivityWithTransition(intent, TransitionKind.SLIDE_FROM_END)
         }
     }
 
     open fun viewAccount(id: String) {
         val intent = AccountActivityIntent(this, id)
-        startActivityWithSlideInAnimation(intent)
+        startActivityWithDefaultTransition(intent)
     }
 
     protected open fun performUrlFallbackAction(url: String, fallbackBehavior: PostLookupFallbackBehavior) {

core/activity/src/main/kotlin/app/pachli/core/activity/extensions/ActivityExtensions.kt

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2024 Pachli Association
+ *
+ * This file is a part of Pachli.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Pachli; if not,
+ * see <http://www.gnu.org/licenses>.
+ */
+
+package app.pachli.core.activity.extensions
+
+import android.app.Activity
+import android.app.Activity.OVERRIDE_TRANSITION_CLOSE
+import android.app.Activity.OVERRIDE_TRANSITION_OPEN
+import android.content.Intent
+import android.os.Build
+import androidx.annotation.ChecksSdkIntAtLeast
+import app.pachli.core.activity.BaseActivity
+import app.pachli.core.activity.BuildConfig
+
+/**
+ * Starts the activity in [intent] (which must be a subclass of [BaseActivity])
+ * using [transitionKind] as the open/close transition.
+ */
+fun Activity.startActivityWithTransition(intent: Intent, transitionKind: TransitionKind) {
+    if (BuildConfig.DEBUG) {
+        if (this !is BaseActivity) {
+            throw IllegalStateException("startActivityWithTransition must be used with BaseActivity subclass")
+        }
+    }
+
+    intent.putExtra(EXTRA_TRANSITION_KIND, transitionKind)
+    startActivity(intent)
+
+    if (canOverrideActivityTransitions()) {
+        overrideActivityTransition(OVERRIDE_TRANSITION_OPEN, transitionKind.openEnter, transitionKind.openExit)
+    } else {
+        @Suppress("DEPRECATION")
+        overridePendingTransition(transitionKind.openEnter, transitionKind.openExit)
+    }
+}
+
+/** See [Activity.startActivityWithTransition] */
+fun Activity.startActivityWithDefaultTransition(intent: Intent) = startActivityWithTransition(intent, TransitionKind.DEFAULT)
+
+/**
+ * Overrides any "close" transition already set for this activity and
+ * replaces them with [transitionKind].
+ *
+ * Call this after calling [Activity.finish]
+ */
+fun Activity.setCloseTransition(transitionKind: TransitionKind) {
+    if (BuildConfig.DEBUG) {
+        if (this !is BaseActivity) {
+            throw IllegalStateException("startActivityWithTransition must be used with BaseActivity subclass")
+        }
+    }
+
+    if (canOverrideActivityTransitions()) {
+        overrideActivityTransition(OVERRIDE_TRANSITION_CLOSE, transitionKind.closeEnter, transitionKind.closeExit)
+    } else {
+        @Suppress("DEPRECATION")
+        overridePendingTransition(transitionKind.closeEnter, transitionKind.closeExit)
+    }
+}
+
+/**
+ * @return True if the Android version supports [Activity.overrideActivityTransition],
+ *   false if [Activity.overridePendingTransition] must be used.
+ */
+@ChecksSdkIntAtLeast(api = Build.VERSION_CODES.UPSIDE_DOWN_CAKE)
+fun canOverrideActivityTransitions() = Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE

core/activity/src/main/kotlin/app/pachli/core/activity/extensions/IntentExtensions.kt

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2024 Pachli Association
+ *
+ * This file is a part of Pachli.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Pachli; if not,
+ * see <http://www.gnu.org/licenses>.
+ */
+
+package app.pachli.core.activity.extensions
+
+import android.content.Intent
+import android.os.Build
+import androidx.annotation.AnimRes
+import app.pachli.core.designsystem.R as DR
+
+const val EXTRA_TRANSITION_KIND = "transition_kind"
+
+/**
+ * The type of transition and animation resources to use when opening and closing
+ * an activity.
+ *
+ * @property openEnter When opening an activity, a resource ID of the animation resource to
+ *     use for the incoming activity. Use 0 for no animation.
+ * @property openExit When opening an activity, a resource ID of the animation resource to
+ *     use for the outgoing activity. Use 0 for no animation
+ * @property closeEnter When closing an activity, a resource ID of the animation resource to
+ *     use for the incoming activity. Use 0 for no animation.
+ * @property closeExit When closing an activity, a resource ID of the animation resource to
+ *     use for the outgoing activity. Use 0 for no animation
+ */
+enum class TransitionKind(
+    @AnimRes val openEnter: Int,
+    @AnimRes val openExit: Int,
+    @AnimRes val closeEnter: Int,
+    @AnimRes val closeExit: Int,
+) {
+    /** Default transition */
+    DEFAULT(DR.anim.activity_open_enter, DR.anim.activity_open_exit, DR.anim.activity_close_enter, DR.anim.activity_close_exit),
+
+    /**
+     * Slide from the user's "end" perspective (right side for LTR text, left side for RTL text).
+     * Use when a spatial relationship makes sense, such as transitioning from a single status
+     * to the thread that contains that status.
+     */
+    SLIDE_FROM_END(DR.anim.slide_from_end, DR.anim.slide_to_start, DR.anim.slide_from_start, DR.anim.slide_to_end),
+
+    /**
+     * Explode out from the centre of the screen. Use to indicate a significant change in
+     * application state (e.g., changing accounts).
+     */
+    EXPLODE(DR.anim.explode, DR.anim.activity_open_exit, 0, 0),
+}
+
+/** @return The [TransitionKind] included in this intent, or null */
+fun Intent.getTransitionKind(): TransitionKind? {
+    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+        getSerializableExtra(EXTRA_TRANSITION_KIND, TransitionKind::class.java)
+    } else {
+        @Suppress("DEPRECATION")
+        getSerializableExtra(EXTRA_TRANSITION_KIND) as? TransitionKind
+    }
+}

core/designsystem/src/main/res/anim-ldrtl-v33/activity_close_enter.xml

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright 2024 Pachli Association
+  ~
+  ~ This file is a part of Pachli.
+  ~
+  ~ This program is free software; you can redistribute it and/or modify it under the terms of the
+  ~ GNU General Public License as published by the Free Software Foundation; either version 3 of the
+  ~ License, or (at your option) any later version.
+  ~
+  ~ Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+  ~ the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+  ~ Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with Pachli; if not,
+  ~ see <http://www.gnu.org/licenses>.
+  -->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="0"
+        android:duration="450" />
+
+    <translate
+        android:fromXDelta="96dp"
+        android:toXDelta="0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <extend
+        android:fromExtendLeft="96dp"
+        android:fromExtendTop="0"
+        android:fromExtendRight="0"
+        android:fromExtendBottom="0"
+        android:toExtendLeft="96dp"
+        android:toExtendTop="0"
+        android:toExtendRight="0"
+        android:toExtendBottom="0"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-ldrtl-v33/activity_close_exit.xml

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright 2024 Pachli Association
+  ~
+  ~ This file is a part of Pachli.
+  ~
+  ~ This program is free software; you can redistribute it and/or modify it under the terms of the
+  ~ GNU General Public License as published by the Free Software Foundation; either version 3 of the
+  ~ License, or (at your option) any later version.
+  ~
+  ~ Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+  ~ the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+  ~ Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with Pachli; if not,
+  ~ see <http://www.gnu.org/licenses>.
+  -->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="0.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="35"
+        android:duration="83" />
+
+    <translate
+        android:fromXDelta="0"
+        android:toXDelta="-96dp"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <extend
+        android:fromExtendLeft="0"
+        android:fromExtendTop="0"
+        android:fromExtendRight="96dp"
+        android:fromExtendBottom="0"
+        android:toExtendLeft="0"
+        android:toExtendTop="0"
+        android:toExtendRight="96dp"
+        android:toExtendBottom="0"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-ldrtl-v33/activity_open_enter.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+/*
+** Copyright 2022, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="50"
+        android:duration="83" />
+
+    <translate
+        android:fromXDelta="-96dp"
+        android:toXDelta="0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <extend
+        android:fromExtendLeft="0"
+        android:fromExtendTop="0"
+        android:fromExtendRight="96dp"
+        android:fromExtendBottom="0"
+        android:toExtendLeft="0"
+        android:toExtendTop="0"
+        android:toExtendRight="96dp"
+        android:toExtendBottom="0"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-ldrtl-v33/activity_open_exit.xml

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+/*
+** Copyright 2022, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/standard_accelerate"
+        android:startOffset="0"
+        android:duration="450" />
+
+    <translate
+        android:fromXDelta="0"
+        android:toXDelta="96dp"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <extend
+        android:fromExtendLeft="9dp"
+        android:fromExtendTop="0"
+        android:fromExtendRight="0"
+        android:fromExtendBottom="0"
+        android:toExtendLeft="96dp"
+        android:toExtendTop="0"
+        android:toExtendRight="0"
+        android:toExtendBottom="0"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-ldrtl/activity_close_enter.xml

@@ -0,0 +1,42 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+** Copyright 2022, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="0"
+        android:duration="450" />
+
+    <translate
+        android:fromXDelta="96dp"
+        android:toXDelta="0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-ldrtl/activity_close_exit.xml

@@ -0,0 +1,42 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+** Copyright 2022, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="0.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="35"
+        android:duration="83" />
+
+    <translate
+        android:fromXDelta="0"
+        android:toXDelta="-96dp"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-ldrtl/activity_open_enter.xml

@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+/*
+** Copyright 2022, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="50"
+        android:duration="83" />
+
+    <translate
+        android:fromXDelta="-96dp"
+        android:toXDelta="0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-ldrtl/activity_open_exit.xml

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+/*
+** Copyright 2022, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/standard_accelerate"
+        android:startOffset="0"
+        android:duration="450" />
+
+    <translate
+        android:fromXDelta="0"
+        android:toXDelta="96dp"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-ldrtl/slide_from_end.xml

@@ -2,5 +2,5 @@
 <set xmlns:android="http://schemas.android.com/apk/res/android">
     <translate android:fromXDelta="0" android:toXDelta="100%p"
         android:interpolator="@android:anim/accelerate_decelerate_interpolator"
-        android:duration="300"/>
+        android:duration="@integer/activity_slide_transition_duration_ms"/>
-</set>
+</set>

core/designsystem/src/main/res/anim-ldrtl/slide_from_start.xml

@@ -2,5 +2,5 @@
 <set xmlns:android="http://schemas.android.com/apk/res/android">
     <translate android:fromXDelta="0" android:toXDelta="-100%p"
         android:interpolator="@android:anim/accelerate_decelerate_interpolator"
-        android:duration="300"/>
+        android:duration="@integer/activity_slide_transition_duration_ms"/>
-</set>
+</set>

core/designsystem/src/main/res/anim-ldrtl/slide_to_end.xml

@@ -2,5 +2,5 @@
 <set xmlns:android="http://schemas.android.com/apk/res/android">
     <translate android:fromXDelta="100%p" android:toXDelta="0"
         android:interpolator="@android:anim/accelerate_decelerate_interpolator"
-        android:duration="300"/>
+        android:duration="@integer/activity_slide_transition_duration_ms"/>
-</set>
+</set>

core/designsystem/src/main/res/anim-ldrtl/slide_to_start.xml

@@ -2,5 +2,5 @@
 <set xmlns:android="http://schemas.android.com/apk/res/android">
     <translate android:fromXDelta="-100%p" android:toXDelta="0"
         android:interpolator="@android:anim/accelerate_decelerate_interpolator"
-        android:duration="300"/>
+        android:duration="@integer/activity_slide_transition_duration_ms"/>
-</set>
+</set>

core/designsystem/src/main/res/anim-v33/activity_close_enter.xml

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+** Copyright 2009, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <translate
+        android:fromXDelta="-96dp"
+        android:toXDelta="0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <extend
+        android:fromExtendLeft="0"
+        android:fromExtendTop="0"
+        android:fromExtendRight="96dp"
+        android:fromExtendBottom="0"
+        android:toExtendLeft="0"
+        android:toExtendTop="0"
+        android:toExtendRight="96dp"
+        android:toExtendBottom="0"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-v33/activity_close_exit.xml

@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+** Copyright 2009, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="0.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="35"
+        android:duration="83" />
+
+    <translate
+        android:fromXDelta="0"
+        android:toXDelta="96dp"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <extend
+        android:fromExtendLeft="96dp"
+        android:fromExtendTop="0"
+        android:fromExtendRight="0"
+        android:fromExtendBottom="0"
+        android:toExtendLeft="96dp"
+        android:toExtendTop="0"
+        android:toExtendRight="0"
+        android:toExtendBottom="0"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-v33/activity_open_enter.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+/*
+** Copyright 2009, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="50"
+        android:duration="83" />
+
+    <translate
+        android:fromXDelta="96dp"
+        android:toXDelta="0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <extend
+        android:fromExtendLeft="96dp"
+        android:fromExtendTop="0"
+        android:fromExtendRight="0"
+        android:fromExtendBottom="0"
+        android:toExtendLeft="96dp"
+        android:toExtendTop="0"
+        android:toExtendRight="0"
+        android:toExtendBottom="0"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim-v33/activity_open_exit.xml

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+/*
+** Copyright 2009, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/standard_accelerate"
+        android:startOffset="0"
+        android:duration="450" />
+
+    <translate
+        android:fromXDelta="0"
+        android:toXDelta="-96dp"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <extend
+        android:fromExtendLeft="0"
+        android:fromExtendTop="0"
+        android:fromExtendRight="96dp"
+        android:fromExtendBottom="0"
+        android:toExtendLeft="0"
+        android:toExtendTop="0"
+        android:toExtendRight="96dp"
+        android:toExtendBottom="0"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim/activity_close_enter.xml

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+** Copyright 2009, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="0"
+        android:duration="450" />
+
+    <translate
+        android:fromXDelta="-96dp"
+        android:toXDelta="0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim/activity_close_exit.xml

@@ -0,0 +1,42 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+** Copyright 2009, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false"
+    android:zAdjustment="top">
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="0.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="35"
+        android:duration="83" />
+
+    <translate
+        android:fromXDelta="0"
+        android:toXDelta="96dp"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim/activity_open_enter.xml

@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+** Copyright 2009, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+    <alpha
+        android:fromAlpha="0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/linear_interpolator"
+        android:startOffset="50"
+        android:duration="83" />
+
+    <translate
+        android:fromXDelta="96dp"
+        android:toXDelta="0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim/activity_open_exit.xml

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+** Copyright 2009, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shareInterpolator="false">
+    <alpha
+        android:fromAlpha="1.0"
+        android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/standard_accelerate"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+
+    <translate
+        android:fromXDelta="0"
+        android:toXDelta="-96dp"
+        android:fillEnabled="true"
+        android:fillBefore="true"
+        android:fillAfter="true"
+        android:interpolator="@anim/fast_out_extra_slow_in"
+        android:startOffset="0"
+        android:duration="@integer/activity_transition_duration_ms" />
+</set>

core/designsystem/src/main/res/anim/fade_in.xml

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<alpha xmlns:android="http://schemas.android.com/apk/res/android"
-    android:interpolator="@android:anim/linear_interpolator"
-    android:fromAlpha="0"
-    android:toAlpha="1"
-    android:duration="300" />

core/designsystem/src/main/res/anim/fade_out.xml

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<alpha xmlns:android="http://schemas.android.com/apk/res/android"
-    android:interpolator="@android:anim/linear_interpolator"
-    android:fromAlpha="1"
-    android:toAlpha="0"
-    android:duration="300" />

core/designsystem/src/main/res/anim/fast_out_extra_slow_in.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2017 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License
+  -->
+<pathInterpolator xmlns:android="http://schemas.android.com/apk/res/android"
+    android:pathData="M 0,0 C 0.05, 0, 0.133333, 0.06, 0.166666, 0.4 C 0.208333, 0.82, 0.25, 1, 1, 1"/>

core/designsystem/src/main/res/anim/linear_interpolator.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright 2024 Pachli Association
+  ~
+  ~ This file is a part of Pachli.
+  ~
+  ~ This program is free software; you can redistribute it and/or modify it under the terms of the
+  ~ GNU General Public License as published by the Free Software Foundation; either version 3 of the
+  ~ License, or (at your option) any later version.
+  ~
+  ~ Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+  ~ the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+  ~ Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with Pachli; if not,
+  ~ see <http://www.gnu.org/licenses>.
+  -->
+
+<linearInterpolator />

core/designsystem/src/main/res/anim/slide_from_end.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+    <translate android:fromXDelta="100%p" android:toXDelta="0"
+        android:interpolator="@android:anim/accelerate_decelerate_interpolator"
+        android:duration="@integer/activity_slide_transition_duration_ms"/>
+</set>

core/designsystem/src/main/res/anim/slide_from_start.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+    <translate android:fromXDelta="-100%p" android:toXDelta="0"
+        android:interpolator="@android:anim/accelerate_decelerate_interpolator"
+        android:duration="@integer/activity_slide_transition_duration_ms"/>
+</set>

core/designsystem/src/main/res/anim/slide_to_end.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+    <translate android:fromXDelta="0" android:toXDelta="100%p"
+        android:interpolator="@android:anim/accelerate_decelerate_interpolator"
+        android:duration="@integer/activity_slide_transition_duration_ms"/>
+</set>

core/designsystem/src/main/res/anim/slide_to_start.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+    <translate android:fromXDelta="0" android:toXDelta="-100%p"
+        android:interpolator="@android:anim/accelerate_decelerate_interpolator"
+        android:duration="@integer/activity_slide_transition_duration_ms"/>
+</set>

core/designsystem/src/main/res/anim/standard_accelerate.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2021 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<pathInterpolator xmlns:android="http://schemas.android.com/apk/res/android"
+    android:controlX1="0.3"
+    android:controlY1="0"
+    android:controlX2="1"
+    android:controlY2="1"/>

core/designsystem/src/main/res/values/integers.xml

@@ -3,4 +3,10 @@
     <integer name="profile_media_column_count">3</integer>
 
     <integer name="trending_column_count">1</integer>
+
+    <!-- Duration for default activity transition, in ms -->
+    <integer name="activity_transition_duration_ms">450</integer>
+
+    <!-- Duration for slide transition, in ms -->
+    <integer name="activity_slide_transition_duration_ms">200</integer>
 </resources>

core/network/src/main/kotlin/app/pachli/core/network/model/Filter.kt

@@ -11,11 +11,11 @@ import kotlinx.parcelize.Parcelize
 @Parcelize
 @JsonClass(generateAdapter = true)
 data class Filter(
-    val id: String,
+    val id: String = "",
-    val title: String,
+    val title: String = "",
-    @Json(name = "context") val contexts: List<FilterContext>,
+    @Json(name = "context") val contexts: List<FilterContext> = emptyList(),
-    @Json(name = "expires_at") val expiresAt: Date?,
+    @Json(name = "expires_at") val expiresAt: Date? = null,
-    @Json(name = "filter_action") val action: Action,
+    @Json(name = "filter_action") val action: Action = Action.WARN,
     // This should not normally be empty. However, Mastodon does not include
     // this in a status' `filtered.filter` property (it's not null or empty,
     // it's missing) which breaks deserialisation. Patch this by ensuring it's

feature/about/src/main/kotlin/app/pachli/feature/about/AboutActivity.kt

@@ -25,20 +25,30 @@ import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentActivity
 import androidx.viewpager2.adapter.FragmentStateAdapter
 import app.pachli.core.activity.BottomSheetActivity
+import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.designsystem.R as DR
 import app.pachli.core.ui.extensions.reduceSwipeSensitivity
 import app.pachli.feature.about.databinding.ActivityAboutBinding
 import com.bumptech.glide.request.target.FixedSizeDrawable
+import com.google.android.material.tabs.TabLayout
 import com.google.android.material.tabs.TabLayoutMediator
 import com.mikepenz.aboutlibraries.LibsBuilder
 import dagger.hilt.android.AndroidEntryPoint
 
 @AndroidEntryPoint
 class AboutActivity : BottomSheetActivity(), MenuProvider {
+
+    private val binding: ActivityAboutBinding by viewBinding(ActivityAboutBinding::inflate)
+
+    private val onBackPressedCallback = object : OnBackPressedCallback(false) {
+        override fun handleOnBackPressed() {
+            binding.pager.currentItem = 0
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
-        val binding = ActivityAboutBinding.inflate(layoutInflater)
         setContentView(binding.root)
 
         setSupportActionBar(binding.toolbar)
@@ -65,14 +75,17 @@ class AboutActivity : BottomSheetActivity(), MenuProvider {
             tab.text = adapter.title(position)
         }.attach()
 
-        onBackPressedDispatcher.addCallback(
+        binding.tabLayout.addOnTabSelectedListener(object : TabLayout.OnTabSelectedListener {
-            this,
+            override fun onTabSelected(tab: TabLayout.Tab) {
-            object : OnBackPressedCallback(true) {
+                onBackPressedCallback.isEnabled = tab.position > 0
-                override fun handleOnBackPressed() {
+            }
-                    if (binding.pager.currentItem != 0) binding.pager.currentItem = 0 else finish()
+
-                }
+            override fun onTabUnselected(tab: TabLayout.Tab) {}
-            },
+
-        )
+            override fun onTabReselected(tab: TabLayout.Tab) {}
+        })
+
+        onBackPressedDispatcher.addCallback(this, onBackPressedCallback)
     }
 }