Floating date

Closes https://github.com/SchildiChat/SchildiChat-android/issues/41

Change-Id: I0eb9c6c3800309be40a1f5bc0c4420bd4066c098

FEATURES.md

@@ -9,6 +9,7 @@ Here you can find some extra features and changes compared to Element Android (w
 - Possibility to select themes for both light and dark system mode individually
 - [UnifiedPush](https://unifiedpush.org/) support
 - "Easy mode" which disables public room functionality
+- Floating date
 - Setting for room previews: show all events, hide membership changes, hide membership changes and reactions (individual settings for direct chats and groups)
 - More prominent unread counter for chats in the room overview (bigger, different placement, more noticeable color in SchildiChat designs)
 - Mark chats as unread ([MSC2867](https://github.com/matrix-org/matrix-spec-proposals/pull/2867), only works with compatible clients (SchildiChat, FluffyChat))

vector/src/main/java/de/spiritcroc/recyclerview/StickyHeaderItemDecoration.kt

@@ -0,0 +1,210 @@
+package de.spiritcroc.recyclerview
+
+/**
+ * Source: https://gist.github.com/jonasbark/f1e1373705cfe8f6a7036763f7326f7c
+ * Modified to
+ * - make isHeader() abstract, so we don't need a predefined list of header ids
+ * - not require EpoxyRecyclerView
+ * - work with reverse layouts
+ * - hide the currently overlaid header for a smoother animation without duplicate headers
+ */
+
+import android.graphics.Canvas
+import android.view.View
+import android.view.ViewGroup
+import androidx.core.view.isVisible
+import androidx.recyclerview.widget.RecyclerView
+import com.airbnb.epoxy.EpoxyController
+import org.matrix.android.sdk.api.extensions.orFalse
+
+abstract class StickyHeaderItemDecoration(
+    private val epoxyController: EpoxyController,
+    private val reverse: Boolean = false
+) : RecyclerView.ItemDecoration() {
+    private var mStickyHeaderHeight: Int = 0
+
+    private var lastHeaderPos: Int? = null
+
+    override fun onDrawOver(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
+        super.onDrawOver(c, parent, state)
+
+        if (parent.childCount == 0) {
+            return
+        }
+        val topChild = if (reverse) {
+            parent.getChildAt(parent.childCount - 1) ?: return
+        } else {
+            parent.getChildAt(0) ?: return
+        }
+
+        val topChildPosition = parent.getChildAdapterPosition(topChild)
+        if (topChildPosition == RecyclerView.NO_POSITION) {
+            return
+        }
+
+        val headerPos = getHeaderPositionForItem(topChildPosition)
+        if (headerPos != RecyclerView.NO_POSITION) {
+            val currentHeader = getHeaderViewForItem(headerPos, parent)
+            fixLayoutSize(parent, currentHeader)
+            val contactPoint = currentHeader.bottom
+            val childInContact = getChildInContact(parent, contactPoint, headerPos)
+
+            if (childInContact != null && isHeader(parent.getChildAdapterPosition(childInContact))) {
+                updateOverlaidHeaders(parent, headerPos)
+                moveHeader(c, currentHeader, childInContact)
+                return
+            }
+
+            // Un-hide views early, so we don't get flashing headers while scrolling
+            val childBellow = getChildInContact(parent, currentHeader.top, headerPos)
+            val overlaidHeaderPos: Int? = if (childBellow != childInContact &&
+                    childBellow != null &&
+                    isHeader(parent.getChildAdapterPosition(childBellow)) &&
+                    contactPoint - childBellow.bottom < (childBellow.bottom - childBellow.top)/8
+            ) {
+                null
+            } else {
+                headerPos
+            }
+
+            updateOverlaidHeaders(parent, overlaidHeaderPos)
+            drawHeader(c, currentHeader)
+        } else {
+            // Show hidden header again
+            updateOverlaidHeaders(parent, null)
+        }
+    }
+
+    private fun updateOverlaidHeaders(parent: RecyclerView, headerPos: Int?) {
+        if (lastHeaderPos != headerPos) {
+            // Show hidden header again
+            lastHeaderPos?.let {
+                updateOverlaidHeader(parent, it, false)
+            }
+            // Remember new hidden header
+            lastHeaderPos = if (headerPos?.let { updateOverlaidHeader(parent, it, true) }.orFalse()) {
+                headerPos
+            } else {
+                null
+            }
+        }
+    }
+
+    /**
+     * Return true if successfully updated the view.
+     * Note: this has some issues when invisible views get recycled, better override this in subclasses.
+     */
+    open fun updateOverlaidHeader(parent: RecyclerView, position: Int, isCurrentlyOverlaid: Boolean): Boolean {
+        val view = parent.findViewHolderForAdapterPosition(position)?.itemView
+        if (view != null) {
+            view.isVisible = !isCurrentlyOverlaid
+            return true
+        }
+        return false
+    }
+
+    open fun getHeaderViewForItem(headerPosition: Int, parent: RecyclerView): View {
+        val viewHolder = epoxyController.adapter.onCreateViewHolder(
+            parent,
+            epoxyController.adapter.getItemViewType(headerPosition)
+        )
+        epoxyController.adapter.onBindViewHolder(viewHolder, headerPosition)
+        return viewHolder.itemView
+    }
+
+    private fun drawHeader(c: Canvas, header: View) {
+        c.save()
+        c.translate(0f, 0f)
+        header.draw(c)
+        c.restore()
+    }
+
+    private fun moveHeader(c: Canvas, currentHeader: View, nextHeader: View) {
+        c.save()
+        c.translate(0f, (nextHeader.top - currentHeader.height).toFloat())
+        currentHeader.draw(c)
+        c.restore()
+    }
+
+    abstract fun isHeader(itemPosition: Int): Boolean
+
+    private fun getChildInContact(parent: RecyclerView, contactPoint: Int, currentHeaderPos: Int): View? {
+        var childInContact: View? = null
+        for (i in 0 until parent.childCount) {
+            var heightTolerance = 0
+            val child = parent.getChildAt(i)
+
+            //measure height tolerance with child if child is another header
+            if (currentHeaderPos != i) {
+                val isChildHeader = isHeader(parent.getChildAdapterPosition(child))
+                if (isChildHeader) {
+                    heightTolerance = mStickyHeaderHeight - child.height
+                }
+            }
+
+            //add heightTolerance if child top be in display area
+            val childBottomPosition = if (child.top > 0) {
+                child.bottom + heightTolerance
+            } else {
+                child.bottom
+            }
+
+            if (childBottomPosition > contactPoint) {
+                if (child.top <= contactPoint) {
+                    // This child overlaps the contactPoint
+                    childInContact = child
+                    break
+                }
+            }
+        }
+        return childInContact
+    }
+
+
+    /**
+     * This method gets called by [StickyHeaderItemDecoration] to fetch the position of the header item in the adapter
+     * that is used for (represents) item at specified position.
+     * @param itemPosition int. Adapter's position of the item for which to do the search of the position of the header item.
+     * @return int. Position of the header item in the adapter.
+     */
+    private fun getHeaderPositionForItem(itemPosition: Int): Int {
+        var tempPosition = itemPosition
+        var headerPosition = RecyclerView.NO_POSITION
+        val directionAdd = if (reverse) 1 else -1
+        do {
+            if (isHeader(tempPosition)) {
+                headerPosition = tempPosition
+                break
+            }
+            tempPosition += directionAdd
+        } while (tempPosition >= -1 && tempPosition < epoxyController.adapter.itemCount)
+        return headerPosition
+    }
+
+    /**
+     * Properly measures and layouts the top sticky header.
+     * @param parent ViewGroup: RecyclerView in this case.
+     */
+    private fun fixLayoutSize(parent: ViewGroup, view: View) {
+
+        // Specs for parent (RecyclerView)
+        val widthSpec = View.MeasureSpec.makeMeasureSpec(parent.width, View.MeasureSpec.EXACTLY)
+        val heightSpec = View.MeasureSpec.makeMeasureSpec(parent.height, View.MeasureSpec.UNSPECIFIED)
+
+        // Specs for children (headers)
+        val childWidthSpec =
+            ViewGroup.getChildMeasureSpec(widthSpec, parent.paddingLeft + parent.paddingRight, view.layoutParams.width)
+        val childHeightSpec = ViewGroup.getChildMeasureSpec(
+            heightSpec,
+            parent.paddingTop + parent.paddingBottom,
+            view.layoutParams.height
+        )
+
+        view.measure(childWidthSpec, childHeightSpec)
+
+        mStickyHeaderHeight = view.measuredHeight
+
+        view.layout(0, 0, view.measuredWidth, view.measuredHeight)
+    }
+
+}

vector/src/main/java/im/vector/app/features/home/room/detail/TimelineFragment.kt

@@ -62,6 +62,7 @@ import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.RecyclerView
 import androidx.transition.TransitionManager
 import com.airbnb.epoxy.EpoxyModel
+import com.airbnb.epoxy.EpoxyViewHolder
 import com.airbnb.epoxy.OnModelBuildFinishedListener
 import com.airbnb.epoxy.addGlidePreloader
 import com.airbnb.epoxy.glidePreloader
@@ -72,10 +73,12 @@ import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import com.vanniktech.emoji.EmojiPopup
 import de.spiritcroc.matrixsdk.util.DbgUtil
 import de.spiritcroc.matrixsdk.util.Dimber
+import de.spiritcroc.recyclerview.StickyHeaderItemDecoration
 import de.spiritcroc.recyclerview.widget.BetterLinearLayoutManager
 import de.spiritcroc.recyclerview.widget.LinearLayoutManager
 import im.vector.app.R
 import im.vector.app.core.animations.play
+import im.vector.app.core.date.DateFormatKind
 import im.vector.app.core.dialogs.ConfirmationDialogBuilder
 import im.vector.app.core.dialogs.GalleryOrCameraDialogHelper
 import im.vector.app.core.epoxy.LayoutManagerStateRestorer
@@ -167,6 +170,7 @@ import im.vector.app.features.home.room.detail.timeline.helper.AudioMessagePlayb
 import im.vector.app.features.home.room.detail.timeline.helper.MatrixItemColorProvider
 import im.vector.app.features.home.room.detail.timeline.image.buildImageContentRendererData
 import im.vector.app.features.home.room.detail.timeline.item.AbsMessageItem
+import im.vector.app.features.home.room.detail.timeline.item.DaySeparatorItem
 import im.vector.app.features.home.room.detail.timeline.item.ItemWithEvents
 import im.vector.app.features.home.room.detail.timeline.item.MessageAudioItem
 import im.vector.app.features.home.room.detail.timeline.item.MessageFileItem
@@ -220,6 +224,7 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import org.billcarsonfr.jsonviewer.JSonViewerDialog
 import org.commonmark.parser.Parser
+import org.matrix.android.sdk.api.extensions.tryOrNull
 import org.matrix.android.sdk.api.session.Session
 import org.matrix.android.sdk.api.session.content.ContentAttachmentData
 import org.matrix.android.sdk.api.session.events.model.EventType
@@ -1478,6 +1483,46 @@ class TimelineFragment @Inject constructor(
         timelineEventController.callback = this
         timelineEventController.timeline = timelineViewModel.timeline
 
+        if (vectorPreferences.floatingDate()) {
+            views.timelineRecyclerView.addItemDecoration(
+                    object : StickyHeaderItemDecoration(timelineEventController, reverse = true) {
+                        override fun isHeader(itemPosition: Int): Boolean {
+                            if (itemPosition != RecyclerView.NO_POSITION) {
+                                val model = timelineEventController.adapter.getModelAtPosition(itemPosition)
+                                return model is DaySeparatorItem
+                            }
+                            return false
+                        }
+
+                        override fun getHeaderViewForItem(headerPosition: Int, parent: RecyclerView): View {
+                            // Same as super
+                            val viewHolder = timelineEventController.adapter.onCreateViewHolder(
+                                    parent,
+                                    timelineEventController.adapter.getItemViewType(headerPosition)
+                            )
+                            timelineEventController.adapter.onBindViewHolder(viewHolder, headerPosition)
+                            // Same as super -- end
+
+                            // We want to hide the separator line for floating dates
+                            (viewHolder.holder as? DaySeparatorItem.Holder)?.let { DaySeparatorItem.asFloatingDate(it) }
+
+                            return viewHolder.itemView
+                        }
+
+                        // While the header has a sticky overlay, only hide its text, not the separator lines
+                        override fun updateOverlaidHeader(parent: RecyclerView, position: Int, isCurrentlyOverlaid: Boolean): Boolean {
+                            val model = tryOrNull { timelineEventController.adapter.getModelAtPosition(position) as? DaySeparatorItem }
+                            if (model != null) {
+                                val viewHolder = ((parent.findViewHolderForAdapterPosition(position) as? EpoxyViewHolder)?.holder) as? DaySeparatorItem.Holder
+                                model.shouldBeVisible(!isCurrentlyOverlaid, viewHolder)
+                                return true
+                            }
+                            return false
+                        }
+                    }
+            )
+        }
+
         views.timelineRecyclerView.trackItemsVisibilityChange()
         layoutManager = object : BetterLinearLayoutManager(context, RecyclerView.VERTICAL, true) {
             override fun onLayoutCompleted(state: RecyclerView.State?) {

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/item/DaySeparatorItem.kt

@@ -16,7 +16,9 @@
 
 package im.vector.app.features.home.room.detail.timeline.item
 
+import android.view.View
 import android.widget.TextView
+import androidx.core.view.isVisible
 import com.airbnb.epoxy.EpoxyAttribute
 import com.airbnb.epoxy.EpoxyModelClass
 import com.airbnb.epoxy.EpoxyModelWithHolder
@@ -28,12 +30,32 @@ abstract class DaySeparatorItem : EpoxyModelWithHolder<DaySeparatorItem.Holder>(
 
     @EpoxyAttribute lateinit var formattedDay: String
 
+    private var shouldBeVisible: Boolean = true
+
     override fun bind(holder: Holder) {
         super.bind(holder)
         holder.dayTextView.text = formattedDay
+        // Just as background space reservation. Use same text for proper measures.
+        holder.dayTextCutoutView.text = formattedDay
+        // As we may hide this for floating dates, ensure we un-hide it on bind
+        holder.dayTextView.isVisible = shouldBeVisible
+    }
+
+    fun shouldBeVisible(shouldBeVisible: Boolean, holder: Holder?) {
+        holder?.dayTextView?.isVisible = shouldBeVisible
+        this.shouldBeVisible = shouldBeVisible
+    }
+
+    companion object {
+        fun asFloatingDate(holder: Holder) {
+            holder.dayTextView.isVisible = true
+            holder.separatorView.isVisible = false
+        }
     }
 
     class Holder : VectorEpoxyHolder() {
         val dayTextView by bind<TextView>(R.id.itemDayTextView)
+        val dayTextCutoutView by bind<TextView>(R.id.itemDayTextCutoutView)
+        val separatorView by bind<View>(R.id.itemDayTextSeparatorView)
     }
 }

vector/src/main/java/im/vector/app/features/settings/VectorPreferences.kt

@@ -222,6 +222,7 @@ class VectorPreferences @Inject constructor(
         private const val SETTINGS_HIDE_CALL_BUTTONS = "SETTINGS_HIDE_CALL_BUTTONS"
         private const val SETTINGS_READ_RECEIPT_FOLLOWS_READ_MARKER = "SETTINGS_READ_RECEIPT_FOLLOWS_READ_MARKER"
         private const val SETTINGS_SHOW_OPEN_ANONYMOUS = "SETTINGS_SHOW_OPEN_ANONYMOUS"
+        private const val SETTINGS_FLOATING_DATE = "SETTINGS_FLOATING_DATE"
 
         private const val DID_ASK_TO_ENABLE_SESSION_PUSH = "DID_ASK_TO_ENABLE_SESSION_PUSH"
 
@@ -1133,6 +1134,10 @@ class VectorPreferences @Inject constructor(
         return defaultPrefs.getBoolean(SETTINGS_SHOW_OPEN_ANONYMOUS, false)
     }
 
+    fun floatingDate(): Boolean {
+        return defaultPrefs.getBoolean(SETTINGS_FLOATING_DATE, true)
+    }
+
     /**
      * I likely do more fresh installs of the app than anyone else, so a shortcut to change some of the default settings to
      * my preferred values can safe me some time
@@ -1158,6 +1163,7 @@ class VectorPreferences @Inject constructor(
                 .putBoolean(SETTINGS_ENABLE_SPACE_PAGER, true)
                 .putBoolean(SETTINGS_READ_RECEIPT_FOLLOWS_READ_MARKER, true)
                 .putBoolean(SETTINGS_SHOW_OPEN_ANONYMOUS, true)
+                .putBoolean(SETTINGS_FLOATING_DATE, true)
                 .apply()
     }
 

vector/src/main/res/drawable/date_background.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<shape
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+
+    <solid android:color="?android:colorBackground" />
+
+    <corners android:radius="3dp" />
+
+</shape>

vector/src/main/res/layout/item_timeline_event_day_separator.xml

@@ -6,6 +6,10 @@
     android:padding="8dp"
     tools:viewBindingIgnore="true">
 
+    <FrameLayout
+        android:id="@+id/itemDayTextSeparatorView"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
     <View
         android:layout_width="match_parent"
         android:layout_height="1dp"
@@ -13,6 +17,20 @@
         android:layout_marginStart="8dp"
         android:layout_marginEnd="8dp"
         android:background="?vctr_list_separator" />
+    <!-- Just to reserve some extra space while not floating. So use invisible text. -->
+    <TextView
+        android:id="@+id/itemDayTextCutoutView"
+        style="@style/Widget.Vector.TextView.Subtitle"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        android:background="?android:colorBackground"
+        android:textColor="@android:color/transparent"
+        android:paddingStart="24dp"
+        android:paddingEnd="24dp"
+        android:textSize="15sp"
+        tools:text="@tools:sample/date/day_of_week" />
+    </FrameLayout>
 
     <TextView
         android:id="@+id/itemDayTextView"
@@ -20,9 +38,9 @@
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_gravity="center"
-        android:background="?android:colorBackground"
-        android:paddingStart="24dp"
-        android:paddingEnd="24dp"
+        android:background="@drawable/date_background"
+        android:paddingStart="8dp"
+        android:paddingEnd="8dp"
         android:textColor="?vctr_content_tertiary"
         android:textSize="15sp"
         tools:text="@tools:sample/date/day_of_week" />

vector/src/main/res/values/strings_sc.xml

@@ -191,4 +191,8 @@
     <string name="room_list_quick_actions_open_anonymous">Open without reading</string>
     <string name="settings_show_open_anonymous">Open without reading</string>
     <string name="settings_show_open_anonymous_summary">Show option to open a room without automatically marking it read</string>
+
+    <string name="settings_floating_date">Floating date</string>
+    <string name="settings_floating_date_summary">Show the date on top of messages while scrolling</string>
+
 </resources>

vector/src/main/res/xml/vector_settings_preferences.xml

@@ -243,6 +243,12 @@
             android:title="@string/settings_vibrate_on_mention"
             app:isPreferenceVisible="@bool/false_not_implemented" />
 
+        <im.vector.app.core.preference.VectorSwitchPreference
+            android:key="SETTINGS_FLOATING_DATE"
+            android:title="@string/settings_floating_date"
+            android:summary="@string/settings_floating_date_summary"
+            android:defaultValue="true" />
+
     </im.vector.app.core.preference.VectorPreferenceCategory>
 
     <im.vector.app.core.preference.VectorPreferenceCategory