Hide dot indicator in fullscreen album

app/src/main/java/org/pixeldroid/app/posts/AlbumActivity.kt

@@ -2,7 +2,6 @@ package org.pixeldroid.app.posts
 
 import android.os.Bundle
 import android.view.MenuItem
-import android.view.MotionEvent
 import android.view.View
 import androidx.activity.viewModels
 import androidx.appcompat.app.AppCompatActivity
@@ -12,6 +11,7 @@ import androidx.core.view.WindowInsetsControllerCompat
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
 import androidx.lifecycle.repeatOnLifecycle
+import androidx.viewpager2.widget.ViewPager2
 import kotlinx.coroutines.launch
 import org.pixeldroid.app.databinding.ActivityAlbumBinding
 
@@ -25,29 +25,43 @@ class AlbumActivity : AppCompatActivity() {
         val binding = ActivityAlbumBinding.inflate(layoutInflater)
         setContentView(binding.root)
 
-        binding.albumPager.adapter = AlbumViewPagerAdapter(model.uiState.value.mediaAttachments,
+        binding.albumPager.adapter = AlbumViewPagerAdapter(
+            model.uiState.value.mediaAttachments,
             sensitive = false,
             opened = true,
             //In the activity, we assume we want to show everything
             alwaysShowNsfw = true,
             clickCallback = ::clickCallback
         )
-        binding.albumPager.currentItem = model.uiState.value.index
+
+        binding.albumPager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
+            override fun onPageSelected(position: Int) { model.positionSelected(position) }
+        })
 
         if (model.uiState.value.mediaAttachments.size == 1) {
             binding.albumPager.isUserInputEnabled = false
-        }
+        } else if ((model.uiState.value.mediaAttachments.size) > 1) {
-        else if ((model.uiState.value.mediaAttachments.size) > 1) {
             binding.postIndicator.setViewPager(binding.albumPager)
             binding.postIndicator.visibility = View.VISIBLE
         } else {
             binding.postIndicator.visibility = View.GONE
         }
 
+        // Not really necessary because the ViewPager saves its state in onSaveInstanceState, but
+        // it's good to stay consistent in case something gets out of sync
+        binding.albumPager.setCurrentItem(model.uiState.value.index, false)
+
         supportActionBar?.setDisplayHomeAsUpEnabled(true)
         supportActionBar?.setDisplayShowTitleEnabled(false)
         supportActionBar?.setBackgroundDrawable(null)
 
+        lifecycleScope.launch {
+            repeatOnLifecycle(Lifecycle.State.STARTED) {
+                model.uiState.collect { uiState ->
+                    binding.albumPager.currentItem = uiState.index
+                }
+            }
+        }
         lifecycleScope.launch {
             repeatOnLifecycle(Lifecycle.State.STARTED) {
                 model.isActionBarHidden.collect { isActionBarHidden ->
@@ -60,6 +74,7 @@ class AlbumActivity : AppCompatActivity() {
                         // Hide both the status bar and the navigation bar
                         supportActionBar?.hide()
                         windowInsetsController.hide(WindowInsetsCompat.Type.systemBars())
+                        binding.postIndicator.visibility = View.GONE
                     } else {
                         // Configure the behavior of the hidden system bars
                         windowInsetsController.systemBarsBehavior =
@@ -67,6 +82,9 @@ class AlbumActivity : AppCompatActivity() {
                         // Show both the status bar and the navigation bar
                         supportActionBar?.show()
                         windowInsetsController.show(WindowInsetsCompat.Type.systemBars())
+                        if ((model.uiState.value.mediaAttachments.size) > 1) {
+                            binding.postIndicator.visibility = View.VISIBLE
+                        }
                     }
                 }
             }

app/src/main/java/org/pixeldroid/app/posts/AlbumViewModel.kt

@@ -17,10 +17,6 @@ data class AlbumUiState(
 
 @HiltViewModel
 class AlbumViewModel @Inject constructor(state: SavedStateHandle) : ViewModel() {
-    fun barHide() {
-        _isActionBarHidden.update { !it }
-    }
-
     companion object {
         const val ALBUM_IMAGES = "AlbumViewImages"
         const val ALBUM_INDEX = "AlbumViewIndex"
@@ -39,4 +35,12 @@ class AlbumViewModel @Inject constructor(state: SavedStateHandle) : ViewModel()
 
     val uiState: StateFlow<AlbumUiState> = _uiState.asStateFlow()
     val isActionBarHidden: StateFlow<Boolean> = _isActionBarHidden
+
+    fun barHide() {
+        _isActionBarHidden.update { !it }
+    }
+
+    fun positionSelected(position: Int) {
+        _uiState.update { it.copy(index = position) }
+    }
 }