Slightly optimize subtitles view & workaround possible crash (#1334)

## Description
Instead of adding/removing the `SubtitleView` from composition
sometimes, instead toggle its visibility. This is technically slightly
more efficient. There's also a couple other minor tweaks that make the
subtitles style a little more efficient.

This should also help prevent crash caused by possible a race condition
in libass-android
(https://github.com/peerless2012/libass-android/issues/75).

### Related issues
I think this fixes #1322

### Testing
Emulator mostly

## Screenshots
N/A

## AI or LLM usage
None

app/src/main/java/com/github/damontecres/wholphin/ui/playback/PlaybackPage.kt

@@ -1,6 +1,7 @@
 package com.github.damontecres.wholphin.ui.playback
 
 import android.view.Gravity
+import android.view.View
 import android.view.ViewGroup
 import android.widget.FrameLayout
 import androidx.activity.compose.BackHandler
@@ -28,6 +29,7 @@ import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableLongStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
@@ -35,12 +37,12 @@ import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.draw.alpha
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.focus.FocusRequester
 import androidx.compose.ui.focus.focusRequester
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.RectangleShape
+import androidx.compose.ui.graphics.graphicsLayer
 import androidx.compose.ui.input.key.onKeyEvent
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.layout.onSizeChanged
@@ -74,7 +76,6 @@ import com.github.damontecres.wholphin.ui.AspectRatios
 import com.github.damontecres.wholphin.ui.LocalImageUrlService
 import com.github.damontecres.wholphin.ui.components.ErrorMessage
 import com.github.damontecres.wholphin.ui.components.LoadingPage
-import com.github.damontecres.wholphin.ui.ifElse
 import com.github.damontecres.wholphin.ui.nav.Destination
 import com.github.damontecres.wholphin.ui.playback.overlay.PauseIndicator
 import com.github.damontecres.wholphin.ui.playback.overlay.PlaybackAction
@@ -435,9 +436,9 @@ fun PlaybackPageContent(
                 remember(subtitleSettings) { subtitleSettings.imageSubtitleOpacity / 100f }
 
             // Subtitles
-            if (skipIndicatorDuration == 0L && currentItemPlayback.subtitleIndexEnabled && !presentationState.coverSurface) {
-                val maxSize by animateFloatAsState(if (controllerViewState.controlsVisible) .7f else 1f)
+            val subtitleMaxSize by animateFloatAsState(if (controllerViewState.controlsVisible) .7f else 1f)
             val isImageSubtitles = remember(cues) { cues.firstOrNull()?.bitmap != null }
+            var cueCount by remember { mutableIntStateOf(0) }
             AndroidView(
                 factory = { context ->
                     SubtitleView(context).apply {
@@ -463,16 +464,24 @@ fun PlaybackPageContent(
                         }
                     }
                 },
-                    update = {
-                        it.setCues(cues)
+                update = { subtitleView ->
+                    val subtitleVisible =
+                        skipIndicatorDuration == 0L && currentItemPlayback.subtitleIndexEnabled && !presentationState.coverSurface
+                    subtitleView.visibility = if (subtitleVisible) View.VISIBLE else View.INVISIBLE
+
+                    subtitleView.setCues(cues)
+                    if (cues.size > cueCount) {
+                        // The output creates a painter for each cue, so need to apply the changes when the number of cues increases
                         Media3SubtitleOverride(subtitleSettings.calculateEdgeSize(density))
-                            .apply(it)
-                        it.children.firstOrNull { it is AssSubtitleView }?.let {
+                            .apply(subtitleView)
+                        cueCount = cues.size
+                    }
+                    subtitleView.children.firstOrNull { it is AssSubtitleView }?.let {
                         (it as? AssSubtitleView)?.apply {
                             val resized =
                                 layoutParams.let { it.width != playerSurfaceSize.width || it.height != playerSurfaceSize.height }
                             if (resized) {
-                                    Timber.v("Resizing AssSubtitleView: $playerSurfaceSize")
+                                Timber.v("Resizing AssSubtitleView: %s", playerSurfaceSize)
                                 layoutParams =
                                     FrameLayout
                                         .LayoutParams(
@@ -488,13 +497,14 @@ fun PlaybackPageContent(
                 },
                 modifier =
                     Modifier
-                            .fillMaxSize(maxSize)
+                        .fillMaxSize(subtitleMaxSize)
                         .align(Alignment.TopCenter)
                         .background(Color.Transparent)
-                            .ifElse(isImageSubtitles, Modifier.alpha(subtitleImageOpacity)),
+                        .graphicsLayer {
+                            alpha = if (isImageSubtitles) subtitleImageOpacity else 1f
+                        },
             )
         }
-        }
 
         // Ask to skip intros, etc button
         AnimatedVisibility(