Workaround HardwareRenderer breakage in Android 14 (#52370)

- Destroy ImageReaders on memory trim.
- Unset the VirtualDisplay's surface on memory trim.
- On resume, recreate ImageReaders.
- On resume, do a dumb little dance and then set the VirtualDisplay's surface

Fixes: flutter/flutter#146499
Fixes: flutter/flutter#144219

Internal bug: b/335646931
Android Fix: https://googleplex-android-review.git.corp.google.com/c/platform/frameworks/base/+/27015418

Android 15 will include the fix. Unclear if Android 14 will be patched.

Author: johnmccutchan

shell/platform/android/io/flutter/embedding/android/FlutterActivityAndFragmentDelegate.java

@@ -583,6 +583,7 @@ void onPostResume() {
     ensureAlive();
     if (flutterEngine != null) {
       updateSystemUiOverlays();
+      flutterEngine.getPlatformViewsController().onResume();
     } else {
       Log.w(TAG, "onPostResume() invoked before FlutterFragment was attached to an Activity.");
     }
@@ -1020,6 +1021,7 @@ void onTrimMemory(int level) {
         flutterEngine.getSystemChannel().sendMemoryPressureWarning();
       }
       flutterEngine.getRenderer().onTrimMemory(level);
+      flutterEngine.getPlatformViewsController().onTrimMemory(level);
     }
   }
 

shell/platform/android/io/flutter/embedding/engine/renderer/FlutterRenderer.java

@@ -7,6 +7,7 @@
 import static io.flutter.Build.API_LEVELS;
 
 import android.annotation.TargetApi;
+import android.content.ComponentCallbacks2;
 import android.graphics.Bitmap;
 import android.graphics.ImageFormat;
 import android.graphics.Rect;
@@ -418,17 +419,18 @@ final class ImageReaderSurfaceProducer
     // Flip when debugging to see verbose logs.
     private static final boolean VERBOSE_LOGS = false;
 
-    // If we cleanup the ImageReaders on memory pressure it breaks VirtualDisplay
-    // backed platform views. Disable for now as this is only necessary to work
-    // around a Samsung-specific Android 14 bug.
-    private static final boolean CLEANUP_ON_MEMORY_PRESSURE = false;
+    // We must always cleanup on memory pressure on Android 14 due to a bug in Android.
+    // It is safe to do on all versions so we unconditionally have this set to true.
+    private static final boolean CLEANUP_ON_MEMORY_PRESSURE = true;
 
     private final long id;
 
     private boolean released;
     // Will be true in tests and on Android API < 33.
     private boolean ignoringFence = false;
 
+    private boolean trimOnMemoryPressure = CLEANUP_ON_MEMORY_PRESSURE;
+
     // The requested width and height are updated by setSize.
     private int requestedWidth = 1;
     private int requestedHeight = 1;
@@ -442,6 +444,7 @@ final class ImageReaderSurfaceProducer
     private long lastDequeueTime = 0;
     private long lastQueueTime = 0;
     private long lastScheduleTime = 0;
+    private int numTrims = 0;
 
     private Object lock = new Object();
     // REQUIRED: The following fields must only be accessed when lock is held.
@@ -659,9 +662,15 @@ PerImage dequeueImage() {
 
     @Override
     public void onTrimMemory(int level) {
-      if (!CLEANUP_ON_MEMORY_PRESSURE) {
+      if (!trimOnMemoryPressure) {
+        return;
+      }
+      if (level < ComponentCallbacks2.TRIM_MEMORY_BACKGROUND) {
         return;
       }
+      synchronized (lock) {
+        numTrims++;
+      }
       cleanup();
       createNewReader = true;
     }
@@ -878,6 +887,13 @@ public int numImageReaders() {
       }
     }
 
+    @VisibleForTesting
+    public int numTrims() {
+      synchronized (lock) {
+        return numTrims;
+      }
+    }
+
     @VisibleForTesting
     public int numImages() {
       int r = 0;

shell/platform/android/io/flutter/plugin/platform/PlatformViewsController.java

@@ -9,6 +9,7 @@
 import static io.flutter.Build.API_LEVELS;
 
 import android.annotation.TargetApi;
+import android.content.ComponentCallbacks2;
 import android.content.Context;
 import android.content.MutableContextWrapper;
 import android.os.Build;
@@ -1053,6 +1054,24 @@ private void diposeAllViews() {
     }
   }
 
+  // Invoked when the Android system is requesting we reduce memory usage.
+  public void onTrimMemory(int level) {
+    if (level < ComponentCallbacks2.TRIM_MEMORY_BACKGROUND) {
+      return;
+    }
+    for (VirtualDisplayController vdc : vdControllers.values()) {
+      vdc.clearSurface();
+    }
+  }
+
+  // Called after the application has been resumed.
+  // This is where we undo whatever may have been done in onTrimMemory.
+  public void onResume() {
+    for (VirtualDisplayController vdc : vdControllers.values()) {
+      vdc.resetSurface();
+    }
+  }
+
   /**
    * Disposes a single
    *

shell/platform/android/io/flutter/plugin/platform/VirtualDisplayController.java

@@ -284,6 +284,49 @@ public void dispatchTouchEvent(MotionEvent event) {
     presentation.dispatchTouchEvent(event);
   }
 
+  public void clearSurface() {
+    virtualDisplay.setSurface(null);
+  }
+
+  public void resetSurface() {
+    final int width = getRenderTargetWidth();
+    final int height = getRenderTargetHeight();
+    final boolean isFocused = getView().isFocused();
+    final SingleViewPresentation.PresentationState presentationState = presentation.detachState();
+
+    // We detach the surface to prevent it being destroyed when releasing the vd.
+    virtualDisplay.setSurface(null);
+    virtualDisplay.release();
+    final DisplayManager displayManager =
+        (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
+    int flags = 0;
+    virtualDisplay =
+        displayManager.createVirtualDisplay(
+            "flutter-vd#" + viewId,
+            width,
+            height,
+            densityDpi,
+            renderTarget.getSurface(),
+            flags,
+            callback,
+            null /* handler */);
+    // Create a new SingleViewPresentation and show() it before we cancel() the existing
+    // presentation. Calling show() and cancel() in this order fixes
+    // https://github.com/flutter/flutter/issues/26345 and maintains seamless transition
+    // of the contents of the presentation.
+    SingleViewPresentation newPresentation =
+        new SingleViewPresentation(
+            context,
+            virtualDisplay.getDisplay(),
+            accessibilityEventsDelegate,
+            presentationState,
+            focusChangeListener,
+            isFocused);
+    newPresentation.show();
+    presentation.cancel();
+    presentation = newPresentation;
+  }
+
   static class OneTimeOnDrawListener implements ViewTreeObserver.OnDrawListener {
     static void schedule(View view, Runnable runnable) {
       OneTimeOnDrawListener listener = new OneTimeOnDrawListener(view, runnable);

shell/platform/android/test/io/flutter/embedding/engine/renderer/FlutterRendererTest.java

@@ -647,13 +647,41 @@ public void ImageReaderSurfaceProducerTrimMemoryCallback() {
     assertEquals(1, texture.numImageReaders());
     assertEquals(1, texture.numImages());
 
-    // Invoke the onTrimMemory callback.
+    // Invoke the onTrimMemory callback with level 0.
     // This should do nothing.
     texture.onTrimMemory(0);
     shadowOf(Looper.getMainLooper()).idle();
 
     assertEquals(1, texture.numImageReaders());
     assertEquals(1, texture.numImages());
+    assertEquals(0, texture.numTrims());
+
+    // Invoke the onTrimMemory callback with level 40.
+    // This should result in a trim.
+    texture.onTrimMemory(40);
+    shadowOf(Looper.getMainLooper()).idle();
+
+    assertEquals(0, texture.numImageReaders());
+    assertEquals(0, texture.numImages());
+    assertEquals(1, texture.numTrims());
+
+    // Request the surface, this should result in a new image reader.
+    surface = texture.getSurface();
+    assertEquals(1, texture.numImageReaders());
+    assertEquals(0, texture.numImages());
+    assertEquals(1, texture.numTrims());
+
+    // Render an image.
+    canvas = surface.lockHardwareCanvas();
+    canvas.drawARGB(255, 255, 0, 0);
+    surface.unlockCanvasAndPost(canvas);
+
+    // Let callbacks run, this will produce a single frame.
+    shadowOf(Looper.getMainLooper()).idle();
+
+    assertEquals(1, texture.numImageReaders());
+    assertEquals(1, texture.numImages());
+    assertEquals(1, texture.numTrims());
   }
 
   // A 0x0 ImageReader is a runtime error.