Fix: The Background and Overlay ImageView leak

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

@@ -1289,6 +1289,13 @@ public void detachFromFlutterEngine() {
     }
     renderSurface.detachFromRenderer();
 
+    releaseImageView();
+
+    previousRenderSurface = null;
+    flutterEngine = null;
+  }
+
+  private void releaseImageView() {
     if (flutterImageView != null) {
       flutterImageView.closeImageReader();
       // Remove the FlutterImageView that was previously added by {@code convertToImageView} to
@@ -1297,8 +1304,6 @@ public void detachFromFlutterEngine() {
       removeView(flutterImageView);
       flutterImageView = null;
     }
-    previousRenderSurface = null;
-    flutterEngine = null;
   }
 
   @VisibleForTesting
@@ -1352,14 +1357,12 @@ public void revertImageView(@NonNull Runnable onDone) {
     }
     renderSurface = previousRenderSurface;
     previousRenderSurface = null;
-    if (flutterEngine == null) {
-      flutterImageView.detachFromRenderer();
-      onDone.run();
-      return;
-    }
+
     final FlutterRenderer renderer = flutterEngine.getRenderer();
-    if (renderer == null) {
+
+    if (flutterEngine == null || renderer == null) {
       flutterImageView.detachFromRenderer();
+      releaseImageView();
       onDone.run();
       return;
     }
@@ -1377,6 +1380,7 @@ public void onFlutterUiDisplayed() {
             onDone.run();
             if (!(renderSurface instanceof FlutterImageView) && flutterImageView != null) {
               flutterImageView.detachFromRenderer();
+              releaseImageView();
             }
           }
 

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

@@ -1205,6 +1205,7 @@ private void finishFrame(boolean isFrameRenderedUsingImageReaders) {
         }
         // Hide overlay surfaces that aren't rendered in the current frame.
         overlayView.setVisibility(View.GONE);
+        flutterView.removeView(overlayView);
       }
     }
 
@@ -1297,4 +1298,9 @@ private void removeOverlaySurfaces() {
     }
     overlayLayerViews.clear();
   }
+
+  @VisibleForTesting
+  public SparseArray<PlatformOverlayView> getOverlayLayerViews() {
+    return overlayLayerViews;
+  }
 }

shell/platform/android/test/io/flutter/plugin/platform/PlatformViewsControllerTest.java

@@ -2,6 +2,8 @@
 
 import static android.os.Looper.getMainLooper;
 import static io.flutter.embedding.engine.systemchannels.PlatformViewsChannel.PlatformViewTouch;
+import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.assertTrue;
 import static org.junit.Assert.*;
 import static org.mockito.ArgumentMatchers.*;
 import static org.mockito.Mockito.*;
@@ -1214,6 +1216,74 @@ public void reattachToFlutterView() {
     verify(newFlutterView, times(1)).addView(any(PlatformViewWrapper.class));
   }
 
+  @Config(
+      shadows = {
+        ShadowFlutterSurfaceView.class,
+        ShadowFlutterJNI.class,
+        ShadowPlatformTaskQueue.class
+      })
+  public void revertImageViewAndRemoveImageView() {
+    final PlatformViewsController platformViewsController = new PlatformViewsController();
+
+    final int platformViewId = 0;
+    assertNull(platformViewsController.getPlatformViewById(platformViewId));
+
+    final PlatformViewFactory viewFactory = mock(PlatformViewFactory.class);
+    final PlatformView platformView = mock(PlatformView.class);
+    final View androidView = mock(View.class);
+    when(platformView.getView()).thenReturn(androidView);
+    when(viewFactory.create(any(), eq(platformViewId), any())).thenReturn(platformView);
+
+    platformViewsController.getRegistry().registerViewFactory("testType", viewFactory);
+
+    final FlutterJNI jni = new FlutterJNI();
+    jni.attachToNative();
+
+    final FlutterView flutterView = attach(jni, platformViewsController);
+
+    jni.onFirstFrame();
+
+    // Simulate create call from the framework.
+    createPlatformView(jni, platformViewsController, platformViewId, "testType", /* hybrid=*/ true);
+
+    // The simulation creates an Overlay on top of the PlatformView
+    // This is going to be called `flutterView.convertToImageView`
+    platformViewsController.createOverlaySurface();
+    platformViewsController.onDisplayOverlaySurface(platformViewId, 0, 0, 10, 10);
+
+    // This will contain three views: Background ImageView、PlatformView、Overlay ImageView
+    assertEquals(flutterView.getChildCount(), 3);
+
+    FlutterImageView imageView = flutterView.getCurrentImageSurface();
+
+    // Make sure the ImageView is inside the current FlutterView.
+    assertTrue(imageView != null);
+    assertTrue(flutterView.indexOfChild(imageView) != -1);
+
+    // Make sure the overlayView is inside the current FlutterView
+    assertTrue(platformViewsController.getOverlayLayerViews().size() != 0);
+    PlatformOverlayView overlayView = platformViewsController.getOverlayLayerViews().get(0);
+    assertTrue(overlayView != null);
+    assertTrue(flutterView.indexOfChild(overlayView) != -1);
+
+    // Simulate in a new frame, there's no PlatformView, which is called
+    // `flutterView.revertImageView`. And register a `FlutterUiDisplayListener` callback.
+    // During callback execution it will invoke `flutterImageView.detachFromRenderer()`.
+    platformViewsController.onBeginFrame();
+    platformViewsController.onEndFrame();
+
+    // Invoke all registered `FlutterUiDisplayListener` callback
+    jni.onFirstFrame();
+
+    assertEquals(null, flutterView.getCurrentImageSurface());
+
+    // Make sure the background ImageVIew is not in the FlutterView
+    assertTrue(flutterView.indexOfChild(imageView) == -1);
+
+    // Make sure the overlay ImageVIew is not in the FlutterView
+    assertTrue(flutterView.indexOfChild(overlayView) == -1);
+  }
+
   private static ByteBuffer encodeMethodCall(MethodCall call) {
     final ByteBuffer buffer = StandardMethodCodec.INSTANCE.encodeMethodCall(call);
     buffer.rewind();