Reenable HardwareBuffer backed Android Platform Views on SDK >= 29 (flutter/engine#44790)

- Fix a bug in the SDK < 33 ImageReader construction code path.
- Fix a bug that resulted in references to Images produced by a closed
ImageReader.
- Fix an order of operations bug in ImageReaderPlatformViewRenderTarget
release/finalizer code path.
- Enable HardwareBuffer backed Android Platform Views on SDK >= 29

Manually tested on device rotating and shutting down the app.

engine/src/flutter/shell/platform/android/hardware_buffer_external_texture.cc

@@ -39,7 +39,8 @@ void HardwareBufferExternalTexture::Paint(PaintContext& context,
         flutter::DlCanvas::SrcRectConstraint::kStrict  // enforce edges
     );
   } else {
-    FML_LOG(WARNING) << "No DlImage available.";
+    FML_LOG(WARNING)
+        << "No DlImage available for HardwareBufferExternalTexture to paint.";
   }
 }
 

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

@@ -322,6 +322,7 @@ public class FlutterRenderer implements TextureRegistry {
 
   @Keep
   final class ImageTextureRegistryEntry implements TextureRegistry.ImageTextureEntry {
+    private static final String TAG = "ImageTextureRegistryEntry";
     private final long id;
     private boolean released;
     private Image image;
@@ -356,8 +357,10 @@ public class FlutterRenderer implements TextureRegistry {
       if (toClose != null) {
         toClose.close();
       }
-      // Mark that we have a new frame available.
-      markTextureFrameAvailable(id);
+      if (image != null) {
+        // Mark that we have a new frame available.
+        markTextureFrameAvailable(id);
+      }
     }
 
     @Override

engine/src/flutter/shell/platform/android/io/flutter/plugin/platform/ImageReaderPlatformViewRenderTarget.java

@@ -11,10 +11,9 @@ import android.os.Handler;
 import android.view.Surface;
 import io.flutter.view.TextureRegistry.ImageTextureEntry;
 
-@TargetApi(26)
+@TargetApi(29)
 public class ImageReaderPlatformViewRenderTarget implements PlatformViewRenderTarget {
   private ImageTextureEntry textureEntry;
-  private boolean mustRecreateImageReader = false;
   private ImageReader reader;
   private int bufferWidth = 0;
   private int bufferHeight = 0;
@@ -22,20 +21,14 @@ public class ImageReaderPlatformViewRenderTarget implements PlatformViewRenderTa
 
   private void closeReader() {
     if (this.reader != null) {
+      // Push a null image, forcing the texture entry to close any cached images.
+      textureEntry.pushImage(null);
+      // Close the reader, which also closes any produced images.
       this.reader.close();
       this.reader = null;
     }
   }
 
-  private void recreateImageReaderIfNeeded() {
-    if (!mustRecreateImageReader) {
-      return;
-    }
-    mustRecreateImageReader = false;
-    closeReader();
-    this.reader = createImageReader();
-  }
-
   private final Handler onImageAvailableHandler = new Handler();
   private final ImageReader.OnImageAvailableListener onImageAvailableListener =
       new ImageReader.OnImageAvailableListener() {
@@ -55,9 +48,12 @@ public class ImageReaderPlatformViewRenderTarget implements PlatformViewRenderTa
     // Allow for double buffering.
     builder.setMaxImages(3);
     // Use PRIVATE image format so that we can support video decoding.
-    // TODO(johnmccutchan): Should we always use PRIVATE here? It may impact our ability
-    // to read back texture data. If we don't always want to use it, how do we decide when
-    // to use it or not? Perhaps PlatformViews can indicate if they may contain DRM'd content.
+    // TODO(johnmccutchan): Should we always use PRIVATE here? It may impact our
+    // ability to read back texture data. If we don't always want to use it, how do we
+    // decide when to use it or not? Perhaps PlatformViews can indicate if they may contain
+    // DRM'd content.
+    // I need to investigate how PRIVATE impacts our ability to take screenshots or capture
+    // the output of Flutter application.
     builder.setImageFormat(ImageFormat.PRIVATE);
     // Hint that consumed images will only be read by GPU.
     builder.setUsage(HardwareBuffer.USAGE_GPU_SAMPLED_IMAGE);
@@ -68,13 +64,15 @@ public class ImageReaderPlatformViewRenderTarget implements PlatformViewRenderTa
 
   @TargetApi(29)
   protected ImageReader createImageReader29() {
-    return ImageReader.newInstance(
-        bufferWidth, bufferHeight, ImageFormat.PRIVATE, 2, HardwareBuffer.USAGE_GPU_SAMPLED_IMAGE);
-  }
-
-  @TargetApi(26)
-  protected ImageReader createImageReader26() {
-    return ImageReader.newInstance(bufferWidth, bufferHeight, ImageFormat.PRIVATE, 2);
+    final ImageReader reader =
+        ImageReader.newInstance(
+            bufferWidth,
+            bufferHeight,
+            ImageFormat.PRIVATE,
+            2,
+            HardwareBuffer.USAGE_GPU_SAMPLED_IMAGE);
+    reader.setOnImageAvailableListener(this.onImageAvailableListener, onImageAvailableHandler);
+    return reader;
   }
 
   protected ImageReader createImageReader() {
@@ -82,15 +80,15 @@ public class ImageReaderPlatformViewRenderTarget implements PlatformViewRenderTa
       return createImageReader33();
     } else if (Build.VERSION.SDK_INT >= 29) {
       return createImageReader29();
-    } else {
-      return createImageReader26();
     }
+    throw new UnsupportedOperationException(
+        "ImageReaderPlatformViewRenderTarget requires API version 29+");
   }
 
   public ImageReaderPlatformViewRenderTarget(ImageTextureEntry textureEntry) {
-    if (Build.VERSION.SDK_INT < 26) {
+    if (Build.VERSION.SDK_INT < 29) {
       throw new UnsupportedOperationException(
-          "ImageReaderPlatformViewRenderTarget requires API version 26+");
+          "ImageReaderPlatformViewRenderTarget requires API version 29+");
     }
     this.textureEntry = textureEntry;
   }
@@ -127,9 +125,9 @@ public class ImageReaderPlatformViewRenderTarget implements PlatformViewRenderTa
   }
 
   public void release() {
+    closeReader();
     // textureEntry has a finalizer attached.
     textureEntry = null;
-    closeReader();
   }
 
   public boolean isReleased() {
@@ -137,7 +135,6 @@ public class ImageReaderPlatformViewRenderTarget implements PlatformViewRenderTa
   }
 
   public Surface getSurface() {
-    recreateImageReaderIfNeeded();
     return this.reader.getSurface();
   }
 }

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

@@ -968,8 +968,7 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
 
   private static PlatformViewRenderTarget makePlatformViewRenderTarget(
       TextureRegistry textureRegistry) {
-    // TODO(johnmccutchan): Enable ImageReaderPlatformViewRenderTarget for public use.
-    if (false) {
+    if (Build.VERSION.SDK_INT >= 29) {
       final TextureRegistry.ImageTextureEntry textureEntry = textureRegistry.createImageTexture();
       return new ImageReaderPlatformViewRenderTarget(textureEntry);
     }

engine/src/flutter/shell/platform/android/surface_texture_external_texture.cc

@@ -65,7 +65,8 @@ void SurfaceTextureExternalTexture::Paint(PaintContext& context,
         flutter::DlCanvas::SrcRectConstraint::kStrict  // enforce edges
     );
   } else {
-    FML_LOG(WARNING) << "No DlImage available.";
+    FML_LOG(WARNING)
+        << "No DlImage available for SurfaceTextureExternalTexture to paint.";
   }
 }