Initial work toward converting the FlutterView to use a FlutterImageView on demand (flutter/engine#19279)

engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterImageView.java

@@ -17,6 +17,8 @@ import android.media.ImageReader;
 import android.view.View;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import io.flutter.embedding.engine.renderer.FlutterRenderer;
+import io.flutter.embedding.engine.renderer.RenderSurface;
 
 /**
  * Paints a Flutter UI provided by an {@link android.media.ImageReader} onto a {@link
@@ -32,10 +34,12 @@ import androidx.annotation.Nullable;
  */
 @SuppressLint("ViewConstructor")
 @TargetApi(19)
-public class FlutterImageView extends View {
+public class FlutterImageView extends View implements RenderSurface {
   private final ImageReader imageReader;
   @Nullable private Image nextImage;
   @Nullable private Image currentImage;
+  @Nullable private Bitmap currentBitmap;
+  @Nullable private FlutterRenderer flutterRenderer;
 
   /**
    * Constructs a {@code FlutterImageView} with an {@link android.media.ImageReader} that provides
@@ -46,6 +50,37 @@ public class FlutterImageView extends View {
     this.imageReader = imageReader;
   }
 
+  @Nullable
+  @Override
+  public FlutterRenderer getAttachedRenderer() {
+    return flutterRenderer;
+  }
+
+  /**
+   * Invoked by the owner of this {@code FlutterImageView} when it wants to begin rendering a
+   * Flutter UI to this {@code FlutterImageView}.
+   */
+  @Override
+  public void attachToRenderer(@NonNull FlutterRenderer flutterRenderer) {
+    if (this.flutterRenderer != null) {
+      this.flutterRenderer.stopRenderingToSurface();
+    }
+
+    this.flutterRenderer = flutterRenderer;
+    flutterRenderer.startRenderingToSurface(imageReader.getSurface());
+  }
+
+  /**
+   * Invoked by the owner of this {@code FlutterImageView} when it no longer wants to render a
+   * Flutter UI to this {@code FlutterImageView}.
+   */
+  public void detachFromRenderer() {
+    if (flutterRenderer != null) {
+      flutterRenderer.stopRenderingToSurface();
+      flutterRenderer = null;
+    }
+  }
+
   /** Acquires the next image to be drawn to the {@link android.graphics.Canvas}. */
   @TargetApi(19)
   public void acquireLatestImage() {
@@ -56,51 +91,44 @@ public class FlutterImageView extends View {
   @Override
   protected void onDraw(Canvas canvas) {
     super.onDraw(canvas);
-    if (nextImage == null) {
-      return;
+    if (nextImage != null) {
+      if (currentImage != null) {
+        currentImage.close();
+      }
+      currentImage = nextImage;
+      nextImage = null;
+      updateCurrentBitmap();
     }
 
-    if (currentImage != null) {
-      currentImage.close();
+    if (currentBitmap != null) {
+      canvas.drawBitmap(currentBitmap, 0, 0, null);
     }
-    currentImage = nextImage;
-    nextImage = null;
-
-    if (android.os.Build.VERSION.SDK_INT >= 29) {
-      drawImageBuffer(canvas);
-      return;
-    }
-
-    drawImagePlane(canvas);
   }
 
   @TargetApi(29)
-  private void drawImageBuffer(@NonNull Canvas canvas) {
-    final HardwareBuffer buffer = currentImage.getHardwareBuffer();
+  private void updateCurrentBitmap() {
+    if (android.os.Build.VERSION.SDK_INT >= 29) {
+      final HardwareBuffer buffer = currentImage.getHardwareBuffer();
+      currentBitmap = Bitmap.wrapHardwareBuffer(buffer, ColorSpace.get(ColorSpace.Named.SRGB));
+    } else {
+      final Plane[] imagePlanes = currentImage.getPlanes();
+      if (imagePlanes.length != 1) {
+        return;
+      }
 
-    final Bitmap bitmap = Bitmap.wrapHardwareBuffer(buffer, ColorSpace.get(ColorSpace.Named.SRGB));
-    canvas.drawBitmap(bitmap, 0, 0, null);
-  }
+      final Plane imagePlane = imagePlanes[0];
+      final int desiredWidth = imagePlane.getRowStride() / imagePlane.getPixelStride();
+      final int desiredHeight = currentImage.getHeight();
 
-  private void drawImagePlane(@NonNull Canvas canvas) {
-    if (currentImage == null) {
-      return;
+      if (currentBitmap == null
+          || currentBitmap.getWidth() != desiredWidth
+          || currentBitmap.getHeight() != desiredHeight) {
+        currentBitmap =
+            Bitmap.createBitmap(
+                desiredWidth, desiredHeight, android.graphics.Bitmap.Config.ARGB_8888);
+      }
+
+      currentBitmap.copyPixelsFromBuffer(imagePlane.getBuffer());
     }
-
-    final Plane[] imagePlanes = currentImage.getPlanes();
-    if (imagePlanes.length != 1) {
-      return;
-    }
-
-    final Plane imagePlane = imagePlanes[0];
-    final int desiredWidth = imagePlane.getRowStride() / imagePlane.getPixelStride();
-    final int desiredHeight = currentImage.getHeight();
-
-    final Bitmap bitmap =
-        android.graphics.Bitmap.createBitmap(
-            desiredWidth, desiredHeight, android.graphics.Bitmap.Config.ARGB_8888);
-
-    bitmap.copyPixelsFromBuffer(imagePlane.getBuffer());
-    canvas.drawBitmap(bitmap, 0, 0, null);
   }
 }

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

@@ -10,6 +10,7 @@ import android.content.Context;
 import android.content.res.Configuration;
 import android.graphics.Insets;
 import android.graphics.Rect;
+import android.media.ImageReader;
 import android.os.Build;
 import android.text.format.DateFormat;
 import android.util.AttributeSet;
@@ -303,6 +304,7 @@ public class FlutterView extends FrameLayout implements MouseCursorPlugin.MouseC
     super(context, attrs);
 
     this.flutterImageView = flutterImageView;
+    this.renderSurface = flutterImageView;
 
     init();
   }
@@ -940,6 +942,32 @@ public class FlutterView extends FrameLayout implements MouseCursorPlugin.MouseC
     flutterEngine = null;
   }
 
+  public void convertToImageView() {
+    renderSurface.detachFromRenderer();
+
+    ImageReader imageReader = PlatformViewsController.createImageReader(getWidth(), getHeight());
+    flutterImageView = new FlutterImageView(getContext(), imageReader);
+    renderSurface = flutterImageView;
+    if (flutterEngine != null) {
+      renderSurface.attachToRenderer(flutterEngine.getRenderer());
+    }
+
+    removeAllViews();
+    addView(flutterImageView);
+
+    // TODO(jsimmons): this is a temporary hack that schedules a redraw of the FlutterImageView
+    // at a time when the engine has presumably posted a frame.  Remove this when
+    // PlatformViewsController.onEndFrame callbacks have been implemented.
+    postDelayed(
+        new Runnable() {
+          public void run() {
+            flutterImageView.acquireLatestImage();
+            flutterImageView.invalidate();
+          }
+        },
+        1000);
+  }
+
   /** Returns true if this {@code FlutterView} is currently attached to a {@link FlutterEngine}. */
   @VisibleForTesting
   public boolean isAttachedToFlutterEngine() {

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

@@ -22,6 +22,7 @@ import androidx.annotation.NonNull;
 import androidx.annotation.UiThread;
 import androidx.annotation.VisibleForTesting;
 import io.flutter.embedding.android.FlutterImageView;
+import io.flutter.embedding.android.FlutterView;
 import io.flutter.embedding.engine.FlutterOverlaySurface;
 import io.flutter.embedding.engine.dart.DartExecutor;
 import io.flutter.embedding.engine.systemchannels.PlatformViewsChannel;
@@ -79,9 +80,12 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
   // Map of unique IDs to views that render overlay layers.
   private final LongSparseArray<FlutterImageView> overlayLayerViews;
 
-  // Next available unique ID for use in overlayLayerViews;
+  // Next available unique ID for use in overlayLayerViews.
   private long nextOverlayLayerId = 0;
 
+  // Tracks whether the flutterView has been converted to use a FlutterImageView.
+  private boolean flutterViewConvertedToImageView = false;
+
   private final PlatformViewsChannel.PlatformViewsHandler channelHandler =
       new PlatformViewsChannel.PlatformViewsHandler() {
         @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
@@ -552,7 +556,10 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
   }
 
   public void onDisplayOverlaySurface(int id, int x, int y, int width, int height) {
-    // TODO: Implement this method. https://github.com/flutter/flutter/issues/58288
+    if (!flutterViewConvertedToImageView) {
+      ((FlutterView) flutterView).convertToImageView();
+      flutterViewConvertedToImageView = true;
+    }
   }
 
   public void onBeginFrame() {
@@ -564,22 +571,22 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
   }
 
   @TargetApi(19)
-  public FlutterOverlaySurface createOverlaySurface() {
-    ImageReader imageReader;
+  public static ImageReader createImageReader(int width, int height) {
     if (android.os.Build.VERSION.SDK_INT >= 29) {
-      imageReader =
-          ImageReader.newInstance(
-              flutterView.getWidth(),
-              flutterView.getHeight(),
-              PixelFormat.RGBA_8888,
-              2,
-              HardwareBuffer.USAGE_GPU_SAMPLED_IMAGE | HardwareBuffer.USAGE_GPU_COLOR_OUTPUT);
+      return ImageReader.newInstance(
+          width,
+          height,
+          PixelFormat.RGBA_8888,
+          2,
+          HardwareBuffer.USAGE_GPU_SAMPLED_IMAGE | HardwareBuffer.USAGE_GPU_COLOR_OUTPUT);
     } else {
-      imageReader =
-          ImageReader.newInstance(
-              flutterView.getWidth(), flutterView.getHeight(), PixelFormat.RGBA_8888, 2);
+      return ImageReader.newInstance(width, height, PixelFormat.RGBA_8888, 2);
     }
+  }
 
+  @TargetApi(19)
+  public FlutterOverlaySurface createOverlaySurface() {
+    ImageReader imageReader = createImageReader(flutterView.getWidth(), flutterView.getHeight());
     FlutterImageView imageView = new FlutterImageView(flutterView.getContext(), imageReader);
     long id = nextOverlayLayerId++;
     overlayLayerViews.put(id, imageView);