Android Embedding PR15: Add Viewport Metrics to FlutterView (#8029)

Author: matthew-carroll

shell/platform/android/io/flutter/embedding/engine/android/FlutterSurfaceView.java

@@ -56,6 +56,7 @@ public void surfaceCreated(SurfaceHolder holder) {
 
     @Override
     public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
+      Log.d(TAG, "SurfaceHolder.Callback.surfaceChanged()");
       if (isAttachedToFlutterRenderer) {
         changeSurfaceSize(width, height);
       }
@@ -97,13 +98,17 @@ private void init() {
    * Invoked by the owner of this {@code FlutterSurfaceView} when it wants to begin rendering
    * a Flutter UI to this {@code FlutterSurfaceView}.
    *
-   * If an Android {@link android.view.Surface} is available, this method will begin rendering
-   * {@link FlutterRenderer}'s Flutter UI to this {@code FlutterSurfaceView}.
+   * If an Android {@link android.view.Surface} is available, this method will give that
+   * {@link android.view.Surface} to the given {@link FlutterRenderer} to begin rendering
+   * Flutter's UI to this {@code FlutterSurfaceView}.
    *
    * If no Android {@link android.view.Surface} is available yet, this {@code FlutterSurfaceView}
-   * will wait until a {@link android.view.Surface} becomes available and then begin rendering.
+   * will wait until a {@link android.view.Surface} becomes available and then give that
+   * {@link android.view.Surface} to the given {@link FlutterRenderer} to begin rendering
+   * Flutter's UI to this {@code FlutterSurfaceView}.
    */
   public void attachToRenderer(@NonNull FlutterRenderer flutterRenderer) {
+    Log.d(TAG, "attachToRenderer");
     if (this.flutterRenderer != null) {
       this.flutterRenderer.detachFromRenderSurface();
     }
@@ -114,6 +119,7 @@ public void attachToRenderer(@NonNull FlutterRenderer flutterRenderer) {
     // If we're already attached to an Android window then we're now attached to both a renderer
     // and the Android window. We can begin rendering now.
     if (isSurfaceAvailableForRendering) {
+      Log.d(TAG, "Surface is available for rendering. Connecting.");
       connectSurfaceToRenderer();
     }
   }
@@ -179,5 +185,6 @@ public void updateSemantics(ByteBuffer buffer, String[] strings) {
   @Override
   public void onFirstFrameRendered() {
     // TODO(mattcarroll): decide where this method should live and what it needs to do.
+    Log.d(TAG, "onFirstFrameRendered()");
   }
 }

shell/platform/android/io/flutter/embedding/engine/android/FlutterTextureView.java

@@ -111,11 +111,14 @@ private void init() {
    * Invoked by the owner of this {@code FlutterTextureView} when it wants to begin rendering
    * a Flutter UI to this {@code FlutterTextureView}.
    *
-   * If an Android {@link SurfaceTexture} is available, this method will begin rendering
-   * {@link FlutterRenderer}'s Flutter UI to this {@code FlutterTextureView}.
+   * If an Android {@link SurfaceTexture} is available, this method will give that
+   * {@link SurfaceTexture} to the given {@link FlutterRenderer} to begin rendering
+   * Flutter's UI to this {@code FlutterTextureView}.
    *
-   * If no Android {@link SurfaceTexture} is available yet, this {@code FlutterSurfaceView}
-   * will wait until a {@link SurfaceTexture} becomes available and then begin rendering.
+   * If no Android {@link SurfaceTexture} is available yet, this {@code FlutterTextureView}
+   * will wait until a {@link SurfaceTexture} becomes available and then give that
+   * {@link SurfaceTexture} to the given {@link FlutterRenderer} to begin rendering
+   * Flutter's UI to this {@code FlutterTextureView}.
    */
   public void attachToRenderer(@NonNull FlutterRenderer flutterRenderer) {
     if (this.flutterRenderer != null) {
@@ -193,5 +196,6 @@ public void updateSemantics(ByteBuffer buffer, String[] strings) {
   @Override
   public void onFirstFrameRendered() {
     // TODO(mattcarroll): decide where this method should live and what it needs to do.
+    Log.d(TAG, "onFirstFrameRendered()");
   }
 }

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

@@ -17,10 +17,9 @@
 import android.view.KeyEvent;
 import android.view.MotionEvent;
 import android.view.WindowInsets;
+import android.view.WindowManager;
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputConnection;
-import android.view.inputmethod.InputMethod;
-import android.view.inputmethod.InputMethodManager;
 import android.widget.FrameLayout;
 
 import java.util.ArrayList;
@@ -30,6 +29,7 @@
 import io.flutter.embedding.engine.FlutterEngine;
 import io.flutter.embedding.engine.renderer.FlutterRenderer;
 import io.flutter.plugin.editing.TextInputPlugin;
+import io.flutter.view.VsyncWaiter;
 
 /**
  * Displays a Flutter UI on an Android device.
@@ -77,6 +77,9 @@ public class FlutterView extends FrameLayout {
   @Nullable
   private AndroidKeyProcessor androidKeyProcessor;
 
+  // Directly implemented View behavior that communicates with Flutter.
+  private final FlutterRenderer.ViewportMetrics viewportMetrics = new FlutterRenderer.ViewportMetrics();
+
   /**
    * Constructs a {@code FlutterSurfaceView} programmatically, without any XML attributes.
    *
@@ -158,8 +161,10 @@ protected void onConfigurationChanged(Configuration newConfig) {
    */
   @Override
   protected void onSizeChanged(int width, int height, int oldWidth, int oldHeight) {
-    // TODO(mattcarroll): hookup to viewport metrics.
     super.onSizeChanged(width, height, oldWidth, oldHeight);
+    viewportMetrics.width = width;
+    viewportMetrics.height = height;
+    sendViewportMetricsToFlutter();
   }
 
   /**
@@ -174,8 +179,22 @@ protected void onSizeChanged(int width, int height, int oldWidth, int oldHeight)
    */
   @Override
   public final WindowInsets onApplyWindowInsets(WindowInsets insets) {
-    // TODO(mattcarroll): hookup to Flutter metrics.
-    return insets;
+    WindowInsets newInsets = super.onApplyWindowInsets(insets);
+
+    // Status bar (top) and left/right system insets should partially obscure the content (padding).
+    viewportMetrics.paddingTop = insets.getSystemWindowInsetTop();
+    viewportMetrics.paddingRight = insets.getSystemWindowInsetRight();
+    viewportMetrics.paddingBottom = 0;
+    viewportMetrics.paddingLeft = insets.getSystemWindowInsetLeft();
+
+    // Bottom system inset (keyboard) should adjust scrollable bottom edge (inset).
+    viewportMetrics.viewInsetTop = 0;
+    viewportMetrics.viewInsetRight = 0;
+    viewportMetrics.viewInsetBottom = insets.getSystemWindowInsetBottom();
+    viewportMetrics.viewInsetLeft = 0;
+    sendViewportMetricsToFlutter();
+
+    return newInsets;
   }
 
   /**
@@ -188,8 +207,23 @@ public final WindowInsets onApplyWindowInsets(WindowInsets insets) {
   @Override
   @SuppressWarnings("deprecation")
   protected boolean fitSystemWindows(Rect insets) {
-    // TODO(mattcarroll): hookup to Flutter metrics.
-    return super.fitSystemWindows(insets);
+    if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.KITKAT) {
+      // Status bar, left/right system insets partially obscure content (padding).
+      viewportMetrics.paddingTop = insets.top;
+      viewportMetrics.paddingRight = insets.right;
+      viewportMetrics.paddingBottom = 0;
+      viewportMetrics.paddingLeft = insets.left;
+
+      // Bottom system inset (keyboard) should adjust scrollable bottom edge (inset).
+      viewportMetrics.viewInsetTop = 0;
+      viewportMetrics.viewInsetRight = 0;
+      viewportMetrics.viewInsetBottom = insets.bottom;
+      viewportMetrics.viewInsetLeft = 0;
+      sendViewportMetricsToFlutter();
+      return true;
+    } else {
+      return super.fitSystemWindows(insets);
+    }
   }
   //------- End: Process View configuration that Flutter cares about. --------
 
@@ -312,13 +346,16 @@ public boolean onHoverEvent(MotionEvent event) {
    * {@link FlutterEngine}.
    */
   public void attachToFlutterEngine(@NonNull FlutterEngine flutterEngine) {
+    Log.d(TAG, "attachToFlutterEngine()");
     if (isAttachedToFlutterEngine()) {
       if (flutterEngine == this.flutterEngine) {
         // We are already attached to this FlutterEngine
+        Log.d(TAG, "Already attached to this engine. Doing nothing.");
         return;
       }
 
       // Detach from a previous FlutterEngine so we can attach to this new one.
+      Log.d(TAG, "Currently attached to a different engine. Detaching.");
       detachFromFlutterEngine();
     }
 
@@ -346,6 +383,7 @@ public void attachToFlutterEngine(@NonNull FlutterEngine flutterEngine) {
     // Push View and Context related information from Android to Flutter.
     sendUserSettingsToFlutter();
     sendLocalesToFlutter(getResources().getConfiguration());
+    sendViewportMetricsToFlutter();
   }
 
   /**
@@ -359,7 +397,9 @@ public void attachToFlutterEngine(@NonNull FlutterEngine flutterEngine) {
    * {@link FlutterEngine}.
    */
   public void detachFromFlutterEngine() {
+    Log.d(TAG, "detachFromFlutterEngine()");
     if (!isAttachedToFlutterEngine()) {
+      Log.d(TAG, "Not attached to an engine. Doing nothing.");
       return;
     }
     Log.d(TAG, "Detaching from Flutter Engine");
@@ -422,6 +462,18 @@ private void sendUserSettingsToFlutter() {
         .send();
   }
 
+  // TODO(mattcarroll): consider introducing a system channel for this communication instead of JNI
+  private void sendViewportMetricsToFlutter() {
+    Log.d(TAG, "sendViewportMetricsToFlutter()");
+    if (!isAttachedToFlutterEngine()) {
+      Log.w(TAG, "Tried to send viewport metrics from Android to Flutter but this FlutterView was not attached to a FlutterEngine.");
+      return;
+    }
+
+    viewportMetrics.devicePixelRatio = getResources().getDisplayMetrics().density;
+    flutterEngine.getRenderer().setViewportMetrics(viewportMetrics);
+  }
+
   /**
    * Render modes for a {@link FlutterView}.
    */

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

@@ -29,7 +29,7 @@
  * code via JNI. The corresponding {@link RenderSurface} is used as a delegate to carry out
  * certain actions on behalf of this {@code FlutterRenderer} within an Android view hierarchy.
  *
- * {@link FlutterView} is an implementation of a {@link RenderSurface}.
+ * {@link io.flutter.embedding.engine.android.FlutterView} is an implementation of a {@link RenderSurface}.
  */
 @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
 public class FlutterRenderer implements TextureRegistry {
@@ -49,14 +49,16 @@ public void attachToRenderSurface(@NonNull RenderSurface renderSurface) {
     }
 
     this.renderSurface = renderSurface;
+    this.renderSurface.attachToRenderer(this);
     this.flutterJNI.setRenderSurface(renderSurface);
   }
 
   public void detachFromRenderSurface() {
     // TODO(mattcarroll): determine desired behavior if we're asked to detach without first being attached
     if (this.renderSurface != null) {
-      surfaceDestroyed();
+      this.renderSurface.detachFromRenderer();
       this.renderSurface = null;
+      surfaceDestroyed();
       this.flutterJNI.setRenderSurface(null);
     }
   }
@@ -157,29 +159,19 @@ public void surfaceDestroyed() {
   }
 
   // TODO(mattcarroll): describe the native behavior that this invokes
-  public void setViewportMetrics(float devicePixelRatio,
-                                 int physicalWidth,
-                                 int physicalHeight,
-                                 int physicalPaddingTop,
-                                 int physicalPaddingRight,
-                                 int physicalPaddingBottom,
-                                 int physicalPaddingLeft,
-                                 int physicalViewInsetTop,
-                                 int physicalViewInsetRight,
-                                 int physicalViewInsetBottom,
-                                 int physicalViewInsetLeft) {
+  public void setViewportMetrics(@NonNull ViewportMetrics viewportMetrics) {
     flutterJNI.setViewportMetrics(
-        devicePixelRatio,
-        physicalWidth,
-        physicalHeight,
-        physicalPaddingTop,
-        physicalPaddingRight,
-        physicalPaddingBottom,
-        physicalPaddingLeft,
-        physicalViewInsetTop,
-        physicalViewInsetRight,
-        physicalViewInsetBottom,
-        physicalViewInsetLeft
+        viewportMetrics.devicePixelRatio,
+        viewportMetrics.width,
+        viewportMetrics.height,
+        viewportMetrics.paddingTop,
+        viewportMetrics.paddingRight,
+        viewportMetrics.paddingBottom,
+        viewportMetrics.paddingLeft,
+        viewportMetrics.viewInsetTop,
+        viewportMetrics.viewInsetRight,
+        viewportMetrics.viewInsetBottom,
+        viewportMetrics.viewInsetLeft
     );
   }
 
@@ -281,4 +273,24 @@ public interface RenderSurface {
      */
     void onFirstFrameRendered();
   }
+
+  /**
+   * Mutable data structure that holds all viewport metrics properties that Flutter cares about.
+   *
+   * All distance measurements, e.g., width, height, padding, viewInsets, are measured in device
+   * pixels, not logical pixels.
+   */
+  public static final class ViewportMetrics {
+    public float devicePixelRatio = 1.0f;
+    public int width = 0;
+    public int height = 0;
+    public int paddingTop = 0;
+    public int paddingRight = 0;
+    public int paddingBottom = 0;
+    public int paddingLeft = 0;
+    public int viewInsetTop = 0;
+    public int viewInsetRight = 0;
+    public int viewInsetBottom = 0;
+    public int viewInsetLeft = 0;
+  }
 }