Android SurfaceViewRenderer: Enable hardware scaler

talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java

Index: talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java
diff --git a/talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java b/talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java
index 170827efc11acd34726b9fe12ca688d6aa6162a1..86c1481eec7579a8a548c70b071fa214d33442d1 100644
--- a/talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java
+++ b/talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java
@@ -83,14 +83,13 @@ public class SurfaceViewRenderer extends SurfaceView
   // traversal of the View tree, followed by an onLayout() pass that is also top-down. During the
   // onLayout() pass, each parent is responsible for positioning its children using the sizes
   // computed in the measure pass.
-  // |desiredLayoutsize| is the layout size we have requested in onMeasure() and are waiting for to
-  // take effect.
+  // |desiredLayoutsize|/|desiredSurfaceSize| is the layout/surface size we have requested in
+  // onMeasure() and are waiting for to take effect.
   private Point desiredLayoutSize = new Point();
+  private final Point desiredSurfaceSize = new Point();
   // |layoutSize|/|surfaceSize| is the actual current layout/surface size. They are updated in
   // onLayout() and surfaceChanged() respectively.
   private final Point layoutSize = new Point();
-  // TODO(magjed): Enable hardware scaler with SurfaceHolder.setFixedSize(). This will decouple
-  // layout and surface size.
   private final Point surfaceSize = new Point();
   // |isSurfaceCreated| keeps track of the current status in surfaceCreated()/surfaceDestroyed().
   private boolean isSurfaceCreated;
@@ -324,7 +323,23 @@ public class SurfaceViewRenderer extends SurfaceView
         return;
       }
       desiredLayoutSize = getDesiredLayoutSize(widthSpec, heightSpec);
-      if (desiredLayoutSize.x != getMeasuredWidth() || desiredLayoutSize.y != getMeasuredHeight()) {
+      // Calculate at what scale we are rendering the frame.
+      final int rotatedFrameWidth = (frameRotation % 180 == 0) ? frameWidth : frameHeight;
+      final int rotatedFrameHeight = (frameRotation % 180 == 0) ? frameHeight : frameWidth;
+      final float displayScale = Math.max((float) desiredLayoutSize.x / rotatedFrameWidth,
+                                          (float) desiredLayoutSize.y / rotatedFrameHeight);
+      if (displayScale > 1) {
+        // Upscaling - decrease surface size and let the HW scaler take care of the upscaling
+        // instead of the GPU.
+        desiredSurfaceSize.x = Math.round(desiredLayoutSize.x / displayScale);
+        desiredSurfaceSize.y = Math.round(desiredLayoutSize.y / displayScale);
+      } else {
+        // Downscaling - render at layout resolution.
+        desiredSurfaceSize.x = desiredLayoutSize.x;
+        desiredSurfaceSize.y = desiredLayoutSize.y;
+      }
+      if (desiredLayoutSize.x != getMeasuredWidth() || desiredLayoutSize.y != getMeasuredHeight()
+          || !desiredSurfaceSize.equals(surfaceSize)) {
         // Clear the surface asap before the layout change to avoid stretched video and other
         // render artifacs. Don't wait for it to finish because the IO thread should never be
         // blocked, so it's a best-effort attempt.
@@ -334,6 +349,7 @@ public class SurfaceViewRenderer extends SurfaceView
           }
         }
       }
+      getHolder().setFixedSize(desiredSurfaceSize.x, desiredSurfaceSize.y);
       setMeasuredDimension(desiredLayoutSize.x, desiredLayoutSize.y);
     }
   }
@@ -423,7 +439,7 @@ public class SurfaceViewRenderer extends SurfaceView
     }
     synchronized (layoutLock) {
       // Return false while we are in the middle of a layout change.
-      return layoutSize.equals(desiredLayoutSize) && surfaceSize.equals(layoutSize);
+      return layoutSize.equals(desiredLayoutSize) && surfaceSize.equals(desiredSurfaceSize);
     }
   }