Provide non-blocking SurfaceView draw notification path.

SurfaceView needs to notify the window manager that
drawing has been completed, so that animations and such
can begin. Currently this is implemented through
having the SurfaceView user block in surfaceRedrawNeeded
(called from  UI thread) until a frame has been completed.
This blocking can be unnecessary serialization during startup, and
also clumsy to implement for some users.

Test: GLSurfaceView and takeSurface API Demos, android.server.cts.SurfaceViewTests
Bug: 31850030
Change-Id: Idda02098a635f25cf392f2d59a3abbe54a1d64d4

1 files changed, 26 insertions, 1 deletions

diff --git a/core/java/android/view/SurfaceHolder.java b/core/java/android/view/SurfaceHolder.java
index a3e8312c0a64..2fd2e966dc38 100644
--- a/core/java/android/view/SurfaceHolder.java
+++ b/core/java/android/view/SurfaceHolder.java
@@ -116,9 +116,34 @@ public interface SurfaceHolder {
          * size before it has been correctly drawn that way).  This will
          * typically be preceeded by a call to {@link #surfaceChanged}.
          *
+         * As of O, {@link #surfaceRedrawNeededAsync} may be implemented
+         * to provide a non-blocking implementation. If {@link #surfaceRedrawNeededAsync}
+         * is not implemented, then this will be called instead.
+         *
          * @param holder The SurfaceHolder whose surface has changed.
          */
-        public void surfaceRedrawNeeded(SurfaceHolder holder);
+        void surfaceRedrawNeeded(SurfaceHolder holder);
+
+        /**
+         * An alternative to surfaceRedrawNeeded where it is not required to block
+         * until the redraw is complete. You should initiate the redraw, and return,
+         * later invoking drawingFinished when your redraw is complete.
+         *
+         * This can be useful to avoid blocking your main application thread on rendering.
+         *
+         * As of O, if this is implemented {@link #surfaceRedrawNeeded} will not be called.
+         * However it is still recommended to implement {@link #surfaceRedrawNeeded} for
+         * compatibility with older versions of the platform.
+         *
+         * @param holder The SurfaceHolder which needs redrawing.
+         * @param drawingFinished A runnable to signal completion. This may be invoked
+         * from any thread.
+         *
+         */
+        default void surfaceRedrawNeededAsync(SurfaceHolder holder, Runnable drawingFinished) {
+            surfaceRedrawNeeded(holder);
+            drawingFinished.run();
+        }
     }
 
     /**