From 21799450ec751fd3c41c7e66e69fefb094b3050b Mon Sep 17 00:00:00 2001
From: Jack Palevich <jackpal@google.com>
Date: Mon, 21 Dec 2009 14:47:35 +0800
Subject: [PATCH] Fix bug 2325244	screen turns black for a brief period
 of time

The problem was a black first frame when creating a surface, or a
garbage frame when the surface was resized.

The cause was lack of synchronization between the render thread and the
UI thread. The UI thread would typically return before the render thread
had a chance to draw its first frame.

The fix was to make the UI thread wait until at least one frame had been
rendered by the rendering thread.

The waiting is done in the surfaceChanged method because we know
that surfaceChanged will be called in both the surface created
and surface changed cases.
---
 opengl/java/android/opengl/GLSurfaceView.java | 29 +++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/opengl/java/android/opengl/GLSurfaceView.java b/opengl/java/android/opengl/GLSurfaceView.java
index 185398bdac218..28b10ec23ecca 100644
--- a/opengl/java/android/opengl/GLSurfaceView.java
+++ b/opengl/java/android/opengl/GLSurfaceView.java
@@ -1066,6 +1066,8 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
                 GL10 gl = null;
                 boolean createEglSurface = false;
                 boolean sizeChanged = false;
+                boolean wantRenderNotification = false;
+                boolean doRenderNotification = false;
                 int w = 0;
                 int h = 0;
                 Runnable event = null;
@@ -1111,6 +1113,13 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
                                 sGLThreadManager.notifyAll();
                             }
 
+                            if (doRenderNotification) {
+                                wantRenderNotification = false;
+                                doRenderNotification = false;
+                                mRenderComplete = true;
+                                sGLThreadManager.notifyAll();
+                            }
+
                             // Ready to draw?
                             if ((!mPaused) && mHasSurface
                                 && (mWidth > 0) && (mHeight > 0)
@@ -1130,6 +1139,8 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
                                         sizeChanged = true;
                                         w = mWidth;
                                         h = mHeight;
+                                        wantRenderNotification = true;
+
                                         if (DRAW_TWICE_AFTER_SIZE_CHANGED) {
                                             // We keep mRequestRender true so that we draw twice after the size changes.
                                             // (Once because of mSizeChanged, the second time because of mRequestRender.)
@@ -1187,6 +1198,10 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
                             Log.i("GLThread", "egl surface lost tid=" + getId());
                         }
                     }
+
+                    if (wantRenderNotification) {
+                        doRenderNotification = true;
+                    }
                 }
             } finally {
                 /*
@@ -1269,7 +1284,20 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
                 mHeight = h;
                 mSizeChanged = true;
                 mRequestRender = true;
+                mRenderComplete = false;
                 sGLThreadManager.notifyAll();
+
+                // Wait for thread to react to resize and render a frame
+                while (! mExited && !mPaused && !mRenderComplete ) {
+                    if (LOG_SURFACE) {
+                        Log.i("Main thread", "onWindowResize waiting for render complete.");
+                    }
+                    try {
+                        sGLThreadManager.wait();
+                    } catch (InterruptedException ex) {
+                        Thread.currentThread().interrupt();
+                    }
+                }
             }
         }
 
@@ -1315,6 +1343,7 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
         private int mHeight;
         private int mRenderMode;
         private boolean mRequestRender;
+        private boolean mRenderComplete;
         private ArrayList<Runnable> mEventQueue = new ArrayList<Runnable>();
         // End of member variables protected by the sGLThreadManager monitor.