SurfaceTexture: use eglWaitSync

This change adds a compile-option to use eglWaitSyncANDROID to ensure that
texturing operations that access the current buffer of a SurfaceTexture do not
occur until the buffer is completely written.  It also moves this
synchronization into a new SurfaceTexture method called doGLFenceWait and
changes SurfaceFlinger's Layer class to use that method rather than performing
its own wait on the fence.

Change-Id: I70afa88086ca7ff49a80e3cd03d423767db7cb88

1 files changed, 9 insertions, 0 deletions

diff --git a/include/gui/SurfaceTexture.h b/include/gui/SurfaceTexture.h
index 80a010b..6e5a478 100644
--- a/include/gui/SurfaceTexture.h
+++ b/include/gui/SurfaceTexture.h
@@ -77,6 +77,9 @@ public:
     //
     // This call may only be made while the OpenGL ES context to which the
     // target texture belongs is bound to the calling thread.
+    //
+    // After calling this method the doGLFenceWait method must be called
+    // before issuing OpenGL ES commands that access the texture contents.
     status_t updateTexImage();
 
     // setReleaseFence stores a fence file descriptor that will signal when the
@@ -154,6 +157,12 @@ public:
     // ready to be read from.
     sp<Fence> getCurrentFence() const;
 
+    // doGLFenceWait inserts a wait command into the OpenGL ES command stream
+    // to ensure that it is safe for future OpenGL ES commands to access the
+    // current texture buffer.  This must be called each time updateTexImage
+    // is called before issuing OpenGL ES commands that access the texture.
+    status_t doGLFenceWait() const;
+
     // isSynchronousMode returns whether the SurfaceTexture is currently in
     // synchronous mode.
     bool isSynchronousMode() const;