commit 2e20bffbab8084fedce39d14d7dd17b08f6e9ba2
author Mathias Agopian <mathias@google.com> Mon May 04 19:29:25 2009 -0700
committer Mathias Agopian <mathias@google.com> Thu May 07 15:07:33 2009 -0700
tree be397ea1383b74bc09e48d591ca7aa2cc54f0539
parent 9bd5da4db97fec7cdbe6e07870411c1fcaff4365

created an new EGL extension called ANDROID_swap_rectangle

ANDROID_swap_rectangle allows to specify the rectangle affected by eglSwapBuffers(), anything outside of this rectangle is unchanged. in particular EGL_BUFFER_DESTROYED only applies to that rectangle. This extension as well as EGL_BUFFER_PRESERVED allow major optimizations on surfaceflinger, which can redraw only the dirty area during compositing.

However, ANDROID_swap_rectangle allows further optimizations in EGL by reducing the amount of copy-back needed. ANDROID_swap_rectangle is particularily important for software implementations.

libs/surfaceflinger/DisplayHardware/DisplayHardware.h

diff --git a/libs/surfaceflinger/DisplayHardware/DisplayHardware.h b/libs/surfaceflinger/DisplayHardware/DisplayHardware.h
index c9c75e2..c3dbff1 100644
--- a/libs/surfaceflinger/DisplayHardware/DisplayHardware.h
+++ b/libs/surfaceflinger/DisplayHardware/DisplayHardware.h
@@ -50,6 +50,7 @@
         BUFFER_PRESERVED        = 0x00010000,
         UPDATE_ON_DEMAND        = 0x00020000,   // video driver feature
         SLOW_CONFIG             = 0x00040000,   // software
+        SWAP_RECTANGLE          = 0x00080000,
     };
 
     DisplayHardware(