Add discard API to SkCanvas, plumb it to glDiscardFramebuffer()

src/gpu/GrContext.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrContext.h"
@@ skipping 1422 matching lines @@
 void GrContext::resolveRenderTarget(GrRenderTarget* target) {
     SkASSERT(target);
     ASSERT_OWNED_RESOURCE(target);
     // In the future we may track whether there are any pending draws to this
     // target. We don't today so we always perform a flush. We don't promise
     // this to our clients, though.
     this->flush();
     fGpu->resolveRenderTarget(target);
 }
 
+void GrContext::discardRenderTarget(GrRenderTarget* target) {
+    SkASSERT(target);
+    ASSERT_OWNED_RESOURCE(target);
+    AutoRestoreEffects are;
+    AutoCheckFlush acf(this);
+    this->prepareToDraw(NULL, BUFFERED_DRAW, &are, &acf)->discard(target);
+}
+
 void GrContext::copyTexture(GrTexture* src, GrRenderTarget* dst, const SkIPoint* topLeft) {
     if (NULL == src || NULL == dst) {
         return;
     }
     ASSERT_OWNED_RESOURCE(src);
 
     // Writes pending to the source texture are not tracked, so a flush
     // is required to ensure that the copy captures the most recent contents
     // of the source texture. See similar behavior in
     // GrContext::resolveRenderTarget.
@@ skipping 332 matching lines @@
     }
     return path;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 #if GR_CACHE_STATS
 void GrContext::printCacheStats() const {
     fTextureCache->printStats();
 }
 #endif