Move some work from backend onClear to base class clear

src/gpu/GrDrawTarget.cpp

 
 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDrawTarget.h"
 
@@ skipping 291 matching lines @@
                               const SkMatrix& viewMatrix,
                               const SkRect& rect,
                               const SkRect& devRect) {
    GrAARectRenderer::FillAARect(this, pipelineBuilder, color, viewMatrix, rect, devRect);
 }
 
 void GrDrawTarget::clear(const SkIRect* rect,
                          GrColor color,
                          bool canIgnoreRect,
                          GrRenderTarget* renderTarget) {
+    SkIRect rtRect = SkIRect::MakeWH(renderTarget->width(), renderTarget->height());
+    SkIRect clippedRect;
+    if (!rect ||
+        (canIgnoreRect && this->caps()->fullClearIsFree()) ||
+        rect->contains(rtRect)) {
+        rect = &rtRect;
+    } else {
+        clippedRect = *rect;
+        if (!clippedRect.intersect(rtRect)) {
+            return;
+        }
+        rect = &clippedRect;
+    }
+
     if (fCaps->useDrawInsteadOfClear()) {
         // This works around a driver bug with clear by drawing a rect instead.
         // The driver will ignore a clear if it is the only thing rendered to a
         // target before the target is read.
-        SkIRect rtRect = SkIRect::MakeWH(renderTarget->width(), renderTarget->height());
-        if (NULL == rect || canIgnoreRect || rect->contains(rtRect)) {
-            rect = &rtRect;
-            // We first issue a discard() since that may help tilers.
+        if (rect == &rtRect) {
             this->discard(renderTarget);
         }
 
         GrPipelineBuilder pipelineBuilder;
         pipelineBuilder.setRenderTarget(renderTarget);
 
         this->drawSimpleRect(pipelineBuilder, color, SkMatrix::I(), *rect);
     } else {       
-        this->onClear(rect, color, canIgnoreRect, renderTarget);
+        this->onClear(*rect, color, renderTarget);
     }
 }
 
 typedef GrTraceMarkerSet::Iter TMIter;
 void GrDrawTarget::saveActiveTraceMarkers() {
     if (this->caps()->gpuTracingSupport()) {
         SkASSERT(0 == fStoredTraceMarkers.count());
         fStoredTraceMarkers.addSet(fActiveTraceMarkers);
         for (TMIter iter = fStoredTraceMarkers.begin(); iter != fStoredTraceMarkers.end(); ++iter) {
             this->removeGpuTraceMarker(&(*iter));
@@ skipping 165 matching lines @@
                                            ars,
                                            scissorState,
                                            devBounds);
 }
 
 void GrClipTarget::purgeResources() {
     // The clip mask manager can rebuild all its clip masks so just
     // get rid of them all.
     fClipMaskManager->purgeResources();
 };