add peekPixels to SkCanvas and SkSurface

samplecode/SampleApp.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 "SampleApp.h"
 
 #include "SkData.h"
 #include "SkCanvas.h"
@@ skipping 1110 matching lines @@
 void SampleWindow::listTitles() {
     int count = fSamples.count();
     SkDebugf("All Slides:\n");
     for (int i = 0; i < count; i++) {
         SkDebugf("    %s\n", getSampleTitle(i).c_str());
     }
 }
 
 static SkBitmap capture_bitmap(SkCanvas* canvas) {
     SkBitmap bm;
-    const SkBitmap& src = canvas->getDevice()->accessBitmap(false);
-    src.copyTo(&bm, src.config());
+    if (bm.allocPixels(canvas->imageInfo())) {
+        canvas->readPixels(&bm, 0, 0);
+    }
     return bm;
 }
 
 static bool bitmap_diff(SkCanvas* canvas, const SkBitmap& orig,
                         SkBitmap* diff) {
     const SkBitmap& src = canvas->getDevice()->accessBitmap(false);
 
     SkAutoLockPixels alp0(src);
     SkAutoLockPixels alp1(orig);
     for (int y = 0; y < src.height(); y++) {
@@ skipping 1469 matching lines @@
     SkGraphics::Init();
     SkEvent::Init();
 }
 
 // FIXME: this should be in a header
 void application_term();
 void application_term() {
     SkEvent::Term();
     SkGraphics::Term();
 }