save/restore the canvas around every bench draw call

bench/benchmain.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.
  */
 
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
@@ skipping 580 matching lines @@
                     // Clear the recorded commands so that they do not accumulate.
                     canvas.reset(recordTo.beginRecording(dim.fX, dim.fY, kRecordFlags));
                 }
 
                 timer.start();
                 // Inner loop that allows us to break the run into smaller
                 // chunks (e.g. frames). This is especially useful for the GPU
                 // as we can flush and/or swap buffers to keep the GPU from
                 // queuing up too much work.
                 for (int loopCount = loopsPerIter; loopCount > 0; ) {
-                    if (NULL != canvas) {
-                        canvas->save();
-                    }
+                    // Save and restore around each call to draw() to guarantee a pristine canvas.
+                    SkAutoCanvasRestore saveRestore(canvas, true/*also save*/);
+
                     if (frameIntervalComputed && loopCount > loopsPerFrame) {
                         bench->setLoops(loopsPerFrame);
                         loopCount -= loopsPerFrame;
                     } else {
                         bench->setLoops(loopCount);
                         loopCount = 0;
                     }
 
                     if (benchMode == kPictureRecord_BenchMode) {
                         recordFrom.draw(canvas);
                     } else {
                         bench->draw(canvas);
                     }
 
                     if (kDeferredSilent_BenchMode == benchMode) {
                         static_cast<SkDeferredCanvas*>(canvas.get())->silentFlush();
                     } else if (NULL != canvas) {
                         canvas->flush();
                     }
 
 #if SK_SUPPORT_GPU
                     // swap drawing buffers on each frame to prevent the GPU
                     // from queuing up too much work
                     if (NULL != glContext) {
                         glContext->swapBuffers();
                     }
 #endif
-                    if (NULL != canvas) {
-                        canvas->restore();
-                    }
                 }
 
 
 
                 // Stop truncated timers before GL calls complete, and stop the full timers after.
                 timer.truncatedEnd();
 #if SK_SUPPORT_GPU
                 if (NULL != glContext) {
                     context->flush();
                     SK_GL(*glContext, Finish());
@@ skipping 66 matching lines @@
     gContextFactory.destroyContexts();
 #endif
     return 0;
 }
 
 #if !defined(SK_BUILD_FOR_IOS) && !defined(SK_BUILD_FOR_NACL)
 int main(int argc, char * const argv[]) {
     return tool_main(argc, (char**) argv);
 }
 #endif