Make RTree handle the case where the playback canvas has empty clip bounds

src/core/SkRecordDraw.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkRecordDraw.h"
 #include "SkPatchUtils.h"
 
 void SkRecordDraw(const SkRecord& record,
                   SkCanvas* canvas,
                   const SkBBoxHierarchy* bbh,
                   SkDrawPictureCallback* callback) {
     SkAutoCanvasRestore saveRestore(canvas, true /*save now, restore at exit*/);
 
     if (bbh) {
         // Draw only ops that affect pixels in the canvas's current clip.
         // The SkRecord and BBH were recorded in identity space.  This canvas
         // is not necessarily in that same space.  getClipBounds() returns us
         // this canvas' clip bounds transformed back into identity space, which
         // lets us query the BBH.
-        SkRect query = { 0, 0, 0, 0 };
-        (void)canvas->getClipBounds(&query);
+        SkRect query;
+        if (!canvas->getClipBounds(&query))

[mtklein, 2014/10/28 17:29:43]

{} ?

+            return;
 
         SkTDArray<unsigned> ops;
         bbh->search(query, &ops);
 
         SkRecords::Draw draw(canvas);
         for (int i = 0; i < ops.count(); i++) {
             if (callback && callback->abortDrawing()) {
                 return;
             }
             record.visit<void>(ops[i], draw);
@@ skipping 513 matching lines @@
     // Used to track the bounds of Save/Restore blocks and the control ops inside them.
     SkTDArray<SaveBounds> fSaveStack;
     SkTDArray<unsigned>   fControlIndices;
 };
 
 }  // namespace SkRecords
 
 void SkRecordFillBounds(const SkRecord& record, SkBBoxHierarchy* bbh) {
     SkRecords::FillBounds(record, bbh);
 }