Make sure pictures draw Clears even when the clip is empty.

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 "SkLayerInfo.h"
 #include "SkRecordDraw.h"
 #include "SkPatchUtils.h"
 
 void SkRecordDraw(const SkRecord& record,
                   SkCanvas* canvas,
                   SkPicture const* const drawablePicts[], int drawableCount,
                   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)) {
+            // We want to make sure our query rectangle is never totally empty.
+            // Clear ignores the clip, so it must draw even if the clip is logically empty.
+            query = SkRect::MakeWH(SK_ScalarNearlyZero, SK_ScalarNearlyZero);
+        }
 
         SkTDArray<unsigned> ops;
         bbh->search(query, &ops);
 
         SkRecords::Draw draw(canvas, drawablePicts, drawableCount);
         for (int i = 0; i < ops.count(); i++) {
             if (callback && callback->abortDrawing()) {
                 return;
             }
             // This visit call uses the SkRecords::Draw::operator() to call
@@ skipping 717 matching lines @@
     SkRecords::CollectLayers visitor(cullRect, record, data);
 
     for (unsigned curOp = 0; curOp < record.count(); curOp++) {
         visitor.setCurrentOp(curOp);
         record.visit<void>(curOp, visitor);
     }
 
     visitor.cleanUp(bbh);
 }