restore clipstack to heap-ptr, so clients can ref it

tests/CanvasTest.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*  Description:
  *      This test defines a series of elementatry test steps that perform
  *      a single or a small group of canvas API calls. Each test step is
@@ skipping 27 matching lines @@
  *      of a single canvas API call.
  *
  *          SIMPLE_TEST_STEP(MytestStep, someCanvasAPIMethod());
  *
  *      There is another macro called SIMPLE_TEST_STEP_WITH_ASSERT that
  *      works the same way as SIMPLE_TEST_STEP, and additionally verifies
  *      that the invoked method returns a non-zero value.
  */
 #include "SkBitmap.h"
 #include "SkCanvas.h"
+#include "SkClipStack.h"
 #include "SkDeferredCanvas.h"
 #include "SkDevice.h"
 #include "SkDocument.h"
 #include "SkMatrix.h"
 #include "SkNWayCanvas.h"
 #include "SkPaint.h"
 #include "SkPath.h"
 #include "SkPicture.h"
 #include "SkPictureRecord.h"
 #include "SkPictureRecorder.h"
@@ skipping 152 matching lines @@
     SkBitmap bm;
     bm.setInfo(SkImageInfo::MakeN32Premul(size.width(), size.height()));
     SkCanvas c(bm);
 
     Canvas2CanvasClipVisitor visitor(&c);
     canvas->replayClips(&visitor);
 
     REPORTER_ASSERT(reporter, equal_clips(c, *canvas));
 }
 
+static void test_clipstack(skiatest::Reporter* reporter) {
+    // The clipstack is refcounted, and needs to be able to out-live the canvas if a client has
+    // ref'd it.
+    const SkClipStack* cs = NULL;
+    {
+        SkCanvas canvas(10, 10);
+        cs = SkRef(canvas.getClipStack());
+    }
+    REPORTER_ASSERT(reporter, cs->unique());
+    cs->unref();
+}
+
 // Format strings that describe the test context.  The %s token is where
 // the name of the test step is inserted.  The context is required for
 // disambiguating the error in the case of failures that are reported in
 // functions that are called multiple times in different contexts (test
 // cases and test steps).
 static const char* const kDefaultAssertMessageFormat = "%s";
 static const char* const kCanvasDrawAssertMessageFormat =
     "Drawing test step %s with SkCanvas";
 static const char* const kDeferredDrawAssertMessageFormat =
     "Drawing test step %s with SkDeferredCanvas";
@@ skipping 434 matching lines @@
     // report correct clipping and device bounds information
     // Issue: http://code.google.com/p/skia/issues/detail?id=501
 
     if (false) { // avoid bit rot, suppress warning
         TestNWayCanvasStateConsistency(reporter, d, testStep, referenceCanvas);
     }
 
     if (false) { // avoid bit rot, suppress warning
         test_clipVisitor(reporter, &referenceCanvas);
     }
+    test_clipstack(reporter);
 }
 
 static void test_newraster(skiatest::Reporter* reporter) {
     SkImageInfo info = SkImageInfo::MakeN32Premul(10, 10);
     const size_t minRowBytes = info.minRowBytes();
     const size_t size = info.getSafeSize(minRowBytes);
     SkAutoMalloc storage(size);
     SkPMColor* baseAddr = static_cast<SkPMColor*>(storage.get());
     sk_bzero(baseAddr, size);
 
@@ skipping 72 matching lines @@
     canvas.restore();
     canvas.save();
     path.moveTo(5, 5);
     canvas.clipPath(path);
     canvas.restore();
     canvas.save();
     path.moveTo(7, 7);
     canvas.clipPath(path);  // should not assert here
     canvas.restore();
 }