Fix pointer aliasing bug in SkImageFilter::computeFastBounds.

tests/ImageFilterTest.cpp

 
 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkBitmapDevice.h"
@@ skipping 731 matching lines @@
 
     SkRect boundsSrc = SkRect::MakeWH(SkIntToScalar(100), SkIntToScalar(100));
     SkRect expectedBounds = SkRect::MakeXYWH(
         SkIntToScalar(-6), SkIntToScalar(-6), SkIntToScalar(112), SkIntToScalar(112));
     SkRect boundsDst = SkRect::MakeEmpty();
     composedFilter->computeFastBounds(boundsSrc, &boundsDst);
 
     REPORTER_ASSERT(reporter, boundsDst == expectedBounds);
 }
 
+DEF_TEST(ImageFilterUnionBounds, reporter) {
+    SkAutoTUnref<SkImageFilter> offset(SkOffsetImageFilter::Create(50, 0));
+    // Regardless of which order they appear in, the image filter bounds should
+    // be combined correctly.
+    {
+        SkAutoTUnref<SkImageFilter> composite(SkXfermodeImageFilter::Create(
+            nullptr, offset.get(), nullptr));
+        SkRect bounds = SkRect::MakeWH(100, 100);
+        // Intentionally aliasing here, as that's what the real callers do.
+        composite->computeFastBounds(bounds, &bounds);
+        REPORTER_ASSERT(reporter, bounds == SkRect::MakeWH(150, 100));
+    }
+    {
+        SkAutoTUnref<SkImageFilter> composite(SkXfermodeImageFilter::Create(
+            nullptr, nullptr, offset.get()));
+        SkRect bounds = SkRect::MakeWH(100, 100);
+        // Intentionally aliasing here, as that's what the real callers do.
+        composite->computeFastBounds(bounds, &bounds);
+        REPORTER_ASSERT(reporter, bounds == SkRect::MakeWH(150, 100));
+    }
+}
+
 static void test_imagefilter_merge_result_size(SkImageFilter::Proxy* proxy,
                                                skiatest::Reporter* reporter,
                                                GrContext* context) {
     SkBitmap greenBM;
     greenBM.allocN32Pixels(20, 20);
     greenBM.eraseColor(SK_ColorGREEN);
     SkAutoTUnref<SkImage> greenImage(SkImage::NewFromBitmap(greenBM));
     SkAutoTUnref<SkImageFilter> source(SkImageSource::Create(greenImage.get()));
     SkAutoTUnref<SkImageFilter> merge(SkMergeImageFilter::Create(source.get(), source.get()));
 
@@ skipping 723 matching lines @@
     test_xfermode_cropped_input(&canvas, reporter);
 }
 
 DEF_GPUTEST_FOR_ALL_CONTEXTS(BlurLargeImage_Gpu, reporter, context) {
     SkAutoTUnref<SkSurface> surface(
         SkSurface::NewRenderTarget(context, SkBudgeted::kYes,
                                    SkImageInfo::MakeN32Premul(100, 100)));
     test_large_blur_input(reporter, surface->getCanvas());
 }
 #endif