Fix filter bounds computation for SkOffsetImageFilter.

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 "SkBicubicImageFilter.h"
 #include "SkBitmap.h"
 #include "SkBitmapDevice.h"
@@ skipping 280 matching lines @@
     SkAutoTUnref<SkColorFilter> cf(SkColorFilter::CreateModeFilter(SK_ColorRED, SkXfermode::kSrcIn_Mode));
     SkPoint3 location(0, 0, SK_Scalar1);
     SkPoint3 target(SK_Scalar1, SK_Scalar1, SK_Scalar1);
     SkScalar kernel[9] = {
         SkIntToScalar( 1), SkIntToScalar( 1), SkIntToScalar( 1),
         SkIntToScalar( 1), SkIntToScalar(-7), SkIntToScalar( 1),
         SkIntToScalar( 1), SkIntToScalar( 1), SkIntToScalar( 1),
     };
     SkISize kernelSize = SkISize::Make(3, 3);
     SkScalar gain = SK_Scalar1, bias = 0;
+    SkScalar five = SkIntToScalar(5);
 
     SkAutoTUnref<SkImageFilter> gradient_source(SkBitmapSource::Create(make_gradient_circle(64, 64)));
+    SkAutoTUnref<SkImageFilter> blur(SkBlurImageFilter::Create(five, five));
     SkMatrix matrix;
+
     matrix.setTranslate(SK_Scalar1, SK_Scalar1);
     matrix.postRotate(SkIntToScalar(45), SK_Scalar1, SK_Scalar1);
 
     struct {
         const char*    fName;
         SkImageFilter* fFilter;
     } filters[] = {
         { "color filter", SkColorFilterImageFilter::Create(cf.get()) },
         { "displacement map", SkDisplacementMapEffect::Create(
               SkDisplacementMapEffect::kR_ChannelSelectorType,
@@ skipping 10 matching lines @@
               SkMatrixConvolutionImageFilter::Create(
                   kernelSize, kernel, gain, bias, SkIPoint::Make(1, 1),
                   SkMatrixConvolutionImageFilter::kRepeat_TileMode, false) },
         { "merge", SkMergeImageFilter::Create(NULL, NULL, SkXfermode::kSrcOver_Mode) },
         { "offset", SkOffsetImageFilter::Create(SK_Scalar1, SK_Scalar1) },
         { "dilate", SkDilateImageFilter::Create(3, 2) },
         { "erode", SkErodeImageFilter::Create(2, 3) },
         { "tile", SkTileImageFilter::Create(SkRect::MakeXYWH(0, 0, 50, 50),
                                             SkRect::MakeXYWH(0, 0, 100, 100), NULL) },
         { "matrix", SkMatrixImageFilter::Create(matrix, SkPaint::kLow_FilterLevel) },
+        { "blur and offset", SkOffsetImageFilter::Create(five, five, blur.get()) },
     };
 
     SkBitmap untiledResult, tiledResult;
     int width = 64, height = 64;
     untiledResult.allocN32Pixels(width, height);
     tiledResult.allocN32Pixels(width, height);
     SkCanvas tiledCanvas(tiledResult);
     SkCanvas untiledCanvas(untiledResult);
     int tileSize = 8;
 
@@ skipping 332 matching lines @@
 }
 
 DEF_GPUTEST(XfermodeImageFilterCroppedInputGPU, reporter, factory) {
     GrContext* context = factory->get(static_cast<GrContextFactory::GLContextType>(0));
     SkAutoTUnref<SkGpuDevice> device(SkGpuDevice::Create(context,
                                                          SkImageInfo::MakeN32Premul(1, 1),
                                                          0));
     test_xfermode_cropped_input(device, reporter);
 }
 #endif