Fix SkComposeImageFilter's bounds computation and offset handling

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"
 #include "SkBitmapSource.h"
 #include "SkBlurImageFilter.h"
 #include "SkCanvas.h"
 #include "SkColorFilterImageFilter.h"
 #include "SkColorMatrixFilter.h"
+#include "SkComposeImageFilter.h"
 #include "SkDeviceImageFilterProxy.h"
 #include "SkDisplacementMapEffect.h"
 #include "SkDropShadowImageFilter.h"
 #include "SkFlattenableSerialization.h"
 #include "SkGradientShader.h"
 #include "SkLightingImageFilter.h"
 #include "SkMatrixConvolutionImageFilter.h"
 #include "SkMatrixImageFilter.h"
 #include "SkMergeImageFilter.h"
 #include "SkMorphologyImageFilter.h"
@@ skipping 552 matching lines @@
     SkAutoTUnref<SkImageFilter> filter1(SkDilateImageFilter::Create(2, 2));
     SkAutoTUnref<SkImageFilter> filter2(makeDropShadow(filter1.get()));
 
     SkIRect bounds = SkIRect::MakeXYWH(0, 0, 100, 100);
     SkIRect expectedBounds = SkIRect::MakeXYWH(-132, -132, 234, 234);
     filter2->filterBounds(bounds, SkMatrix::I(), &bounds);
 
     REPORTER_ASSERT(reporter, bounds == expectedBounds);
 }
 
+DEF_TEST(ImageFilterComposedBlurFastBounds, reporter) {
+    SkAutoTUnref<SkImageFilter> filter1(makeBlur());
+    SkAutoTUnref<SkImageFilter> filter2(makeBlur());
+    SkAutoTUnref<SkImageFilter> composedFilter(SkComposeImageFilter::Create(filter1.get(), filter2.get()));
+
+    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);
+}
+
 static void draw_blurred_rect(SkCanvas* canvas) {
     SkAutoTUnref<SkImageFilter> filter(SkBlurImageFilter::Create(SkIntToScalar(8), 0));
     SkPaint filterPaint;
     filterPaint.setColor(SK_ColorWHITE);
     filterPaint.setImageFilter(filter);
     canvas->saveLayer(NULL, &filterPaint);
     SkPaint whitePaint;
     whitePaint.setColor(SK_ColorWHITE);
     canvas->drawRect(SkRect::Make(SkIRect::MakeWH(4, 4)), whitePaint);
     canvas->restore();
@@ skipping 464 matching lines @@
     REPORTER_ASSERT(reporter, pixel == SK_ColorGREEN);
 }
 
 DEF_TEST(XfermodeImageFilterCroppedInput, reporter) {
     SkBitmap temp;
     temp.allocN32Pixels(100, 100);
     SkBitmapDevice device(temp);
     test_xfermode_cropped_input(&device, reporter);
 }
 
+DEF_TEST(ComposedImageFilterOffset, reporter) {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(100, 100);
+    bitmap.eraseARGB(0, 0, 0, 0);
+    SkBitmapDevice device(bitmap);
+    SkDeviceImageFilterProxy proxy(&device, SkSurfaceProps(SkSurfaceProps::kLegacyFontHost_InitType));
+
+    SkImageFilter::CropRect cropRect(SkRect::MakeXYWH(1, 0, 20, 20));
+    SkAutoTUnref<SkImageFilter> offsetFilter(SkOffsetImageFilter::Create(0, 0, NULL, &cropRect));
+    SkAutoTUnref<SkImageFilter> composedFilter(SkComposeImageFilter::Create(makeBlur(), offsetFilter.get()));
+    SkBitmap result;
+    SkIPoint offset;
+    SkImageFilter::Context ctx(SkMatrix::I(), SkIRect::MakeLargest(), NULL);
+    REPORTER_ASSERT(reporter, composedFilter->filterImage(&proxy, bitmap, ctx, &result, &offset));
+    REPORTER_ASSERT(reporter, offset.fX == 1 && offset.fY == 0);
+}
+
 #if SK_SUPPORT_GPU
 const SkSurfaceProps gProps = SkSurfaceProps(SkSurfaceProps::kLegacyFontHost_InitType);
 
 DEF_GPUTEST(ImageFilterCropRectGPU, reporter, factory) {
     GrContext* context = factory->get(static_cast<GrContextFactory::GLContextType>(0));
     SkAutoTUnref<SkGpuDevice> device(SkGpuDevice::Create(context,
                                                          SkSurface::kNo_Budgeted,
                                                          SkImageInfo::MakeN32Premul(100, 100),
                                                          0,
                                                          &gProps));
@@ skipping 23 matching lines @@
 DEF_GPUTEST(TestNegativeBlurSigmaGPU, reporter, factory) {
     GrContext* context = factory->get(static_cast<GrContextFactory::GLContextType>(0));
     SkAutoTUnref<SkGpuDevice> device(SkGpuDevice::Create(context,
                                                          SkSurface::kNo_Budgeted,
                                                          SkImageInfo::MakeN32Premul(1, 1),
                                                          0,
                                                          &gProps));
     test_negative_blur_sigma(device, reporter);
 }
 #endif