Image filters: optimize crop rect application

src/effects/SkMatrixConvolutionImageFilter.cpp

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMatrixConvolutionImageFilter.h"
 #include "SkBitmap.h"
 #include "SkColorPriv.h"
@@ skipping 319 matching lines @@
     dst.fRight += w;
     dst.fBottom += h;
     if (kReverse_MapDirection == direction) {
         dst.offset(-fKernelOffset);
     } else {
         dst.offset(fKernelOffset - SkIPoint::Make(w, h));
     }
     return dst;
 }
 
-bool SkMatrixConvolutionImageFilter::canComputeFastBounds() const {
+bool SkMatrixConvolutionImageFilter::affectsTransparentBlack() const {
     // Because the kernel is applied in device-space, we have no idea what
     // pixels it will affect in object-space.
-    return false;
+    return true;
 }
 
 #if SK_SUPPORT_GPU
 
 static GrTextureDomain::Mode convert_tilemodes(
         SkMatrixConvolutionImageFilter::TileMode tileMode) {
     switch (tileMode) {
         case SkMatrixConvolutionImageFilter::kClamp_TileMode:
             return GrTextureDomain::kClamp_Mode;
         case SkMatrixConvolutionImageFilter::kRepeat_TileMode:
@@ skipping 36 matching lines @@
             str->appendf("%f ", fKernel[y * fKernelSize.width() + x]);
         }
     }
     str->appendf(")");
     str->appendf("gain: %f bias: %f ", fGain, fBias);
     str->appendf("offset: (%d, %d) ", fKernelOffset.fX, fKernelOffset.fY);
     str->appendf("convolveAlpha: %s", fConvolveAlpha ? "true" : "false");
     str->append(")");
 }
 #endif