Fix SkColorFilterImageFilter matrix optimization.

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"
@@ skipping 140 matching lines @@
 
     {
         // Check that a color filter image filter with a crop rect cannot
         // be expressed as a color filter.
         SkImageFilter::CropRect cropRect(SkRect::MakeXYWH(0, 0, 100, 100));
         SkAutoTUnref<SkImageFilter> grayWithCrop(make_grayscale(NULL, &cropRect));
         REPORTER_ASSERT(reporter, false == grayWithCrop->asColorFilter(NULL));
     }
 
     {
+        // Check that two non-commutative matrices are concatenated in
+        // the correct order.
+        SkScalar blueToRedMatrix[20] = { 0 };
+        blueToRedMatrix[2] = blueToRedMatrix[18] = SK_Scalar1;
+        SkScalar redToGreenMatrix[20] = { 0 };
+        redToGreenMatrix[5] = redToGreenMatrix[18] = SK_Scalar1;
+        SkAutoTUnref<SkColorFilter> blueToRed(SkColorMatrixFilter::Create(blueToRedMatrix));
+        SkAutoTUnref<SkImageFilter> filter1(SkColorFilterImageFilter::Create(blueToRed.get()));
+        SkAutoTUnref<SkColorFilter> redToGreen(SkColorMatrixFilter::Create(redToGreenMatrix));
+        SkAutoTUnref<SkImageFilter> filter2(SkColorFilterImageFilter::Create(redToGreen.get(), filter1.get()));
+
+        SkBitmap result;
+        result.allocN32Pixels(kBitmapSize, kBitmapSize);
+
+        SkPaint paint;
+        paint.setColor(SK_ColorBLUE);
+        paint.setImageFilter(filter2.get());
+        SkCanvas canvas(result);
+        canvas.clear(0x0);
+        SkRect rect = SkRect::Make(SkIRect::MakeWH(kBitmapSize, kBitmapSize));
+        canvas.drawRect(rect, paint);
+        uint32_t pixel = *result.getAddr32(0, 0);
+        // The result here should be green, since we have effectively shifted blue to green.
+        REPORTER_ASSERT(reporter, pixel == SK_ColorGREEN);
+    }
+
+    {
         // Tests pass by not asserting
         SkBitmap bitmap, result;
         make_small_bitmap(bitmap);
         result.allocN32Pixels(kBitmapSize, kBitmapSize);
 
         {
             // This tests for :
             // 1 ) location at (0,0,1)
             SkPoint3 location(0, 0, SK_Scalar1);
             // 2 ) location and target at same value
@@ skipping 563 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