commit 3df05015efce95c306fb79c21efc77c79f1ac1ba
author senorblanco <senorblanco@chromium.org> Thu Jul 03 11:13:09 2014 -0700
committer Commit bot <commit-bot@chromium.org> Thu Jul 03 11:13:09 2014 -0700
tree caa93d5d9af225c88b45e8f8af302dd80167028f
parent 46e51e10ae9a061456a5135a9973755f0b64547c

Fix SkColorFilterImageFilter matrix optimization.

The order of matrices passed to multiplication was wrong (apparently,
this optimization was only being tested with matrices which commute).

See Chrome bug http://crbug.com/378362

R=sugoi@chromium.org

Author: senorblanco@chromium.org

Review URL: https://codereview.chromium.org/371523002

src/effects/SkColorFilterImageFilter.cpp

diff --git a/src/effects/SkColorFilterImageFilter.cpp b/src/effects/SkColorFilterImageFilter.cpp
index 8cdd546..f2490e3 100755
--- a/src/effects/SkColorFilterImageFilter.cpp
+++ b/src/effects/SkColorFilterImageFilter.cpp
@@ -68,7 +68,7 @@
         SkAutoUnref autoUnref(inputColorFilter);
         if (inputColorFilter->asColorMatrix(inputMatrix) && !matrix_needs_clamping(inputMatrix)) {
             SkScalar combinedMatrix[20];
-            mult_color_matrix(inputMatrix, colorMatrix, combinedMatrix);
+            mult_color_matrix(colorMatrix, inputMatrix, combinedMatrix);
             SkAutoTUnref<SkColorFilter> newCF(SkColorMatrixFilter::Create(combinedMatrix));
             return SkNEW_ARGS(SkColorFilterImageFilter, (newCF, input->getInput(0), cropRect));
         }

tests/ImageFilterTest.cpp

diff --git a/tests/ImageFilterTest.cpp b/tests/ImageFilterTest.cpp
index d3471ad..3f71b01 100644
--- a/tests/ImageFilterTest.cpp
+++ b/tests/ImageFilterTest.cpp
@@ -158,6 +158,33 @@
     }
 
     {
+        // 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);