commit c3e159a325892e5a271c06285631c2f5a2277617
author senorblanco@chromium.org <senorblanco@chromium.org@2bbb7eff-a529-9590-31e7-b0007b416f81> Thu Jan 05 16:59:27 2012 +0000
committer senorblanco@chromium.org <senorblanco@chromium.org@2bbb7eff-a529-9590-31e7-b0007b416f81> Thu Jan 05 16:59:27 2012 +0000
tree b78a1e201fcff61e402ee1b558ce0fee37ee675e
parent dc9a695a62ffe0f18e2835bffd325b60b64b547b

When applying a color matrix, unpremultiply the source, and premultiply
the result.

Review URL:  http://codereview.appspot.com/5520046/



git-svn-id: http://skia.googlecode.com/svn/trunk@2969 2bbb7eff-a529-9590-31e7-b0007b416f81

gm/colormatrix.cpp

diff --git a/gm/colormatrix.cpp b/gm/colormatrix.cpp
index 7d57b32..0a4acfd 100644
--- a/gm/colormatrix.cpp
+++ b/gm/colormatrix.cpp
@@ -90,6 +90,19 @@
         matrix.setYUV2RGB();
         filter->setMatrix(matrix);
         canvas->drawBitmap(fBitmap, 80, 160, &paint);
+
+        SkScalar s1 = SK_Scalar1;
+        SkScalar s255 = SkIntToScalar(255);
+        // Move red into alpha, set color to white
+        SkScalar data[20] = {
+            0,  0, 0, 0, s255,
+            0,  0, 0, 0, s255,
+            0,  0, 0, 0, s255,
+            s1, 0, 0, 0, 0,
+        };
+
+        filter->setArray(data);
+        canvas->drawBitmap(fBitmap, 160, 160, &paint);
     }
     
 private:

src/gpu/GrGLProgram.cpp

diff --git a/src/gpu/GrGLProgram.cpp b/src/gpu/GrGLProgram.cpp
index ce87b85..4d733a9 100644
--- a/src/gpu/GrGLProgram.cpp
+++ b/src/gpu/GrGLProgram.cpp
@@ -373,7 +373,8 @@
  */
 static void addColorMatrix(GrStringBuilder* fsCode, const char * outputVar,
                            const char* inColor) {
-    fsCode->appendf("%s = %s * %s + %s;\n", outputVar, COL_MATRIX_UNI_NAME, inColor, COL_MATRIX_VEC_UNI_NAME);
+    fsCode->appendf("\t%s = %s * vec4(%s.rgb / %s.a, %s.a) + %s;\n", outputVar, COL_MATRIX_UNI_NAME, inColor, inColor, inColor, COL_MATRIX_VEC_UNI_NAME);
+    fsCode->appendf("\t%s.rgb *= %s.a;\n", outputVar, outputVar);
 }
 
 namespace {