Skia's ColorMatrix vector is in the 0..255 range not 0..1

Bug #7248980

Change-Id: I9873540e3bc1ea0526ea0884279a427c0de96006

Author: Romain Guy

libs/hwui/SkiaColorFilter.cpp

@@ -36,6 +36,12 @@ SkiaColorFilter::~SkiaColorFilter() {
 
 SkiaColorMatrixFilter::SkiaColorMatrixFilter(SkColorFilter* skFilter, float* matrix, float* vector):
         SkiaColorFilter(skFilter, kColorMatrix, true), mMatrix(matrix), mVector(vector) {
+    // Skia uses the range [0..255] for the addition vector, but we need
+    // the [0..1] range to apply the vector in GLSL
+    for (int i = 0; i < 4; i++) {
+        mVector[i] /= 255.0f;
+    }
+
     // TODO: We should be smarter about this
     mBlend = true;
 }