Make skpaint->grpaint flow work for composing draws

include/gpu/SkGr.h

Index: include/gpu/SkGr.h
diff --git a/include/gpu/SkGr.h b/include/gpu/SkGr.h
index 145d4090b734731ab026783137b9212678eef480..74d880abbe0e8fb0464e7fedf016d4281cfe66ba 100644
--- a/include/gpu/SkGr.h
+++ b/include/gpu/SkGr.h
@@ -54,7 +54,7 @@ static inline GrPixelConfig SkImageInfo2GrPixelConfig(const SkImageInfo& info) {
 
 bool GrPixelConfig2ColorAndProfileType(GrPixelConfig, SkColorType*, SkColorProfileType*);
 
-static inline GrColor SkColor2GrColor(SkColor c) {
+static inline GrColor SkColorToPremulGrColor(SkColor c) {
     SkPMColor pm = SkPreMultiplyColor(c);
     unsigned r = SkGetPackedR32(pm);
     unsigned g = SkGetPackedG32(pm);
@@ -63,7 +63,23 @@ static inline GrColor SkColor2GrColor(SkColor c) {
     return GrColorPackRGBA(r, g, b, a);
 }
 

[robertphillips, 2015/09/25 19:52:17]

We used to always be able to say GrColor was premul. :(

[bsalomon, 2015/09/25 20:45:07]

Sorry, but it cannot be anymore if we want to correctly support compose and
drawVertices. drawVertices is supposed to interpolate unpremul vertex colors and
then premul the interpolated color.

-static inline GrColor SkColor2GrColorJustAlpha(SkColor c) {
+static inline GrColor SkColorToUnpremulGrColor(SkColor c) {
+    unsigned r = SkColorGetR(c);
+    unsigned g = SkColorGetG(c);
+    unsigned b = SkColorGetB(c);
+    unsigned a = SkColorGetA(c);
+    return GrColorPackRGBA(r, g, b, a);
+}
+
+static inline GrColor SkColorToOpaqueGrColor(SkColor c) {
+    unsigned r = SkColorGetR(c);
+    unsigned g = SkColorGetG(c);
+    unsigned b = SkColorGetB(c);
+    return GrColorPackRGBA(r, g, b, 0xFF);
+}
+
+/** Replicates the SkColor's alpha to all four channels of the GrColor. */
+static inline GrColor SkColorAlphaToGrColor(SkColor c) {
     U8CPU a = SkColorGetA(c);
     return GrColorPackRGBA(a, a, a, a);
 }
@@ -108,23 +124,6 @@ GrTexture* GrCreateTextureForPixels(GrContext*, const GrUniqueKey& optionalKey,
 
 ////////////////////////////////////////////////////////////////////////////////
 
-// Converts a SkPaint to a GrPaint, ignoring the SkPaint's shader.
-// Sets the color of GrPaint to the value of the parameter paintColor
-// Callers may subsequently modify the GrPaint. Setting constantColor indicates
-// that the final paint will draw the same color at every pixel. This allows
-// an optimization where the color filter can be applied to the SkPaint's
-// color once while converting to GrPaint and then ignored. TODO: Remove this
-// bool and use the invariant info to automatically apply the color filter.
-bool SkPaint2GrPaintNoShader(GrContext* context, const SkPaint& skPaint, GrColor paintColor,
-                             bool constantColor, GrPaint* grPaint);
-
-// This function is similar to skPaint2GrPaintNoShader but also converts
-// skPaint's shader to a GrFragmentProcessor if possible.
-// constantColor has the same meaning as in skPaint2GrPaintNoShader.
-bool SkPaint2GrPaint(GrContext* context, const SkPaint& skPaint, const SkMatrix& viewM,
-                     bool constantColor, GrPaint* grPaint);
-
-
 SkImageInfo GrMakeInfoFromTexture(GrTexture* tex, int w, int h, bool isOpaque);
 
 // Using the dreaded SkGrPixelRef ...