Make skpaint->grpaint flow work for composing draws

src/gpu/SkGrPriv.h

Index: src/gpu/SkGrPriv.h
diff --git a/src/gpu/SkGrPriv.h b/src/gpu/SkGrPriv.h
index 5cf4dd24d63acb98b684560dc39ce5f85c59fcab..56a086e93527470768bc1745426968e069ce4f42 100644
--- a/src/gpu/SkGrPriv.h
+++ b/src/gpu/SkGrPriv.h
@@ -9,10 +9,17 @@
 #define SkGrPriv_DEFINED
 
 #include "GrTypes.h"
-#include "SkPoint.h"
+#include "SkImageInfo.h"
+#include "SkXfermode.h"
 
 class GrCaps;
+class GrContext;
+class GrFragmentProcessor;
+class GrPaint;
 class GrUniqueKey;
+class SkPaint;
+class SkMatrix;
+struct SkIRect;
 
 /**
  *  Our key includes the offset, width, and height so that bitmaps created by extractSubset()
@@ -28,4 +35,35 @@ class GrUniqueKey;
 void GrMakeKeyFromImageID(GrUniqueKey* key, uint32_t imageID, const SkIRect& imageBounds,
                           const GrCaps&, SkImageUsageType);
 
+/** Converts an SkPaint to a GrPaint for a given GrContext. The matrix is required in order
+    to convert the SkShader (if any) on the SkPaint. */
+bool SkPaintToGrPaint(GrContext*,
+                      const SkPaint& skPaint,
+                      const SkMatrix& viewM,
+                      GrPaint* grPaint);
+
+/** Ignores the SkShader (if any) on skPaint. */
+bool SkPaintToGrPaintNoShader(GrContext* context,
+                              const SkPaint& skPaint,
+                              GrPaint* grPaint);
+
+/** Replaces the SkShader (if any) on skPaint with the passed in GrFragmentProcessor. The processor
+    should expect an unpremul input color and produce a premultiplied output color. */
+bool SkPaintToGrPaintReplaceShader(GrContext*,
+                                   const SkPaint& skPaint,
+                                   const GrFragmentProcessor* shaderFP,
+                                   GrPaint* grPaint);
+
+/** Blends the SkPaint's shader (or color if no shader) with the color which specified via a
+    GrBatch's GrPrimitiveProcesssor. Currently there is a bool param to indicate whether the
+    primitive color is the dst or src color to the blend in order to work around differences between
+    drawVertices and drawAtlas.
+ */
+bool SkPaintToGrPaintWithXfermode(GrContext* context,
+                                  const SkPaint& skPaint,
+                                  const SkMatrix& viewM,
+                                  SkXfermode::Mode primColorMode,
+                                  bool primitiveIsSrc,
+                                  GrPaint* grPaint);
+
 #endif