Add interface to SkXfermode to return a GrEffect and blend coeffs.

Review URL: https://codereview.chromium.org/13097006

git-svn-id: http://skia.googlecode.com/svn/trunk@8412 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 20 insertions, 2 deletions

diff --git a/include/core/SkXfermode.h b/include/core/SkXfermode.h
index 930403f8da..0a0099f3e2 100644
--- a/include/core/SkXfermode.h
+++ b/include/core/SkXfermode.h
@@ -13,6 +13,8 @@
 #include "SkFlattenable.h"
 #include "SkColor.h"
 
+class GrContext;
+class GrEffectRef;
 class SkString;
 
 /** \class SkXfermode
@@ -74,7 +76,7 @@ public:
 
     /**
      *  The same as calling xfermode->asCoeff(..), except that this also checks
-     *  if the xfermode is NULL, and if so, treats its as kSrcOver_Mode.
+     *  if the xfermode is NULL, and if so, treats it as kSrcOver_Mode.
      */
     static bool AsCoeff(const SkXfermode*, Coeff* src, Coeff* dst);
 
@@ -136,7 +138,7 @@ public:
 
     /**
      *  The same as calling xfermode->asMode(mode), except that this also checks
-     *  if the xfermode is NULL, and if so, treats its as kSrcOver_Mode.
+     *  if the xfermode is NULL, and if so, treats it as kSrcOver_Mode.
      */
     static bool AsMode(const SkXfermode*, Mode* mode);
 
@@ -181,6 +183,22 @@ public:
         return AsMode(xfer, mode);
     }
 
+    /** A subclass may implement this factory function to work with the GPU backend. It is legal
+        to call this with all but the context param NULL to simply test the return value. effect,
+        src, and dst must all be NULL or all non-NULL. If effect is non-NULL then the xfermode may
+        optionally allocate an effect to return and the caller as *effect. The caller will install
+        it and own a ref to it. Since the xfermode may or may not assign *effect, the caller should
+        set *effect to NULL beforehand. If the function returns true then the src and dst coeffs
+        will be applied to the draw regardless of whether an effect was returned.
+     */
+    virtual bool asNewEffect(GrContext*, GrEffectRef** effect, Coeff* src, Coeff* dst) const;
+
+    /**
+     *  The same as calling xfermode->asNewEffect(...), except that this also checks if the xfermode
+     *  is NULL, and if so, treats it as kSrcOver_Mode.
+     */
+    static bool AsNewEffect(SkXfermode*, GrContext*, GrEffectRef** effect, Coeff* src, Coeff* dst);
+
     SkDEVCODE(virtual void toString(SkString* str) const = 0;)
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
 protected: