move xfermode modes from porterduff into xfermode itself

git-svn-id: http://skia.googlecode.com/svn/trunk@232 2bbb7eff-a529-9590-31e7-b0007b416f81

4 files changed, 87 insertions, 3 deletions

diff --git a/include/core/SkMath.h b/include/core/SkMath.h
index 0c89065855..9198412634 100644
--- a/include/core/SkMath.h
+++ b/include/core/SkMath.h
@@ -217,5 +217,12 @@ static inline unsigned SkMul16ShiftRound(unsigned a, unsigned b, int shift) {
     return (prod + (prod >> shift)) >> shift;
 }
 
+/** Just the rounding step in SkDiv255Round: round(value / 255)
+ */
+static inline unsigned SkDiv255Round(unsigned prod) {
+    prod += 128;
+    return (prod + (prod >> 8)) >> 8;
+}
+
 #endif
 
diff --git a/include/core/SkPaint.h b/include/core/SkPaint.h
index dd3aa13d11..5865fe85bd 100644
--- a/include/core/SkPaint.h
+++ b/include/core/SkPaint.h
@@ -19,6 +19,9 @@
 
 #include "SkColor.h"
 #include "SkMath.h"
+#include "SkXfermode.h"
+
+// DEPRECATED - remove
 #include "SkPorterDuff.h"
 
 class SkAutoGlyphCache;
@@ -37,7 +40,6 @@ class SkRasterizer;
 class SkShader;
 class SkDrawLooper;
 class SkTypeface;
-class SkXfermode;
 
 typedef const SkGlyph& (*SkDrawCacheProc)(SkGlyphCache*, const char**,
                                            SkFixed x, SkFixed y);
@@ -456,8 +458,15 @@ public:
         @return         xfermode
     */
     SkXfermode* setXfermode(SkXfermode* xfermode);
-    
-    /** Helper for setXfermode, passing the corresponding xfermode object
+
+    /** Create an xfermode based on the specified Mode, and assign it into the
+        paint, returning the mode that was set. If the Mode is SrcOver, then
+        the paint's xfermode is set to null.
+     */
+    SkXfermode* setXfermode(SkXfermode::Mode);
+
+    /** DEPRECATED
+        Helper for setXfermode, passing the corresponding xfermode object
         returned from the PorterDuff factory.
         @param mode The porter-duff mode used to create an xfermode for the
                     paint.
diff --git a/include/core/SkPorterDuff.h b/include/core/SkPorterDuff.h
index 44c5477352..52021b1e7b 100644
--- a/include/core/SkPorterDuff.h
+++ b/include/core/SkPorterDuff.h
@@ -21,6 +21,8 @@
 
 class SkXfermode;
 
+/** DEPRECATED - use SkXfermode::Mode instead
+ */
 class SkPorterDuff {
 public:
     /** List of predefined xfermodes. In general, the algebra for the modes
diff --git a/include/core/SkXfermode.h b/include/core/SkXfermode.h
index 6a7edecc3f..7a064673eb 100644
--- a/include/core/SkXfermode.h
+++ b/include/core/SkXfermode.h
@@ -75,6 +75,69 @@ public:
      */
     virtual bool asCoeff(Coeff* src, Coeff* dst);
 
+    /** List of predefined xfermodes.
+        The algebra for the modes uses the following symbols:
+        Sa, Sc  - source alpha and color
+        Da, Dc - destination alpha and color (before compositing)
+        [a, c] - Resulting (alpha, color) values
+        For these equations, the colors are in premultiplied state.
+        If no xfermode is specified, kSrcOver is assumed.
+     */
+    enum Mode {
+        kClear_Mode,    //!< [0, 0]
+        kSrc_Mode,      //!< [Sa, Sc]
+        kDst_Mode,      //!< [Da, Dc]
+        kSrcOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc]
+        kDstOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc]
+        kSrcIn_Mode,    //!< [Sa * Da, Sc * Da]
+        kDstIn_Mode,    //!< [Sa * Da, Sa * Dc]
+        kSrcOut_Mode,   //!< [Sa * (1 - Da), Sc * (1 - Da)]
+        kDstOut_Mode,   //!< [Da * (1 - Sa), Dc * (1 - Sa)]
+        kSrcATop_Mode,  //!< [Da, Sc * Da + (1 - Sa) * Dc]
+        kDstATop_Mode,  //!< [Sa, Sa * Dc + Sc * (1 - Da)]
+        kXor_Mode,      //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc]
+
+        // these modes are defined in the SVG Compositing standard
+        // http://www.w3.org/TR/2009/WD-SVGCompositing-20090430/
+        kPlus_Mode,
+        kMultiply_Mode,
+        kScreen_Mode,
+        kOverlay_Mode,
+        kDarken_Mode,
+        kLighten_Mode,
+        kColorDodge_Mode,
+        kColorBurn_Mode,
+        kHardLight_Mode,
+        kSoftLight_Mode,
+        kDifference_Mode,
+        kExclusion_Mode,
+
+        kLastMode = kExclusion_Mode
+    };
+
+    /** Return an SkXfermode object for the specified mode.
+     */
+    static SkXfermode* Create(Mode mode);
+
+    /** Return a function pointer to a routine that applies the specified
+        porter-duff transfer mode.
+     */
+    static SkXfermodeProc GetProc(Mode mode);
+
+    /** Return a function pointer to a routine that applies the specified
+        porter-duff transfer mode and srcColor to a 16bit device color. Note,
+        if the mode+srcColor might return a non-opaque color, then there is not
+        16bit proc, and this will return NULL.
+      */
+    static SkXfermodeProc16 GetProc16(Mode mode, SkColor srcColor);
+
+    /** If the specified xfermode advertises itself as one of the porterduff
+        modes (via SkXfermode::Coeff), return true and if not null, set mode
+        to the corresponding porterduff mode. If it is not recognized as a one,
+        return false and ignore the mode parameter.
+     */
+    static bool IsMode(SkXfermode*, Mode* mode);
+
 protected:
     SkXfermode(SkFlattenableReadBuffer& rb) : SkFlattenable(rb) {}
     
@@ -89,6 +152,9 @@ protected:
     virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst);
 
 private:
+    enum {
+        kModeCount = kLastMode + 1
+    };
     typedef SkFlattenable INHERITED;
 };