1 files changed, 80 insertions, 0 deletions
diff --git a/skia/include/SkPorterDuff.h b/skia/include/SkPorterDuff.h
new file mode 100644
index 0000000..8ea2363
--- /dev/null
+++ b/skia/include/SkPorterDuff.h
@@ -0,0 +1,80 @@
+/* include/graphics/SkPorterDuff.h
+**
+** Copyright 2006, Google Inc.
+**
+** Licensed under the Apache License, Version 2.0 (the "License"); 
+** you may not use this file except in compliance with the License. 
+** You may obtain a copy of the License at 
+**
+**     http://www.apache.org/licenses/LICENSE-2.0 
+**
+** Unless required by applicable law or agreed to in writing, software 
+** distributed under the License is distributed on an "AS IS" BASIS, 
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
+** See the License for the specific language governing permissions and 
+** limitations under the License.
+*/
+
+#ifndef SkPorterDuff_DEFINED
+#define SkPorterDuff_DEFINED
+
+#include "SkColor.h"
+
+class SkXfermode;
+
+class SkPorterDuff {
+public:
+    /** List of predefined xfermodes. In general, 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]
+        kDarken_Mode,   //!< [Sa + Da - Sa*Da, Sc\u00B7(1 - Da) + Dc\u00B7(1 - Sa) + min(Sc, Dc)]
+        kLighten_Mode,  //!< [Sa + Da - Sa*Da, Sc\u00B7(1 - Da) + Dc\u00B7(1 - Sa) + max(Sc, Dc)]
+        kMultiply_Mode, //!< [Sa * Da, Sc * Dc]
+        kScreen_Mode,   //!< [Sa + Da - Sa * Da, Sc + Dc - Sc * Dc]
+
+        kModeCount
+    };
+    /** Return an SkXfermode object for the specified mode.
+    */
+    static SkXfermode* CreateXfermode(Mode mode);
+    
+    /** Return a function pointer to a routine that applies the specified
+        porter-duff transfer mode.
+    */
+    static SkXfermodeProc GetXfermodeProc(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 GetXfermodeProc16(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);
+};
+
+#endif
+