grab from latest android
git-svn-id: http://skia.googlecode.com/svn/trunk@27 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/core/SkComposeShader.h b/include/core/SkComposeShader.h
new file mode 100644
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+++ b/include/core/SkComposeShader.h
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+/*
+ * Copyright (C) 2006 The Android Open Source Project
+ *
+ * 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 SkComposeShader_DEFINED
+#define SkComposeShader_DEFINED
+
+#include "SkShader.h"
+
+class SkXfermode;
+
+///////////////////////////////////////////////////////////////////////////////////////////
+
+/** \class SkComposeShader
+ This subclass of shader returns the coposition of two other shaders, combined by
+ a xfermode.
+*/
+class SkComposeShader : public SkShader {
+public:
+ /** Create a new compose shader, given shaders A, B, and a combining xfermode mode.
+ When the xfermode is called, it will be given the result from shader A as its
+ "dst", and the result of from shader B as its "src".
+ mode->xfer32(sA_result, sB_result, ...)
+ @param shaderA The colors from this shader are seen as the "dst" by the xfermode
+ @param shaderB The colors from this shader are seen as the "src" by the xfermode
+ @param mode The xfermode that combines the colors from the two shaders. If mode
+ is null, then SRC_OVER is assumed.
+ */
+ SkComposeShader(SkShader* sA, SkShader* sB, SkXfermode* mode = NULL);
+ virtual ~SkComposeShader();
+
+ // override
+ virtual bool setContext(const SkBitmap& device, const SkPaint& paint, const SkMatrix& matrix);
+ virtual void shadeSpan(int x, int y, SkPMColor result[], int count);
+ virtual void beginSession();
+ virtual void endSession();
+
+protected:
+ SkComposeShader(SkFlattenableReadBuffer& );
+ virtual void flatten(SkFlattenableWriteBuffer& );
+ virtual Factory getFactory() { return CreateProc; }
+
+private:
+ static SkFlattenable* CreateProc(SkFlattenableReadBuffer& buffer) {
+ return SkNEW_ARGS(SkComposeShader, (buffer)); }
+
+ SkShader* fShaderA;
+ SkShader* fShaderB;
+ SkXfermode* fMode;
+
+ typedef SkShader INHERITED;
+};
+
+#endif