d252db03d9
git-svn-id: http://skia.googlecode.com/svn/trunk@140 2bbb7eff-a529-9590-31e7-b0007b416f81
134 lines
4.8 KiB
C++
134 lines
4.8 KiB
C++
/*
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* Copyright (C) 2006 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef SkXfermode_DEFINED
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#define SkXfermode_DEFINED
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#include "SkFlattenable.h"
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#include "SkColor.h"
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/** \class SkXfermode
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SkXfermode is the base class for objects that are called to implement custom
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"transfer-modes" in the drawing pipeline. The static function Create(Modes)
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can be called to return an instance of any of the predefined subclasses as
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specified in the Modes enum. When an SkXfermode is assigned to an SkPaint,
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then objects drawn with that paint have the xfermode applied.
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*/
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class SkXfermode : public SkFlattenable {
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public:
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SkXfermode() {}
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virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
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const SkAlpha aa[]);
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virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count,
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const SkAlpha aa[]);
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virtual void xfer4444(uint16_t dst[], const SkPMColor src[], int count,
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const SkAlpha aa[]);
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virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count,
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const SkAlpha aa[]);
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/** Enum of possible coefficients to describe some xfermodes
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*/
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enum Coeff {
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kZero_Coeff, /** 0 */
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kOne_Coeff, /** 1 */
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kSC_Coeff, /** src color */
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kISC_Coeff, /** inverse src color (i.e. 1 - sc) */
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kDC_Coeff, /** dst color */
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kIDC_Coeff, /** inverse dst color (i.e. 1 - dc) */
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kSA_Coeff, /** src alpha */
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kISA_Coeff, /** inverse src alpha (i.e. 1 - sa) */
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kDA_Coeff, /** dst alpha */
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kIDA_Coeff, /** inverse dst alpha (i.e. 1 - da) */
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kCoeffCount
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};
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/** If the xfermode can be expressed as an equation using the coefficients
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in Coeff, then asCoeff() returns true, and sets (if not null) src and
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dst accordingly.
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result = src_coeff * src_color + dst_coeff * dst_color;
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As examples, here are some of the porterduff coefficients
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MODE SRC_COEFF DST_COEFF
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clear zero zero
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src one zero
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dst zero one
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srcover one isa
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dstover ida one
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*/
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virtual bool asCoeff(Coeff* src, Coeff* dst);
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protected:
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SkXfermode(SkFlattenableReadBuffer& rb) : SkFlattenable(rb) {}
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/** The default implementation of xfer32/xfer16/xferA8 in turn call this
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method, 1 color at a time (upscaled to a SkPMColor). The default
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implmentation of this method just returns dst. If performance is
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important, your subclass should override xfer32/xfer16/xferA8 directly.
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This method will not be called directly by the client, so it need not
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be implemented if your subclass has overridden xfer32/xfer16/xferA8
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*/
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virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst);
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private:
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typedef SkFlattenable INHERITED;
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};
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///////////////////////////////////////////////////////////////////////////////
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/** \class SkProcXfermode
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SkProcXfermode is a xfermode that applies the specified proc to its colors.
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This class is not exported to java.
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*/
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class SkProcXfermode : public SkXfermode {
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public:
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SkProcXfermode(SkXfermodeProc proc) : fProc(proc) {}
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// overrides from SkXfermode
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virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
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const SkAlpha aa[]);
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virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count,
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const SkAlpha aa[]);
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virtual void xfer4444(uint16_t dst[], const SkPMColor src[], int count,
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const SkAlpha aa[]);
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virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count,
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const SkAlpha aa[]);
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// overrides from SkFlattenable
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virtual Factory getFactory() { return CreateProc; }
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virtual void flatten(SkFlattenableWriteBuffer&);
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protected:
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SkProcXfermode(SkFlattenableReadBuffer&);
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private:
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SkXfermodeProc fProc;
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static SkFlattenable* CreateProc(SkFlattenableReadBuffer& buffer) {
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return SkNEW_ARGS(SkProcXfermode, (buffer)); }
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typedef SkXfermode INHERITED;
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};
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#endif
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