80 lines
3.1 KiB
C++
80 lines
3.1 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 SkPorterDuff_DEFINED
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#define SkPorterDuff_DEFINED
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#include "SkColor.h"
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class SkXfermode;
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class SkPorterDuff {
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public:
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/** List of predefined xfermodes. In general, the algebra for the modes
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uses the following symbols:
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Sa, Sc - source alpha and color
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Da, Dc - destination alpha and color (before compositing)
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[a, c] - Resulting (alpha, color) values
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For these equations, the colors are in premultiplied state.
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If no xfermode is specified, kSrcOver is assumed.
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*/
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enum Mode {
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kClear_Mode, //!< [0, 0]
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kSrc_Mode, //!< [Sa, Sc]
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kDst_Mode, //!< [Da, Dc]
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kSrcOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc]
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kDstOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc]
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kSrcIn_Mode, //!< [Sa * Da, Sc * Da]
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kDstIn_Mode, //!< [Sa * Da, Sa * Dc]
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kSrcOut_Mode, //!< [Sa * (1 - Da), Sc * (1 - Da)]
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kDstOut_Mode, //!< [Da * (1 - Sa), Dc * (1 - Sa)]
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kSrcATop_Mode, //!< [Da, Sc * Da + (1 - Sa) * Dc]
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kDstATop_Mode, //!< [Sa, Sa * Dc + Sc * (1 - Da)]
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kXor_Mode, //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc]
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kDarken_Mode, //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + min(Sc, Dc)]
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kLighten_Mode, //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + max(Sc, Dc)]
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kMultiply_Mode, //!< [Sa * Da, Sc * Dc]
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kScreen_Mode, //!< [Sa + Da - Sa * Da, Sc + Dc - Sc * Dc]
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kModeCount
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};
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/** Return an SkXfermode object for the specified mode.
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*/
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static SkXfermode* CreateXfermode(Mode mode);
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/** Return a function pointer to a routine that applies the specified
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porter-duff transfer mode.
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*/
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static SkXfermodeProc GetXfermodeProc(Mode mode);
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/** Return a function pointer to a routine that applies the specified
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porter-duff transfer mode and srcColor to a 16bit device color. Note,
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if the mode+srcColor might return a non-opaque color, then there is not
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16bit proc, and this will return NULL.
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*/
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static SkXfermodeProc16 GetXfermodeProc16(Mode mode, SkColor srcColor);
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/** If the specified xfermode advertises itself as one of the porterduff
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modes (via SkXfermode::Coeff), return true and if not null, set mode
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to the corresponding porterduff mode. If it is not recognized as a one,
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return false and ignore the mode parameter.
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*/
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static bool IsMode(SkXfermode*, Mode* mode);
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};
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#endif
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