1/*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SkPorterDuff_DEFINED
9#define SkPorterDuff_DEFINED
10
11#include "SkColor.h"
12#include "SkXfermode.h"
13
14class SkXfermode;
15
16class SK_API SkPorterDuff {
17public:
18    /** List of predefined xfermodes. In general, the algebra for the modes
19        uses the following symbols:
20        Sa, Sc  - source alpha and color
21        Da, Dc - destination alpha and color (before compositing)
22        [a, c] - Resulting (alpha, color) values
23        For these equations, the colors are in premultiplied state.
24        If no xfermode is specified, kSrcOver is assumed.
25    */
26    enum Mode {
27        kClear_Mode,    //!< [0, 0]
28        kSrc_Mode,      //!< [Sa, Sc]
29        kDst_Mode,      //!< [Da, Dc]
30        kSrcOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc]
31        kDstOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc]
32        kSrcIn_Mode,    //!< [Sa * Da, Sc * Da]
33        kDstIn_Mode,    //!< [Sa * Da, Sa * Dc]
34        kSrcOut_Mode,   //!< [Sa * (1 - Da), Sc * (1 - Da)]
35        kDstOut_Mode,   //!< [Da * (1 - Sa), Dc * (1 - Sa)]
36        kSrcATop_Mode,  //!< [Da, Sc * Da + (1 - Sa) * Dc]
37        kDstATop_Mode,  //!< [Sa, Sa * Dc + Sc * (1 - Da)]
38        kXor_Mode,      //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc]
39        kDarken_Mode,   //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + min(Sc, Dc)]
40        kLighten_Mode,  //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + max(Sc, Dc)]
41        kModulate_Mode, //!< [Sa * Da, Sc * Dc] multiplies all components
42        kScreen_Mode,   //!< [Sa + Da - Sa * Da, Sc + Dc - Sc * Dc]
43        kAdd_Mode,      //!< Saturate(S + D)
44#ifdef SK_BUILD_FOR_ANDROID
45        kOverlay_Mode,
46#endif
47
48        kModeCount
49    };
50
51    /** Return an SkXfermode object for the specified mode.
52    */
53    static SkXfermode* CreateXfermode(Mode mode);
54
55    /** Return a function pointer to a routine that applies the specified
56        porter-duff transfer mode.
57    */
58    static SkXfermodeProc GetXfermodeProc(Mode mode);
59
60    /** Return a function pointer to a routine that applies the specified
61        porter-duff transfer mode and srcColor to a 16bit device color. Note,
62        if the mode+srcColor might return a non-opaque color, then there is not
63        16bit proc, and this will return NULL.
64    */
65    static SkXfermodeProc16 GetXfermodeProc16(Mode mode, SkColor srcColor);
66
67    /** If the specified xfermode advertises itself as one of the porterduff
68        modes (via SkXfermode::Coeff), return true and if not null, set mode
69        to the corresponding porterduff mode. If it is not recognized as a one,
70        return false and ignore the mode parameter.
71    */
72    static bool IsMode(SkXfermode*, Mode* mode);
73
74    /** Return the corersponding SkXfermode::Mode
75     */
76    static SkXfermode::Mode ToXfermodeMode(Mode);
77} SK_ATTR_DEPRECATED("use SkXfermode::Mode");
78
79#endif
80