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
16/** DEPRECATED - use SkXfermode::Mode instead
17 */
18class SK_API SkPorterDuff {
19public:
20    /** List of predefined xfermodes. In general, the algebra for the modes
21        uses the following symbols:
22        Sa, Sc  - source alpha and color
23        Da, Dc - destination alpha and color (before compositing)
24        [a, c] - Resulting (alpha, color) values
25        For these equations, the colors are in premultiplied state.
26        If no xfermode is specified, kSrcOver is assumed.
27    */
28    enum Mode {
29        kClear_Mode,    //!< [0, 0]
30        kSrc_Mode,      //!< [Sa, Sc]
31        kDst_Mode,      //!< [Da, Dc]
32        kSrcOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc]
33        kDstOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc]
34        kSrcIn_Mode,    //!< [Sa * Da, Sc * Da]
35        kDstIn_Mode,    //!< [Sa * Da, Sa * Dc]
36        kSrcOut_Mode,   //!< [Sa * (1 - Da), Sc * (1 - Da)]
37        kDstOut_Mode,   //!< [Da * (1 - Sa), Dc * (1 - Sa)]
38        kSrcATop_Mode,  //!< [Da, Sc * Da + (1 - Sa) * Dc]
39        kDstATop_Mode,  //!< [Sa, Sa * Dc + Sc * (1 - Da)]
40        kXor_Mode,      //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc]
41        kDarken_Mode,   //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + min(Sc, Dc)]
42        kLighten_Mode,  //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + max(Sc, Dc)]
43        kModulate_Mode, //!< [Sa * Da, Sc * Dc] multiplies all components
44        kScreen_Mode,   //!< [Sa + Da - Sa * Da, Sc + Dc - Sc * Dc]
45        kAdd_Mode,      //!< Saturate(S + D)
46#ifdef SK_BUILD_FOR_ANDROID
47        kOverlay_Mode,
48#endif
49
50        kModeCount
51    };
52
53    /** Return an SkXfermode object for the specified mode.
54    */
55    static SkXfermode* CreateXfermode(Mode mode);
56
57    /** Return a function pointer to a routine that applies the specified
58        porter-duff transfer mode.
59    */
60    static SkXfermodeProc GetXfermodeProc(Mode mode);
61
62    /** Return a function pointer to a routine that applies the specified
63        porter-duff transfer mode and srcColor to a 16bit device color. Note,
64        if the mode+srcColor might return a non-opaque color, then there is not
65        16bit proc, and this will return NULL.
66    */
67    static SkXfermodeProc16 GetXfermodeProc16(Mode mode, SkColor srcColor);
68
69    /** If the specified xfermode advertises itself as one of the porterduff
70        modes (via SkXfermode::Coeff), return true and if not null, set mode
71        to the corresponding porterduff mode. If it is not recognized as a one,
72        return false and ignore the mode parameter.
73    */
74    static bool IsMode(SkXfermode*, Mode* mode);
75
76    /** Return the corersponding SkXfermode::Mode
77     */
78    static SkXfermode::Mode ToXfermodeMode(Mode);
79};
80
81#endif
82