SkAvoidXfermode.h revision a2ca41e3afdd8fad5e0e924dec029f33918e0a67 
1
2/*
3 * Copyright 2006 The Android Open Source Project
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9
10#ifndef SkAvoidXfermode_DEFINED
11#define SkAvoidXfermode_DEFINED
12
13#include "SkXfermode.h"
14
15/** \class SkAvoidXfermode
16
17    This xfermode will draw the src everywhere except on top of the specified
18    color.
19*/
20class SkAvoidXfermode : public SkXfermode {
21public:
22    enum Mode {
23        kAvoidColor_Mode,   //!< draw everywhere except on the opColor
24        kTargetColor_Mode   //!< draw only on top of the opColor
25    };
26
27    /** This xfermode draws, or doesn't draw, based on the destination's
28        distance from an op-color.
29
30        There are two modes, and each mode interprets a tolerance value.
31
32        Avoid: In this mode, drawing is allowed only on destination pixels that
33               are different from the op-color.
34               Tolerance near 0: avoid any colors even remotely similar to the op-color
35               Tolerance near 255: avoid only colors nearly identical to the op-color
36
37        Target: In this mode, drawing only occurs on destination pixels that
38                are similar to the op-color
39                Tolerance near 0: draw only on colors that are nearly identical to the op-color
40                Tolerance near 255: draw on any colors even remotely similar to the op-color
41     */
42    SkAvoidXfermode(SkColor opColor, U8CPU tolerance, Mode mode);
43
44    // overrides from SkXfermode
45    virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
46                        const SkAlpha aa[]) SK_OVERRIDE;
47    virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count,
48                        const SkAlpha aa[]) SK_OVERRIDE;
49    virtual void xfer4444(uint16_t dst[], const SkPMColor src[], int count,
50                          const SkAlpha aa[]) SK_OVERRIDE;
51    virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count,
52                        const SkAlpha aa[]) SK_OVERRIDE;
53
54    // overrides from SkFlattenable
55    virtual Factory getFactory() SK_OVERRIDE;
56    virtual void flatten(SkFlattenableWriteBuffer&) SK_OVERRIDE;
57
58    static SkFlattenable* CreateProc(SkFlattenableReadBuffer& buffer) {
59        return SkNEW_ARGS(SkAvoidXfermode, (buffer));
60    }
61
62protected:
63    SkAvoidXfermode(SkFlattenableReadBuffer&);
64
65private:
66    SkColor     fOpColor;
67    uint32_t    fDistMul;   // x.14
68    Mode        fMode;
69
70    static SkFlattenable* Create(SkFlattenableReadBuffer&);
71
72    typedef SkXfermode INHERITED;
73};
74
75#endif
76