1/*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef SkAvoidXfermode_DEFINED
18#define SkAvoidXfermode_DEFINED
19
20#include "SkXfermode.h"
21
22/** \class SkAvoidXfermode
23
24    This xfermode will draw the src everywhere except on top of the specified
25    color.
26*/
27class SkAvoidXfermode : public SkXfermode {
28public:
29    enum Mode {
30        kAvoidColor_Mode,   //!< draw everywhere except on the opColor
31        kTargetColor_Mode   //!< draw only on top of the opColor
32    };
33
34    /** This xfermode draws, or doesn't draw, based on the destination's
35        distance from an op-color.
36
37        There are two modes, and each mode interprets a tolerance value.
38
39        Avoid: In this mode, drawing is allowed only on destination pixels that
40               are different from the op-color.
41               Tolerance near 0: avoid any colors even remotely similar to the op-color
42               Tolerance near 255: avoid only colors nearly identical to the op-color
43
44        Target: In this mode, drawing only occurs on destination pixels that
45                are similar to the op-color
46                Tolerance near 0: draw only on colors that are nearly identical to the op-color
47                Tolerance near 255: draw on any colors even remotely similar to the op-color
48     */
49    SkAvoidXfermode(SkColor opColor, U8CPU tolerance, Mode mode);
50
51    // overrides from SkXfermode
52    virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
53                        const SkAlpha aa[]);
54    virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count,
55                        const SkAlpha aa[]);
56    virtual void xfer4444(uint16_t dst[], const SkPMColor src[], int count,
57                          const SkAlpha aa[]);
58    virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count,
59                        const SkAlpha aa[]);
60
61    // overrides from SkFlattenable
62    virtual Factory getFactory();
63    virtual void flatten(SkFlattenableWriteBuffer&);
64
65protected:
66    SkAvoidXfermode(SkFlattenableReadBuffer&);
67
68private:
69    SkColor     fOpColor;
70    uint32_t    fDistMul;   // x.14
71    Mode        fMode;
72
73    static SkFlattenable* Create(SkFlattenableReadBuffer&);
74
75    typedef SkXfermode INHERITED;
76};
77
78#endif
79