SkTableMaskFilter.h revision 6806fe87e0b39e283291c1a1c7d1d864230aa2aa 
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 SkTableMaskFilter_DEFINED
9#define SkTableMaskFilter_DEFINED
10
11#include "SkMaskFilter.h"
12#include "SkScalar.h"
13
14/** \class SkTableMaskFilter
15
16    Applies a table lookup on each of the alpha values in the mask.
17    Helper methods create some common tables (e.g. gamma, clipping)
18 */
19class SK_API SkTableMaskFilter : public SkMaskFilter {
20public:
21    SkTableMaskFilter();
22    SkTableMaskFilter(const uint8_t table[256]);
23    virtual ~SkTableMaskFilter();
24
25    void setTable(const uint8_t table[256]);
26
27    /** Utility that sets the gamma table
28     */
29    static void MakeGammaTable(uint8_t table[256], SkScalar gamma);
30
31    /** Utility that creates a clipping table: clamps values below min to 0
32        and above max to 255, and rescales the remaining into 0..255
33     */
34    static void MakeClipTable(uint8_t table[256], uint8_t min, uint8_t max);
35
36    static SkTableMaskFilter* CreateGamma(SkScalar gamma) {
37        uint8_t table[256];
38        MakeGammaTable(table, gamma);
39        return SkNEW_ARGS(SkTableMaskFilter, (table));
40    }
41
42    static SkTableMaskFilter* CreateClip(uint8_t min, uint8_t max) {
43        uint8_t table[256];
44        MakeClipTable(table, min, max);
45        return SkNEW_ARGS(SkTableMaskFilter, (table));
46    }
47
48    // overrides from SkMaskFilter
49    virtual SkMask::Format getFormat();
50    virtual bool filterMask(SkMask*, const SkMask&, const SkMatrix&, SkIPoint*);
51
52    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkTableMaskFilter)
53
54protected:
55    SkTableMaskFilter(SkFlattenableReadBuffer& rb);
56    virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
57
58private:
59    uint8_t fTable[256];
60
61    typedef SkMaskFilter INHERITED;
62};
63
64#endif
65