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    virtual ~SkTableMaskFilter();
22
23    /** Utility that sets the gamma table
24     */
25    static void MakeGammaTable(uint8_t table[256], SkScalar gamma);
26
27    /** Utility that creates a clipping table: clamps values below min to 0
28        and above max to 255, and rescales the remaining into 0..255
29     */
30    static void MakeClipTable(uint8_t table[256], uint8_t min, uint8_t max);
31
32    static SkTableMaskFilter* Create(const uint8_t table[256]) {
33        return SkNEW_ARGS(SkTableMaskFilter, (table));
34    }
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    virtual SkMask::Format getFormat() const SK_OVERRIDE;
49    virtual bool filterMask(SkMask*, const SkMask&, const SkMatrix&,
50                            SkIPoint*) const SK_OVERRIDE;
51
52    SK_TO_STRING_OVERRIDE()
53    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkTableMaskFilter)
54
55protected:
56    SkTableMaskFilter();
57    explicit SkTableMaskFilter(const uint8_t table[256]);
58    explicit SkTableMaskFilter(SkReadBuffer& rb);
59    virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
60
61private:
62    uint8_t fTable[256];
63
64    typedef SkMaskFilter INHERITED;
65};
66
67#endif
68