SkTableMaskFilter.h revision 0bd80fa01bba2b3f0f49937fcb17928c74bde5a6 
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    /** Utility that sets the gamma table
26     */
27    static void MakeGammaTable(uint8_t table[256], SkScalar gamma);
28
29    /** Utility that creates a clipping table: clamps values below min to 0
30        and above max to 255, and rescales the remaining into 0..255
31     */
32    static void MakeClipTable(uint8_t table[256], uint8_t min, uint8_t max);
33
34    static SkTableMaskFilter* CreateGamma(SkScalar gamma) {
35        uint8_t table[256];
36        MakeGammaTable(table, gamma);
37        return SkNEW_ARGS(SkTableMaskFilter, (table));
38    }
39
40    static SkTableMaskFilter* CreateClip(uint8_t min, uint8_t max) {
41        uint8_t table[256];
42        MakeClipTable(table, min, max);
43        return SkNEW_ARGS(SkTableMaskFilter, (table));
44    }
45
46    virtual SkMask::Format getFormat() const SK_OVERRIDE;
47    virtual bool filterMask(SkMask*, const SkMask&, const SkMatrix&,
48                            SkIPoint*) const SK_OVERRIDE;
49
50    SkDEVCODE(virtual void toString(SkString* str) const SK_OVERRIDE;)
51    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkTableMaskFilter)
52
53protected:
54    SkTableMaskFilter(SkFlattenableReadBuffer& rb);
55    virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
56
57private:
58    uint8_t fTable[256];
59
60    typedef SkMaskFilter INHERITED;
61};
62
63#endif
64