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 SkTableMaskFilter_DEFINED
18#define SkTableMaskFilter_DEFINED
19
20#include "SkMaskFilter.h"
21#include "SkScalar.h"
22
23/** \class SkTableMaskFilter
24
25    Applies a table lookup on each of the alpha values in the mask.
26    Helper methods create some common tables (e.g. gamma, clipping)
27 */
28class SkTableMaskFilter : public SkMaskFilter {
29public:
30    SkTableMaskFilter();
31    SkTableMaskFilter(const uint8_t table[256]);
32    virtual ~SkTableMaskFilter();
33
34    void setTable(const uint8_t table[256]);
35
36    /** Utility that sets the gamma table
37     */
38    static void MakeGammaTable(uint8_t table[256], SkScalar gamma);
39
40    /** Utility that creates a clipping table: clamps values below min to 0
41        and above max to 255, and rescales the remaining into 0..255
42     */
43    static void MakeClipTable(uint8_t table[256], uint8_t min, uint8_t max);
44
45    static SkTableMaskFilter* CreateGamma(SkScalar gamma) {
46        uint8_t table[256];
47        MakeGammaTable(table, gamma);
48        return SkNEW_ARGS(SkTableMaskFilter, (table));
49    }
50
51    static SkTableMaskFilter* CreateClip(uint8_t min, uint8_t max) {
52        uint8_t table[256];
53        MakeClipTable(table, min, max);
54        return SkNEW_ARGS(SkTableMaskFilter, (table));
55    }
56
57    // overrides from SkMaskFilter
58    virtual SkMask::Format getFormat();
59    virtual bool filterMask(SkMask*, const SkMask&, const SkMatrix&, SkIPoint*);
60
61    // overrides from SkFlattenable
62    virtual void flatten(SkFlattenableWriteBuffer& wb);
63    virtual Factory getFactory();
64
65protected:
66    SkTableMaskFilter(SkFlattenableReadBuffer& rb);
67    static SkFlattenable* Factory(SkFlattenableReadBuffer&);
68
69private:
70    uint8_t fTable[256];
71
72    typedef SkMaskFilter INHERITED;
73};
74
75#endif
76
77