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  */
19 class SK_API SkTableMaskFilter : public SkMaskFilter {
20 public:
21     /** Utility that sets the gamma table
22      */
23     static void MakeGammaTable(uint8_t table[256], SkScalar gamma);
24 
25     /** Utility that creates a clipping table: clamps values below min to 0
26         and above max to 255, and rescales the remaining into 0..255
27      */
28     static void MakeClipTable(uint8_t table[256], uint8_t min, uint8_t max);
29 
Create(const uint8_t table[256])30     static SkMaskFilter* Create(const uint8_t table[256]) {
31         return new SkTableMaskFilter(table);
32     }
33 
CreateGamma(SkScalar gamma)34     static SkMaskFilter* CreateGamma(SkScalar gamma) {
35         uint8_t table[256];
36         MakeGammaTable(table, gamma);
37         return new SkTableMaskFilter(table);
38     }
39 
CreateClip(uint8_t min,uint8_t max)40     static SkMaskFilter* CreateClip(uint8_t min, uint8_t max) {
41         uint8_t table[256];
42         MakeClipTable(table, min, max);
43         return new SkTableMaskFilter(table);
44     }
45 
46     SkMask::Format getFormat() const override;
47     bool filterMask(SkMask*, const SkMask&, const SkMatrix&, SkIPoint*) const override;
48 
49     SK_TO_STRING_OVERRIDE()
50     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkTableMaskFilter)
51 
52 protected:
53     virtual ~SkTableMaskFilter();
54 
55     void flatten(SkWriteBuffer&) const override;
56 
57 private:
58     SkTableMaskFilter();
59     explicit SkTableMaskFilter(const uint8_t table[256]);
60 
61     uint8_t fTable[256];
62 
63     typedef SkMaskFilter INHERITED;
64 };
65 
66 #endif
67