1/*
2 * Copyright 2015 Google Inc.
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#ifndef SkSampler_DEFINED
8#define SkSampler_DEFINED
9
10#include "include/codec/SkCodec.h"
11#include "include/core/SkTypes.h"
12#include "src/codec/SkCodecPriv.h"
13
14class SkSampler : public SkNoncopyable {
15public:
16 /**
17 * Update the sampler to sample every sampleX'th pixel. Returns the
18 * width after sampling.
19 */
20 int setSampleX(int sampleX) {
21 return this->onSetSampleX(sampleX);
22 }
23
24 /**
25 * Update the sampler to sample every sampleY'th row.
26 */
27 void setSampleY(int sampleY) {
28 fSampleY = sampleY;
29 }
30
31 /**
32 * Retrieve the value set for sampleY.
33 */
34 int sampleY() const {
35 return fSampleY;
36 }
37
38 /**
39 * Based on fSampleY, return whether this row belongs in the output.
40 *
41 * @param row Row of the image, starting with the first row in the subset.
42 */
43 bool rowNeeded(int row) const {
44 return (row - get_start_coord(fSampleY)) % fSampleY == 0;
45 }
46
47 /**
48 * Fill the remainder of the destination with 0.
49 *
50 * 0 has a different meaning depending on the SkColorType. For color types
51 * with transparency, this means transparent. For k565 and kGray, 0 is
52 * black.
53 *
54 * @param info
55 * Contains the color type of the rows to fill.
56 * Contains the pixel width of the destination rows to fill
57 * Contains the number of rows that we need to fill.
58 *
59 * @param dst
60 * The destination row to fill.
61 *
62 * @param rowBytes
63 * Stride in bytes of the destination.
64 *
65 * @param zeroInit
66 * Indicates whether memory is already zero initialized.
67 */
68 static void Fill(const SkImageInfo& info, void* dst, size_t rowBytes,
69 SkCodec::ZeroInitialized zeroInit);
70
71 virtual int fillWidth() const = 0;
72
73 SkSampler()
74 : fSampleY(1)
75 {}
76
77 virtual ~SkSampler() {}
78private:
79 int fSampleY;
80
81 virtual int onSetSampleX(int) = 0;
82};
83
84#endif // SkSampler_DEFINED
85