SkBmpStandardCodec.h revision 571b30f6117eede6d64cd2b924dc1f6aaa59e70e 
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 SkBmpStandardCodec_DEFINED
8#define SkBmpStandardCodec_DEFINED
9
10#include "SkBmpBaseCodec.h"
11#include "SkColorTable.h"
12#include "SkImageInfo.h"
13#include "SkSwizzler.h"
14#include "SkTypes.h"
15
16/*
17 * This class implements the decoding for bmp images that use "standard" modes,
18 * which essentially means they do not contain bit masks or RLE codes.
19 */
20class SkBmpStandardCodec : public SkBmpBaseCodec {
21public:
22
23    /*
24     * Creates an instance of the decoder
25     *
26     * Called only by SkBmpCodec::NewFromStream
27     * There should be no other callers despite this being public
28     *
29     * @param info contains properties of the encoded data
30     * @param stream the stream of encoded image data
31     * @param bitsPerPixel the number of bits used to store each pixel
32     * @param numColors the number of colors in the color table
33     * @param bytesPerColor the number of bytes in the stream used to represent
34                            each color in the color table
35     * @param offset the offset of the image pixel data from the end of the
36     *               headers
37     * @param rowOrder indicates whether rows are ordered top-down or bottom-up
38     * @param isOpaque indicates if the bmp itself is opaque (before applying
39     *                 the icp mask, if there is one)
40     * @param inIco    indicates if the bmp is embedded in an ico file
41     */
42    SkBmpStandardCodec(int width, int height, const SkEncodedInfo& info, SkStream* stream,
43            uint16_t bitsPerPixel, uint32_t numColors, uint32_t bytesPerColor,
44            uint32_t offset, SkCodec::SkScanlineOrder rowOrder, bool isOpaque,
45            bool inIco);
46
47protected:
48
49    Result onGetPixels(const SkImageInfo& dstInfo, void* dst,
50                       size_t dstRowBytes, const Options&,
51                       int*) override;
52
53    bool onInIco() const override {
54        return fInIco;
55    }
56
57    SkCodec::Result onPrepareToDecode(const SkImageInfo& dstInfo,
58            const SkCodec::Options& options) override;
59
60
61    uint64_t onGetFillValue(const SkImageInfo&) const override;
62
63    SkSampler* getSampler(bool createIfNecessary) override {
64        SkASSERT(fSwizzler);
65        return fSwizzler.get();
66    }
67
68private:
69
70    /*
71     * Creates the color table
72     */
73    bool createColorTable(SkColorType colorType, SkAlphaType alphaType);
74
75    void initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts);
76
77    int decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
78            const Options& opts) override;
79
80    /*
81     * @param stream This may be a pointer to the stream owned by the parent SkCodec
82     *               or a sub-stream of the stream owned by the parent SkCodec.
83     *               Either way, this stream is unowned.
84     */
85    void decodeIcoMask(SkStream* stream, const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes);
86
87    sk_sp<SkColorTable>         fColorTable;
88    // fNumColors is the number specified in the header, or 0 if not present in the header.
89    const uint32_t              fNumColors;
90    const uint32_t              fBytesPerColor;
91    const uint32_t              fOffset;
92    std::unique_ptr<SkSwizzler> fSwizzler;
93    const bool                  fIsOpaque;
94    const bool                  fInIco;
95    const size_t                fAndMaskRowBytes; // only used for fInIco decodes
96
97    typedef SkBmpBaseCodec INHERITED;
98};
99#endif  // SkBmpStandardCodec_DEFINED
100