SkBmpStandardCodec.h revision c5560bef14149f4c945a4536988aeba1a16adedc 
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
8#include "SkBmpCodec.h"
9#include "SkColorTable.h"
10#include "SkImageInfo.h"
11#include "SkSwizzler.h"
12#include "SkTypes.h"
13
14/*
15 * This class implements the decoding for bmp images that use "standard" modes,
16 * which essentially means they do not contain bit masks or RLE codes.
17 */
18class SkBmpStandardCodec : public SkBmpCodec {
19public:
20
21    /*
22     * Creates an instance of the decoder
23     *
24     * Called only by SkBmpCodec::NewFromStream
25     * There should be no other callers despite this being public
26     *
27     * @param srcInfo contains the source width and height
28     * @param stream the stream of encoded image data
29     * @param bitsPerPixel the number of bits used to store each pixel
30     * @param format the format of the bmp file
31     * @param numColors the number of colors in the color table
32     * @param bytesPerColor the number of bytes in the stream used to represent
33                            each color in the color table
34     * @param offset the offset of the image pixel data from the end of the
35     *               headers
36     * @param rowOrder indicates whether rows are ordered top-down or bottom-up
37     */
38    SkBmpStandardCodec(const SkImageInfo& srcInfo, SkStream* stream,
39            uint16_t bitsPerPixel, uint32_t numColors, uint32_t bytesPerColor,
40            uint32_t offset, SkCodec::SkScanlineOrder rowOrder,
41            bool isIco);
42
43protected:
44
45    Result onGetPixels(const SkImageInfo& dstInfo, void* dst,
46                       size_t dstRowBytes, const Options&, SkPMColor*,
47                       int*, int*) override;
48
49    bool onInIco() const override {
50        return fInIco;
51    }
52
53    SkCodec::Result prepareToDecode(const SkImageInfo& dstInfo,
54            const SkCodec::Options& options, SkPMColor inputColorPtr[],
55            int* inputColorCount) override;
56
57
58    uint32_t onGetFillValue(SkColorType) const override;
59
60    SkSampler* getSampler(bool createIfNecessary) override {
61        SkASSERT(fSwizzler);
62        return fSwizzler;
63    }
64
65private:
66
67    /*
68     * Creates the color table
69     * Sets colorCount to the new color count if it is non-nullptr
70     */
71    bool createColorTable(SkAlphaType alphaType, int* colorCount);
72
73    bool initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts);
74
75    int decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
76            const Options& opts) override;
77
78    /*
79     * @param stream This may be a pointer to the stream owned by the parent SkCodec
80     *               or a sub-stream of the stream owned by the parent SkCodec.
81     *               Either way, this stream is unowned.
82     */
83    void decodeIcoMask(SkStream* stream, const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes);
84
85    SkAutoTUnref<SkColorTable>          fColorTable;     // owned
86    // fNumColors is the number specified in the header, or 0 if not present in the header.
87    const uint32_t                      fNumColors;
88    const uint32_t                      fBytesPerColor;
89    const uint32_t                      fOffset;
90    SkAutoTDelete<SkSwizzler>           fSwizzler;
91    const size_t                        fSrcRowBytes;
92    SkAutoTDeleteArray<uint8_t>         fSrcBuffer;
93    const bool                          fInIco;
94    const size_t                        fAndMaskRowBytes; // only used for fInIco decodes
95
96    typedef SkBmpCodec INHERITED;
97};
98