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  */
18 class SkBmpStandardCodec : public SkBmpCodec {
19 public:
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 numColors the number of colors in the color table
31      * @param bytesPerColor the number of bytes in the stream used to represent
32                             each color in the color table
33      * @param offset the offset of the image pixel data from the end of the
34      *               headers
35      * @param rowOrder indicates whether rows are ordered top-down or bottom-up
36      * @param isOpaque indicates if the bmp itself is opaque (before applying
37      *                 the icp mask, if there is one)
38      * @param inIco    indicates if the bmp is embedded in an ico file
39      */
40     SkBmpStandardCodec(const SkImageInfo& srcInfo, SkStream* stream,
41             uint16_t bitsPerPixel, uint32_t numColors, uint32_t bytesPerColor,
42             uint32_t offset, SkCodec::SkScanlineOrder rowOrder, bool isOpaque,
43             bool inIco);
44 
45 protected:
46 
47     Result onGetPixels(const SkImageInfo& dstInfo, void* dst,
48                        size_t dstRowBytes, const Options&, SkPMColor*,
49                        int*, int*) override;
50 
onInIco()51     bool onInIco() const override {
52         return fInIco;
53     }
54 
55     SkCodec::Result prepareToDecode(const SkImageInfo& dstInfo,
56             const SkCodec::Options& options, SkPMColor inputColorPtr[],
57             int* inputColorCount) override;
58 
59 
onGetFillValue(SkColorType)60     uint32_t onGetFillValue(SkColorType) const override;
61 
62     SkSampler* getSampler(bool createIfNecessary) override {
63         SkASSERT(fSwizzler);
64         return fSwizzler;
65     }
66 
67 private:
68 
69     /*
70      * Creates the color table
71      * Sets colorCount to the new color count if it is non-nullptr
72      */
73     bool createColorTable(SkAlphaType alphaType, int* colorCount);
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     SkAutoTUnref<SkColorTable>          fColorTable;     // owned
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     SkAutoTDelete<SkSwizzler>           fSwizzler;
93     SkAutoTDeleteArray<uint8_t>         fSrcBuffer;
94     const bool                          fIsOpaque;
95     const bool                          fInIco;
96     const size_t                        fAndMaskRowBytes; // only used for fInIco decodes
97 
98     typedef SkBmpCodec INHERITED;
99 };
100