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#ifndef SkJpegCodec_DEFINED
9#define SkJpegCodec_DEFINED
10
11#include "SkCodec.h"
12#include "SkColorSpace.h"
13#include "SkColorSpaceXform.h"
14#include "SkImageInfo.h"
15#include "SkSwizzler.h"
16#include "SkStream.h"
17#include "SkTemplates.h"
18
19class JpegDecoderMgr;
20
21/*
22 *
23 * This class implements the decoding for jpeg images
24 *
25 */
26class SkJpegCodec : public SkCodec {
27public:
28    static bool IsJpeg(const void*, size_t);
29
30    /*
31     * Assumes IsJpeg was called and returned true
32     * Takes ownership of the stream
33     */
34    static SkCodec* NewFromStream(SkStream*, Result*);
35
36protected:
37
38    /*
39     * Recommend a set of destination dimensions given a requested scale
40     */
41    SkISize onGetScaledDimensions(float desiredScale) const override;
42
43    /*
44     * Initiates the jpeg decode
45     */
46    Result onGetPixels(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes, const Options&,
47            int*) override;
48
49    bool onQueryYUV8(SkYUVSizeInfo* sizeInfo, SkYUVColorSpace* colorSpace) const override;
50
51    Result onGetYUV8Planes(const SkYUVSizeInfo& sizeInfo, void* planes[3]) override;
52
53    SkEncodedImageFormat onGetEncodedFormat() const override {
54        return SkEncodedImageFormat::kJPEG;
55    }
56
57    bool onRewind() override;
58
59    bool onDimensionsSupported(const SkISize&) override;
60
61private:
62
63    /*
64     * Allows SkRawCodec to communicate the color space from the exif data.
65     */
66    static SkCodec* NewFromStream(SkStream*, Result*, sk_sp<SkColorSpace> defaultColorSpace);
67
68    /*
69     * Read enough of the stream to initialize the SkJpegCodec.
70     * Returns a bool representing success or failure.
71     *
72     * @param codecOut
73     * If this returns true, and codecOut was not nullptr,
74     * codecOut will be set to a new SkJpegCodec.
75     *
76     * @param decoderMgrOut
77     * If this returns true, and codecOut was nullptr,
78     * decoderMgrOut must be non-nullptr and decoderMgrOut will be set to a new
79     * JpegDecoderMgr pointer.
80     *
81     * @param stream
82     * Deleted on failure.
83     * codecOut will take ownership of it in the case where we created a codec.
84     * Ownership is unchanged when we set decoderMgrOut.
85     *
86     * @param defaultColorSpace
87     * If the jpeg does not have an embedded color space, the image data should
88     * be tagged with this color space.
89     */
90    static Result ReadHeader(SkStream* stream, SkCodec** codecOut,
91            JpegDecoderMgr** decoderMgrOut, sk_sp<SkColorSpace> defaultColorSpace);
92
93    /*
94     * Creates an instance of the decoder
95     * Called only by NewFromStream
96     *
97     * @param info contains properties of the encoded data
98     * @param stream the encoded image data
99     * @param decoderMgr holds decompress struct, src manager, and error manager
100     *                   takes ownership
101     */
102    SkJpegCodec(int width, int height, const SkEncodedInfo& info, SkStream* stream,
103            JpegDecoderMgr* decoderMgr, sk_sp<SkColorSpace> colorSpace, Origin origin);
104
105    /*
106     * Checks if the conversion between the input image and the requested output
107     * image has been implemented.
108     *
109     * Sets the output color space.
110     */
111    bool setOutputColorSpace(const SkImageInfo& dst);
112
113    void initializeSwizzler(const SkImageInfo& dstInfo, const Options& options,
114                            bool needsCMYKToRGB);
115    void allocateStorage(const SkImageInfo& dstInfo);
116    int readRows(const SkImageInfo& dstInfo, void* dst, size_t rowBytes, int count, const Options&);
117
118    /*
119     * Scanline decoding.
120     */
121    SkSampler* getSampler(bool createIfNecessary) override;
122    Result onStartScanlineDecode(const SkImageInfo& dstInfo,
123            const Options& options) override;
124    int onGetScanlines(void* dst, int count, size_t rowBytes) override;
125    bool onSkipScanlines(int count) override;
126
127    std::unique_ptr<JpegDecoderMgr>    fDecoderMgr;
128
129    // We will save the state of the decompress struct after reading the header.
130    // This allows us to safely call onGetScaledDimensions() at any time.
131    const int                          fReadyState;
132
133
134    SkAutoTMalloc<uint8_t>             fStorage;
135    uint8_t*                           fSwizzleSrcRow;
136    uint32_t*                          fColorXformSrcRow;
137
138    // libjpeg-turbo provides some subsetting.  In the case that libjpeg-turbo
139    // cannot take the exact the subset that we need, we will use the swizzler
140    // to further subset the output from libjpeg-turbo.
141    SkIRect                            fSwizzlerSubset;
142
143    std::unique_ptr<SkSwizzler>        fSwizzler;
144
145    friend class SkRawCodec;
146
147    typedef SkCodec INHERITED;
148};
149
150#endif
151