SkIcoCodec.h revision 8e6c7ada5a4c5a950cded765d14d3e6906acdc79 
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 "SkCodec.h"
9#include "SkImageInfo.h"
10#include "SkStream.h"
11#include "SkTypes.h"
12
13/*
14 * This class implements the decoding for bmp images
15 */
16class SkIcoCodec : public SkCodec {
17public:
18    static bool IsIco(const void*, size_t);
19
20    /*
21     * Assumes IsIco was called and returned true
22     * Creates an Ico decoder
23     * Reads enough of the stream to determine the image format
24     */
25    static SkCodec* NewFromStream(SkStream*);
26
27protected:
28
29    /*
30     * Chooses the best dimensions given the desired scale
31     */
32    SkISize onGetScaledDimensions(float desiredScale) const override;
33
34    bool onDimensionsSupported(const SkISize&) override;
35
36    /*
37     * Initiates the Ico decode
38     */
39    Result onGetPixels(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes, const Options&,
40            SkPMColor*, int*, int*) override;
41
42    SkEncodedFormat onGetEncodedFormat() const override {
43        return kICO_SkEncodedFormat;
44    }
45
46    SkScanlineOrder onGetScanlineOrder() const override;
47
48private:
49
50    Result onStartScanlineDecode(const SkImageInfo& dstInfo, const SkCodec::Options& options,
51            SkPMColor inputColorPtr[], int* inputColorCount) override;
52
53    int onGetScanlines(void* dst, int count, size_t rowBytes) override;
54
55    bool onSkipScanlines(int count) override;
56
57    Result onStartIncrementalDecode(const SkImageInfo& dstInfo, void* pixels, size_t rowBytes,
58            const SkCodec::Options&, SkPMColor*, int*) override;
59
60    Result onIncrementalDecode(int* rowsDecoded) override;
61
62    SkSampler* getSampler(bool createIfNecessary) override;
63
64    /*
65     * Searches fEmbeddedCodecs for a codec that matches requestedSize.
66     * The search starts at startIndex and ends when an appropriate codec
67     * is found, or we have reached the end of the array.
68     *
69     * @return the index of the matching codec or -1 if there is no
70     *         matching codec between startIndex and the end of
71     *         the array.
72     */
73    int chooseCodec(const SkISize& requestedSize, int startIndex);
74
75    /*
76     * Constructor called by NewFromStream
77     * @param embeddedCodecs codecs for the embedded images, takes ownership
78     */
79    SkIcoCodec(int width, int height, const SkEncodedInfo& info,
80            SkTArray<SkAutoTDelete<SkCodec>, true>* embeddedCodecs);
81
82    SkAutoTDelete<SkTArray<SkAutoTDelete<SkCodec>, true>> fEmbeddedCodecs; // owned
83
84    // Only used by the scanline decoder.  onStartScanlineDecode() will set
85    // fCurrScanlineCodec to one of the fEmbeddedCodecs, if it can find a
86    // codec of the appropriate size.  We will use fCurrScanlineCodec for
87    // subsequent calls to onGetScanlines() or onSkipScanlines().
88    // fCurrScanlineCodec is owned by this class, but should not be an
89    // SkAutoTDelete.  It will be deleted by the destructor of fEmbeddedCodecs.
90    SkCodec* fCurrScanlineCodec;
91
92    // Only used by incremental decoder.  onStartIncrementalDecode() will set
93    // fCurrIncrementalCodec to one of the fEmbeddedCodecs, if it can find a
94    // codec of the appropriate size.  We will use fCurrIncrementalCodec for
95    // subsequent calls to incrementalDecode().
96    // fCurrIncrementalCodec is owned by this class, but should not be an
97    // SkAutoTDelete.  It will be deleted by the destructor of fEmbeddedCodecs.
98    SkCodec* fCurrIncrementalCodec;
99
100    typedef SkCodec INHERITED;
101};
102