SkIcoCodec.h revision 9a89a0966bba433a109f2b1275aaaeb630321bae 
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    SkSampler* getSampler(bool createIfNecessary) override;
58
59    /*
60     * Searches fEmbeddedCodecs for a codec that matches requestedSize.
61     * The search starts at startIndex and ends when an appropriate codec
62     * is found, or we have reached the end of the array.
63     *
64     * @return the index of the matching codec or -1 if there is no
65     *         matching codec between startIndex and the end of
66     *         the array.
67     */
68    int chooseCodec(const SkISize& requestedSize, int startIndex);
69
70    /*
71     * Constructor called by NewFromStream
72     * @param embeddedCodecs codecs for the embedded images, takes ownership
73     */
74    SkIcoCodec(int width, int height, const SkEncodedInfo& info,
75            SkTArray<SkAutoTDelete<SkCodec>, true>* embeddedCodecs);
76
77    SkAutoTDelete<SkTArray<SkAutoTDelete<SkCodec>, true>> fEmbeddedCodecs; // owned
78
79    // Only used by the scanline decoder.  onStartScanlineDecode() will set
80    // fCurrScanlineCodec to one of the fEmbeddedCodecs, if it can find a
81    // codec of the appropriate size.  We will use fCurrScanlineCodec for
82    // subsequent calls to onGetScanlines() or onSkipScanlines().
83    // fCurrScanlineCodec is owned by this class, but should not be an
84    // SkAutoTDelete.  It will be deleted by the destructor of fEmbeddedCodecs.
85    SkCodec* fCurrScanlineCodec;
86
87    typedef SkCodec INHERITED;
88};
89