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      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  */
     16 class SkIcoCodec : public SkCodec {
     17 public:
     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 
     27 protected:
     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 
     48 private:
     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(const SkImageInfo& srcInfo, SkTArray<SkAutoTDelete<SkCodec>, true>* embeddedCodecs);
     75 
     76     SkAutoTDelete<SkTArray<SkAutoTDelete<SkCodec>, true>> fEmbeddedCodecs; // owned
     77 
     78     // Only used by the scanline decoder.  onStartScanlineDecode() will set
     79     // fCurrScanlineCodec to one of the fEmbeddedCodecs, if it can find a
     80     // codec of the appropriate size.  We will use fCurrScanlineCodec for
     81     // subsequent calls to onGetScanlines() or onSkipScanlines().
     82     // fCurrScanlineCodec is owned by this class, but should not be an
     83     // SkAutoTDelete.  It will be deleted by the destructor of fEmbeddedCodecs.
     84     SkCodec* fCurrScanlineCodec;
     85 
     86     typedef SkCodec INHERITED;
     87 };
     88