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 SkPngChunkReader_DEFINED 9 #define SkPngChunkReader_DEFINED 10 11 #include "SkTypes.h" 12 #include "SkRefCnt.h" 13 14 /** 15 * SkPngChunkReader 16 * 17 * Base class for optional callbacks to retrieve meta/chunk data out of a PNG 18 * encoded image as it is being decoded. 19 * Used by SkCodec. 20 */ 21 class SkPngChunkReader : public SkRefCnt { 22 public: 23 /** 24 * This will be called by the decoder when it sees an unknown chunk. 25 * 26 * Use by SkCodec: 27 * Depending on the location of the unknown chunks, this callback may be 28 * called by 29 * - the factory (NewFromStream/NewFromData) 30 * - getPixels 31 * - startScanlineDecode 32 * - the first call to getScanlines/skipScanlines 33 * The callback may be called from a different thread (e.g. if the SkCodec 34 * is passed to another thread), and it may be called multiple times, if 35 * the SkCodec is used multiple times. 36 * 37 * @param tag Name for this type of chunk. 38 * @param data Data to be interpreted by the subclass. 39 * @param length Number of bytes of data in the chunk. 40 * @return true to continue decoding, or false to indicate an error, which 41 * will cause the decoder to not return the image. 42 */ 43 virtual bool readChunk(const char tag[], const void* data, size_t length) = 0; 44 }; 45 #endif // SkPngChunkReader_DEFINED 46