xref: /aosp_15_r20/external/skia/include/codec/SkPngChunkReader.h (revision c8dee2aa9b3f27cf6c858bd81872bdeb2c07ed17)
1*c8dee2aaSAndroid Build Coastguard Worker /*
2*c8dee2aaSAndroid Build Coastguard Worker  * Copyright 2015 Google Inc.
3*c8dee2aaSAndroid Build Coastguard Worker  *
4*c8dee2aaSAndroid Build Coastguard Worker  * Use of this source code is governed by a BSD-style license that can be
5*c8dee2aaSAndroid Build Coastguard Worker  * found in the LICENSE file.
6*c8dee2aaSAndroid Build Coastguard Worker  */
7*c8dee2aaSAndroid Build Coastguard Worker 
8*c8dee2aaSAndroid Build Coastguard Worker #ifndef SkPngChunkReader_DEFINED
9*c8dee2aaSAndroid Build Coastguard Worker #define SkPngChunkReader_DEFINED
10*c8dee2aaSAndroid Build Coastguard Worker 
11*c8dee2aaSAndroid Build Coastguard Worker #include "include/core/SkRefCnt.h"
12*c8dee2aaSAndroid Build Coastguard Worker #include "include/core/SkTypes.h"
13*c8dee2aaSAndroid Build Coastguard Worker 
14*c8dee2aaSAndroid Build Coastguard Worker /**
15*c8dee2aaSAndroid Build Coastguard Worker  *  SkPngChunkReader
16*c8dee2aaSAndroid Build Coastguard Worker  *
17*c8dee2aaSAndroid Build Coastguard Worker  *  Base class for optional callbacks to retrieve meta/chunk data out of a PNG
18*c8dee2aaSAndroid Build Coastguard Worker  *  encoded image as it is being decoded.
19*c8dee2aaSAndroid Build Coastguard Worker  *  Used by SkCodec.
20*c8dee2aaSAndroid Build Coastguard Worker  */
21*c8dee2aaSAndroid Build Coastguard Worker class SkPngChunkReader : public SkRefCnt {
22*c8dee2aaSAndroid Build Coastguard Worker public:
23*c8dee2aaSAndroid Build Coastguard Worker     /**
24*c8dee2aaSAndroid Build Coastguard Worker      *  This will be called by the decoder when it sees an unknown chunk.
25*c8dee2aaSAndroid Build Coastguard Worker      *
26*c8dee2aaSAndroid Build Coastguard Worker      *  Use by SkCodec:
27*c8dee2aaSAndroid Build Coastguard Worker      *  Depending on the location of the unknown chunks, this callback may be
28*c8dee2aaSAndroid Build Coastguard Worker      *  called by
29*c8dee2aaSAndroid Build Coastguard Worker      *      - the factory (NewFromStream/NewFromData)
30*c8dee2aaSAndroid Build Coastguard Worker      *      - getPixels
31*c8dee2aaSAndroid Build Coastguard Worker      *      - startScanlineDecode
32*c8dee2aaSAndroid Build Coastguard Worker      *      - the first call to getScanlines/skipScanlines
33*c8dee2aaSAndroid Build Coastguard Worker      *  The callback may be called from a different thread (e.g. if the SkCodec
34*c8dee2aaSAndroid Build Coastguard Worker      *  is passed to another thread), and it may be called multiple times, if
35*c8dee2aaSAndroid Build Coastguard Worker      *  the SkCodec is used multiple times.
36*c8dee2aaSAndroid Build Coastguard Worker      *
37*c8dee2aaSAndroid Build Coastguard Worker      *  @param tag Name for this type of chunk.
38*c8dee2aaSAndroid Build Coastguard Worker      *  @param data Data to be interpreted by the subclass.
39*c8dee2aaSAndroid Build Coastguard Worker      *  @param length Number of bytes of data in the chunk.
40*c8dee2aaSAndroid Build Coastguard Worker      *  @return true to continue decoding, or false to indicate an error, which
41*c8dee2aaSAndroid Build Coastguard Worker      *      will cause the decoder to not return the image.
42*c8dee2aaSAndroid Build Coastguard Worker      */
43*c8dee2aaSAndroid Build Coastguard Worker     virtual bool readChunk(const char tag[], const void* data, size_t length) = 0;
44*c8dee2aaSAndroid Build Coastguard Worker };
45*c8dee2aaSAndroid Build Coastguard Worker #endif // SkPngChunkReader_DEFINED
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