1/*
2 * Copyright 2013 The Android Open Source Project
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 "SkErrorInternals.h"
9#include "SkImageDecoder.h"
10#include "SkStream.h"
11#include "SkTRegistry.h"
12
13// This file is used for registration of SkImageDecoders. It also holds a function
14// for checking all the the registered SkImageDecoders for one that matches an
15// input SkStreamRewindable.
16
17template SkImageDecoder_DecodeReg* SkImageDecoder_DecodeReg::gHead;
18
19SkImageDecoder* image_decoder_from_stream(SkStreamRewindable*);
20
21SkImageDecoder* image_decoder_from_stream(SkStreamRewindable* stream) {
22    SkImageDecoder* codec = nullptr;
23    const SkImageDecoder_DecodeReg* curr = SkImageDecoder_DecodeReg::Head();
24    while (curr) {
25        codec = curr->factory()(stream);
26        // we rewind here, because we promise later when we call "decode", that
27        // the stream will be at its beginning.
28        bool rewindSuceeded = stream->rewind();
29
30        // our image decoder's require that rewind is supported so we fail early
31        // if we are given a stream that does not support rewinding.
32        if (!rewindSuceeded) {
33            SkDEBUGF(("Unable to rewind the image stream."));
34            delete codec;
35            return nullptr;
36        }
37
38        if (codec) {
39            return codec;
40        }
41        curr = curr->next();
42    }
43    return nullptr;
44}
45
46template SkImageDecoder_FormatReg* SkImageDecoder_FormatReg::gHead;
47
48SkImageDecoder::Format SkImageDecoder::GetStreamFormat(SkStreamRewindable* stream) {
49    const SkImageDecoder_FormatReg* curr = SkImageDecoder_FormatReg::Head();
50    while (curr != nullptr) {
51        Format format = curr->factory()(stream);
52        if (!stream->rewind()) {
53            SkErrorInternals::SetError(kInvalidOperation_SkError,
54                                       "Unable to rewind the image stream\n");
55            return kUnknown_Format;
56        }
57        if (format != kUnknown_Format) {
58            return format;
59        }
60        curr = curr->next();
61    }
62    return kUnknown_Format;
63}
64