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 SkStream.
16
17typedef SkTRegistry<SkImageDecoder*, SkStream*> DecodeReg;
18
19// N.B. You can't use "DecodeReg::gHead here" due to complex C++
20// corner cases.
21template DecodeReg* SkTRegistry<SkImageDecoder*, SkStream*>::gHead;
22
23SkImageDecoder* image_decoder_from_stream(SkStream*);
24
25SkImageDecoder* image_decoder_from_stream(SkStream* stream) {
26    SkImageDecoder* codec = NULL;
27    const DecodeReg* curr = DecodeReg::Head();
28    while (curr) {
29        codec = curr->factory()(stream);
30        // we rewind here, because we promise later when we call "decode", that
31        // the stream will be at its beginning.
32        bool rewindSuceeded = stream->rewind();
33
34        // our image decoder's require that rewind is supported so we fail early
35        // if we are given a stream that does not support rewinding.
36        if (!rewindSuceeded) {
37            SkDEBUGF(("Unable to rewind the image stream."));
38            SkDELETE(codec);
39            return NULL;
40        }
41
42        if (codec) {
43            return codec;
44        }
45        curr = curr->next();
46    }
47    return NULL;
48}
49
50typedef SkTRegistry<SkImageDecoder::Format, SkStream*> FormatReg;
51
52template FormatReg* SkTRegistry<SkImageDecoder::Format, SkStream*>::gHead;
53
54SkImageDecoder::Format SkImageDecoder::GetStreamFormat(SkStream* stream) {
55    const FormatReg* curr = FormatReg::Head();
56    while (curr != NULL) {
57        Format format = curr->factory()(stream);
58        if (!stream->rewind()) {
59            SkErrorInternals::SetError(kInvalidOperation_SkError,
60                                       "Unable to rewind the image stream\n");
61            return kUnknown_Format;
62        }
63        if (format != kUnknown_Format) {
64            return format;
65        }
66        curr = curr->next();
67    }
68    return kUnknown_Format;
69}
70