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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 "SkCodecPriv.h" | |
9 #include "SkJpegUtility.h" | |
10 | |
11 /* | |
12 * Initialize the source manager | |
13 */ | |
14 static void sk_init_source(j_decompress_ptr dinfo) { | |
15 skjpeg_source_mgr* src = (skjpeg_source_mgr*) dinfo->src; | |
16 src->next_input_byte = (const JOCTET*) src->fBuffer; | |
17 src->bytes_in_buffer = 0; | |
18 } | |
19 | |
20 /* | |
21 * Fill the input buffer from the stream | |
22 */ | |
23 static boolean sk_fill_input_buffer(j_decompress_ptr dinfo) { | |
24 skjpeg_source_mgr* src = (skjpeg_source_mgr*) dinfo->src; | |
25 size_t bytes = src->fStream->read(src->fBuffer, skjpeg_source_mgr::kBufferSi
ze); | |
26 | |
27 // libjpeg is still happy with a less than full read, as long as the result
is non-zero | |
28 if (bytes == 0) { | |
29 return false; | |
30 } | |
31 | |
32 src->next_input_byte = (const JOCTET*) src->fBuffer; | |
33 src->bytes_in_buffer = bytes; | |
34 return true; | |
35 } | |
36 | |
37 /* | |
38 * Skip a certain number of bytes in the stream | |
39 */ | |
40 static void sk_skip_input_data(j_decompress_ptr dinfo, long numBytes) { | |
41 skjpeg_source_mgr* src = (skjpeg_source_mgr*) dinfo->src; | |
42 size_t bytes = (size_t) numBytes; | |
43 | |
44 if (bytes > src->bytes_in_buffer) { | |
45 size_t bytesToSkip = bytes - src->bytes_in_buffer; | |
46 if (bytesToSkip != src->fStream->skip(bytesToSkip)) { | |
47 SkCodecPrintf("Failure to skip.\n"); | |
48 dinfo->err->error_exit((j_common_ptr) dinfo); | |
49 return; | |
50 } | |
51 | |
52 src->next_input_byte = (const JOCTET*) src->fBuffer; | |
53 src->bytes_in_buffer = 0; | |
54 } else { | |
55 src->next_input_byte += numBytes; | |
56 src->bytes_in_buffer -= numBytes; | |
57 } | |
58 } | |
59 | |
60 /* | |
61 * We do not need to do anything to terminate our stream | |
62 */ | |
63 static void sk_term_source(j_decompress_ptr dinfo) | |
64 {} | |
65 | |
66 /* | |
67 * Constructor for the source manager that we provide to libjpeg | |
68 * We provide skia implementations of all of the stream processing functions req
uired by libjpeg | |
69 */ | |
70 skjpeg_source_mgr::skjpeg_source_mgr(SkStream* stream) | |
71 : fStream(stream) | |
72 { | |
73 init_source = sk_init_source; | |
74 fill_input_buffer = sk_fill_input_buffer; | |
75 skip_input_data = sk_skip_input_data; | |
76 resync_to_restart = jpeg_resync_to_restart; | |
77 term_source = sk_term_source; | |
78 } | |
79 | |
80 /* | |
81 * Call longjmp to continue execution on an error | |
82 */ | |
83 void skjpeg_err_exit(j_common_ptr dinfo) { | |
84 // Simply return to Skia client code | |
85 // JpegDecoderMgr will take care of freeing memory | |
86 skjpeg_error_mgr* error = (skjpeg_error_mgr*) dinfo->err; | |
87 (*error->output_message) (dinfo); | |
88 longjmp(error->fJmpBuf, 1); | |
89 } | |
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