diff options
author | msarett <msarett@google.com> | 2015-04-15 07:32:19 -0700 |
---|---|---|
committer | Commit bot <commit-bot@chromium.org> | 2015-04-15 07:32:20 -0700 |
commit | e16b04aa6041efb6507546547737e9603fa1606e (patch) | |
tree | 3bd78e41a9ff3df445c64d3c0429d83bb698570d /src/codec/SkJpegUtility.cpp | |
parent | f91e676f941c7e9ec91ac298eaa32e4bf8f52762 (diff) |
SkJpegCodec
Enables basic decoding for jpegs
Includes rewinding
565, YUV, and Jpeg encoding are not yet implemented
BUG=skia:3257
Review URL: https://codereview.chromium.org/1076923002
Diffstat (limited to 'src/codec/SkJpegUtility.cpp')
-rw-r--r-- | src/codec/SkJpegUtility.cpp | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/src/codec/SkJpegUtility.cpp b/src/codec/SkJpegUtility.cpp new file mode 100644 index 0000000000..5dccf942bc --- /dev/null +++ b/src/codec/SkJpegUtility.cpp @@ -0,0 +1,89 @@ +/* + * Copyright 2015 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#include "SkCodecPriv.h" +#include "SkJpegUtility.h" + +/* + * Initialize the source manager + */ +static void sk_init_source(j_decompress_ptr dinfo) { + skjpeg_source_mgr* src = (skjpeg_source_mgr*) dinfo->src; + src->next_input_byte = (const JOCTET*) src->fBuffer; + src->bytes_in_buffer = 0; +} + +/* + * Fill the input buffer from the stream + */ +static boolean sk_fill_input_buffer(j_decompress_ptr dinfo) { + skjpeg_source_mgr* src = (skjpeg_source_mgr*) dinfo->src; + size_t bytes = src->fStream->read(src->fBuffer, skjpeg_source_mgr::kBufferSize); + + // libjpeg is still happy with a less than full read, as long as the result is non-zero + if (bytes == 0) { + return false; + } + + src->next_input_byte = (const JOCTET*) src->fBuffer; + src->bytes_in_buffer = bytes; + return true; +} + +/* + * Skip a certain number of bytes in the stream + */ +static void sk_skip_input_data(j_decompress_ptr dinfo, long numBytes) { + skjpeg_source_mgr* src = (skjpeg_source_mgr*) dinfo->src; + size_t bytes = (size_t) numBytes; + + if (bytes > src->bytes_in_buffer) { + size_t bytesToSkip = bytes - src->bytes_in_buffer; + if (bytesToSkip != src->fStream->skip(bytesToSkip)) { + SkCodecPrintf("Failure to skip.\n"); + dinfo->err->error_exit((j_common_ptr) dinfo); + return; + } + + src->next_input_byte = (const JOCTET*) src->fBuffer; + src->bytes_in_buffer = 0; + } else { + src->next_input_byte += numBytes; + src->bytes_in_buffer -= numBytes; + } +} + +/* + * We do not need to do anything to terminate our stream + */ +static void sk_term_source(j_decompress_ptr dinfo) +{} + +/* + * Constructor for the source manager that we provide to libjpeg + * We provide skia implementations of all of the stream processing functions required by libjpeg + */ +skjpeg_source_mgr::skjpeg_source_mgr(SkStream* stream) + : fStream(stream) +{ + init_source = sk_init_source; + fill_input_buffer = sk_fill_input_buffer; + skip_input_data = sk_skip_input_data; + resync_to_restart = jpeg_resync_to_restart; + term_source = sk_term_source; +} + +/* + * Call longjmp to continue execution on an error + */ +void skjpeg_err_exit(j_common_ptr dinfo) { + // Simply return to Skia client code + // JpegDecoderMgr will take care of freeing memory + skjpeg_error_mgr* error = (skjpeg_error_mgr*) dinfo->err; + (*error->output_message) (dinfo); + longjmp(error->fJmpBuf, 1); +} |