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- /*
- * 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 "src/codec/SkJpegUtility.h"
- #include "src/codec/SkCodecPriv.h"
- /*
- * 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);
- if (error->fJmpBufStack.empty()) {
- SK_ABORT("JPEG error with no jmp_buf set.");
- }
- longjmp(*error->fJmpBufStack.back(), 1);
- }
- // Functions for buffered sources //
- /*
- * Initialize the buffered source manager
- */
- static void sk_init_buffered_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_buffered_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) {
- // Let libjpeg know that the buffer needs to be refilled
- src->next_input_byte = nullptr;
- src->bytes_in_buffer = 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_buffered_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)
- {
- // The current implementation of SkJpegCodec does not call
- // jpeg_finish_decompress(), so this function is never called.
- // If we want to modify this function to do something, we also
- // need to modify SkJpegCodec to call jpeg_finish_decompress().
- }
- // Functions for memory backed sources //
- /*
- * Initialize the mem backed source manager
- */
- static void sk_init_mem_source(j_decompress_ptr dinfo) {
- /* no work necessary here, all things are done in constructor */
- }
- static void sk_skip_mem_input_data (j_decompress_ptr cinfo, long num_bytes) {
- jpeg_source_mgr* src = cinfo->src;
- size_t bytes = static_cast<size_t>(num_bytes);
- if(bytes > src->bytes_in_buffer) {
- src->next_input_byte = nullptr;
- src->bytes_in_buffer = 0;
- } else {
- src->next_input_byte += bytes;
- src->bytes_in_buffer -= bytes;
- }
- }
- static boolean sk_fill_mem_input_buffer (j_decompress_ptr cinfo) {
- /* The whole JPEG data is expected to reside in the supplied memory,
- * buffer, so any request for more data beyond the given buffer size
- * is treated as an error.
- */
- return false;
- }
- /*
- * 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)
- {
- if (stream->hasLength() && stream->getMemoryBase()) {
- init_source = sk_init_mem_source;
- fill_input_buffer = sk_fill_mem_input_buffer;
- skip_input_data = sk_skip_mem_input_data;
- resync_to_restart = jpeg_resync_to_restart;
- term_source = sk_term_source;
- bytes_in_buffer = static_cast<size_t>(stream->getLength());
- next_input_byte = static_cast<const JOCTET*>(stream->getMemoryBase());
- } else {
- init_source = sk_init_buffered_source;
- fill_input_buffer = sk_fill_buffered_input_buffer;
- skip_input_data = sk_skip_buffered_input_data;
- resync_to_restart = jpeg_resync_to_restart;
- term_source = sk_term_source;
- }
- }
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