| /* |
| * 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 "include/core/SkStream.h" |
| #include "include/core/SkTypes.h" |
| #include "include/private/SkTArray.h" |
| #include "src/codec/SkCodecPriv.h" |
| #include "src/codec/SkJpegPriv.h" |
| |
| #include <csetjmp> |
| #include <cstddef> |
| |
| extern "C" { |
| #include "jmorecfg.h" |
| #include "jpeglib.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; |
| } |
| } |