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JPEGLoader.cpp
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JPEGLoader.cpp
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#include "JPEGLoader.h"
#include <setjmp.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <jpeglib.h>
#include <jerror.h>
#include "ifilesystem.h"
#include "stream/ScopedArchiveBuffer.h"
#include "RGBAImage.h"
typedef unsigned char byte;
/* Expanded data source object for stdio input */
typedef struct {
struct jpeg_source_mgr pub; /* public fields */
int src_size;
JOCTET* src_buffer;
JOCTET* buffer; /* start of buffer */
boolean start_of_file; /* have we gotten any data yet? */
} my_source_mgr;
typedef my_source_mgr* my_src_ptr;
#define INPUT_BUF_SIZE 4096 /* choose an efficiently fread'able size */
/*
* Initialize source --- called by jpeg_read_header
* before any data is actually read.
*/
static void my_init_source(j_decompress_ptr cinfo)
{
my_src_ptr src = (my_src_ptr)cinfo->src;
/* We reset the empty-input-file flag for each image,
* but we don't clear the input buffer.
* This is correct behavior for reading a series of images from one source.
*/
src->start_of_file = TRUE;
}
/*
* Fill the input buffer --- called whenever buffer is emptied.
*
* In typical applications, this should read fresh data into the buffer
* (ignoring the current state of next_input_byte & bytes_in_buffer),
* reset the pointer & count to the start of the buffer, and return TRUE
* indicating that the buffer has been reloaded. It is not necessary to
* fill the buffer entirely, only to obtain at least one more byte.
*
* There is no such thing as an EOF return. If the end of the file has been
* reached, the routine has a choice of ERREXIT() or inserting fake data into
* the buffer. In most cases, generating a warning message and inserting a
* fake EOI marker is the best course of action --- this will allow the
* decompressor to output however much of the image is there. However,
* the resulting error message is misleading if the real problem is an empty
* input file, so we handle that case specially.
*
* In applications that need to be able to suspend compression due to input
* not being available yet, a FALSE return indicates that no more data can be
* obtained right now, but more may be forthcoming later. In this situation,
* the decompressor will return to its caller (with an indication of the
* number of scanlines it has read, if any). The application should resume
* decompression after it has loaded more data into the input buffer. Note
* that there are substantial restrictions on the use of suspension --- see
* the documentation.
*
* When suspending, the decompressor will back up to a convenient restart point
* (typically the start of the current MCU). next_input_byte & bytes_in_buffer
* indicate where the restart point will be if the current call returns FALSE.
* Data beyond this point must be rescanned after resumption, so move it to
* the front of the buffer rather than discarding it.
*/
static boolean my_fill_input_buffer(j_decompress_ptr cinfo)
{
my_src_ptr src = (my_src_ptr)cinfo->src;
size_t nbytes;
if (src->src_size > INPUT_BUF_SIZE)
nbytes = INPUT_BUF_SIZE;
else
nbytes = src->src_size;
memcpy(src->buffer, src->src_buffer, nbytes);
src->src_buffer += nbytes;
src->src_size -= static_cast<int>(nbytes);
if (nbytes <= 0) {
if (src->start_of_file) /* Treat empty input file as fatal error */
ERREXIT(cinfo, JERR_INPUT_EMPTY);
WARNMS(cinfo, JWRN_JPEG_EOF);
/* Insert a fake EOI marker */
src->buffer[0] = (JOCTET)0xFF;
src->buffer[1] = (JOCTET)JPEG_EOI;
nbytes = 2;
}
src->pub.next_input_byte = src->buffer;
src->pub.bytes_in_buffer = nbytes;
src->start_of_file = FALSE;
return TRUE;
}
/*
* Skip data --- used to skip over a potentially large amount of
* uninteresting data (such as an APPn marker).
*
* Writers of suspendable-input applications must note that skip_input_data
* is not granted the right to give a suspension return. If the skip extends
* beyond the data currently in the buffer, the buffer can be marked empty so
* that the next read will cause a fill_input_buffer call that can suspend.
* Arranging for additional bytes to be discarded before reloading the input
* buffer is the application writer's problem.
*/
static void my_skip_input_data(j_decompress_ptr cinfo, long num_bytes)
{
my_src_ptr src = (my_src_ptr)cinfo->src;
/* Just a dumb implementation for now. Could use fseek() except
* it doesn't work on pipes. Not clear that being smart is worth
* any trouble anyway --- large skips are infrequent.
*/
if (num_bytes > 0) {
while (num_bytes > (long)src->pub.bytes_in_buffer) {
num_bytes -= (long)src->pub.bytes_in_buffer;
(void)my_fill_input_buffer(cinfo);
/* note we assume that fill_input_buffer will never return FALSE,
* so suspension need not be handled.
*/
}
src->pub.next_input_byte += (size_t)num_bytes;
src->pub.bytes_in_buffer -= (size_t)num_bytes;
}
}
/*
* An additional method that can be provided by data source modules is the
* resync_to_restart method for error recovery in the presence of RST markers.
* For the moment, this source module just uses the default resync method
* provided by the JPEG library. That method assumes that no backtracking
* is possible.
*/
/*
* Terminate source --- called by jpeg_finish_decompress
* after all data has been read. Often a no-op.
*
* NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
* application must deal with any cleanup that should happen even
* for error exit.
*/
static void my_term_source(j_decompress_ptr cinfo)
{
/* no work necessary here */
}
/*
* Prepare for input from a stdio stream.
* The caller must have already opened the stream, and is responsible
* for closing it after finishing decompression.
*/
static void jpeg_buffer_src(j_decompress_ptr cinfo, void* buffer, int bufsize)
{
my_src_ptr src;
/* The source object and input buffer are made permanent so that a series
* of JPEG images can be read from the same file by calling jpeg_stdio_src
* only before the first one. (If we discarded the buffer at the end of
* one image, we'd likely lose the start of the next one.)
* This makes it unsafe to use this manager and a different source
* manager serially with the same JPEG object. Caveat programmer.
*/
if (cinfo->src == NULL) { /* first time for this JPEG object? */
cinfo->src = (struct jpeg_source_mgr*)
(*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT,
sizeof(my_source_mgr));
src = (my_src_ptr)cinfo->src;
src->buffer = (JOCTET*)
(*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT,
INPUT_BUF_SIZE * sizeof(JOCTET));
}
src = (my_src_ptr)cinfo->src;
src->pub.init_source = my_init_source;
src->pub.fill_input_buffer = my_fill_input_buffer;
src->pub.skip_input_data = my_skip_input_data;
src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
src->pub.term_source = my_term_source;
src->src_buffer = (JOCTET*)buffer;
src->src_size = bufsize;
src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
src->pub.next_input_byte = NULL; /* until buffer loaded */
}
// =============================================================================
static char errormsg[JMSG_LENGTH_MAX];
typedef struct my_jpeg_error_mgr
{
struct jpeg_error_mgr pub; // "public" fields
jmp_buf setjmp_buffer; // for return to caller
} bt_jpeg_error_mgr;
static void my_jpeg_error_exit(j_common_ptr cinfo)
{
my_jpeg_error_mgr* myerr = (bt_jpeg_error_mgr*)cinfo->err;
(*cinfo->err->format_message) (cinfo, errormsg);
longjmp(myerr->setjmp_buffer, 1);
}
// stash a scanline
static void j_putRGBScanline(unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
{
int offset = row * widthPix * 4;
int count;
for (count = 0; count < widthPix; count++)
{
unsigned char iRed, iBlu, iGrn;
unsigned char* oRed, * oBlu, * oGrn, * oAlp;
iRed = *(jpegline + count * 3 + 0);
iGrn = *(jpegline + count * 3 + 1);
iBlu = *(jpegline + count * 3 + 2);
oRed = outBuf + offset + count * 4 + 0;
oGrn = outBuf + offset + count * 4 + 1;
oBlu = outBuf + offset + count * 4 + 2;
oAlp = outBuf + offset + count * 4 + 3;
*oRed = iRed;
*oGrn = iGrn;
*oBlu = iBlu;
*oAlp = 255;
}
}
// stash a scanline
static void j_putRGBAScanline(unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
{
int offset = row * widthPix * 4;
int count;
for (count = 0; count < widthPix; count++)
{
unsigned char iRed, iBlu, iGrn, iAlp;
unsigned char* oRed, * oBlu, * oGrn, * oAlp;
iRed = *(jpegline + count * 4 + 0);
iGrn = *(jpegline + count * 4 + 1);
iBlu = *(jpegline + count * 4 + 2);
iAlp = *(jpegline + count * 4 + 3);
oRed = outBuf + offset + count * 4 + 0;
oGrn = outBuf + offset + count * 4 + 1;
oBlu = outBuf + offset + count * 4 + 2;
oAlp = outBuf + offset + count * 4 + 3;
*oRed = iRed;
*oGrn = iGrn;
*oBlu = iBlu;
//!\todo fix jpeglib, it leaves alpha channel uninitialised
#if 1
iAlp = 255;
#endif
*oAlp = iAlp;
}
}
// stash a gray scanline
static void j_putGrayScanlineToRGB(unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
{
int offset = row * widthPix * 4;
int count;
for (count = 0; count < widthPix; count++)
{
unsigned char iGray;
unsigned char* oRed, * oBlu, * oGrn, * oAlp;
// get our grayscale value
iGray = *(jpegline + count);
oRed = outBuf + offset + count * 4;
oGrn = outBuf + offset + count * 4 + 1;
oBlu = outBuf + offset + count * 4 + 2;
oAlp = outBuf + offset + count * 4 + 3;
*oRed = iGray;
*oGrn = iGray;
*oBlu = iGray;
*oAlp = 255;
}
}
static image::RGBAImagePtr LoadJPGBuff_(const void* src_buffer, int src_size)
{
struct jpeg_decompress_struct cinfo;
struct my_jpeg_error_mgr jerr;
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = my_jpeg_error_exit;
if (setjmp(jerr.setjmp_buffer)) //< TODO: use c++ exceptions instead of setjmp/longjmp to handle errors
{
rError() << "WARNING: JPEG library error: " << errormsg << "\n";
jpeg_destroy_decompress(&cinfo);
return {};
}
jpeg_create_decompress(&cinfo);
jpeg_buffer_src(&cinfo, const_cast<void*>(src_buffer), src_size);
jpeg_read_header(&cinfo, TRUE);
jpeg_start_decompress(&cinfo);
int row_stride = cinfo.output_width * cinfo.output_components;
image::RGBAImagePtr image(new image::RGBAImage(cinfo.output_width, cinfo.output_height));
JSAMPARRAY buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr)&cinfo, JPOOL_IMAGE, row_stride, 1);
while (cinfo.output_scanline < cinfo.output_height)
{
jpeg_read_scanlines(&cinfo, buffer, 1);
if (cinfo.out_color_components == 4)
j_putRGBAScanline(buffer[0], cinfo.output_width, image->getPixels(), cinfo.output_scanline - 1);
else if (cinfo.out_color_components == 3)
j_putRGBScanline(buffer[0], cinfo.output_width, image->getPixels(), cinfo.output_scanline - 1);
else if (cinfo.out_color_components == 1)
j_putGrayScanlineToRGB(buffer[0], cinfo.output_width, image->getPixels(), cinfo.output_scanline - 1);
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
return image;
}
namespace image
{
ImagePtr JPEGLoader::load(ArchiveFile& file) const
{
archive::ScopedArchiveBuffer buffer(file);
return LoadJPGBuff_(buffer.buffer, static_cast<int>(buffer.length));
}
ImageTypeLoader::Extensions JPEGLoader::getExtensions() const
{
Extensions extensions;
extensions.push_back("jpg");
extensions.push_back("jpeg");
return extensions;
}
}