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/*
SDL_image: An example image loading library for use with SDL
Copyright (C) 1997-2009 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Sam Lantinga
slouken@libsdl.org
*/
#if !defined(__APPLE__) || defined(SDL_IMAGE_USE_COMMON_BACKEND)
/* This is a JPEG image file loading framework */
#include <stdio.h>
#include <string.h>
#include <setjmp.h>
#include "SDL_image.h"
#ifdef LOAD_JPG
#include <jpeglib.h>
/* Define this for fast loading and not as good image quality */
/*#define FAST_JPEG*/
/* Define this for quicker (but less perfect) JPEG identification */
#define FAST_IS_JPEG
static struct {
int loaded;
void *handle;
void (*jpeg_calc_output_dimensions) (j_decompress_ptr cinfo);
void (*jpeg_CreateDecompress) (j_decompress_ptr cinfo, int version, size_t structsize);
void (*jpeg_destroy_decompress) (j_decompress_ptr cinfo);
boolean (*jpeg_finish_decompress) (j_decompress_ptr cinfo);
int (*jpeg_read_header) (j_decompress_ptr cinfo, boolean require_image);
JDIMENSION (*jpeg_read_scanlines) (j_decompress_ptr cinfo, JSAMPARRAY scanlines, JDIMENSION max_lines);
boolean (*jpeg_resync_to_restart) (j_decompress_ptr cinfo, int desired);
boolean (*jpeg_start_decompress) (j_decompress_ptr cinfo);
struct jpeg_error_mgr * (*jpeg_std_error) (struct jpeg_error_mgr * err);
} lib;
#ifdef LOAD_JPG_DYNAMIC
int IMG_InitJPG()
{
if ( lib.loaded == 0 ) {
lib.handle = SDL_LoadObject(LOAD_JPG_DYNAMIC);
if ( lib.handle == NULL ) {
return -1;
}
lib.jpeg_calc_output_dimensions =
(void (*) (j_decompress_ptr))
SDL_LoadFunction(lib.handle, "jpeg_calc_output_dimensions");
if ( lib.jpeg_calc_output_dimensions == NULL ) {
SDL_UnloadObject(lib.handle);
return -1;
}
lib.jpeg_CreateDecompress =
(void (*) (j_decompress_ptr, int, size_t))
SDL_LoadFunction(lib.handle, "jpeg_CreateDecompress");
if ( lib.jpeg_CreateDecompress == NULL ) {
SDL_UnloadObject(lib.handle);
return -1;
}
lib.jpeg_destroy_decompress =
(void (*) (j_decompress_ptr))
SDL_LoadFunction(lib.handle, "jpeg_destroy_decompress");
if ( lib.jpeg_destroy_decompress == NULL ) {
SDL_UnloadObject(lib.handle);
return -1;
}
lib.jpeg_finish_decompress =
(boolean (*) (j_decompress_ptr))
SDL_LoadFunction(lib.handle, "jpeg_finish_decompress");
if ( lib.jpeg_finish_decompress == NULL ) {
SDL_UnloadObject(lib.handle);
return -1;
}
lib.jpeg_read_header =
(int (*) (j_decompress_ptr, boolean))
SDL_LoadFunction(lib.handle, "jpeg_read_header");
if ( lib.jpeg_read_header == NULL ) {
SDL_UnloadObject(lib.handle);
return -1;
}
lib.jpeg_read_scanlines =
(JDIMENSION (*) (j_decompress_ptr, JSAMPARRAY, JDIMENSION))
SDL_LoadFunction(lib.handle, "jpeg_read_scanlines");
if ( lib.jpeg_read_scanlines == NULL ) {
SDL_UnloadObject(lib.handle);
return -1;
}
lib.jpeg_resync_to_restart =
(boolean (*) (j_decompress_ptr, int))
SDL_LoadFunction(lib.handle, "jpeg_resync_to_restart");
if ( lib.jpeg_resync_to_restart == NULL ) {
SDL_UnloadObject(lib.handle);
return -1;
}
lib.jpeg_start_decompress =
(boolean (*) (j_decompress_ptr))
SDL_LoadFunction(lib.handle, "jpeg_start_decompress");
if ( lib.jpeg_start_decompress == NULL ) {
SDL_UnloadObject(lib.handle);
return -1;
}
lib.jpeg_std_error =
(struct jpeg_error_mgr * (*) (struct jpeg_error_mgr *))
SDL_LoadFunction(lib.handle, "jpeg_std_error");
if ( lib.jpeg_std_error == NULL ) {
SDL_UnloadObject(lib.handle);
return -1;
}
}
++lib.loaded;
return 0;
}
void IMG_QuitJPG()
{
if ( lib.loaded == 0 ) {
return;
}
if ( lib.loaded == 1 ) {
SDL_UnloadObject(lib.handle);
}
--lib.loaded;
}
#else
int IMG_InitJPG()
{
if ( lib.loaded == 0 ) {
lib.jpeg_calc_output_dimensions = jpeg_calc_output_dimensions;
lib.jpeg_CreateDecompress = jpeg_CreateDecompress;
lib.jpeg_destroy_decompress = jpeg_destroy_decompress;
lib.jpeg_finish_decompress = jpeg_finish_decompress;
lib.jpeg_read_header = jpeg_read_header;
lib.jpeg_read_scanlines = jpeg_read_scanlines;
lib.jpeg_resync_to_restart = jpeg_resync_to_restart;
lib.jpeg_start_decompress = jpeg_start_decompress;
lib.jpeg_std_error = jpeg_std_error;
}
++lib.loaded;
return 0;
}
void IMG_QuitJPG()
{
if ( lib.loaded == 0 ) {
return;
}
if ( lib.loaded == 1 ) {
}
--lib.loaded;
}
#endif /* LOAD_JPG_DYNAMIC */
/* See if an image is contained in a data source */
int IMG_isJPG(SDL_RWops *src)
{
int start;
int is_JPG;
int in_scan;
Uint8 magic[4];
/* This detection code is by Steaphan Greene <stea@cs.binghamton.edu> */
/* Blame me, not Sam, if this doesn't work right. */
/* And don't forget to report the problem to the the sdl list too! */
if ( !src )
return 0;
start = SDL_RWtell(src);
is_JPG = 0;
in_scan = 0;
if ( SDL_RWread(src, magic, 2, 1) ) {
if ( (magic[0] == 0xFF) && (magic[1] == 0xD8) ) {
is_JPG = 1;
while (is_JPG == 1) {
if(SDL_RWread(src, magic, 1, 2) != 2) {
is_JPG = 0;
} else if( (magic[0] != 0xFF) && (in_scan == 0) ) {
is_JPG = 0;
} else if( (magic[0] != 0xFF) || (magic[1] == 0xFF) ) {
/* Extra padding in JPEG (legal) */
/* or this is data and we are scanning */
SDL_RWseek(src, -1, RW_SEEK_CUR);
} else if(magic[1] == 0xD9) {
/* Got to end of good JPEG */
break;
} else if( (in_scan == 1) && (magic[1] == 0x00) ) {
/* This is an encoded 0xFF within the data */
} else if( (magic[1] >= 0xD0) && (magic[1] < 0xD9) ) {
/* These have nothing else */
} else if(SDL_RWread(src, magic+2, 1, 2) != 2) {
is_JPG = 0;
} else {
/* Yes, it's big-endian */
Uint32 start;
Uint32 size;
Uint32 end;
start = SDL_RWtell(src);
size = (magic[2] << 8) + magic[3];
end = SDL_RWseek(src, size-2, RW_SEEK_CUR);
if ( end != start + size - 2 ) is_JPG = 0;
if ( magic[1] == 0xDA ) {
/* Now comes the actual JPEG meat */
#ifdef FAST_IS_JPEG
/* Ok, I'm convinced. It is a JPEG. */
break;
#else
/* I'm not convinced. Prove it! */
in_scan = 1;
#endif
}
}
}
}
}
SDL_RWseek(src, start, RW_SEEK_SET);
return(is_JPG);
}
#define INPUT_BUFFER_SIZE 4096
typedef struct {
struct jpeg_source_mgr pub;
SDL_RWops *ctx;
Uint8 buffer[INPUT_BUFFER_SIZE];
} my_source_mgr;
/*
* Initialize source --- called by jpeg_read_header
* before any data is actually read.
*/
static void init_source (j_decompress_ptr cinfo)
{
/* We don't actually need to do anything */
return;
}
/*
* Fill the input buffer --- called whenever buffer is emptied.
*/
static int fill_input_buffer (j_decompress_ptr cinfo)
{
my_source_mgr * src = (my_source_mgr *) cinfo->src;
int nbytes;
nbytes = SDL_RWread(src->ctx, src->buffer, 1, INPUT_BUFFER_SIZE);
if (nbytes <= 0) {
/* Insert a fake EOI marker */
src->buffer[0] = (Uint8) 0xFF;
src->buffer[1] = (Uint8) JPEG_EOI;
nbytes = 2;
}
src->pub.next_input_byte = src->buffer;
src->pub.bytes_in_buffer = nbytes;
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 skip_input_data (j_decompress_ptr cinfo, long num_bytes)
{
my_source_mgr * src = (my_source_mgr *) 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) src->pub.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;
}
}
/*
* Terminate source --- called by jpeg_finish_decompress
* after all data has been read.
*/
static void term_source (j_decompress_ptr cinfo)
{
/* We don't actually need to do anything */
return;
}
/*
* 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_SDL_RW_src (j_decompress_ptr cinfo, SDL_RWops *ctx)
{
my_source_mgr *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_source_mgr *) cinfo->src;
}
src = (my_source_mgr *) cinfo->src;
src->pub.init_source = init_source;
src->pub.fill_input_buffer = fill_input_buffer;
src->pub.skip_input_data = skip_input_data;
src->pub.resync_to_restart = lib.jpeg_resync_to_restart; /* use default method */
src->pub.term_source = term_source;
src->ctx = ctx;
src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
src->pub.next_input_byte = NULL; /* until buffer loaded */
}
struct my_error_mgr {
struct jpeg_error_mgr errmgr;
jmp_buf escape;
};
static void my_error_exit(j_common_ptr cinfo)
{
struct my_error_mgr *err = (struct my_error_mgr *)cinfo->err;
longjmp(err->escape, 1);
}
static void output_no_message(j_common_ptr cinfo)
{
/* do nothing */
}
/* Load a JPEG type image from an SDL datasource */
SDL_Surface *IMG_LoadJPG_RW(SDL_RWops *src)
{
int start;
struct jpeg_decompress_struct cinfo;
JSAMPROW rowptr[1];
SDL_Surface *volatile surface = NULL;
struct my_error_mgr jerr;
if ( !src ) {
/* The error message has been set in SDL_RWFromFile */
return NULL;
}
start = SDL_RWtell(src);
if ( !IMG_Init(IMG_INIT_JPG) ) {
return NULL;
}
/* Create a decompression structure and load the JPEG header */
cinfo.err = lib.jpeg_std_error(&jerr.errmgr);
jerr.errmgr.error_exit = my_error_exit;
jerr.errmgr.output_message = output_no_message;
if(setjmp(jerr.escape)) {
/* If we get here, libjpeg found an error */
lib.jpeg_destroy_decompress(&cinfo);
if ( surface != NULL ) {
SDL_FreeSurface(surface);
}
SDL_RWseek(src, start, RW_SEEK_SET);
IMG_SetError("JPEG loading error");
return NULL;
}
lib.jpeg_create_decompress(&cinfo);
jpeg_SDL_RW_src(&cinfo, src);
lib.jpeg_read_header(&cinfo, TRUE);
if(cinfo.num_components == 4) {
/* Set 32-bit Raw output */
cinfo.out_color_space = JCS_CMYK;
cinfo.quantize_colors = FALSE;
lib.jpeg_calc_output_dimensions(&cinfo);
/* Allocate an output surface to hold the image */
surface = SDL_AllocSurface(SDL_SWSURFACE,
cinfo.output_width, cinfo.output_height, 32,
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
0x00FF0000, 0x0000FF00, 0x000000FF, 0xFF000000);
#else
0x0000FF00, 0x00FF0000, 0xFF000000, 0x000000FF);
#endif
} else {
/* Set 24-bit RGB output */
cinfo.out_color_space = JCS_RGB;
cinfo.quantize_colors = FALSE;
#ifdef FAST_JPEG
cinfo.scale_num = 1;
cinfo.scale_denom = 1;
cinfo.dct_method = JDCT_FASTEST;
cinfo.do_fancy_upsampling = FALSE;
#endif
lib.jpeg_calc_output_dimensions(&cinfo);
/* Allocate an output surface to hold the image */
surface = SDL_AllocSurface(SDL_SWSURFACE,
cinfo.output_width, cinfo.output_height, 24,
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
0x0000FF, 0x00FF00, 0xFF0000,
#else
0xFF0000, 0x00FF00, 0x0000FF,
#endif
0);
}
if ( surface == NULL ) {
lib.jpeg_destroy_decompress(&cinfo);
SDL_RWseek(src, start, RW_SEEK_SET);
IMG_SetError("Out of memory");
return NULL;
}
/* Decompress the image */
lib.jpeg_start_decompress(&cinfo);
while ( cinfo.output_scanline < cinfo.output_height ) {
rowptr[0] = (JSAMPROW)(Uint8 *)surface->pixels +
cinfo.output_scanline * surface->pitch;
lib.jpeg_read_scanlines(&cinfo, rowptr, (JDIMENSION) 1);
}
lib.jpeg_finish_decompress(&cinfo);
lib.jpeg_destroy_decompress(&cinfo);
return(surface);
}
#else
int IMG_InitJPG()
{
IMG_SetError("JPEG images are not supported");
return(-1);
}
void IMG_QuitJPG()
{
}
/* See if an image is contained in a data source */
int IMG_isJPG(SDL_RWops *src)
{
return(0);
}
/* Load a JPEG type image from an SDL datasource */
SDL_Surface *IMG_LoadJPG_RW(SDL_RWops *src)
{
return(NULL);
}
#endif /* LOAD_JPG */
#endif /* !defined(__APPLE__) || defined(SDL_IMAGE_USE_COMMON_BACKEND) */
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