move all image decoders into separate files
This commit is contained in:
parent
a3d62033d8
commit
85ba66e7e8
11 changed files with 1313 additions and 1255 deletions
581
code/renderer/tr_image_jpg.c
Normal file
581
code/renderer/tr_image_jpg.c
Normal file
|
@ -0,0 +1,581 @@
|
|||
/*
|
||||
===========================================================================
|
||||
Copyright (C) 1999-2005 Id Software, Inc.
|
||||
|
||||
This file is part of Quake III Arena source code.
|
||||
|
||||
Quake III Arena source code is free software; you can redistribute it
|
||||
and/or modify it under the terms of the GNU General Public License as
|
||||
published by the Free Software Foundation; either version 2 of the License,
|
||||
or (at your option) any later version.
|
||||
|
||||
Quake III Arena source code 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 General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with Quake III Arena source code; if not, write to the Free Software
|
||||
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
||||
===========================================================================
|
||||
*/
|
||||
|
||||
#include "tr_local.h"
|
||||
|
||||
/*
|
||||
* Include file for users of JPEG library.
|
||||
* You will need to have included system headers that define at least
|
||||
* the typedefs FILE and size_t before you can include jpeglib.h.
|
||||
* (stdio.h is sufficient on ANSI-conforming systems.)
|
||||
* You may also wish to include "jerror.h".
|
||||
*/
|
||||
|
||||
#define JPEG_INTERNALS
|
||||
#include "../jpeg-6/jpeglib.h"
|
||||
|
||||
void LoadJPG( const char *filename, unsigned char **pic, int *width, int *height ) {
|
||||
/* This struct contains the JPEG decompression parameters and pointers to
|
||||
* working space (which is allocated as needed by the JPEG library).
|
||||
*/
|
||||
struct jpeg_decompress_struct cinfo = {NULL};
|
||||
/* We use our private extension JPEG error handler.
|
||||
* Note that this struct must live as long as the main JPEG parameter
|
||||
* struct, to avoid dangling-pointer problems.
|
||||
*/
|
||||
/* This struct represents a JPEG error handler. It is declared separately
|
||||
* because applications often want to supply a specialized error handler
|
||||
* (see the second half of this file for an example). But here we just
|
||||
* take the easy way out and use the standard error handler, which will
|
||||
* print a message on stderr and call exit() if compression fails.
|
||||
* Note that this struct must live as long as the main JPEG parameter
|
||||
* struct, to avoid dangling-pointer problems.
|
||||
*/
|
||||
struct jpeg_error_mgr jerr;
|
||||
/* More stuff */
|
||||
JSAMPARRAY buffer; /* Output row buffer */
|
||||
unsigned row_stride; /* physical row width in output buffer */
|
||||
unsigned pixelcount, memcount;
|
||||
unsigned char *out;
|
||||
byte *fbuffer;
|
||||
byte *buf;
|
||||
|
||||
/* In this example we want to open the input file before doing anything else,
|
||||
* so that the setjmp() error recovery below can assume the file is open.
|
||||
* VERY IMPORTANT: use "b" option to fopen() if you are on a machine that
|
||||
* requires it in order to read binary files.
|
||||
*/
|
||||
|
||||
ri.FS_ReadFile ( ( char * ) filename, (void **)&fbuffer);
|
||||
if (!fbuffer) {
|
||||
return;
|
||||
}
|
||||
|
||||
/* Step 1: allocate and initialize JPEG decompression object */
|
||||
|
||||
/* We have to set up the error handler first, in case the initialization
|
||||
* step fails. (Unlikely, but it could happen if you are out of memory.)
|
||||
* This routine fills in the contents of struct jerr, and returns jerr's
|
||||
* address which we place into the link field in cinfo.
|
||||
*/
|
||||
cinfo.err = jpeg_std_error(&jerr);
|
||||
|
||||
/* Now we can initialize the JPEG decompression object. */
|
||||
jpeg_create_decompress(&cinfo);
|
||||
|
||||
/* Step 2: specify data source (eg, a file) */
|
||||
|
||||
jpeg_stdio_src(&cinfo, fbuffer);
|
||||
|
||||
/* Step 3: read file parameters with jpeg_read_header() */
|
||||
|
||||
(void) jpeg_read_header(&cinfo, TRUE);
|
||||
/* We can ignore the return value from jpeg_read_header since
|
||||
* (a) suspension is not possible with the stdio data source, and
|
||||
* (b) we passed TRUE to reject a tables-only JPEG file as an error.
|
||||
* See libjpeg.doc for more info.
|
||||
*/
|
||||
|
||||
/* Step 4: set parameters for decompression */
|
||||
|
||||
/* In this example, we don't need to change any of the defaults set by
|
||||
* jpeg_read_header(), so we do nothing here.
|
||||
*/
|
||||
|
||||
/* Step 5: Start decompressor */
|
||||
|
||||
(void) jpeg_start_decompress(&cinfo);
|
||||
/* We can ignore the return value since suspension is not possible
|
||||
* with the stdio data source.
|
||||
*/
|
||||
|
||||
/* We may need to do some setup of our own at this point before reading
|
||||
* the data. After jpeg_start_decompress() we have the correct scaled
|
||||
* output image dimensions available, as well as the output colormap
|
||||
* if we asked for color quantization.
|
||||
* In this example, we need to make an output work buffer of the right size.
|
||||
*/
|
||||
/* JSAMPLEs per row in output buffer */
|
||||
|
||||
pixelcount = cinfo.output_width * cinfo.output_height;
|
||||
|
||||
if(!cinfo.output_width || !cinfo.output_height
|
||||
|| ((pixelcount * 4) / cinfo.output_width) / 4 != cinfo.output_height
|
||||
|| pixelcount > 0x1FFFFFFF || cinfo.output_components > 4) // 4*1FFFFFFF == 0x7FFFFFFC < 0x7FFFFFFF
|
||||
{
|
||||
ri.Error (ERR_DROP, "LoadJPG: %s has an invalid image size: %dx%d*4=%d, components: %d\n", filename,
|
||||
cinfo.output_width, cinfo.output_height, pixelcount * 4, cinfo.output_components);
|
||||
}
|
||||
|
||||
memcount = pixelcount * 4;
|
||||
row_stride = cinfo.output_width * cinfo.output_components;
|
||||
|
||||
out = ri.Malloc(memcount);
|
||||
|
||||
*width = cinfo.output_width;
|
||||
*height = cinfo.output_height;
|
||||
|
||||
/* Step 6: while (scan lines remain to be read) */
|
||||
/* jpeg_read_scanlines(...); */
|
||||
|
||||
/* Here we use the library's state variable cinfo.output_scanline as the
|
||||
* loop counter, so that we don't have to keep track ourselves.
|
||||
*/
|
||||
while (cinfo.output_scanline < cinfo.output_height) {
|
||||
/* jpeg_read_scanlines expects an array of pointers to scanlines.
|
||||
* Here the array is only one element long, but you could ask for
|
||||
* more than one scanline at a time if that's more convenient.
|
||||
*/
|
||||
buf = ((out+(row_stride*cinfo.output_scanline)));
|
||||
buffer = &buf;
|
||||
(void) jpeg_read_scanlines(&cinfo, buffer, 1);
|
||||
}
|
||||
|
||||
buf = out;
|
||||
|
||||
// If we are processing an 8-bit JPEG (greyscale), we'll have to convert
|
||||
// the greyscale values to RGBA.
|
||||
if(cinfo.output_components == 1)
|
||||
{
|
||||
int sindex = pixelcount, dindex = memcount;
|
||||
unsigned char greyshade;
|
||||
|
||||
// Only pixelcount number of bytes have been written.
|
||||
// Expand the color values over the rest of the buffer, starting
|
||||
// from the end.
|
||||
do
|
||||
{
|
||||
greyshade = buf[--sindex];
|
||||
|
||||
buf[--dindex] = 255;
|
||||
buf[--dindex] = greyshade;
|
||||
buf[--dindex] = greyshade;
|
||||
buf[--dindex] = greyshade;
|
||||
} while(sindex);
|
||||
}
|
||||
else
|
||||
{
|
||||
// clear all the alphas to 255
|
||||
int i;
|
||||
|
||||
for ( i = 3 ; i < memcount ; i+=4 )
|
||||
{
|
||||
buf[i] = 255;
|
||||
}
|
||||
}
|
||||
|
||||
*pic = out;
|
||||
|
||||
/* Step 7: Finish decompression */
|
||||
|
||||
(void) jpeg_finish_decompress(&cinfo);
|
||||
/* We can ignore the return value since suspension is not possible
|
||||
* with the stdio data source.
|
||||
*/
|
||||
|
||||
/* Step 8: Release JPEG decompression object */
|
||||
|
||||
/* This is an important step since it will release a good deal of memory. */
|
||||
jpeg_destroy_decompress(&cinfo);
|
||||
|
||||
/* After finish_decompress, we can close the input file.
|
||||
* Here we postpone it until after no more JPEG errors are possible,
|
||||
* so as to simplify the setjmp error logic above. (Actually, I don't
|
||||
* think that jpeg_destroy can do an error exit, but why assume anything...)
|
||||
*/
|
||||
ri.FS_FreeFile (fbuffer);
|
||||
|
||||
/* At this point you may want to check to see whether any corrupt-data
|
||||
* warnings occurred (test whether jerr.pub.num_warnings is nonzero).
|
||||
*/
|
||||
|
||||
/* And we're done! */
|
||||
}
|
||||
|
||||
|
||||
/* Expanded data destination object for stdio output */
|
||||
|
||||
typedef struct {
|
||||
struct jpeg_destination_mgr pub; /* public fields */
|
||||
|
||||
byte* outfile; /* target stream */
|
||||
int size;
|
||||
} my_destination_mgr;
|
||||
|
||||
typedef my_destination_mgr * my_dest_ptr;
|
||||
|
||||
|
||||
/*
|
||||
* Initialize destination --- called by jpeg_start_compress
|
||||
* before any data is actually written.
|
||||
*/
|
||||
|
||||
void init_destination (j_compress_ptr cinfo)
|
||||
{
|
||||
my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
|
||||
|
||||
dest->pub.next_output_byte = dest->outfile;
|
||||
dest->pub.free_in_buffer = dest->size;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Empty the output buffer --- called whenever buffer fills up.
|
||||
*
|
||||
* In typical applications, this should write the entire output buffer
|
||||
* (ignoring the current state of next_output_byte & free_in_buffer),
|
||||
* reset the pointer & count to the start of the buffer, and return TRUE
|
||||
* indicating that the buffer has been dumped.
|
||||
*
|
||||
* In applications that need to be able to suspend compression due to output
|
||||
* overrun, a FALSE return indicates that the buffer cannot be emptied now.
|
||||
* In this situation, the compressor will return to its caller (possibly with
|
||||
* an indication that it has not accepted all the supplied scanlines). The
|
||||
* application should resume compression after it has made more room in the
|
||||
* output buffer. Note that there are substantial restrictions on the use of
|
||||
* suspension --- see the documentation.
|
||||
*
|
||||
* When suspending, the compressor will back up to a convenient restart point
|
||||
* (typically the start of the current MCU). next_output_byte & free_in_buffer
|
||||
* indicate where the restart point will be if the current call returns FALSE.
|
||||
* Data beyond this point will be regenerated after resumption, so do not
|
||||
* write it out when emptying the buffer externally.
|
||||
*/
|
||||
|
||||
boolean empty_output_buffer (j_compress_ptr cinfo)
|
||||
{
|
||||
return TRUE;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Compression initialization.
|
||||
* Before calling this, all parameters and a data destination must be set up.
|
||||
*
|
||||
* We require a write_all_tables parameter as a failsafe check when writing
|
||||
* multiple datastreams from the same compression object. Since prior runs
|
||||
* will have left all the tables marked sent_table=TRUE, a subsequent run
|
||||
* would emit an abbreviated stream (no tables) by default. This may be what
|
||||
* is wanted, but for safety's sake it should not be the default behavior:
|
||||
* programmers should have to make a deliberate choice to emit abbreviated
|
||||
* images. Therefore the documentation and examples should encourage people
|
||||
* to pass write_all_tables=TRUE; then it will take active thought to do the
|
||||
* wrong thing.
|
||||
*/
|
||||
|
||||
GLOBAL void
|
||||
jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables)
|
||||
{
|
||||
if (cinfo->global_state != CSTATE_START)
|
||||
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
|
||||
|
||||
if (write_all_tables)
|
||||
jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */
|
||||
|
||||
/* (Re)initialize error mgr and destination modules */
|
||||
(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
|
||||
(*cinfo->dest->init_destination) (cinfo);
|
||||
/* Perform master selection of active modules */
|
||||
jinit_compress_master(cinfo);
|
||||
/* Set up for the first pass */
|
||||
(*cinfo->master->prepare_for_pass) (cinfo);
|
||||
/* Ready for application to drive first pass through jpeg_write_scanlines
|
||||
* or jpeg_write_raw_data.
|
||||
*/
|
||||
cinfo->next_scanline = 0;
|
||||
cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING);
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Write some scanlines of data to the JPEG compressor.
|
||||
*
|
||||
* The return value will be the number of lines actually written.
|
||||
* This should be less than the supplied num_lines only in case that
|
||||
* the data destination module has requested suspension of the compressor,
|
||||
* or if more than image_height scanlines are passed in.
|
||||
*
|
||||
* Note: we warn about excess calls to jpeg_write_scanlines() since
|
||||
* this likely signals an application programmer error. However,
|
||||
* excess scanlines passed in the last valid call are *silently* ignored,
|
||||
* so that the application need not adjust num_lines for end-of-image
|
||||
* when using a multiple-scanline buffer.
|
||||
*/
|
||||
|
||||
GLOBAL JDIMENSION
|
||||
jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines,
|
||||
JDIMENSION num_lines)
|
||||
{
|
||||
JDIMENSION row_ctr, rows_left;
|
||||
|
||||
if (cinfo->global_state != CSTATE_SCANNING)
|
||||
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
|
||||
if (cinfo->next_scanline >= cinfo->image_height)
|
||||
WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
|
||||
|
||||
/* Call progress monitor hook if present */
|
||||
if (cinfo->progress != NULL) {
|
||||
cinfo->progress->pass_counter = (long) cinfo->next_scanline;
|
||||
cinfo->progress->pass_limit = (long) cinfo->image_height;
|
||||
(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
|
||||
}
|
||||
|
||||
/* Give master control module another chance if this is first call to
|
||||
* jpeg_write_scanlines. This lets output of the frame/scan headers be
|
||||
* delayed so that application can write COM, etc, markers between
|
||||
* jpeg_start_compress and jpeg_write_scanlines.
|
||||
*/
|
||||
if (cinfo->master->call_pass_startup)
|
||||
(*cinfo->master->pass_startup) (cinfo);
|
||||
|
||||
/* Ignore any extra scanlines at bottom of image. */
|
||||
rows_left = cinfo->image_height - cinfo->next_scanline;
|
||||
if (num_lines > rows_left)
|
||||
num_lines = rows_left;
|
||||
|
||||
row_ctr = 0;
|
||||
(*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines);
|
||||
cinfo->next_scanline += row_ctr;
|
||||
return row_ctr;
|
||||
}
|
||||
|
||||
/*
|
||||
* Terminate destination --- called by jpeg_finish_compress
|
||||
* after all data has been written. Usually needs to flush buffer.
|
||||
*
|
||||
* NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
|
||||
* application must deal with any cleanup that should happen even
|
||||
* for error exit.
|
||||
*/
|
||||
|
||||
static int hackSize;
|
||||
|
||||
void term_destination (j_compress_ptr cinfo)
|
||||
{
|
||||
my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
|
||||
size_t datacount = dest->size - dest->pub.free_in_buffer;
|
||||
hackSize = datacount;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Prepare for output to a stdio stream.
|
||||
* The caller must have already opened the stream, and is responsible
|
||||
* for closing it after finishing compression.
|
||||
*/
|
||||
|
||||
void jpegDest (j_compress_ptr cinfo, byte* outfile, int size)
|
||||
{
|
||||
my_dest_ptr dest;
|
||||
|
||||
/* The destination object is made permanent so that multiple JPEG images
|
||||
* can be written to the same file without re-executing jpeg_stdio_dest.
|
||||
* This makes it dangerous to use this manager and a different destination
|
||||
* manager serially with the same JPEG object, because their private object
|
||||
* sizes may be different. Caveat programmer.
|
||||
*/
|
||||
if (cinfo->dest == NULL) { /* first time for this JPEG object? */
|
||||
cinfo->dest = (struct jpeg_destination_mgr *)
|
||||
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
|
||||
sizeof(my_destination_mgr));
|
||||
}
|
||||
|
||||
dest = (my_dest_ptr) cinfo->dest;
|
||||
dest->pub.init_destination = init_destination;
|
||||
dest->pub.empty_output_buffer = empty_output_buffer;
|
||||
dest->pub.term_destination = term_destination;
|
||||
dest->outfile = outfile;
|
||||
dest->size = size;
|
||||
}
|
||||
|
||||
void SaveJPG(char * filename, int quality, int image_width, int image_height, unsigned char *image_buffer) {
|
||||
/* This struct contains the JPEG compression parameters and pointers to
|
||||
* working space (which is allocated as needed by the JPEG library).
|
||||
* It is possible to have several such structures, representing multiple
|
||||
* compression/decompression processes, in existence at once. We refer
|
||||
* to any one struct (and its associated working data) as a "JPEG object".
|
||||
*/
|
||||
struct jpeg_compress_struct cinfo;
|
||||
/* This struct represents a JPEG error handler. It is declared separately
|
||||
* because applications often want to supply a specialized error handler
|
||||
* (see the second half of this file for an example). But here we just
|
||||
* take the easy way out and use the standard error handler, which will
|
||||
* print a message on stderr and call exit() if compression fails.
|
||||
* Note that this struct must live as long as the main JPEG parameter
|
||||
* struct, to avoid dangling-pointer problems.
|
||||
*/
|
||||
struct jpeg_error_mgr jerr;
|
||||
/* More stuff */
|
||||
JSAMPROW row_pointer[1]; /* pointer to JSAMPLE row[s] */
|
||||
int row_stride; /* physical row width in image buffer */
|
||||
unsigned char *out;
|
||||
|
||||
/* Step 1: allocate and initialize JPEG compression object */
|
||||
|
||||
/* We have to set up the error handler first, in case the initialization
|
||||
* step fails. (Unlikely, but it could happen if you are out of memory.)
|
||||
* This routine fills in the contents of struct jerr, and returns jerr's
|
||||
* address which we place into the link field in cinfo.
|
||||
*/
|
||||
cinfo.err = jpeg_std_error(&jerr);
|
||||
/* Now we can initialize the JPEG compression object. */
|
||||
jpeg_create_compress(&cinfo);
|
||||
|
||||
/* Step 2: specify data destination (eg, a file) */
|
||||
/* Note: steps 2 and 3 can be done in either order. */
|
||||
|
||||
/* Here we use the library-supplied code to send compressed data to a
|
||||
* stdio stream. You can also write your own code to do something else.
|
||||
* VERY IMPORTANT: use "b" option to fopen() if you are on a machine that
|
||||
* requires it in order to write binary files.
|
||||
*/
|
||||
out = ri.Hunk_AllocateTempMemory(image_width*image_height*4);
|
||||
jpegDest(&cinfo, out, image_width*image_height*4);
|
||||
|
||||
/* Step 3: set parameters for compression */
|
||||
|
||||
/* First we supply a description of the input image.
|
||||
* Four fields of the cinfo struct must be filled in:
|
||||
*/
|
||||
cinfo.image_width = image_width; /* image width and height, in pixels */
|
||||
cinfo.image_height = image_height;
|
||||
cinfo.input_components = 4; /* # of color components per pixel */
|
||||
cinfo.in_color_space = JCS_RGB; /* colorspace of input image */
|
||||
/* Now use the library's routine to set default compression parameters.
|
||||
* (You must set at least cinfo.in_color_space before calling this,
|
||||
* since the defaults depend on the source color space.)
|
||||
*/
|
||||
jpeg_set_defaults(&cinfo);
|
||||
/* Now you can set any non-default parameters you wish to.
|
||||
* Here we just illustrate the use of quality (quantization table) scaling:
|
||||
*/
|
||||
jpeg_set_quality(&cinfo, quality, TRUE /* limit to baseline-JPEG values */);
|
||||
/* If quality is set high, disable chroma subsampling */
|
||||
if (quality >= 85) {
|
||||
cinfo.comp_info[0].h_samp_factor = 1;
|
||||
cinfo.comp_info[0].v_samp_factor = 1;
|
||||
}
|
||||
|
||||
/* Step 4: Start compressor */
|
||||
|
||||
/* TRUE ensures that we will write a complete interchange-JPEG file.
|
||||
* Pass TRUE unless you are very sure of what you're doing.
|
||||
*/
|
||||
jpeg_start_compress(&cinfo, TRUE);
|
||||
|
||||
/* Step 5: while (scan lines remain to be written) */
|
||||
/* jpeg_write_scanlines(...); */
|
||||
|
||||
/* Here we use the library's state variable cinfo.next_scanline as the
|
||||
* loop counter, so that we don't have to keep track ourselves.
|
||||
* To keep things simple, we pass one scanline per call; you can pass
|
||||
* more if you wish, though.
|
||||
*/
|
||||
row_stride = image_width * 4; /* JSAMPLEs per row in image_buffer */
|
||||
|
||||
while (cinfo.next_scanline < cinfo.image_height) {
|
||||
/* jpeg_write_scanlines expects an array of pointers to scanlines.
|
||||
* Here the array is only one element long, but you could pass
|
||||
* more than one scanline at a time if that's more convenient.
|
||||
*/
|
||||
row_pointer[0] = & image_buffer[((cinfo.image_height-1)*row_stride)-cinfo.next_scanline * row_stride];
|
||||
(void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
|
||||
}
|
||||
|
||||
/* Step 6: Finish compression */
|
||||
|
||||
jpeg_finish_compress(&cinfo);
|
||||
/* After finish_compress, we can close the output file. */
|
||||
ri.FS_WriteFile( filename, out, hackSize );
|
||||
|
||||
ri.Hunk_FreeTempMemory(out);
|
||||
|
||||
/* Step 7: release JPEG compression object */
|
||||
|
||||
/* This is an important step since it will release a good deal of memory. */
|
||||
jpeg_destroy_compress(&cinfo);
|
||||
|
||||
/* And we're done! */
|
||||
}
|
||||
|
||||
/*
|
||||
=================
|
||||
SaveJPGToBuffer
|
||||
=================
|
||||
*/
|
||||
int SaveJPGToBuffer( byte *buffer, int quality,
|
||||
int image_width, int image_height,
|
||||
byte *image_buffer )
|
||||
{
|
||||
struct jpeg_compress_struct cinfo;
|
||||
struct jpeg_error_mgr jerr;
|
||||
JSAMPROW row_pointer[1]; /* pointer to JSAMPLE row[s] */
|
||||
int row_stride; /* physical row width in image buffer */
|
||||
|
||||
/* Step 1: allocate and initialize JPEG compression object */
|
||||
cinfo.err = jpeg_std_error(&jerr);
|
||||
/* Now we can initialize the JPEG compression object. */
|
||||
jpeg_create_compress(&cinfo);
|
||||
|
||||
/* Step 2: specify data destination (eg, a file) */
|
||||
/* Note: steps 2 and 3 can be done in either order. */
|
||||
jpegDest(&cinfo, buffer, image_width*image_height*4);
|
||||
|
||||
/* Step 3: set parameters for compression */
|
||||
cinfo.image_width = image_width; /* image width and height, in pixels */
|
||||
cinfo.image_height = image_height;
|
||||
cinfo.input_components = 4; /* # of color components per pixel */
|
||||
cinfo.in_color_space = JCS_RGB; /* colorspace of input image */
|
||||
|
||||
jpeg_set_defaults(&cinfo);
|
||||
jpeg_set_quality(&cinfo, quality, TRUE /* limit to baseline-JPEG values */);
|
||||
/* If quality is set high, disable chroma subsampling */
|
||||
if (quality >= 85) {
|
||||
cinfo.comp_info[0].h_samp_factor = 1;
|
||||
cinfo.comp_info[0].v_samp_factor = 1;
|
||||
}
|
||||
|
||||
/* Step 4: Start compressor */
|
||||
jpeg_start_compress(&cinfo, TRUE);
|
||||
|
||||
/* Step 5: while (scan lines remain to be written) */
|
||||
/* jpeg_write_scanlines(...); */
|
||||
row_stride = image_width * 4; /* JSAMPLEs per row in image_buffer */
|
||||
|
||||
while (cinfo.next_scanline < cinfo.image_height) {
|
||||
/* jpeg_write_scanlines expects an array of pointers to scanlines.
|
||||
* Here the array is only one element long, but you could pass
|
||||
* more than one scanline at a time if that's more convenient.
|
||||
*/
|
||||
row_pointer[0] = & image_buffer[((cinfo.image_height-1)*row_stride)-cinfo.next_scanline * row_stride];
|
||||
(void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
|
||||
}
|
||||
|
||||
/* Step 6: Finish compression */
|
||||
jpeg_finish_compress(&cinfo);
|
||||
|
||||
/* Step 7: release JPEG compression object */
|
||||
jpeg_destroy_compress(&cinfo);
|
||||
|
||||
/* And we're done! */
|
||||
return hackSize;
|
||||
}
|
Loading…
Add table
Add a link
Reference in a new issue