ref: 9cf3dc9a259cadc80e6d3840c658ef1d5f7c94a4
dir: /sys/src/cmd/gs/jpeg/rdtarga.c/
/*
* rdtarga.c
*
* Copyright (C) 1991-1996, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains routines to read input images in Targa format.
*
* These routines may need modification for non-Unix environments or
* specialized applications. As they stand, they assume input from
* an ordinary stdio stream. They further assume that reading begins
* at the start of the file; start_input may need work if the
* user interface has already read some data (e.g., to determine that
* the file is indeed Targa format).
*
* Based on code contributed by Lee Daniel Crocker.
*/
#include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
#ifdef TARGA_SUPPORTED
/* Macros to deal with unsigned chars as efficiently as compiler allows */
#ifdef HAVE_UNSIGNED_CHAR
typedef unsigned char U_CHAR;
#define UCH(x) ((int) (x))
#else /* !HAVE_UNSIGNED_CHAR */
#ifdef CHAR_IS_UNSIGNED
typedef char U_CHAR;
#define UCH(x) ((int) (x))
#else
typedef char U_CHAR;
#define UCH(x) ((int) (x) & 0xFF)
#endif
#endif /* HAVE_UNSIGNED_CHAR */
#define ReadOK(file,buffer,len) (JFREAD(file,buffer,len) == ((size_t) (len)))
/* Private version of data source object */
typedef struct _tga_source_struct * tga_source_ptr;
typedef struct _tga_source_struct {
struct cjpeg_source_struct pub; /* public fields */
j_compress_ptr cinfo; /* back link saves passing separate parm */
JSAMPARRAY colormap; /* Targa colormap (converted to my format) */
jvirt_sarray_ptr whole_image; /* Needed if funny input row order */
JDIMENSION current_row; /* Current logical row number to read */
/* Pointer to routine to extract next Targa pixel from input file */
JMETHOD(void, read_pixel, (tga_source_ptr sinfo));
/* Result of read_pixel is delivered here: */
U_CHAR tga_pixel[4];
int pixel_size; /* Bytes per Targa pixel (1 to 4) */
/* State info for reading RLE-coded pixels; both counts must be init to 0 */
int block_count; /* # of pixels remaining in RLE block */
int dup_pixel_count; /* # of times to duplicate previous pixel */
/* This saves the correct pixel-row-expansion method for preload_image */
JMETHOD(JDIMENSION, get_pixel_rows, (j_compress_ptr cinfo,
cjpeg_source_ptr sinfo));
} tga_source_struct;
/* For expanding 5-bit pixel values to 8-bit with best rounding */
static const UINT8 c5to8bits[32] = {
0, 8, 16, 25, 33, 41, 49, 58,
66, 74, 82, 90, 99, 107, 115, 123,
132, 140, 148, 156, 165, 173, 181, 189,
197, 206, 214, 222, 230, 239, 247, 255
};
LOCAL(int)
read_byte (tga_source_ptr sinfo)
/* Read next byte from Targa file */
{
register FILE *infile = sinfo->pub.input_file;
register int c;
if ((c = getc(infile)) == EOF)
ERREXIT(sinfo->cinfo, JERR_INPUT_EOF);
return c;
}
LOCAL(void)
read_colormap (tga_source_ptr sinfo, int cmaplen, int mapentrysize)
/* Read the colormap from a Targa file */
{
int i;
/* Presently only handles 24-bit BGR format */
if (mapentrysize != 24)
ERREXIT(sinfo->cinfo, JERR_TGA_BADCMAP);
for (i = 0; i < cmaplen; i++) {
sinfo->colormap[2][i] = (JSAMPLE) read_byte(sinfo);
sinfo->colormap[1][i] = (JSAMPLE) read_byte(sinfo);
sinfo->colormap[0][i] = (JSAMPLE) read_byte(sinfo);
}
}
/*
* read_pixel methods: get a single pixel from Targa file into tga_pixel[]
*/
METHODDEF(void)
read_non_rle_pixel (tga_source_ptr sinfo)
/* Read one Targa pixel from the input file; no RLE expansion */
{
register FILE *infile = sinfo->pub.input_file;
register int i;
for (i = 0; i < sinfo->pixel_size; i++) {
sinfo->tga_pixel[i] = (U_CHAR) getc(infile);
}
}
METHODDEF(void)
read_rle_pixel (tga_source_ptr sinfo)
/* Read one Targa pixel from the input file, expanding RLE data as needed */
{
register FILE *infile = sinfo->pub.input_file;
register int i;
/* Duplicate previously read pixel? */
if (sinfo->dup_pixel_count > 0) {
sinfo->dup_pixel_count--;
return;
}
/* Time to read RLE block header? */
if (--sinfo->block_count < 0) { /* decrement pixels remaining in block */
i = read_byte(sinfo);
if (i & 0x80) { /* Start of duplicate-pixel block? */
sinfo->dup_pixel_count = i & 0x7F; /* number of dups after this one */
sinfo->block_count = 0; /* then read new block header */
} else {
sinfo->block_count = i & 0x7F; /* number of pixels after this one */
}
}
/* Read next pixel */
for (i = 0; i < sinfo->pixel_size; i++) {
sinfo->tga_pixel[i] = (U_CHAR) getc(infile);
}
}
/*
* Read one row of pixels.
*
* We provide several different versions depending on input file format.
*/
METHODDEF(JDIMENSION)
get_8bit_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading 8-bit grayscale pixels */
{
tga_source_ptr source = (tga_source_ptr) sinfo;
register JSAMPROW ptr;
register JDIMENSION col;
ptr = source->pub.buffer[0];
for (col = cinfo->image_width; col > 0; col--) {
(*source->read_pixel) (source); /* Load next pixel into tga_pixel */
*ptr++ = (JSAMPLE) UCH(source->tga_pixel[0]);
}
return 1;
}
METHODDEF(JDIMENSION)
get_8bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading 8-bit colormap indexes */
{
tga_source_ptr source = (tga_source_ptr) sinfo;
register int t;
register JSAMPROW ptr;
register JDIMENSION col;
register JSAMPARRAY colormap = source->colormap;
ptr = source->pub.buffer[0];
for (col = cinfo->image_width; col > 0; col--) {
(*source->read_pixel) (source); /* Load next pixel into tga_pixel */
t = UCH(source->tga_pixel[0]);
*ptr++ = colormap[0][t];
*ptr++ = colormap[1][t];
*ptr++ = colormap[2][t];
}
return 1;
}
METHODDEF(JDIMENSION)
get_16bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading 16-bit pixels */
{
tga_source_ptr source = (tga_source_ptr) sinfo;
register int t;
register JSAMPROW ptr;
register JDIMENSION col;
ptr = source->pub.buffer[0];
for (col = cinfo->image_width; col > 0; col--) {
(*source->read_pixel) (source); /* Load next pixel into tga_pixel */
t = UCH(source->tga_pixel[0]);
t += UCH(source->tga_pixel[1]) << 8;
/* We expand 5 bit data to 8 bit sample width.
* The format of the 16-bit (LSB first) input word is
* xRRRRRGGGGGBBBBB
*/
ptr[2] = (JSAMPLE) c5to8bits[t & 0x1F];
t >>= 5;
ptr[1] = (JSAMPLE) c5to8bits[t & 0x1F];
t >>= 5;
ptr[0] = (JSAMPLE) c5to8bits[t & 0x1F];
ptr += 3;
}
return 1;
}
METHODDEF(JDIMENSION)
get_24bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading 24-bit pixels */
{
tga_source_ptr source = (tga_source_ptr) sinfo;
register JSAMPROW ptr;
register JDIMENSION col;
ptr = source->pub.buffer[0];
for (col = cinfo->image_width; col > 0; col--) {
(*source->read_pixel) (source); /* Load next pixel into tga_pixel */
*ptr++ = (JSAMPLE) UCH(source->tga_pixel[2]); /* change BGR to RGB order */
*ptr++ = (JSAMPLE) UCH(source->tga_pixel[1]);
*ptr++ = (JSAMPLE) UCH(source->tga_pixel[0]);
}
return 1;
}
/*
* Targa also defines a 32-bit pixel format with order B,G,R,A.
* We presently ignore the attribute byte, so the code for reading
* these pixels is identical to the 24-bit routine above.
* This works because the actual pixel length is only known to read_pixel.
*/
#define get_32bit_row get_24bit_row
/*
* This method is for re-reading the input data in standard top-down
* row order. The entire image has already been read into whole_image
* with proper conversion of pixel format, but it's in a funny row order.
*/
METHODDEF(JDIMENSION)
get_memory_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
tga_source_ptr source = (tga_source_ptr) sinfo;
JDIMENSION source_row;
/* Compute row of source that maps to current_row of normal order */
/* For now, assume image is bottom-up and not interlaced. */
/* NEEDS WORK to support interlaced images! */
source_row = cinfo->image_height - source->current_row - 1;
/* Fetch that row from virtual array */
source->pub.buffer = (*cinfo->mem->access_virt_sarray)
((j_common_ptr) cinfo, source->whole_image,
source_row, (JDIMENSION) 1, FALSE);
source->current_row++;
return 1;
}
/*
* This method loads the image into whole_image during the first call on
* get_pixel_rows. The get_pixel_rows pointer is then adjusted to call
* get_memory_row on subsequent calls.
*/
METHODDEF(JDIMENSION)
preload_image (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
tga_source_ptr source = (tga_source_ptr) sinfo;
JDIMENSION row;
cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;
/* Read the data into a virtual array in input-file row order. */
for (row = 0; row < cinfo->image_height; row++) {
if (progress != NULL) {
progress->pub.pass_counter = (long) row;
progress->pub.pass_limit = (long) cinfo->image_height;
(*progress->pub.progress_monitor) ((j_common_ptr) cinfo);
}
source->pub.buffer = (*cinfo->mem->access_virt_sarray)
((j_common_ptr) cinfo, source->whole_image, row, (JDIMENSION) 1, TRUE);
(*source->get_pixel_rows) (cinfo, sinfo);
}
if (progress != NULL)
progress->completed_extra_passes++;
/* Set up to read from the virtual array in unscrambled order */
source->pub.get_pixel_rows = get_memory_row;
source->current_row = 0;
/* And read the first row */
return get_memory_row(cinfo, sinfo);
}
/*
* Read the file header; return image size and component count.
*/
METHODDEF(void)
start_input_tga (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
tga_source_ptr source = (tga_source_ptr) sinfo;
U_CHAR targaheader[18];
int idlen, cmaptype, subtype, flags, interlace_type, components;
unsigned int width, height, maplen;
boolean is_bottom_up;
#define GET_2B(offset) ((unsigned int) UCH(targaheader[offset]) + \
(((unsigned int) UCH(targaheader[offset+1])) << 8))
if (! ReadOK(source->pub.input_file, targaheader, 18))
ERREXIT(cinfo, JERR_INPUT_EOF);
/* Pretend "15-bit" pixels are 16-bit --- we ignore attribute bit anyway */
if (targaheader[16] == 15)
targaheader[16] = 16;
idlen = UCH(targaheader[0]);
cmaptype = UCH(targaheader[1]);
subtype = UCH(targaheader[2]);
maplen = GET_2B(5);
width = GET_2B(12);
height = GET_2B(14);
source->pixel_size = UCH(targaheader[16]) >> 3;
flags = UCH(targaheader[17]); /* Image Descriptor byte */
is_bottom_up = ((flags & 0x20) == 0); /* bit 5 set => top-down */
interlace_type = flags >> 6; /* bits 6/7 are interlace code */
if (cmaptype > 1 || /* cmaptype must be 0 or 1 */
source->pixel_size < 1 || source->pixel_size > 4 ||
(UCH(targaheader[16]) & 7) != 0 || /* bits/pixel must be multiple of 8 */
interlace_type != 0) /* currently don't allow interlaced image */
ERREXIT(cinfo, JERR_TGA_BADPARMS);
if (subtype > 8) {
/* It's an RLE-coded file */
source->read_pixel = read_rle_pixel;
source->block_count = source->dup_pixel_count = 0;
subtype -= 8;
} else {
/* Non-RLE file */
source->read_pixel = read_non_rle_pixel;
}
/* Now should have subtype 1, 2, or 3 */
components = 3; /* until proven different */
cinfo->in_color_space = JCS_RGB;
switch (subtype) {
case 1: /* Colormapped image */
if (source->pixel_size == 1 && cmaptype == 1)
source->get_pixel_rows = get_8bit_row;
else
ERREXIT(cinfo, JERR_TGA_BADPARMS);
TRACEMS2(cinfo, 1, JTRC_TGA_MAPPED, width, height);
break;
case 2: /* RGB image */
switch (source->pixel_size) {
case 2:
source->get_pixel_rows = get_16bit_row;
break;
case 3:
source->get_pixel_rows = get_24bit_row;
break;
case 4:
source->get_pixel_rows = get_32bit_row;
break;
default:
ERREXIT(cinfo, JERR_TGA_BADPARMS);
break;
}
TRACEMS2(cinfo, 1, JTRC_TGA, width, height);
break;
case 3: /* Grayscale image */
components = 1;
cinfo->in_color_space = JCS_GRAYSCALE;
if (source->pixel_size == 1)
source->get_pixel_rows = get_8bit_gray_row;
else
ERREXIT(cinfo, JERR_TGA_BADPARMS);
TRACEMS2(cinfo, 1, JTRC_TGA_GRAY, width, height);
break;
default:
ERREXIT(cinfo, JERR_TGA_BADPARMS);
break;
}
if (is_bottom_up) {
/* Create a virtual array to buffer the upside-down image. */
source->whole_image = (*cinfo->mem->request_virt_sarray)
((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
(JDIMENSION) width * components, (JDIMENSION) height, (JDIMENSION) 1);
if (cinfo->progress != NULL) {
cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;
progress->total_extra_passes++; /* count file input as separate pass */
}
/* source->pub.buffer will point to the virtual array. */
source->pub.buffer_height = 1; /* in case anyone looks at it */
source->pub.get_pixel_rows = preload_image;
} else {
/* Don't need a virtual array, but do need a one-row input buffer. */
source->whole_image = NULL;
source->pub.buffer = (*cinfo->mem->alloc_sarray)
((j_common_ptr) cinfo, JPOOL_IMAGE,
(JDIMENSION) width * components, (JDIMENSION) 1);
source->pub.buffer_height = 1;
source->pub.get_pixel_rows = source->get_pixel_rows;
}
while (idlen--) /* Throw away ID field */
(void) read_byte(source);
if (maplen > 0) {
if (maplen > 256 || GET_2B(3) != 0)
ERREXIT(cinfo, JERR_TGA_BADCMAP);
/* Allocate space to store the colormap */
source->colormap = (*cinfo->mem->alloc_sarray)
((j_common_ptr) cinfo, JPOOL_IMAGE, (JDIMENSION) maplen, (JDIMENSION) 3);
/* and read it from the file */
read_colormap(source, (int) maplen, UCH(targaheader[7]));
} else {
if (cmaptype) /* but you promised a cmap! */
ERREXIT(cinfo, JERR_TGA_BADPARMS);
source->colormap = NULL;
}
cinfo->input_components = components;
cinfo->data_precision = 8;
cinfo->image_width = width;
cinfo->image_height = height;
}
/*
* Finish up at the end of the file.
*/
METHODDEF(void)
finish_input_tga (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
/* no work */
}
/*
* The module selection routine for Targa format input.
*/
GLOBAL(cjpeg_source_ptr)
jinit_read_targa (j_compress_ptr cinfo)
{
tga_source_ptr source;
/* Create module interface object */
source = (tga_source_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(tga_source_struct));
source->cinfo = cinfo; /* make back link for subroutines */
/* Fill in method ptrs, except get_pixel_rows which start_input sets */
source->pub.start_input = start_input_tga;
source->pub.finish_input = finish_input_tga;
return (cjpeg_source_ptr) source;
}
#endif /* TARGA_SUPPORTED */