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/*
* jrdtarga.c
*
* Copyright (C) 1991, 1992, 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; input_init may need work if the
* user interface has already read some data (e.g., to determine that
* the file is indeed Targa format).
*
* These routines are invoked via the methods get_input_row
* and input_init/term.
*
* Based on code contributed by Lee Daniel Crocker.
*/
#include "jinclude.h"
#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)))
static JSAMPARRAY colormap; /* Targa colormap (converted to my format) */
static big_sarray_ptr whole_image; /* Needed if funny input row order */
static long current_row; /* Current logical row number to read */
/* Pointer to routine to extract next Targa pixel from input file */
static void (*read_pixel) PP((compress_info_ptr cinfo));
/* Result of read_pixel is delivered here: */
static U_CHAR tga_pixel[4];
static int pixel_size; /* Bytes per Targa pixel (1 to 4) */
/* State info for reading RLE-coded pixels; both counts must be init to 0 */
static int block_count; /* # of pixels remaining in RLE block */
static int dup_pixel_count; /* # of times to duplicate previous pixel */
/* This saves the correct pixel-row-expansion method for preload_image */
static void (*get_pixel_row) PP((compress_info_ptr cinfo,
JSAMPARRAY pixel_row));
/* For expanding 5-bit pixel values to 8-bit with best rounding */
static const UINT8 c5to8bits[32] = {
0, 8, 16, 24, 32, 41, 49, 57,
65, 74, 82, 90, 98, 106, 115, 123,
131, 139, 148, 156, 164, 172, 180, 189,
197, 205, 213, 222, 230, 238, 246, 255
};
LOCAL int
read_byte (compress_info_ptr cinfo)
/* Read next byte from Targa file */
{
register FILE *infile = cinfo->input_file;
register int c;
if ((c = getc(infile)) == EOF)
ERREXIT(cinfo->emethods, "Premature EOF in Targa file");
return c;
}
LOCAL void
read_colormap (compress_info_ptr cinfo, int cmaplen, int mapentrysize)
/* Read the colormap from a Targa file */
{
int i;
/* Presently only handles 24-bit BGR format */
if (mapentrysize != 24)
ERREXIT(cinfo->emethods, "Unsupported Targa colormap format");
for (i = 0; i < cmaplen; i++) {
colormap[2][i] = (JSAMPLE) read_byte(cinfo);
colormap[1][i] = (JSAMPLE) read_byte(cinfo);
colormap[0][i] = (JSAMPLE) read_byte(cinfo);
}
}
/*
* read_pixel methods: get a single pixel from Targa file into tga_pixel[]
*/
LOCAL void
read_non_rle_pixel (compress_info_ptr cinfo)
/* Read one Targa pixel from the input file; no RLE expansion */
{
register FILE * infile = cinfo->input_file;
register int i;
for (i = 0; i < pixel_size; i++) {
tga_pixel[i] = (U_CHAR) getc(infile);
}
}
LOCAL void
read_rle_pixel (compress_info_ptr cinfo)
/* Read one Targa pixel from the input file, expanding RLE data as needed */
{
register FILE * infile = cinfo->input_file;
register int i;
/* Duplicate previously read pixel? */
if (dup_pixel_count > 0) {
dup_pixel_count--;
return;
}
/* Time to read RLE block header? */
if (--block_count < 0) { /* decrement pixels remaining in block */
i = read_byte(cinfo);
if (i & 0x80) { /* Start of duplicate-pixel block? */
dup_pixel_count = i & 0x7F; /* number of duplications after this one */
block_count = 0; /* then read new block header */
} else {
block_count = i & 0x7F; /* number of pixels after this one */
}
}
/* Read next pixel */
for (i = 0; i < pixel_size; i++) {
tga_pixel[i] = (U_CHAR) getc(infile);
}
}
/*
* Read one row of pixels.
*
* We provide several different versions depending on input file format.
*/
METHODDEF void
get_8bit_gray_row (compress_info_ptr cinfo, JSAMPARRAY pixel_row)
/* This version is for reading 8-bit grayscale pixels */
{
register JSAMPROW ptr0;
register long col;
ptr0 = pixel_row[0];
for (col = cinfo->image_width; col > 0; col--) {
(*read_pixel) (cinfo); /* Load next pixel into tga_pixel */
*ptr0++ = (JSAMPLE) UCH(tga_pixel[0]);
}
}
METHODDEF void
get_8bit_row (compress_info_ptr cinfo, JSAMPARRAY pixel_row)
/* This version is for reading 8-bit colormap indexes */
{
register int t;
register JSAMPROW ptr0, ptr1, ptr2;
register long col;
ptr0 = pixel_row[0];
ptr1 = pixel_row[1];
ptr2 = pixel_row[2];
for (col = cinfo->image_width; col > 0; col--) {
(*read_pixel) (cinfo); /* Load next pixel into tga_pixel */
t = UCH(tga_pixel[0]);
*ptr0++ = colormap[0][t];
*ptr1++ = colormap[1][t];
*ptr2++ = colormap[2][t];
}
}
METHODDEF void
get_16bit_row (compress_info_ptr cinfo, JSAMPARRAY pixel_row)
/* This version is for reading 16-bit pixels */
{
register int t;
register JSAMPROW ptr0, ptr1, ptr2;
register long col;
ptr0 = pixel_row[0];
ptr1 = pixel_row[1];
ptr2 = pixel_row[2];
for (col = cinfo->image_width; col > 0; col--) {
(*read_pixel) (cinfo); /* Load next pixel into tga_pixel */
t = UCH(tga_pixel[0]);
t += UCH(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
*/
*ptr2++ = (JSAMPLE) c5to8bits[t & 0x1F];
t >>= 5;
*ptr1++ = (JSAMPLE) c5to8bits[t & 0x1F];
t >>= 5;
*ptr0++ = (JSAMPLE) c5to8bits[t & 0x1F];
}
}
METHODDEF void
get_24bit_row (compress_info_ptr cinfo, JSAMPARRAY pixel_row)
/* This version is for reading 24-bit pixels */
{
register JSAMPROW ptr0, ptr1, ptr2;
register long col;
ptr0 = pixel_row[0];
ptr1 = pixel_row[1];
ptr2 = pixel_row[2];
for (col = cinfo->image_width; col > 0; col--) {
(*read_pixel) (cinfo); /* Load next pixel into tga_pixel */
*ptr0++ = (JSAMPLE) UCH(tga_pixel[2]); /* convert BGR to RGB order */
*ptr1++ = (JSAMPLE) UCH(tga_pixel[1]);
*ptr2++ = (JSAMPLE) UCH(tga_pixel[0]);
}
}
/*
* 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 void
get_memory_row (compress_info_ptr cinfo, JSAMPARRAY pixel_row)
{
JSAMPARRAY image_ptr;
long 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 - current_row - 1;
/* Fetch that row from virtual array */
image_ptr = (*cinfo->emethods->access_big_sarray)
(whole_image, source_row * cinfo->input_components, FALSE);
jcopy_sample_rows(image_ptr, 0, pixel_row, 0,
cinfo->input_components, cinfo->image_width);
current_row++;
}
/*
* This method loads the image into whole_image during the first call on
* get_input_row. The get_input_row pointer is then adjusted to call
* get_memory_row on subsequent calls.
*/
METHODDEF void
preload_image (compress_info_ptr cinfo, JSAMPARRAY pixel_row)
{
JSAMPARRAY image_ptr;
long row;
/* Read the data into a virtual array in input-file row order */
for (row = 0; row < cinfo->image_height; row++) {
(*cinfo->methods->progress_monitor) (cinfo, row, cinfo->image_height);
image_ptr = (*cinfo->emethods->access_big_sarray)
(whole_image, row * cinfo->input_components, TRUE);
(*get_pixel_row) (cinfo, image_ptr);
}
cinfo->completed_passes++;
/* Set up to read from the virtual array in unscrambled order */
cinfo->methods->get_input_row = get_memory_row;
current_row = 0;
/* And read the first row */
get_memory_row(cinfo, pixel_row);
}
/*
* Read the file header; return image size and component count.
*/
METHODDEF void
input_init (compress_info_ptr cinfo)
{
U_CHAR targaheader[18];
int idlen, cmaptype, subtype, flags, interlace_type, components;
UINT16 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(cinfo->input_file, targaheader, 18))
ERREXIT(cinfo->emethods, "Unexpected end of file");
/* 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);
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 */
pixel_size < 1 || 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->emethods, "Invalid or unsupported Targa file");
if (subtype > 8) {
/* It's an RLE-coded file */
read_pixel = read_rle_pixel;
block_count = dup_pixel_count = 0;
subtype -= 8;
} else {
/* Non-RLE file */
read_pixel = read_non_rle_pixel;
}
/* Now should have subtype 1, 2, or 3 */
components = 3; /* until proven different */
cinfo->in_color_space = CS_RGB;
switch (subtype) {
case 1: /* colormapped image */
if (pixel_size == 1 && cmaptype == 1)
get_pixel_row = get_8bit_row;
else
ERREXIT(cinfo->emethods, "Invalid or unsupported Targa file");
TRACEMS2(cinfo->emethods, 1, "%ux%u colormapped Targa image",
width, height);
break;
case 2: /* RGB image */
switch (pixel_size) {
case 2:
get_pixel_row = get_16bit_row;
break;
case 3:
get_pixel_row = get_24bit_row;
break;
case 4:
get_pixel_row = get_32bit_row;
break;
default:
ERREXIT(cinfo->emethods, "Invalid or unsupported Targa file");
break;
}
TRACEMS2(cinfo->emethods, 1, "%ux%u RGB Targa image",
width, height);
break;
case 3: /* Grayscale image */
components = 1;
cinfo->in_color_space = CS_GRAYSCALE;
if (pixel_size == 1)
get_pixel_row = get_8bit_gray_row;
else
ERREXIT(cinfo->emethods, "Invalid or unsupported Targa file");
TRACEMS2(cinfo->emethods, 1, "%ux%u grayscale Targa image",
width, height);
break;
default:
ERREXIT(cinfo->emethods, "Invalid or unsupported Targa file");
break;
}
if (is_bottom_up) {
whole_image = (*cinfo->emethods->request_big_sarray)
((long) width, (long) height * components,
(long) components);
cinfo->methods->get_input_row = preload_image;
cinfo->total_passes++; /* count file reading as separate pass */
} else {
whole_image = NULL;
cinfo->methods->get_input_row = get_pixel_row;
}
while (idlen--) /* Throw away ID field */
(void) read_byte(cinfo);
if (maplen > 0) {
if (maplen > 256 || GET_2B(3) != 0)
ERREXIT(cinfo->emethods, "Colormap too large");
/* Allocate space to store the colormap */
colormap = (*cinfo->emethods->alloc_small_sarray)
((long) maplen, 3L);
/* and read it from the file */
read_colormap(cinfo, (int) maplen, UCH(targaheader[7]));
} else {
if (cmaptype) /* but you promised a cmap! */
ERREXIT(cinfo->emethods, "Invalid or unsupported Targa file");
colormap = NULL;
}
cinfo->input_components = components;
cinfo->image_width = width;
cinfo->image_height = height;
cinfo->data_precision = 8; /* always, even if 12-bit JSAMPLEs */
}
/*
* Finish up at the end of the file.
*/
METHODDEF void
input_term (compress_info_ptr cinfo)
{
/* no work (we let free_all release the workspace) */
}
/*
* The method selection routine for Targa format input.
* Note that this must be called by the user interface before calling
* jpeg_compress. If multiple input formats are supported, the
* user interface is responsible for discovering the file format and
* calling the appropriate method selection routine.
*/
GLOBAL void
jselrtarga (compress_info_ptr cinfo)
{
cinfo->methods->input_init = input_init;
/* cinfo->methods->get_input_row is set by input_init */
cinfo->methods->input_term = input_term;
}
#endif /* TARGA_SUPPORTED */
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