/*

* 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 {

} 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 */