/* loads and converts a targa from disk */
void * tga_load( const char * filename,
int * width, int * height, unsigned int format ) {
ubyte idlen; // length of the image_id string below.
ubyte cmap_type; // paletted image <=> cmap_type
ubyte image_type; // can be any of the IMG_TYPE constants above.
uint16 cmap_first; //
uint16 cmap_length; // how long the colormap is
ubyte cmap_entry_size; // how big a palette entry is.
uint16 img_spec_xorig; // the x origin of the image in the image data.
uint16 img_spec_yorig; // the y origin of the image in the image data.
uint16 img_spec_width; // the width of the image.
uint16 img_spec_height; // the height of the image.
ubyte img_spec_pix_depth; // the depth of a pixel in the image.
ubyte img_spec_img_desc; // the image descriptor.
FILE * targafile;
ubyte * tga_hdr = NULL;
ubyte * colormap = NULL;
//***********************************************************************
// Add by Yu-Chi because of variable initialization.
// Add all = 0 to all the following variables
//***********************************************************************
ubyte cmap_bytes_entry = 0;
uint32 cmap_bytes = 0;
uint32 tmp_col = 0;
uint32 tmp_int32 = 0;
ubyte tmp_byte = 0;
ubyte alphabits = 0;
uint32 num_pixels = 0;
uint32 i = 0;
uint32 j = 0;
ubyte * image_data = 0;
uint32 img_dat_len = 0;
ubyte bytes_per_pix = 0;
ubyte true_bits_per_pixel = 0;
uint32 bytes_total = 0;
ubyte packet_header = 0;
ubyte repcount = 0;
switch( format ) {
case TGA_TRUECOLOR_24:
case TGA_TRUECOLOR_32:
break;
default:
TargaError = TGA_ERR_BAD_FORMAT;
return( NULL );
}
/* open binary image file */
targafile = fopen( filename, "rb" );
if( targafile == NULL ) {
TargaError = TGA_ERR_OPEN_FAILS;
return( NULL );
}
/* allocate memory for the header */
tga_hdr = (ubyte *)malloc( HDR_LENGTH );
/* read the header in. */
if( fread( (void *)tga_hdr, 1, HDR_LENGTH, targafile ) != HDR_LENGTH ) {
free( tga_hdr );
TargaError = TGA_ERR_BAD_HEADER;
return( NULL );
}
/* byte order is important here. */
idlen = (ubyte)tga_hdr[HDR_IDLEN];
image_type = (ubyte)tga_hdr[HDR_IMAGE_TYPE];
cmap_type = (ubyte)tga_hdr[HDR_CMAP_TYPE];
cmap_first = ttohs( *(uint16 *)(&tga_hdr[HDR_CMAP_FIRST]) );
cmap_length = ttohs( *(uint16 *)(&tga_hdr[HDR_CMAP_LENGTH]) );
cmap_entry_size = (ubyte)tga_hdr[HDR_CMAP_ENTRY_SIZE];
img_spec_xorig = ttohs( *(uint16 *)(&tga_hdr[HDR_IMG_SPEC_XORIGIN]) );
img_spec_yorig = ttohs( *(uint16 *)(&tga_hdr[HDR_IMG_SPEC_YORIGIN]) );
img_spec_width = ttohs( *(uint16 *)(&tga_hdr[HDR_IMG_SPEC_WIDTH]) );
img_spec_height = ttohs( *(uint16 *)(&tga_hdr[HDR_IMG_SPEC_HEIGHT]) );
img_spec_pix_depth = (ubyte)tga_hdr[HDR_IMG_SPEC_PIX_DEPTH];
img_spec_img_desc = (ubyte)tga_hdr[HDR_IMG_SPEC_IMG_DESC];
free( tga_hdr );
num_pixels = img_spec_width * img_spec_height;
if( num_pixels == 0 ) {
TargaError = TGA_ERR_BAD_DIMENSIONS;
return( NULL );
}
alphabits = img_spec_img_desc & 0x0F;
/* seek past the image id, if there is one */
if( idlen ) {
if( fseek( targafile, idlen, SEEK_CUR ) ) {
TargaError = TGA_ERR_UNEXPECTED_EOF;
return( NULL );
}
}
/* if this is a 'nodata' image, just jump out. */
if( image_type == TGA_IMG_NODATA ) {
TargaError = TGA_ERR_NODATA_IMAGE;
return( NULL );
}
/* now we're starting to get into the meat of the matter. */
/* deal with the colormap, if there is one. */
if( cmap_type ) {
switch( image_type ) {
case TGA_IMG_UNC_PALETTED:
case TGA_IMG_RLE_PALETTED:
break;
case TGA_IMG_UNC_TRUECOLOR:
case TGA_IMG_RLE_TRUECOLOR:
// this should really be an error, but some really old
// crusty targas might actually be like this (created by TrueVision, no less!)
// so, we'll hack our way through it.
break;
case TGA_IMG_UNC_GRAYSCALE:
case TGA_IMG_RLE_GRAYSCALE:
TargaError = TGA_ERR_COLORMAP_FOR_GRAY;
return( NULL );
}
/* ensure colormap entry size is something we support */
if( !(cmap_entry_size == 15 ||
cmap_entry_size == 16 ||
cmap_entry_size == 24 ||
cmap_entry_size == 32) ) {
TargaError = TGA_ERR_BAD_COLORMAP_ENTRY_SIZE;
return( NULL );
}
/* allocate memory for a colormap */
if( cmap_entry_size & 0x07 ) {
cmap_bytes_entry = (((8 - (cmap_entry_size & 0x07)) + cmap_entry_size) >> 3);
} else {
void write_short( int16 value, FILE * file )
{
value = ttohs( value );
fwrite( &value, 2, 1, file );
}
