#include "stdio.h"
#include "stdlib.h"
#include "math.h"
/*
The following is rather crude demonstration code to read
uncompressed and compressed TGA files of 16, 24, or 32 bit
TGA.
*/
typedef struct {
char idlength;
char colourmaptype;
char datatypecode;
short int colourmaporigin;
short int colourmaplength;
char colourmapdepth;
short int x_origin;
short int y_origin;
short width;
short height;
char bitsperpixel;
char imagedescriptor;
} HEADER;
typedef struct {
unsigned char r,g,b,a;
} PIXEL;
void MergeBytes(PIXEL *,unsigned char *,int);
int main(int argc,char **argv)
{
int n=0,i,j;
int bytes2read,skipover = 0;
unsigned char p[5];
FILE *fptr;
HEADER header;
PIXEL *pixels;
if (argc < 2) {
fprintf(stderr,"Usage: %s tgafile\n",argv[0]);
exit(-1);
}
/* Open the file */
if ((fptr = fopen(argv[1],"rb")) == NULL) {
fprintf(stderr,"File open failed\n");
exit(-1);
}
/* Display the header fields */
header.idlength = fgetc(fptr);
fprintf(stderr,"ID length: %d\n",header.idlength);
header.colourmaptype = fgetc(fptr);
fprintf(stderr,"Colourmap type: %d\n",header.colourmaptype);
header.datatypecode = fgetc(fptr);
fprintf(stderr,"Image type: %d\n",header.datatypecode);
fread(&header.colourmaporigin,2,1,fptr);
fprintf(stderr,"Colour map offset: %d\n",header.colourmaporigin);
fread(&header.colourmaplength,2,1,fptr);
fprintf(stderr,"Colour map length: %d\n",header.colourmaplength);
header.colourmapdepth = fgetc(fptr);
fprintf(stderr,"Colour map depth: %d\n",header.colourmapdepth);
fread(&header.x_origin,2,1,fptr);
fprintf(stderr,"X origin: %d\n",header.x_origin);
fread(&header.y_origin,2,1,fptr);
fprintf(stderr,"Y origin: %d\n",header.y_origin);
fread(&header.width,2,1,fptr);
fprintf(stderr,"Width: %d\n",header.width);
fread(&header.height,2,1,fptr);
fprintf(stderr,"Height: %d\n",header.height);
header.bitsperpixel = fgetc(fptr);
fprintf(stderr,"Bits per pixel: %d\n",header.bitsperpixel);
header.imagedescriptor = fgetc(fptr);
fprintf(stderr,"Descriptor: %d\n",header.imagedescriptor);
/* Allocate space for the image */
if ((pixels = malloc(header.width*header.height*sizeof(PIXEL))) == NULL) {
fprintf(stderr,"malloc of image failed\n");
exit(-1);
}
for (i=0;i<header.width*header.height;i++) {
pixels[i].r = 0;
pixels[i].g = 0;
pixels[i].b = 0;
pixels[i].a = 0;
}
/* What can we handle */
/*if (header.datatypecode != 2 && header.datatypecode != 10) {
printf(stderr,"Can only handle image type 2 and 10\n");
exit(-1);
}*/
if (header.bitsperpixel != 16 &&
header.bitsperpixel != 24 && header.bitsperpixel != 32) {
fprintf(stderr,"Can only handle pixel depths of 16, 24, and 32\n");
exit(-1);
}
if (header.colourmaptype != 0 && header.colourmaptype != 1) {
fprintf(stderr,"Can only handle colour map types of 0 and 1\n");
exit(-1);
}
/* Skip over unnecessary stuff */
skipover += header.idlength;
skipover += header.colourmaptype * header.colourmaplength;
fprintf(stderr,"Skip over %d bytes\n",skipover);
fseek(fptr,skipover,SEEK_CUR);
/* Read the image */
bytes2read = header.bitsperpixel / 8;
while (n < header.width * header.height) {
if (header.datatypecode == 2) { /* Uncompressed */
if (fread(p,1,bytes2read,fptr) != bytes2read) {
fprintf(stderr,"Unexpected end of file at pixel %d\n",i);
exit(-1);
}
MergeBytes(&(pixels[n]),p,bytes2read);
n++;
} else if (header.datatypecode == 10) { /* Compressed */
if (fread(p,1,bytes2read+1,fptr) != bytes2read+1) {
fprintf(stderr,"Unexpected end of file at pixel %d\n",i);
exit(-1);
}
j = p[0] & 0x7f;
MergeBytes(&(pixels[n]),&(p[1]),bytes2read);
n++;
if (p[0] & 0x80) { /* RLE chunk */
for (i=0;i<j;i++) {
MergeBytes(&(pixels[n]),&(p[1]),bytes2read);
n++;
}
} else { /* Normal chunk */
for (i=0;i<j;i++) {
if (fread(p,1,bytes2read,fptr) != bytes2read) {
fprintf(stderr,"Unexpected end of file at pixel %d\n",i);
exit(-1);
}
MergeBytes(&(pixels[n]),p,bytes2read);
n++;
}
}
}
}
fclose(fptr);
/* Write the result as a uncompressed TGA */
if ((fptr = fopen("tgatest.tga","wb")) == NULL) {
fprintf(stderr,"Failed to open outputfile\n");
exit(-1);
}
putc(0,fptr);
putc(0,fptr);
putc(2,fptr); /* uncompressed RGB */
putc(0,fptr); putc(0,fptr);
putc(0,fptr); putc(0,fptr);
putc(0,fptr);
putc(0,fptr); putc(0,fptr); /* X origin */
putc(0,fptr); putc(0,fptr); /* y origin */
putc((header.width & 0x00FF),fptr);
putc((header.width & 0xFF00) / 256,fptr);
putc((header.height & 0x00FF),fptr);
putc((header.height & 0xFF00) / 256,fptr);
putc(32,fptr); /* 24 bit bitmap */
putc(0,fptr);
for (i=0;i<header.height*header.width;i++) {
putc(pixels[i].b,fptr);
putc(pixels[i].g,fptr);
putc(pixels[i].r,fptr);
putc(pixels[i].a,fptr);
}
fclose(fptr);
}
void MergeBytes(PIXEL *pixel,unsigned char *p,int bytes)
{
if (bytes == 4) {
pixel->r = p[2];
pixel->g = p[1];
pixel->b = p[0];
pixel->a = p[3];
} else if (bytes == 3) {
pixel->r = p[2];
pixel->g = p[1];
pixel->b = p[0];
pixel->a = 0;
} else if (bytes == 2) {
pixel->r = (p[1] & 0x7c) << 1;
pixel->g = ((p[1] & 0x03) << 6) | ((p[0] & 0xe0) >> 2);
pixel->b = (p[0] & 0x1f) << 3;
pixel->a = (p[1] & 0x80);
}
}
