Hi
I have been working through a tutorial book that uses SDL. I have a piece of code that reads a ppm file and displays the image on the screen. The program seems to read the file and set the hight and width correctly creating a window the width and hight as the image but there is no image. If i move the image file the program return an error incating the image is missing so i know its reading it. Any help would be greatly appreicated. I have included the code.
Thankd
Steve
Code:
#include <stdio.h>
#include <stdlib.h>
#include <SDL.h>
#include <string.h>
//A public class is the same as a 'struct’
class CImage {
public:
unsigned char red;
unsigned char green;
unsigned char blue;
};
void ppm_read_comments ( FILE *fp )
{
int c;
while ( (c = getc ( fp ) ) == ‘#’ ) {
while ( getc( fp ) != ‘\n’ )
;
}
ungetc ( c, fp );
}
class ppm_error
{
public:
ppm_error() {
printf("\nIncorrect PPM format!\n");
exit ( 1 );
}
};
//change from (R, G, B) to (B, G, R)
void ppm2sdl ( CImage *ibuf, int width, int height )
{
unsigned char temp;
for ( int i = 0; i < height; ++i ) {
int row_offset = i * width;
for ( int j = 0; j < width; ++j ){
int offset = row_offset + j;
temp = ibuf[offset].red;
ibuf[offset].red = ibuf[offset].blue;
ibuf[offset].blue = temp;
}
}
}
int main( int argc, char* args[] )
{
int ppmh[20], c; //PPM header
int width, height; //image width and height
SDL_Surface *screen;
char filename[] = “C:/data/beach.ppm”;
FILE *input = fopen (filename, “rb”); //PPM file for testing read
if ( !input ) {
printf("\nError opening input file %s!\n", filename);
return 1;
}
//read PPM input file
ppm_read_comments ( input ); //read comments
char temp[100];
fscanf ( input, “%2s”, temp );
temp[3] = 0;
if ( strncmp ( temp, “P6”, 2 ) )
throw ppm_error();
ppm_read_comments ( input );
fscanf ( input, “%d”, &width );
ppm_read_comments ( input );
fscanf ( input, “%d”, &height );
ppm_read_comments ( input );
int colorlevels;
fscanf ( input, “%d”, &colorlevels );
printf("\n%s PPM file: “, temp );
printf(” \n\twidth=%d\theight=%d\tcolorlevles=%d\n", width,height,colorlevels+1 );
ppm_read_comments ( input );
while ( ( c = getc ( input )) == ‘\n’ ); //get rid of extra line returns
ungetc ( c ,input );
// May use CImage ibuf[width][height] if we do not use SDL_QUIT;
CImage *ibuf = (CImage *) malloc ( width * height * 3 );
fread ( ibuf, 3, width * height, input ); //read image data from file
fclose ( input );
//initialize video system
if ( SDL_Init( SDL_INIT_VIDEO ) < 0 ) {
fprintf(stderr, “Unable to init SDL: %s\n”, SDL_GetError());
exit(1);
}
//ensure SDL_Quit is called when the program exits
atexit(SDL_Quit); //if not use this, we need to
// do house cleaning manually when program ends
//set video mode of width x height with 24-bit pixels
screen = SDL_SetVideoMode( width, height, 24, SDL_SWSURFACE);
if ( screen == NULL ) {
fprintf(stderr, “Unable to set %dx%d video: %s\n”, width, height, SDL_GetError());
exit(1);
}
//convert PPM format (R, G, B) to SDL format (B, G, R)
ppm2sdl ( ibuf, width, height );
screen->pixels = ibuf; //point framebuffer to data buffer
// ibuf needs to be dynamically allocated if SDL_QUIT is used
printf("update rect\n" );
SDL_UpdateRect ( screen, 0, 0, 0, 0 ); //blit data to screen
// SDL_Flip(screen);
// SDL_CreateRGBSurface(screen, 0, 0, 0, 0,0,0,0);
SDL_Delay ( 4000 ); //delay 4 seconds before exit
printf(“Displaying PPM image %s successful!\n”, filename );
//do NOT free( ibuf ) if use SDL_QUIT which does the house cleaning
return 0;
}------------------------
Steve