c++ SDL iterating over an image

[Xender1]

Trying to figure out how I can look at what color each pixel is of a SDL_Surface. Here is my code:


#include <stdlib.h>
#include <iostream>
#include "SDL/SDL.h"
#include "SDL/SDL_image.h"

using namespace std;

/*
*
*/
int main(int argc, char** argv) {
SDL_Init(SDL_INIT_VIDEO);

SDL_Surface *image;
image = IMG_Load("testimg.gif");

cout << "Height: " << image->h << endl;
cout << "Width: " << image->w << endl;

//FOR LOOP to look at each pixel
for (Sint32 y = 0; y < image->h; y++) {
for (Sint32 x = 0; x < image->w; x++) {
//something

}
}


return (EXIT_SUCCESS);
}

Now I am just curious as to know how to access the color of the pixel im looking at and compare it to see what color it is. Thanks.

[Zugzwang]

In the SDL documentation wiki, the is some "getpixel" function code: http://www.libsdl.org/cgi/docwiki.cgi/Pixel_Access

Don't forget to lock the surface before doing that (and unlocking the surface afterwards)!

[Drone022]

I have been using this:

Uint32 get_pixel32(SDL_Surface *surface, int x, int y){
//Convert pixels to 32 bits
Uint32 *pixels = (Uint32*)surface->pixels;

return pixels[(y*surface->w) + x];
}

This is obviously restricted to a 32 bit pixel depth though.




SDL_Surface* hello = NULL;
Uint32 temp = 0;


if(SDL_MUSTLOCK(hello)){
SDL_LockSurface( hello );
}

for(int x =0; x < hello->w; x++){
for(int y = 0; y < hello->h; y++){
temp = get_pixel32(hello, x, y);
// do something with the retrieved value?
}
}

if( SDL_MUSTLOCK( hello ) ) {
SDL_UnlockSurface( hello );
}