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I'm trying to figure out why calling SDL_GetWindowPixelFormat is returning SDL_PIXELFORMAT_RGB888, even though I'm creating the window with the flag "SDL_WINDOW_FULLSCREEN_DESKTOP", and my desktop uses 32-bit color.

Perhaps I'm misunderstanding what this flag means. I'm running my program on a Windows 7 machine, and I checked the display color-depth using Control Panel -> Display -> Adjust Resolution -> Advanced Settings -> Monitor (which displays "50 Hz, True Color 32-bit".)

I'm coding using SDL2 (version 2.0.6). I was expecting this call to return SDL_PIXELFORMAT_RGB8888 or some other 32-bit format. Any help appreciated on clarifying this. My code is below.

#include "SDL2/SDL.h"
#include <stdio.h>

SDL_Window* window;

int main(int argc, char* args[]) {

    SDL_Init(SDL_INIT_VIDEO);

    window = SDL_CreateWindow("TUTOR", 
            SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 
            0, 0, SDL_WINDOW_FULLSCREEN_DESKTOP);

    Uint32 global_pixel_format = SDL_GetWindowPixelFormat(window);
    const char* temp = SDL_GetPixelFormatName(global_pixel_format);
    printf(" SDL_Window created with pixel format %s\n", temp);

    SDL_Quit();

    return 0;
}
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  • \$\begingroup\$ Typically 32-bit colour on desktops means 8 red, 8 green, 8 blue and the remainder unused. Likewise, several APIs will report "RGB" or "R8G8B8", which are actually 32-bit formats but just omitting the unused bits from the name. \$\endgroup\$ – Maximus Minimus Jun 14 '18 at 15:22
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Pixel format isn't specified by your desktop, it's just the format that SDL2 uses for pixels.

As @Maximus Minimus said, the 8 bits are unused, with 24 bits being 8 red, 8 green, 8 blue. This is 32 bits in total.

Look at: https://wiki.libsdl.org/SDL_PixelFormat and https://wiki.libsdl.org/SDL_PixelFormatEnum for more information.

Hope this helps.

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