libminifb

MiniFB (Mini FrameBuffer) is a small cross platform library that makes it easy to render (32-bit) pixels in a window.

An example is the best way to show how it works:

struct mfb_window *window = mfb_open_ex("my display", 800, 600, WF_RESIZABLE);
if (!window)
    return 0;

buffer = (uint32_t *) malloc(800 * 600 * 4);

do {
    int state;

    // TODO: add some fancy rendering to the buffer of size 800 * 600

    state = mfb_update_ex(window, buffer, 800, 600);

    if (state < 0) {
        window = NULL;
        break;
    }
} while(mfb_wait_sync(window));