macOS CGConfigureDisplayOrigin doesn't work as expected

Question

I have multiple monitors and try to change the main display using Quarz Display APIs, my function is

int setDisplayOrigin(CGDirectDisplayID display, int x, int y) {
    CGDisplayConfigRef cfg;
    auto ret = CGBeginDisplayConfiguration(&cfg);
    if (ret != kCGErrorSuccess) return ret;
    ret = CGConfigureDisplayOrigin(cfg, display, x, y);
    if (ret != kCGErrorSuccess) return ret;
    ret = CGCompleteDisplayConfiguration(cfg, kCGConfigureForAppOnly);
    return ret;
}

to set specific monitor as the main one, I call this function with both 0 with x and y

setDisplayOrigin(directDisplayID, 0, 0)

macOS did rearrange the displays, but the related display won't have origin with (0, 0) when I check its bounds again, and every returned value was successful (KCGErrorSuccess)

Answer 1

Thanks the hint from Ken, reposition the current main display and then set the target display's origin to (0, 0) which is the way to make it work.