fn query_monitor_list()

in src/platform_impl/linux/x11/monitor.rs [214:262]

• 39 lines of code
• 11 McCabe index (conditional complexity)

    fn query_monitor_list(&self) -> Vec<MonitorHandle> {
        unsafe {
            let mut major = 0;
            let mut minor = 0;
            (self.xrandr.XRRQueryVersion)(self.display, &mut major, &mut minor);

            let root = (self.xlib.XDefaultRootWindow)(self.display);
            let resources = if (major == 1 && minor >= 3) || major > 1 {
                (self.xrandr.XRRGetScreenResourcesCurrent)(self.display, root)
            } else {
                // WARNING: this function is supposedly very slow, on the order of hundreds of ms.
                // Upon failure, `resources` will be null.
                (self.xrandr.XRRGetScreenResources)(self.display, root)
            };

            if resources.is_null() {
                panic!("[winit] `XRRGetScreenResources` returned NULL. That should only happen if the root window doesn't exist.");
            }

            let mut available;
            let mut has_primary = false;

            let primary = (self.xrandr.XRRGetOutputPrimary)(self.display, root);
            available = Vec::with_capacity((*resources).ncrtc as usize);
            for crtc_index in 0..(*resources).ncrtc {
                let crtc_id = *((*resources).crtcs.offset(crtc_index as isize));
                let crtc = (self.xrandr.XRRGetCrtcInfo)(self.display, resources, crtc_id);
                let is_active = (*crtc).width > 0 && (*crtc).height > 0 && (*crtc).noutput > 0;
                if is_active {
                    let is_primary = *(*crtc).outputs.offset(0) == primary;
                    has_primary |= is_primary;
                    MonitorHandle::new(self, resources, crtc_id, crtc, is_primary)
                        .map(|monitor_id| available.push(monitor_id));
                }
                (self.xrandr.XRRFreeCrtcInfo)(crtc);
            }

            // If no monitors were detected as being primary, we just pick one ourselves!
            if !has_primary {
                if let Some(ref mut fallback) = available.first_mut() {
                    // Setting this here will come in handy if we ever add an `is_primary` method.
                    fallback.primary = true;
                }
            }

            (self.xrandr.XRRFreeScreenResources)(resources);
            available
        }
    }