kde-workspace/kcontrol/randr/module/randrpolltest.cpp

#include <X11/Xlib.h>
#include <X11/extensions/Xrandr.h>
#include <stdio.h>
#include <unistd.h>

int main( int argc, char* argv[] )
{
    Display* dpy = XOpenDisplay( NULL );
    XSetWindowAttributes attrs;
    Window w = XCreateWindow( dpy, DefaultRootWindow( dpy ), 0, 0, 100, 100, 0, CopyFromParent, CopyFromParent,
                              CopyFromParent, 0, &attrs );
//    XMapWindow( dpy, w );
    int base, error;
    if( !XRRQueryExtension( dpy, &base, &error ))
        return 1;
    int major = 1;
    int minor = 2;
    if( !XRRQueryVersion( dpy, &major, &minor ) || major < 1 || (major == 1 && minor < 2 ))
        return 2;
    XRRSelectInput( dpy, w,
                    RRScreenChangeNotifyMask | RRCrtcChangeNotifyMask | RROutputChangeNotifyMask | RROutputPropertyNotifyMask );
    for(;;)
    {
        XEvent ev;
        int a, b, c, d;
        static int cnt = 0;
        if( ++cnt % 30 == 0 )
        {
//            XRRFreeScreenResources(XRRGetScreenResources( dpy, w ));
            XRRGetScreenSizeRange( dpy, w, &a, &b, &c, &d );
//            XSync( dpy, False );
            printf( "Poll\n" );
        }
        sleep( 1 );
        if( !XPending( dpy ))
            continue;
        XNextEvent( dpy, &ev );
        if( ev.xany.type == base + RRScreenChangeNotify )
        {
            printf( "Screen Change\n" );
        }
        if( ev.xany.type == base + RRNotify )
        {
            XRRNotifyEvent* e = reinterpret_cast< XRRNotifyEvent* >( &ev );
            switch( e->subtype )
            {
            case RRNotify_CrtcChange:
                printf( "Crtc Change\n" );
                break;
            case RRNotify_OutputChange:
                printf( "Output Change\n" );
                break;
            case RRNotify_OutputProperty:
                printf( "Output Property Change\n" );
                break;
            default:
                printf( "Unknown Notify\n" );
                break;
            }
        }
    }
    XCloseDisplay( dpy );
}