User:Paolo Liberatore/Xexample.c
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< User:Paolo Liberatore
/* Simple Xlib application that draws a box in a window and
* terminate when the user presses a key. */
#include<X11/Xlib.h>
int main() {
Display *d;
int s;
Window w;
XEvent e;
/* open connection with the server; this will also generate
* a request for creation of a default graphic context; it
* may also generate a request for existence of some
* extensions */
d=XOpenDisplay(NULL);
if(d==NULL) {
printf("Cannot open display\n");
exit(1);
}
s=DefaultScreen(d);
/* create a window; while the function returns the
* identifier of a window, this identifier is actually
* chosen by the library, which is part of the client, not
* by the server */
w=XCreateSimpleWindow(d, RootWindow(d, s), 10, 10, 100, 100, 1,
BlackPixel(d, s), WhitePixel(d, s));
/* select kind of events we are interested in; this will
* generate a request for changing the window attributes */
XSelectInput(d, w, ExposureMask | KeyPressMask);
/* request the window to be mapped (shown on the screen) */
XMapWindow(d, w);
/* event loop (wait for event, take the appropriate action */
while(1) {
/* this instruction checks for events in the local queue,
* blocking if not event is present */
XNextEvent(d, &e);
/* if the event is an expose event, redraw the box */
if(e.type==Expose)
XFillRectangle(d, w, DefaultGC(d, s), 20, 20, 10, 10);
/* this particular client terminates if a key is pressed */
if(e.type==KeyPress)
break;
}
/* close connection to server */
XCloseDisplay(d);
return 0;
}
