// from http://en.wikipedia.org/wiki/Shape_extension
// gcc -o xhole xhole.c -lX11 -lXext

/*

  xhole.c

A sample application using the shape extension.
Creates a window with a hole in the middle. Works
with twm, fvwm, and mwm, but kde refuses to add
a title bar to it.
*/

#include <stdlib.h>
#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/extensions/shape.h>

int main() {
  Display *d;
  int s;
  Window w;
  Pixmap p;
  GC gw, gp;
  XEvent e;
  int x, y;

                        /* open connection with the server */
  d=XOpenDisplay(NULL);
  if(d==NULL) {
    printf("Cannot open display\n");
    exit(1);
  }
  s=DefaultScreen(d);
  gw=DefaultGC(d, s);

                        /* create window, select events, map  */
  w=XCreateSimpleWindow(d, RootWindow(d, s), 10, 10, 300, 200, 1,
                        BlackPixel(d, s), WhitePixel(d, s));
  XSelectInput(d, w, ExposureMask | KeyPressMask | ButtonPressMask);
  XStoreName(d, w, "Hole");
  XMapWindow(d, w);

                        /* create the pixmap that specifies the shape */
  p=XCreatePixmap(d, w, 400, 300, 1);
  gp=XCreateGC(d, p, 0, NULL);
  XSetForeground(d, gp, WhitePixel(d, s));
  XFillRectangle(d, p, gp, 0, 0, 400, 300);
  XSetForeground(d, gp, BlackPixel(d, s));
  XFillArc(d, p, gp, 120, 100, 100, 100, 0, 360*64);

                        /* set the pixmap as the new window mask;
                        the pixmap is slightly larger than the window
                        to allow for the window border and title bar
                        (as added by the window manager) to be visible */
  XShapeCombineMask(d, w, ShapeBounding, -20, -50, p, ShapeSet);

                        /* event polling loop */
  while(1) {
    XNextEvent(d, &e);
                        /* draw or redraw the window */
    if(e.type==Expose) {
      /* not the correct way of drawing text... */
      for(y=10; y<=210; y+=11)
        for(x=0; x<300; x+=25)
          XDrawString(d, w, gw, x, y, "test", 4);
    }

                        /* exit on button press */
    if(e.type==ButtonPress)
      break;
  }

                        /* close connection to display */
  XCloseDisplay(d);

  return 0;
}