x11_shape_test.c

// gcc test.c -lX11 -lXext
/* Some clumsy app to test X11 Shape extension.
 *
 * The app window consists of three zones:
 *     +-------+
 *     |   A   |
 *     +---+---+
 *     | B | C |
 *     +---+---+
 *
 * - Zone A is completly transparent.
 * - Zones B and C is white.
 * - Zone B should be clickable through, i.e. you should able to click the window underneath.
 * - Clicking on zone C causes printing "ButtonPress" to stdout.
 */

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

/* size of the window */
#define W_WIDTH  500
#define W_HEIGHT 500

int main(int argc, char **argv)
{
    Display *dpy;
    Window w;
    Pixmap pmap;
    GC shape_gc;
    GC win_gc;
    XGCValues xgcv;

    /* open the display */
    if(!(dpy = XOpenDisplay(getenv("DISPLAY")))) {
        fprintf(stderr, "can't open display\n");
        return EXIT_FAILURE;
    }

    /* create the window */
    w = XCreateWindow(dpy, DefaultRootWindow(dpy), 0, 0, W_WIDTH,
            W_HEIGHT, 0, CopyFromParent, InputOutput,
            CopyFromParent, 0, NULL);


    /* create a graphics context for drawing on the window */
    xgcv.foreground = WhitePixel(dpy, DefaultScreen(dpy));
    xgcv.line_width = 1;
    xgcv.line_style = LineSolid;
    win_gc = XCreateGC(dpy, w, GCForeground | GCLineWidth | GCLineStyle, &xgcv);

    /* create the pixmap that we'll use for shaping the window */
    pmap = XCreatePixmap(dpy, w, W_WIDTH, W_HEIGHT, 1);

    /* create a graphics context for drawing on the pixmap */
    shape_gc = XCreateGC(dpy, pmap, 0, &xgcv);

    XSelectInput(dpy, w, ButtonPressMask | ExposureMask | StructureNotifyMask);

    XMapWindow(dpy, w);
    XSync(dpy, False);

    while(1) {
        XEvent xe;
        XNextEvent(dpy, &xe);
        switch (xe.type) {
            case Expose:
                XSetForeground(dpy, win_gc, WhitePixel(dpy, DefaultScreen(dpy)));
                XFillRectangle(dpy, w, win_gc, 0, 0, W_WIDTH, W_HEIGHT);
                XSync(dpy, False);
                break;

            case ConfigureNotify:
                XSetForeground(dpy, shape_gc, 0);
                XFillRectangle(dpy, pmap, shape_gc, 0, 0, W_WIDTH, W_HEIGHT);

                XSetForeground(dpy, shape_gc, 1);
                XFillRectangle(dpy, pmap, shape_gc, W_WIDTH/2, 0, W_WIDTH/2, W_HEIGHT);

                XShapeCombineMask (dpy, w, ShapeInput, 0, 0, pmap, ShapeSet);


                XSetForeground(dpy, shape_gc, 0);
                XFillRectangle(dpy, pmap, shape_gc, 0, 0, W_WIDTH, W_HEIGHT);

                XSetForeground(dpy, shape_gc, 1);
                XFillRectangle(dpy, pmap, shape_gc, 0, W_HEIGHT/2, W_WIDTH, W_HEIGHT/2);

                XShapeCombineMask (dpy, w, ShapeBounding, 0, 0, pmap, ShapeSet);

                XSync(dpy, False);

                break;

            case ButtonPress:
                printf("ButtonPress\n");
                break;

            default:
                printf("Caught event %i\n", xe.type);
        }
    }

    XFreePixmap(dpy, pmap);
    XDestroyWindow(dpy, w);
    XCloseDisplay(dpy);

    return 0;
}