/*
 * xroot.c
 * A clickable swatch of root window for rootless X servers.
 * Greg Parker January 9, 2003
 * Modified by Colin Harrison for c code cross-compilation by MinGW.
 *
 * This code is in the public domain and may be copied or modified without
 * permission.
 *
 * Example: xroot -geometry 50x50+500+50 -color SteelBlue
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h> /* XWMGeometry */

void draw(Display *dpy, Window w, GC gc)
{
    XFillRectangle(dpy, w, gc, 0, 0, 20000, 20000);
}

int main(int argc, char **argv)
{
    char *display = NULL;
    char *geometry = NULL;
    char *color = NULL;
    int arg;

    /* read command-line arguments */
    for (arg = 0; arg < argc; arg++) {
        if (0 == strcmp(argv[arg], "-d")  ||
            0 == strcmp(argv[arg], "-display")) {
            if (arg+1 < argc) display = argv[arg+1];
        }
        if (0 == strcmp(argv[arg], "-geometry")) {
            if (arg+1 < argc) geometry = argv[arg+1];
        }
        if (0 == strcmp(argv[arg], "-color")) {
            if (arg+1 < argc) color = argv[arg+1];
        }
        if (0 == strcmp(argv[arg], "-help")  ||
            0 == strcmp(argv[arg], "-h")) {
            fprintf(stderr, "usage:  %s [-display displayname] [-geometry geom] [-color colourname]\n", argv[0]);
            return 0;
        }
    }

    /* environment variables */
    if (!display) display = getenv("DISPLAY");

    /* open display */
    Display *dpy = XOpenDisplay(display);
    if (!dpy) {
        fprintf(stderr, "%s: couldn't open display '%s'\n",
                argv[0], display ? display : "");
        return 1;
    }

    /* grab some colours */
    int blackColor = BlackPixel(dpy, DefaultScreen(dpy));
    int whiteColor = WhitePixel(dpy, DefaultScreen(dpy));

    /* parse geometry */
    int x, y, w, h, g;
    XSizeHints hints = {0};
    XWMGeometry(dpy, DefaultScreen(dpy), geometry, "100x100+0+0", 0, &hints,
                &x, &y, &w, &h, &g);

    /* create window */
    Window win = XCreateSimpleWindow(dpy, DefaultRootWindow(dpy), x, y,
                                     w, h, 0, blackColor, whiteColor);
    XSelectInput(dpy, win, StructureNotifyMask);

    /* We want all input events to propagate to the root window
       We want override-redirect set so the window manager doesn't trap events
       (a window manager's container window would almost certainly have
       do_not_propagate set) */
    XSetWindowAttributes attr;
    attr.do_not_propagate_mask = NoEventMask;
    attr.override_redirect = True;
    XChangeWindowAttributes(dpy, win, CWOverrideRedirect | CWDontPropagate, &attr);

    XMapWindow(dpy, win);

    /* create gc using specified colour */
    GC gc = XCreateGC(dpy, win, 0, NULL);
    XSetForeground(dpy, gc, whiteColor); /* default white */
    if (color) {
        XColor screenColor, exactColor;
        if (XAllocNamedColor(dpy, DefaultColormap(dpy, DefaultScreen(dpy)),
                             color, &screenColor, &exactColor))
            XSetForeground(dpy, gc, screenColor.pixel);
    }

    /* run until killed */
    while (1) {
        XEvent e;
        XNextEvent(dpy, &e);
        switch (e.type) {
        case MapNotify:
        case Expose:
        case ConfigureNotify:
            draw(dpy, win, gc);
            break;
        }
    }
}