/* xrootbg.c - sets desktop wallpaper with xlib (root background)
 * PUBLIC DOMAIN - CC0 http://creativecommons.org/publicdomain/zero/1.0/
 * J.Mayo 2013
 *
 * gcc -Wall -W -g3 -o xrootbg xrootbg.c -lX11 -lImlib2
 *
 */
#include <stdio.h>
#include <X11/Xlib.h>
#include <Imlib2.h>

int main(int argc, char **argv)
{
	Imlib_Image img;
	Display *dpy;
	Pixmap pix;
	Window root;
	Screen *scn;
	int width, height;
	const char *filename = NULL;

	if (argc < 2)
		goto usage;
	filename = argv[1];

	img = imlib_load_image(filename);
	if (!img) {
		fprintf(stderr, "%s:Unable to load image\n", filename);
		goto usage;
	}
	imlib_context_set_image(img);

	dpy = XOpenDisplay(NULL);
	if (!dpy)
		return 0;
	scn = DefaultScreenOfDisplay(dpy);
	root = DefaultRootWindow(dpy);

	if (1) { /* tile */
		width = imlib_image_get_width();
		height = imlib_image_get_height();
	} else { /* scale to screen */
		width = WidthOfScreen(scn);
		height = HeightOfScreen(scn);
	}

	pix = XCreatePixmap(dpy, root, width, height,
		DefaultDepthOfScreen(scn));
	XFillRectangle(dpy, pix, DefaultGCOfScreen(scn), 0, 0, width, height);

	imlib_context_set_display(dpy);
	imlib_context_set_visual(DefaultVisualOfScreen(scn));
	imlib_context_set_colormap(DefaultColormapOfScreen(scn));
	imlib_context_set_drawable(pix);

	imlib_render_image_on_drawable_at_size(0, 0, width, height);
	XSetWindowBackgroundPixmap(dpy, root, pix);
	XClearWindow(dpy, root);

	while (XPending(dpy)) {
		XEvent ev;
		XNextEvent(dpy, &ev);
	}
	XFreePixmap(dpy, pix);
	imlib_free_image();
	XCloseDisplay(dpy);
	return 0;
usage:
	fprintf(stderr, "usage: %s <image_file>\n", argv[0]);
	return 1;
}