1 files changed, 162 insertions, 0 deletions
diff --git a/xnext.c b/xnext.c
new file mode 100644
index 0000000..d02230d
--- /dev/null
+++ b/xnext.c
@@ -0,0 +1,162 @@
+#define _POSIX_C_SOURCE 200809L
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <X11/Xlib.h>
+
+#define WM_STATE_FORMAT	32
+
+static Bool is_normal(Display *dpy, Window win)
+{
+	static Atom state = None;
+	if (state == None) {
+		state = XInternAtom(dpy, "WM_STATE", True);
+		if (state == None) {
+			return False;
+		}
+	}
+
+	Atom type = AnyPropertyType;
+	int format = WM_STATE_FORMAT;
+	unsigned long nitems = 0;
+	unsigned long bytes = 0;
+	unsigned char *prop = NULL;
+
+	int r = XGetWindowProperty(dpy,
+		win,
+		state,
+		0,
+		0,
+		False,
+		type,
+		&type,
+		&format,
+		&nitems,
+		&bytes,
+		&prop);
+
+	if (r == Success && prop != NULL) {
+		XFree(prop);
+		return True;
+	}
+
+	return False;
+}
+
+static int compar(const void *a, const void *b)
+{
+	const Window *wina = a;
+	const Window *winb = b;
+	if (*wina > *winb) {
+		return 1;
+	}
+	if (*wina < *winb) {
+		return -1;
+	}
+	return 0;
+}
+
+static Window *walk_tree(Display *dpy, Window win, Window *list, size_t *nwin)
+{
+	Window root = win, parent = win, *children = NULL;
+	unsigned int nchildren = 0;
+	if (!XQueryTree(dpy, win, &root, &parent, &children, &nchildren)) {
+		return NULL;
+	}
+
+	for (unsigned int i = 0; i < nchildren; i++) {
+		list = walk_tree(dpy, children[i], list, nwin);
+
+		if (is_normal(dpy, children[i])) {
+			list = realloc(list, sizeof(*list) * (*nwin + 1));
+			if (list == NULL) {
+				return NULL;
+			}
+			list[*nwin] = children[i];
+			(*nwin)++;
+		}
+	}
+
+	return list;
+}
+
+int switch_to(Display *dpy, Window root, Window prev, Window win)
+{
+	Atom ActiveWindowAtom = XInternAtom(dpy, "_NET_ACTIVE_WINDOW", False);
+	XEvent xev = {
+		.xclient.type = ClientMessage,
+		.xclient.window = win,
+		.xclient.message_type = ActiveWindowAtom,
+		.xclient.format = 32,
+		.xclient.data.l = { 1, 1, 0, 0 },
+	};
+	XSendEvent(dpy, root, False, SubstructureRedirectMask, &xev);
+	XMapRaised(dpy, win);
+	XRaiseWindow(dpy, win);
+	XWarpPointer(dpy, prev, win, 0, 0, 0, 0, 0, 0);
+	XSetInputFocus(dpy, win, RevertToNone, CurrentTime);
+	XCloseDisplay(dpy);
+	return 0;
+}
+
+Window find_normal_parent(Display *dpy, Window win)
+{
+	if (win == PointerRoot || win == None || is_normal(dpy, win)) {
+		return win;
+	}
+
+	Window root = win, parent = win, *children = NULL;
+	unsigned int nchildren = 0;
+	if (!XQueryTree(dpy, win, &root, &parent, &children, &nchildren)) {
+		return None;
+	}
+
+	if (parent == win || is_normal(dpy, parent)) {
+		return parent;
+	}
+
+	return find_normal_parent(dpy, win);
+}
+
+int main(int argc, char *argv[])
+{
+	int previous = 0;
+
+	int c = 0;
+	while ((c = getopt(argc, argv, "p")) != -1) {
+		switch (c) {
+		case 'p':
+			previous = 1;
+			break;
+		default:
+			return 1;
+		}
+	}
+
+	Display *dpy = XOpenDisplay("");
+	Window root = XDefaultRootWindow(dpy);
+
+	Window focused = root;
+	int revert = RevertToNone;
+	XGetInputFocus(dpy, &focused, &revert);
+	focused = find_normal_parent(dpy, focused);
+
+	size_t nwin = 0;
+	Window *list = walk_tree(dpy, root, NULL, &nwin);
+	if (list == NULL) {
+		return 1;
+	}
+
+	qsort(list, nwin, sizeof(*list), compar);
+	if (focused == PointerRoot || focused == None) {
+		return switch_to(dpy, root, focused, list[previous ? nwin - 1 : 0]);
+	}
+
+	for (size_t i = 0; i < nwin; i++) {
+		if (list[i] == focused) {
+			return switch_to(dpy, root, focused, list[(i + (previous ? -1 : 1)) % nwin]);
+		}
+	}
+
+	return 1;
+}