From bece225934216f1d047ebecc5b574ed1b15886f2 Mon Sep 17 00:00:00 2001
From: Stivvo <stivvo01@gmail.com>
Date: Mon, 14 Sep 2020 17:40:14 +0200
Subject: [PATCH] Handle monitor unplug

Floating widndows with "x < removed monitor's width" aren't resized
(they used to disappear in negative coordinates).

Actually delete monitors when they are unplugged, recalculate sgeom and
give a new monitor to clients that were on the removed one with setmon()

arrangefloat() funcion has been exploded to save iterations in
cleanupmon().

Also if a monitor that supports auto suspension is turned off, dwl will
count it as unplugged (it will become unreachable and all clients will
be moved to the leftmost monitor). However, if at least one monitor
isn't plugged in, dwl will still crash the same as before.

Unlike sway, when the output configuration is changed and restored,
(unplug + plug the same monitor for example) previous application
positions aren't kept. This is due to the fact that on sway every
workspace is unique among all monitors.
---
 dwl.c | 41 +++++++++++++++++++++++++----------------
 1 file changed, 25 insertions(+), 16 deletions(-)

diff --git a/dwl.c b/dwl.c
index 23a7211..6f2e800 100644
--- a/dwl.c
+++ b/dwl.c
@@ -195,7 +195,6 @@ static void applyexclusive(struct wlr_box *usable_area, uint32_t anchor,
 		int32_t margin_bottom, int32_t margin_left);
 static void applyrules(Client *c);
 static void arrange(Monitor *m);
-static void arrangefloat(Monitor *m, int sign);
 static void arrangelayer(Monitor *m, struct wl_list *list,
 		struct wlr_box *usable_area, bool exclusive);
 static void arrangelayers(Monitor *m);
@@ -470,17 +469,6 @@ arrange(Monitor *m)
 	/* XXX recheck pointer focus here... or in resize()? */
 }
 
-void
-arrangefloat(Monitor *m, int sign)
-{
-	Client *c;
-	wl_list_for_each(c, &clients, link) {
-		if (c->isfloating)
-			resize(c, c->geom.x + m->w.width * sign, c->geom.y,
-					c->geom.width, c->geom.height, 0);
-	}
-}
-
 void
 arrangelayer(Monitor *m, struct wl_list *list, struct wlr_box *usable_area, bool exclusive)
 {
@@ -699,13 +687,29 @@ void
 cleanupmon(struct wl_listener *listener, void *data)
 {
 	struct wlr_output *wlr_output = data;
-	Monitor *m = wlr_output->data;
+	Monitor *m = wlr_output->data, *newmon;
+	Client *c;
 
 	wl_list_remove(&m->destroy.link);
-	free(m);
+	wl_list_remove(&m->frame.link);
+	wl_list_remove(&m->link);
+	wlr_output_layout_remove(output_layout, m->wlr_output);
 
+	sgeom = *wlr_output_layout_get_box(output_layout, NULL);
 	updatemons();
-	arrangefloat(m, -1);
+
+	wl_list_for_each(newmon, &mons, link) {
+		wl_list_for_each(c, &clients, link) {
+			if (c->isfloating && c->geom.x > m->m.width) {
+				resize(c, c->geom.x - m->w.width, c->geom.y,
+						c->geom.width, c->geom.height, 0);
+			}
+			if (c->mon == m)
+				setmon(c, newmon, 0);
+		}
+		break;
+	}
+	free(m);
 }
 
 void
@@ -836,7 +840,12 @@ createmon(struct wl_listener *listener, void *data)
 	updatemons();
 	wl_list_for_each(m, &mons, link) {
 		/* the first monitor in the list is the most recently added */
-		arrangefloat(m, 1);
+		Client *c;
+		wl_list_for_each(c, &clients, link) {
+			if (c->isfloating)
+				resize(c, c->geom.x + m->w.width, c->geom.y,
+						c->geom.width, c->geom.height, 0);
+		}
 		return;
 	}
 }