From 9e67b8a4fd30635d9d30d62948d458c243d7c056 Mon Sep 17 00:00:00 2001
From: bakkeby <bakkeby@gmail.com>
Date: Tue, 7 Apr 2020 11:45:42 +0200
Subject: [PATCH] zoomswap, swap positions when a window becomes the new master

The default behaviour in dwm when using zoom (i.e. moving a window to become the new master)
is to use pop to re-attach the window on top of the chain. This has the side effect of moving
every window down as well, resulting in every window on the screen changing position. The
zoomswap patch changes this behaviour so that the current master swaps position with the other
window that is to become the new master. Applying zoom on the current master will result in it
swapping back to the previous master.

This patch includes some slight alteration of code compared to the original.

Original author:
   Jan Christoph Ebersbach - <jceb at e-jc dot de>

Refer to https://dwm.suckless.org/patches/zoomswap/
---
 dwm.c | 46 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/dwm.c b/dwm.c
index 4465af1..49dfda2 100644
--- a/dwm.c
+++ b/dwm.c
@@ -185,6 +185,7 @@ static void motionnotify(XEvent *e);
 static void movemouse(const Arg *arg);
 static Client *nexttiled(Client *c);
 static void pop(Client *);
+static Client *prevtiled(Client *c);
 static void propertynotify(XEvent *e);
 static void quit(const Arg *arg);
 static Monitor *recttomon(int x, int y, int w, int h);
@@ -235,6 +236,7 @@ static int xerrorstart(Display *dpy, XErrorEvent *ee);
 static void zoom(const Arg *arg);
 
 /* variables */
+static Client *prevzoom = NULL;
 static const char broken[] = "broken";
 static char stext[256];
 static int screen;
@@ -1208,6 +1210,15 @@ pop(Client *c)
 	arrange(c->mon);
 }
 
+Client *
+prevtiled(Client *c) {
+	Client *p;
+	if (!c || c == c->mon->clients)
+		return NULL;
+	for (p = c->mon->clients; p && p->next != c; p = p->next);
+	return p;
+}
+
 void
 propertynotify(XEvent *e)
 {
@@ -2114,14 +2125,39 @@ void
 zoom(const Arg *arg)
 {
 	Client *c = selmon->sel;
+	Client *at = NULL, *cold, *cprevious = NULL;
 
 	if (!selmon->lt[selmon->sellt]->arrange
-	|| (selmon->sel && selmon->sel->isfloating))
+	|| (selmon->sel && selmon->sel->isfloating) || !c)
 		return;
-	if (c == nexttiled(selmon->clients))
-		if (!c || !(c = nexttiled(c->next)))
-			return;
-	pop(c);
+
+	if (c == nexttiled(selmon->clients)) {
+		at = prevtiled(prevzoom);
+		if (at)
+			cprevious = nexttiled(at->next);
+		if (!cprevious || cprevious != prevzoom) {
+			prevzoom = NULL;
+			if (!c || !(c = nexttiled(c->next)))
+				return;
+		} else
+			c = cprevious;
+	}
+	cold = nexttiled(selmon->clients);
+	if (c != cold && !at)
+		at = prevtiled(c);
+	detach(c);
+	attach(c);
+	/* swap windows instead of pushing the previous one down */
+	if (c != cold && at) {
+		prevzoom = cold;
+		if (cold && at != cold) {
+			detach(cold);
+			cold->next = at->next;
+			at->next = cold;
+		}
+	}
+	focus(c);
+	arrange(c->mon);
 }
 
 int
-- 
2.17.1