From f2e1a6e15ba38b29d20f1fa8fa979f8f380e93ae Mon Sep 17 00:00:00 2001
From: Bakkeby <bakkeby@gmail.com>
Date: Mon, 10 Jan 2022 12:57:26 +0100
Subject: [PATCH] Monitor rules patch

This patch allows the user to define layout, mfact, nmaster, showbar,
and topbar settings on a per monitor basis. An example use case could
be to have a layout with a horizontal split for a secondary vertical
monitor.
---
 config.def.h |  6 ++++++
 dwm.c        | 36 ++++++++++++++++++++++++++++++++----
 2 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/config.def.h b/config.def.h
index a2ac963..7718adc 100644
--- a/config.def.h
+++ b/config.def.h
@@ -31,6 +31,12 @@ static const Rule rules[] = {
 	{ "Firefox",  NULL,       NULL,       1 << 8,       0,           -1 },
 };
 
+static const MonitorRule monrules[] = {
+	/* monitor layout  mfact  nmaster  showbar  topbar */
+	{  1,      2,      -1,    -1,      -1,      -1     }, // use a different layout for the second monitor
+	{  -1,     0,      -1,    -1,      -1,      -1     }, // default
+};
+
 /* layout(s) */
 static const float mfact     = 0.55; /* factor of master area size [0.05..0.95] */
 static const int nmaster     = 1;    /* number of clients in master area */
diff --git a/dwm.c b/dwm.c
index a96f33c..31e5834 100644
--- a/dwm.c
+++ b/dwm.c
@@ -141,6 +141,15 @@ typedef struct {
 	int monitor;
 } Rule;
 
+typedef struct {
+	int monitor;
+	int layout;
+	float mfact;
+	int nmaster;
+	int showbar;
+	int topbar;
+} MonitorRule;
+
 /* function declarations */
 static void applyrules(Client *c);
 static int applysizehints(Client *c, int *x, int *y, int *w, int *h, int interact);
@@ -631,7 +640,9 @@ configurerequest(XEvent *e)
 Monitor *
 createmon(void)
 {
-	Monitor *m;
+	Monitor *m, *mon;
+	unsigned int mi, j;
+	const MonitorRule *mr;
 
 	m = ecalloc(1, sizeof(Monitor));
 	m->tagset[0] = m->tagset[1] = 1;
@@ -639,9 +650,26 @@ createmon(void)
 	m->nmaster = nmaster;
 	m->showbar = showbar;
 	m->topbar = topbar;
-	m->lt[0] = &layouts[0];
-	m->lt[1] = &layouts[1 % LENGTH(layouts)];
-	strncpy(m->ltsymbol, layouts[0].symbol, sizeof m->ltsymbol);
+
+	for (mi = 0, mon = mons; mon; mon = mon->next, mi++);
+	for (j = 0; j < LENGTH(monrules); j++) {
+		mr = &monrules[j];
+		if ((mr->monitor == -1 || mr->monitor == mi)) {
+			m->lt[0] = &layouts[mr->layout];
+			m->lt[1] = &layouts[1 % LENGTH(layouts)];
+			strncpy(m->ltsymbol, layouts[mr->layout].symbol, sizeof m->ltsymbol);
+
+			if (mr->mfact > -1)
+				m->mfact = mr->mfact;
+			if (mr->nmaster > -1)
+				m->nmaster = mr->nmaster;
+			if (mr->showbar > -1)
+				m->showbar = mr->showbar;
+			if (mr->topbar > -1)
+				m->topbar = mr->topbar;
+			break;
+		}
+	}
 	return m;
 }
 
-- 
2.19.1