add gappless grid layout

config.def.h

@@ -121,12 +121,14 @@ static const int nmaster     = 1;    /* number of clients in master area */
 static const int resizehints = 1;    /* 1 means respect size hints in tiled resizals */
 static const int lockfullscreen = 1; /* 1 will force focus on the fullscreen window */
 
+#include "gaplessgrid.c"
 static const Layout layouts[] = {
 	/* symbol     arrange function */
 	{ "[]=",      tile },    /* first entry is default */
 	{ "><>",      NULL },    /* no layout function means floating behavior */
 	{ "[M]",      monocle },
 	{ "[D]",      deck },
+	{ "###",      gaplessgrid },
 };
 
 /* key definitions */

gaplessgrid.c

@@ -0,0 +1,47 @@
+void
+gaplessgrid(Monitor *m)
+{
+	unsigned int i, n;
+	int x, y, cols, rows, ch, cw, cn, rn, rrest, crest; // counters
+	Client *c;
+
+	for (n = 0, c = nexttiled(m->clients); c; c = nexttiled(c->next), n++);
+	if ( n == 0 )
+		return;
+
+	/* grid dimensions */
+	for (cols = 0; cols <= n/2; cols++)
+		if (cols*cols >= n)
+			break;
+	if (n == 5) /* set layout against the general calculation: not 1:2:2, but 2:3 */
+		cols = 2;
+	rows = n/cols;
+	cn = rn = 0; // reset column no, row no, client count
+
+	ch = (m->wh - 2*gappx - gappx * (rows - 1)) / rows;
+	cw = (m->ww - 2*gappx - gappx * (cols - 1)) / cols;
+	rrest = (m->wh - 2*gappx - gappx * (rows - 1)) - ch * rows;
+	crest = (m->ww - 2*gappx - gappx * (cols - 1)) - cw * cols;
+	x = m->wx + gappx;
+	y = m->wy + gappx;
+
+	for (i = 0, c = nexttiled(m->clients); c; i++, c = nexttiled(c->next)) {
+		if (i/rows + 1 > cols - n%cols) {
+			rows = n/cols + 1;
+			ch = (m->wh - 2*gappx - gappx * (rows - 1)) / rows;
+			rrest = (m->wh - 2*gappx - gappx * (rows - 1)) - ch * rows;
+		}
+		resize(c,
+			x,
+			y + rn*(ch + gappx) + MIN(rn, rrest),
+			cw + (cn < crest ? 1 : 0) - 2*c->bw,
+			ch + (rn < rrest ? 1 : 0) - 2*c->bw,
+			0);
+		rn++;
+		if (rn >= rows) {
+			rn = 0;
+			x += cw + gappx + (cn < crest ? 1 : 0);
+			cn++;
+		}
+	}
+}

patches/layouts/dwm-gaplessgrid-20160731-56a31dc.diff

@@ -0,0 +1,43 @@
+URL: http://dwm.suckless.org/patches/gapless_grid
+Add gapless grid layout.
+
+Index: dwm/gaplessgrid.c
+===================================================================
+--- /dev/null
++++ dwm/gaplessgrid.c
+@@ -0,0 +1,35 @@
++void
++gaplessgrid(Monitor *m) {
++	unsigned int n, cols, rows, cn, rn, i, cx, cy, cw, ch;
++	Client *c;
++
++	for(n = 0, c = nexttiled(m->clients); c; c = nexttiled(c->next), n++) ;
++	if(n == 0)
++		return;
++
++	/* grid dimensions */
++	for(cols = 0; cols <= n/2; cols++)
++		if(cols*cols >= n)
++			break;
++	if(n == 5) /* set layout against the general calculation: not 1:2:2, but 2:3 */
++		cols = 2;
++	rows = n/cols;
++
++	/* window geometries */
++	cw = cols ? m->ww / cols : m->ww;
++	cn = 0; /* current column number */
++	rn = 0; /* current row number */
++	for(i = 0, c = nexttiled(m->clients); c; i++, c = nexttiled(c->next)) {
++		if(i/rows + 1 > cols - n%cols)
++			rows = n/cols + 1;
++		ch = rows ? m->wh / rows : m->wh;
++		cx = m->wx + cn*cw;
++		cy = m->wy + rn*ch;
++		resize(c, cx, cy, cw - 2 * c->bw, ch - 2 * c->bw, False);
++		rn++;
++		if(rn >= rows) {
++			rn = 0;
++			cn++;
++		}
++	}
++}

scripts/layoutmenu.sh

@@ -5,4 +5,5 @@ cat <<EOF | xmenu
 ><> Floating Layout	1
 [M] Monocle Layout	2
 [D] Deck Layout	3
+### Grid Layout	4
 EOF