dwm-scratchpad-20200727-bb2e7222baeec7776930354d0e9f210cc2aaad5f.diff

diff --git a/config.def.h b/config.def.h
index 1c0b587..48cf601 100644
--- a/config.def.h
+++ b/config.def.h
@@ -94,6 +94,9 @@ static Key keys[] = {
 	TAGKEYS(                        XK_8,                      7)
 	TAGKEYS(                        XK_9,                      8)
 	{ MODKEY|ShiftMask,             XK_q,      quit,           {0} },
+	{ MODKEY,                       XK_minus, scratchpad_show, {0} },
+	{ MODKEY|ShiftMask,             XK_minus, scratchpad_hide, {0} },
+	{ MODKEY,                       XK_equal,scratchpad_remove,{0} },
 };
 
 /* button definitions */
diff --git a/dwm.c b/dwm.c
index 9fd0286..c647493 100644
--- a/dwm.c
+++ b/dwm.c
@@ -195,6 +195,12 @@ static void resizemouse(const Arg *arg);
 static void restack(Monitor *m);
 static void run(void);
 static void scan(void);
+static void scratchpad_hide ();
+static _Bool scratchpad_last_showed_is_killed (void);
+static void scratchpad_remove ();
+static void scratchpad_show ();
+static void scratchpad_show_client (Client * c);
+static void scratchpad_show_first (void);
 static int sendevent(Client *c, Atom proto);
 static void sendmon(Client *c, Monitor *m);
 static void setclientstate(Client *c, long state);
@@ -269,11 +275,15 @@ static Drw *drw;
 static Monitor *mons, *selmon;
 static Window root, wmcheckwin;
 
+/* scratchpad */
+# define SCRATCHPAD_MASK (1u << sizeof tags / sizeof * tags)
+static Client * scratchpad_last_showed = NULL;
+
 /* configuration, allows nested code to access above variables */
 #include "config.h"
 
 /* compile-time check if all tags fit into an unsigned int bit array. */
-struct NumTags { char limitexceeded[LENGTH(tags) > 31 ? -1 : 1]; };
+struct NumTags { char limitexceeded[LENGTH(tags) > 30 ? -1 : 1]; };
 
 /* function implementations */
 void
@@ -309,7 +319,8 @@ applyrules(Client *c)
 		XFree(ch.res_class);
 	if (ch.res_name)
 		XFree(ch.res_name);
-	c->tags = c->tags & TAGMASK ? c->tags & TAGMASK : c->mon->tagset[c->mon->seltags];
+	if (c->tags != SCRATCHPAD_MASK)
+		c->tags = c->tags & TAGMASK ? c->tags & TAGMASK : c->mon->tagset[c->mon->seltags];
 }
 
 int
@@ -1408,6 +1419,98 @@ scan(void)
 	}
 }
 
+static void scratchpad_hide ()
+{
+	if (selmon -> sel)
+	{
+		selmon -> sel -> tags = SCRATCHPAD_MASK;
+		selmon -> sel -> isfloating = 1;
+		focus(NULL);
+		arrange(selmon);
+	}
+}
+
+static _Bool scratchpad_last_showed_is_killed (void)
+{
+	_Bool killed = 1;
+	for (Client * c = selmon -> clients; c != NULL; c = c -> next)
+	{
+		if (c == scratchpad_last_showed)
+		{
+			killed = 0;
+			break;
+		}
+	}
+	return killed;
+}
+
+static void scratchpad_remove ()
+{
+	if (selmon -> sel && scratchpad_last_showed != NULL && selmon -> sel == scratchpad_last_showed)
+		scratchpad_last_showed = NULL;
+}
+
+static void scratchpad_show ()
+{
+	if (scratchpad_last_showed == NULL || scratchpad_last_showed_is_killed ())
+		scratchpad_show_first ();
+	else
+	{
+		if (scratchpad_last_showed -> tags != SCRATCHPAD_MASK)
+		{
+			scratchpad_last_showed -> tags = SCRATCHPAD_MASK;
+			focus(NULL);
+			arrange(selmon);
+		}
+		else
+		{
+			_Bool found_current = 0;
+			_Bool found_next = 0;
+			for (Client * c = selmon -> clients; c != NULL; c = c -> next)
+			{
+				if (found_current == 0)
+				{
+					if (c == scratchpad_last_showed)
+					{
+						found_current = 1;
+						continue;
+					}
+				}
+				else
+				{
+					if (c -> tags == SCRATCHPAD_MASK)
+					{
+						found_next = 1;
+						scratchpad_show_client (c);
+						break;
+					}
+				}
+			}
+			if (found_next == 0) scratchpad_show_first ();
+		}
+	}
+}
+
+static void scratchpad_show_client (Client * c)
+{
+	scratchpad_last_showed = c;
+	c -> tags = selmon->tagset[selmon->seltags];
+	focus(c);
+	arrange(selmon);
+}
+
+static void scratchpad_show_first (void)
+{
+	for (Client * c = selmon -> clients; c != NULL; c = c -> next)
+	{
+		if (c -> tags == SCRATCHPAD_MASK)
+		{
+			scratchpad_show_client (c);
+			break;
+		}
+	}
+}
+
 void
 sendmon(Client *c, Monitor *m)
 {
@@ -1781,6 +1884,8 @@ unmanage(Client *c, int destroyed)
 		XSetErrorHandler(xerror);
 		XUngrabServer(dpy);
 	}
+	if (scratchpad_last_showed == c)
+		scratchpad_last_showed = NULL;
 	free(c);
 	focus(NULL);
 	updateclientlist();