Adding alt-tab patch ref. #303

README.md

@@ -19,6 +19,8 @@ Browsing patches? There is a [map of patches](https://coggle.it/diagram/X9IiSSM6
 
 ### Changelog:
 
+2022-10-08 - Added the alt-tab patch
+
 2022-08-12 - Added the nametag patch
 
 2022-08-02 - Added the bidi patch
@@ -230,6 +232,9 @@ Browsing patches? There is a [map of patches](https://coggle.it/diagram/X9IiSSM6
    - [alpha](https://dwm.suckless.org/patches/alpha/)
       - adds transparency for the status bar
 
+   - [alt-tab](https://dwm.suckless.org/patches/alt-tab/)
+      - adds a window task switcher toggled using alt-tab
+
    - [alternativetags](https://dwm.suckless.org/patches/alternativetags/)
       - adds alternative tags which can be toggled on the fly for the sole purpose of providing
         visual aid

config.def.h

@@ -122,6 +122,16 @@ static const int ulineall = 0;                  /* 1 to show underline on all ta
 #define NAMETAG_COMMAND "dmenu < /dev/null"
 #endif // NAMETAG_PATCH
 
+#if ALT_TAB_PATCH
+/* alt-tab configuration */
+static const unsigned int tabmodkey        = 0x40; /* (Alt) when this key is held down the alt-tab functionality stays active. Must be the same modifier as used to run alttabstart */
+static const unsigned int tabcyclekey      = 0x17; /* (Tab) when this key is hit the menu moves one position forward in client stack. Must be the same key as used to run alttabstart */
+static const unsigned int tabposy          = 1;    /* tab position on Y axis, 0 = top, 1 = center, 2 = bottom */
+static const unsigned int tabposx          = 1;    /* tab position on X axis, 0 = left, 1 = center, 2 = right */
+static const unsigned int maxwtab          = 600;  /* tab menu width */
+static const unsigned int maxhtab          = 200;  /* tab menu height */
+#endif // ALT_TAB_PATCH
+
 /* Indicators: see patch/bar_indicators.h for options */
 static int tagindicatortype              = INDICATOR_TOP_LEFT_SQUARE;
 static int tiledindicatortype            = INDICATOR_NONE;
@@ -996,7 +1006,11 @@ static const Key keys[] = {
 	{ MODKEY|Mod4Mask,              XK_0,          togglegaps,             {0} },
 	{ MODKEY|Mod4Mask|ShiftMask,    XK_0,          defaultgaps,            {0} },
 	#endif // VANITYGAPS_PATCH
+	#if ALT_TAB_PATCH
+	{ Mod1Mask,                     XK_Tab,        alttabstart,            {0} },
+	#else
 	{ MODKEY,                       XK_Tab,        view,                   {0} },
+	#endif // ALT_TAB_PATCH
 	#if SHIFTTAG_PATCH
 	{ MODKEY|ShiftMask,             XK_Left,       shifttag,               { .i = -1 } }, // note keybinding conflict with focusadjacenttag tagtoleft
 	{ MODKEY|ShiftMask,             XK_Right,      shifttag,               { .i = +1 } }, // note keybinding conflict with focusadjacenttag tagtoright

config.mk

@@ -29,7 +29,7 @@ FREETYPEINC = /usr/include/freetype2
 #KVMLIB = -lkvm
 
 # Uncomment this for the alpha patch and the winicon patch (BAR_ALPHA_PATCH, BAR_WINICON_PATCH)
-#XRENDER = -lXrender
+XRENDER = -lXrender
 
 # Uncomment this for the mdpcontrol patch / MDPCONTROL_PATCH
 #MPDCLIENT = -lmpdclient

dwm.c

@@ -1245,6 +1245,10 @@ cleanup(void)
 	Layout foo = { "", NULL };
 	size_t i;
 
+	#if ALT_TAB_PATCH
+	alttabend();
+	#endif // ALT_TAB_PATCH
+
 	#if SEAMLESS_RESTART_PATCH
 	for (m = mons; m; m = m->next)
 		persistmonitorstate(m);

patch/alttab.c

@@ -0,0 +1,222 @@
+int alttabn;          /* move that many clients forward */
+int ntabs;            /* number of active clients in tag */
+int isalt;
+Client **altsnext;    /* array of all clients in the tag */
+Window alttabwin;
+
+void
+alttab()
+{
+	Monitor *m = selmon;
+
+	/* move to next window */
+	if (m->sel && m->sel->snext) {
+		alttabn++;
+		if (alttabn >= ntabs)
+			alttabn = 0; /* reset alttabn */
+
+		focus(altsnext[alttabn]);
+		restack(m);
+	}
+
+	/* redraw tab */
+	XRaiseWindow(dpy, alttabwin);
+	drawtab(ntabs, 0, m);
+}
+
+void
+alttabend()
+{
+	Monitor *m = selmon;
+	Client *buff;
+	int i;
+
+	if (!isalt)
+		return;
+
+	/* Move all clients between first and choosen position,
+	 * one down in stack and put choosen client to the first position
+	 * so they remain in right order for the next time that alt-tab is used
+	 */
+	if (ntabs > 1) {
+		if (alttabn != 0) { /* if user picked original client do nothing */
+			buff = altsnext[alttabn];
+			if (alttabn > 1)
+				for (i = alttabn; i > 0; i--)
+					altsnext[i] = altsnext[i - 1];
+			else /* swap them if there are just 2 clients */
+				altsnext[alttabn] = altsnext[0];
+			altsnext[0] = buff;
+		}
+
+		/* restack clients */
+		for (i = ntabs - 1; i >= 0; i--) {
+		    focus(altsnext[i]);
+		    restack(m);
+		}
+
+		free(altsnext); /* free list of clients */
+	}
+
+	/* destroy the window */
+	isalt = 0;
+	ntabs = 0;
+	XUnmapWindow(dpy, alttabwin);
+	XDestroyWindow(dpy, alttabwin);
+}
+
+void
+drawtab(int nwins, int first, Monitor *m)
+{
+	Client *c;
+	int i, h;
+	int y = 0;
+	int px = m->mx;
+	int py = m->my;
+
+	if (first) {
+		XSetWindowAttributes wa = {
+			.override_redirect = True,
+			#if BAR_ALPHA_PATCH
+			.background_pixel = 0,
+			.border_pixel = 0,
+			.colormap = cmap,
+			#else
+			.background_pixmap = ParentRelative,
+			#endif // BAR_ALPHA_PATCH
+			.event_mask = ButtonPressMask|ExposureMask
+		};
+
+		/* decide position of tabwin */
+		if (tabposx == 1)
+			px = m->mx + (m->mw / 2) - (maxwtab / 2);
+		else if (tabposx == 2)
+			px = m->mx + m->mw - maxwtab;
+
+		if (tabposy == 1)
+			py = m->my + (m->mh / 2) - (maxhtab / 2);
+		else if (tabposy == 2)
+			py = m->my + m->mh - maxhtab;
+
+		h = maxhtab;
+
+		#if BAR_ALPHA_PATCH
+		alttabwin = XCreateWindow(dpy, root, px, py, maxwtab, maxhtab, 2, depth,
+		                             InputOutput, visual,
+		                             CWOverrideRedirect|CWBackPixel|CWBorderPixel|CWColormap|CWEventMask, &wa);
+		#else
+		alttabwin = XCreateWindow(dpy, root, px, py, maxwtab, maxhtab, 2, DefaultDepth(dpy, screen),
+		                             CopyFromParent, DefaultVisual(dpy, screen),
+		                             CWOverrideRedirect|CWBackPixmap|CWEventMask, &wa);
+		#endif // BAR_ALPHA_PATCH
+
+		XDefineCursor(dpy, alttabwin, cursor[CurNormal]->cursor);
+		XMapRaised(dpy, alttabwin);
+	}
+
+	h = maxhtab / ntabs;
+	for (i = 0; i < ntabs; i++) { /* draw all clients into tabwin */
+		c = altsnext[i];
+		if (!ISVISIBLE(c))
+			continue;
+		if (HIDDEN(c))
+			continue;
+
+		drw_setscheme(drw, scheme[c == m->sel ? SchemeSel : SchemeNorm]);
+		drw_text(drw, 0, y, maxwtab, h, 0, c->name, 0, 0);
+		y += h;
+	}
+
+	drw_setscheme(drw, scheme[SchemeNorm]);
+	drw_map(drw, alttabwin, 0, 0, maxwtab, maxhtab);
+}
+
+void
+alttabstart(const Arg *arg)
+{
+	Client *c;
+	Monitor *m = selmon;
+	int grabbed;
+	int i;
+
+	altsnext = NULL;
+	if (alttabwin)
+		alttabend();
+
+	if (isalt == 1) {
+		alttabend();
+		return;
+	}
+
+	isalt = 1;
+	alttabn = 0;
+	ntabs = 0;
+
+	for (c = m->clients; c; c = c->next) {
+		if (!ISVISIBLE(c))
+			continue;
+		if (HIDDEN(c))
+			continue;
+
+		++ntabs;
+	}
+
+	if (!ntabs) {
+		alttabend();
+		return;
+	}
+
+	altsnext = (Client **) malloc(ntabs * sizeof(Client *));
+
+	for (i = 0, c = m->stack; c; c = c->snext, i++) {
+		if (!ISVISIBLE(c))
+			continue;
+		if (HIDDEN(c))
+			continue;
+
+		altsnext[i] = c;
+	}
+
+	drawtab(ntabs, 1, m);
+
+	struct timespec ts = { .tv_sec = 0, .tv_nsec = 1000000 };
+
+	/* grab keyboard (take all input from keyboard) */
+	grabbed = 1;
+	for (i = 0; i < 1000; i++) {
+		if (XGrabKeyboard(dpy, root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess)
+			break;
+		nanosleep(&ts, NULL);
+		if (i == 1000 - 1)
+			grabbed = 0;
+	}
+
+	XEvent event;
+	alttab();
+
+	if (grabbed == 0) {
+		alttabend();
+		return;
+	}
+
+	while (grabbed) {
+		XNextEvent(dpy, &event);
+		if (event.type == KeyPress || event.type == KeyRelease) {
+			if (event.type == KeyRelease && event.xkey.keycode == tabmodkey) /* if mod key is released break cycle */
+				break;
+
+			if (event.type == KeyPress) {
+				if (event.xkey.keycode == tabcyclekey) { /* if tab is pressed move to the next window */
+					alttab();
+				}
+			}
+		}
+	}
+
+	c = m->sel;
+	alttabend();
+
+	XUngrabKeyboard(dpy, CurrentTime);
+	focus(c);
+	restack(m);
+}

patch/alttab.h

@@ -0,0 +1,5 @@
+#include <time.h>
+
+static void drawtab(int nwins, int first, Monitor *m);
+static void alttabstart(const Arg *arg);
+static void alttabend();

patch/include.c

@@ -98,6 +98,9 @@
 #endif
 
 /* Other patches */
+#if ALT_TAB_PATCH
+#include "alttab.c"
+#endif
 #if ASPECTRESIZE_PATCH
 #include "aspectresize.c"
 #endif

patch/include.h

@@ -98,6 +98,9 @@
 #endif
 
 /* Other patches */
+#if ALT_TAB_PATCH
+#include "alttab.h"
+#endif
 #if ASPECTRESIZE_PATCH
 #include "aspectresize.h"
 #endif

patches.def.h

@@ -438,6 +438,11 @@
  * Other patches
  */
 
+/* Adds a window task switcher toggled using alt-tab.
+ * https://dwm.suckless.org/patches/alt-tab/
+ */
+#define ALT_TAB_PATCH 0
+
 /* All floating windows are centered, like the center patch, but without a rule.
  * The center patch takes precedence over this patch.
  * This patch interferes with the center transient windows patches.