From 42f97e88bd901d81b81da61c44a790b583706308 Mon Sep 17 00:00:00 2001
From: wochap <gean.marroquin@gmail.com>
Date: Fri, 5 Jul 2024 11:18:49 -0500
Subject: [PATCH] implement gestures

---
 config.def.h |  9 +++++++
 dwl.c        | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/config.def.h b/config.def.h
index 22d2171..8b75564 100644
--- a/config.def.h
+++ b/config.def.h
@@ -14,6 +14,8 @@ static const float urgentcolor[]           = COLOR(0xff0000ff);
 /* This conforms to the xdg-protocol. Set the alpha to zero to restore the old behavior */
 static const float fullscreen_bg[]         = {0.1f, 0.1f, 0.1f, 1.0f}; /* You can also use glsl colors */
 
+static const unsigned int swipe_min_threshold = 0;
+
 /* tagging - TAGCOUNT must be no greater than 31 */
 #define TAGCOUNT (9)
 
@@ -174,3 +176,10 @@ static const Button buttons[] = {
 	{ MODKEY, BTN_MIDDLE, togglefloating, {0} },
 	{ MODKEY, BTN_RIGHT,  moveresize,     {.ui = CurResize} },
 };
+
+static const Gesture gestures[] = {
+	// { MODKEY, SWIPE_LEFT, 4, shiftview, { .i = 1 } },
+	// { MODKEY, SWIPE_RIGHT, 4, shiftview, { .i = -1 } },
+	{ MODKEY, SWIPE_UP, 3, focusstack, {.i = 1} },
+	{ MODKEY, SWIPE_DOWN, 3, focusstack, {.i = -1} },
+};
diff --git a/dwl.c b/dwl.c
index ded83e2..5d861e8 100644
--- a/dwl.c
+++ b/dwl.c
@@ -88,6 +88,7 @@ enum { LyrBg, LyrBottom, LyrTile, LyrFloat, LyrTop, LyrFS, LyrOverlay, LyrBlock,
 enum { NetWMWindowTypeDialog, NetWMWindowTypeSplash, NetWMWindowTypeToolbar,
 	NetWMWindowTypeUtility, NetLast }; /* EWMH atoms */
 #endif
+enum { SWIPE_LEFT, SWIPE_RIGHT, SWIPE_DOWN, SWIPE_UP };
 
 typedef union {
 	int i;
@@ -103,6 +104,14 @@ typedef struct {
 	const Arg arg;
 } Button;
 
+typedef struct {
+	unsigned int mod;
+	unsigned int motion;
+	unsigned int fingers_count;
+	void (*func)(const Arg *);
+	const Arg arg;
+} Gesture;
+
 typedef struct Monitor Monitor;
 typedef struct {
 	/* Must keep these three elements in this order */
@@ -251,6 +260,7 @@ static void arrangelayer(Monitor *m, struct wl_list *list,
 static void arrangelayers(Monitor *m);
 static void axisnotify(struct wl_listener *listener, void *data);
 static void buttonpress(struct wl_listener *listener, void *data);
+static int ongesture(struct wlr_pointer_swipe_end_event *event);
 static void swipe_begin(struct wl_listener *listener, void *data);
 static void swipe_update(struct wl_listener *listener, void *data);
 static void swipe_end(struct wl_listener *listener, void *data);
@@ -416,6 +426,10 @@ static struct wlr_box sgeom;
 static struct wl_list mons;
 static Monitor *selmon;
 
+static uint32_t swipe_fingers = 0;
+static double swipe_dx = 0;
+static double swipe_dy = 0;
+
 #ifdef XWAYLAND
 static void activatex11(struct wl_listener *listener, void *data);
 static void associatex11(struct wl_listener *listener, void *data);
@@ -435,6 +449,8 @@ static xcb_atom_t netatom[NetLast];
 /* attempt to encapsulate suck into one file */
 #include "client.h"
 
+static const unsigned int abzsquare = swipe_min_threshold * swipe_min_threshold;
+
 /* function implementations */
 void
 applybounds(Client *c, struct wlr_box *bbox)
@@ -657,6 +673,11 @@ swipe_begin(struct wl_listener *listener, void *data)
 {
 	struct wlr_pointer_swipe_begin_event *event = data;
 
+	swipe_fingers = event->fingers;
+	// Reset swipe distance at the beginning of a swipe
+	swipe_dx = 0;
+	swipe_dy = 0;
+
 	// Forward swipe begin event to client
 	wlr_pointer_gestures_v1_send_swipe_begin(
 		pointer_gestures, 
@@ -671,6 +692,11 @@ swipe_update(struct wl_listener *listener, void *data)
 {
 	struct wlr_pointer_swipe_update_event *event = data;
 
+	swipe_fingers = event->fingers;
+	// Accumulate swipe distance
+	swipe_dx += event->dx;
+	swipe_dy += event->dy;
+
 	// Forward swipe update event to client
 	wlr_pointer_gestures_v1_send_swipe_update(
 		pointer_gestures, 
@@ -681,11 +707,53 @@ swipe_update(struct wl_listener *listener, void *data)
 	);
 }
 
+int
+ongesture(struct wlr_pointer_swipe_end_event *event)
+{
+	struct wlr_keyboard *keyboard;
+	uint32_t mods;
+	const Gesture *g;
+	unsigned int motion;
+	unsigned int adx = (int)round(fabs(swipe_dx));
+	unsigned int ady = (int)round(fabs(swipe_dy));
+	int handled = 0;
+
+	if (event->cancelled) {
+		return handled;
+	}
+
+	// Require absolute distance movement beyond a small thresh-hold
+	if (adx * adx + ady * ady < abzsquare) {
+		return handled;
+	}
+
+	if (adx > ady) {
+		motion = swipe_dx < 0 ? SWIPE_LEFT : SWIPE_RIGHT;
+	} else {
+		motion = swipe_dy < 0 ? SWIPE_UP : SWIPE_DOWN;
+	}
+
+	keyboard = wlr_seat_get_keyboard(seat);
+	mods = keyboard ? wlr_keyboard_get_modifiers(keyboard) : 0;
+	for (g = gestures; g < END(gestures); g++) {
+		if (CLEANMASK(mods) == CLEANMASK(g->mod) &&
+			 swipe_fingers == g->fingers_count &&
+			 motion == g->motion && g->func) {
+			g->func(&g->arg);
+			handled = 1;
+		}
+	}
+	return handled;
+}
+
 void
 swipe_end(struct wl_listener *listener, void *data)
 {
 	struct wlr_pointer_swipe_end_event *event = data;
 
+	// TODO: should we stop here if the event has been handled?
+	ongesture(event);
+
 	// Forward swipe end event to client
 	wlr_pointer_gestures_v1_send_swipe_end(
 		pointer_gestures, 
-- 
2.45.1
