Merge branch 'main' into wlroots-next

2026-11-03 11:52:22 +00:00 · 2026-10-27 23:33:05 +01:00
parent 5af5dd5e7e 12a5856427
commit 7622bd3187
3 changed files with 359 additions and 123 deletions
@@ -153,6 +153,7 @@ given the base on which it is built. Implemented default features are:
 - Support screen lockers via ext-session-lock-v1 protocol
 - Various Wayland protocols
 - XWayland support as provided by wlroots (can be enabled in `config.mk`)
+- Zero flickering - Wayland users naturally expect that "every frame is perfect"
 - Layer shell popups (used by Waybar)
 - Damage tracking provided by scenegraph API

@@ -258,48 +258,6 @@ client_is_float_type(Client *c)
 			(min.width == max.width || min.height == max.height));
 }

-static inline int
-client_is_rendered_on_mon(Client *c, Monitor *m)
-{
-	/* This is needed for when you don't want to check formal assignment,
-	 * but rather actual displaying of the pixels.
-	 * Usually VISIBLEON suffices and is also faster. */
-	struct wlr_surface_output *s;
-	int unused_lx, unused_ly;
-	if (!wlr_scene_node_coords(&c->scene->node, &unused_lx, &unused_ly))
-		return 0;
-	wl_list_for_each(s, &client_surface(c)->current_outputs, link)
-		if (s->output == m->wlr_output)
-			return 1;
-	return 0;
-}
-
-static inline int
-client_is_stopped(Client *c)
-{
-	int pid;
-	siginfo_t in = {0};
-#ifdef XWAYLAND
-	if (client_is_x11(c))
-		return 0;
-#endif
-
-	wl_client_get_credentials(c->surface.xdg->client->client, &pid, NULL, NULL);
-	if (waitid(P_PID, pid, &in, WNOHANG|WCONTINUED|WSTOPPED|WNOWAIT) < 0) {
-		/* This process is not our child process, while is very unlikely that
-		 * it is stopped, in order to do not skip frames, assume that it is. */
-		if (errno == ECHILD)
-			return 1;
-	} else if (in.si_pid) {
-		if (in.si_code == CLD_STOPPED || in.si_code == CLD_TRAPPED)
-			return 1;
-		if (in.si_code == CLD_CONTINUED)
-			return 0;
-	}
-
-	return 0;
-}
-
 static inline int
 client_is_unmanaged(Client *c)
 {
@@ -366,19 +324,36 @@ client_set_scale(struct wlr_surface *s, float scale)
 	wlr_surface_set_preferred_buffer_scale(s, (int32_t)ceilf(scale));
 }

-static inline void
+/* Returns nonzero if the client has to commit a buffer with the new size */
+static inline uint32_t
 client_set_size(Client *c, uint32_t width, uint32_t height)
 {
 #ifdef XWAYLAND
 	if (client_is_x11(c)) {
 		wlr_xwayland_surface_configure(c->surface.xwayland,
 				c->geom.x + c->bw, c->geom.y + c->bw, width, height);
-		return;
+		return (int)width != client_surface(c)->current.width
+				|| (int)height != client_surface(c)->current.height;
 	}
 #endif
-	if ((int32_t)width != c->surface.xdg->toplevel->current.width
-			|| (int32_t)height != c->surface.xdg->toplevel->current.height)
-		wlr_xdg_toplevel_set_size(c->surface.xdg->toplevel, (int32_t)width, (int32_t)height);
+	if ((int32_t)width == c->surface.xdg->toplevel->scheduled.width
+			&& (int32_t)height == c->surface.xdg->toplevel->scheduled.height)
+		return 0;
+	return wlr_xdg_toplevel_set_size(c->surface.xdg->toplevel, (int32_t)width, (int32_t)height);
+}
+
+static inline void
+client_send_frame_done_iterator(struct wlr_surface *s, int sx, int sy, void *data)
+{
+	wlr_surface_send_frame_done(s, data);
+}
+
+static inline void
+client_send_frame_done(Client *c)
+{
+	struct timespec now;
+	clock_gettime(CLOCK_MONOTONIC, &now);
+	wlr_surface_for_each_surface(client_surface(c), client_send_frame_done_iterator, &now);
 }

 static inline void
@@ -126,6 +126,9 @@ typedef struct {
 	struct wl_list flink;
 	struct wlr_box geom; /* layout-relative, includes border */
 	struct wlr_box prev; /* layout-relative, includes border */
+	struct wlr_box current; /* geom currently shown in the scene graph */
+	struct wlr_scene_node *snapshot; /* content shown while resizing */
+	uint32_t resize_serial; /* nonzero while waiting for a resized buffer */
 	struct wlr_box bounds; /* only width and height are used */
 	union {
 		struct wlr_xdg_surface *xdg;
@@ -262,6 +265,7 @@ typedef struct {

 /* function declarations */
 static void applybounds(Client *c, struct wlr_box *bbox);
+static void applygeom(Client *c);
 static void applyrules(Client *c);
 static void arrange(Monitor *m);
 static void arrangelayer(Monitor *m, struct wl_list *list,
@@ -324,6 +328,7 @@ static void mapnotify(struct wl_listener *listener, void *data);
 static void maximizenotify(struct wl_listener *listener, void *data);
 static void monocle(Monitor *m);
 static void motionabsolute(struct wl_listener *listener, void *data);
+static char **monoff(struct wlr_output *wlr_output);
 static void motionnotify(uint32_t time, struct wlr_input_device *device, double sx,
 		double sy, double sx_unaccel, double sy_unaccel);
 static void motionrelative(struct wl_listener *listener, void *data);
@@ -349,9 +354,12 @@ static void setfullscreen(Client *c, int fullscreen);
 static void setlayout(const Arg *arg);
 static void setmfact(const Arg *arg);
 static void setmon(Client *c, Monitor *m, uint32_t newtags);
+static void setmonoff(struct wlr_output *wlr_output, int off);
 static void setpsel(struct wl_listener *listener, void *data);
 static void setsel(struct wl_listener *listener, void *data);
 static void setup(void);
+static struct wlr_scene_node *snapshot(struct wlr_scene_node *node,
+		struct wlr_scene_tree *parent, void *data);
 static void spawn(const Arg *arg);
 static void startdrag(struct wl_listener *listener, void *data);
 static void tag(const Arg *arg);
@@ -361,6 +369,11 @@ static void togglefloating(const Arg *arg);
 static void togglefullscreen(const Arg *arg);
 static void toggletag(const Arg *arg);
 static void toggleview(const Arg *arg);
+static void transactionapply(void);
+static void transactioncheck(void *data);
+static void transactioncommit(Client *c, int ready);
+static void transactionschedule(void);
+static int transactiontimeout(void *data);
 static void unlocksession(struct wl_listener *listener, void *data);
 static void unmaplayersurfacenotify(struct wl_listener *listener, void *data);
 static void unmapnotify(struct wl_listener *listener, void *data);
@@ -432,6 +445,15 @@ static struct wl_list mons;
 static Monitor *selmon;
 static int consumed[KEY_MAX + 1];

+/* Transactions: the scene graph is updated only once all visible clients have
+ * committed buffers with their new size, or after TRANSACTION_TIMEOUT ms */
+#define TRANSACTION_TIMEOUT 100
+static struct wl_event_source *transaction_idle;
+static struct wl_event_source *transaction_timer;
+static int transaction_waiting;
+static struct wl_array ghosts; /* struct wlr_scene_node *, unmapped clients */
+static struct wl_array offmons; /* char *, names of outputs turned off by clients */
+
 /* global event handlers */
 static struct wl_listener cursor_axis = {.notify = axisnotify};
 static struct wl_listener cursor_button = {.notify = buttonpress};
@@ -460,12 +482,14 @@ static struct wl_listener request_set_sel = {.notify = setsel};
 static struct wl_listener request_set_cursor_shape = {.notify = setcursorshape};
 static struct wl_listener request_start_drag = {.notify = requeststartdrag};
 static struct wl_listener start_drag = {.notify = startdrag};
+static struct wl_listener drag_icon_destroy = {.notify = destroydragicon};
 static struct wl_listener new_session_lock = {.notify = locksession};
 static struct wl_listener new_foreign_toplevel_capture_request = {.notify = capturerequest};

 #ifdef XWAYLAND
 static void activatex11(struct wl_listener *listener, void *data);
 static void associatex11(struct wl_listener *listener, void *data);
+static void commitx11(struct wl_listener *listener, void *data);
 static void configurex11(struct wl_listener *listener, void *data);
 static void createnotifyx11(struct wl_listener *listener, void *data);
 static void dissociatex11(struct wl_listener *listener, void *data);
@@ -516,6 +540,41 @@ applybounds(Client *c, struct wlr_box *bbox)
 		c->geom.y = bbox->y;
 }

+void
+applygeom(Client *c)
+{
+	struct wlr_box clip;
+	Client *p = client_get_parent(c);
+
+	/* We move all floating clients to LyrTile while in floating layout
+	 * to avoid "real" floating clients be always on top */
+	wlr_scene_node_reparent(&c->scene->node, layers[c->isfullscreen
+			|| (p && p->isfullscreen) ? LyrFS
+			: c->isfloating && c->mon->lt[c->mon->sellt]->arrange ? LyrFloat
+			: LyrTile]);
+
+	c->current = c->geom;
+	if (c->snapshot) {
+		wlr_scene_node_destroy(c->snapshot);
+		c->snapshot = NULL;
+		wlr_scene_node_set_enabled(&c->scene_surface->node, 1);
+	}
+
+	/* Update scene-graph, including borders */
+	wlr_scene_node_set_position(&c->scene->node, c->geom.x, c->geom.y);
+	wlr_scene_node_set_position(&c->scene_surface->node, c->bw, c->bw);
+	wlr_scene_rect_set_size(c->border[0], c->geom.width, c->bw);
+	wlr_scene_rect_set_size(c->border[1], c->geom.width, c->bw);
+	wlr_scene_rect_set_size(c->border[2], c->bw, c->geom.height - 2 * c->bw);
+	wlr_scene_rect_set_size(c->border[3], c->bw, c->geom.height - 2 * c->bw);
+	wlr_scene_node_set_position(&c->border[1]->node, 0, c->geom.height - c->bw);
+	wlr_scene_node_set_position(&c->border[2]->node, 0, c->bw);
+	wlr_scene_node_set_position(&c->border[3]->node, c->geom.width - c->bw, c->bw);
+
+	client_get_clip(c, &clip);
+	wlr_scene_subsurface_tree_set_clip(&c->scene_surface->node, &clip);
+}
+
 void
 applyrules(Client *c)
 {
@@ -555,37 +614,18 @@ arrange(Monitor *m)
 		return;

 	wl_list_for_each(c, &clients, link) {
-		if (c->mon == m) {
-			wlr_scene_node_set_enabled(&c->scene->node, VISIBLEON(c, m));
+		if (c->mon == m)
 			client_set_suspended(c, !VISIBLEON(c, m)
 					&& (!c->image_capture_source
 					|| wl_list_empty(&c->image_capture_source->resources)));
 	}
-	}
-
-	wlr_scene_node_set_enabled(&m->fullscreen_bg->node,
-			(c = focustop(m)) && c->isfullscreen);

 	strncpy(m->ltsymbol, m->lt[m->sellt]->symbol, LENGTH(m->ltsymbol));

-	/* We move all clients (except fullscreen and unmanaged) to LyrTile while
-	 * in floating layout to avoid "real" floating clients be always on top */
-	wl_list_for_each(c, &clients, link) {
-		if (c->mon != m || c->scene->node.parent == layers[LyrFS])
-			continue;
-
-		wlr_scene_node_reparent(&c->scene->node,
-				(!m->lt[m->sellt]->arrange && c->isfloating)
-						? layers[LyrTile]
-						: (m->lt[m->sellt]->arrange && c->isfloating)
-								? layers[LyrFloat]
-								: c->scene->node.parent);
-	}
-
 	if (m->lt[m->sellt]->arrange)
 		m->lt[m->sellt]->arrange(m);
-	motionnotify(0, NULL, 0, 0, 0, 0);
-	checkidleinhibitor(NULL);
+
+	transactionschedule();
 }

 void
@@ -642,7 +682,6 @@ arrangelayers(Monitor *m)
 					l->layer_surface->current.keyboard_interactive != ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_EXCLUSIVE ||
 					!l->mapped)
 				continue;
-			/* Deactivate the focused client. */
 			focusclient(NULL, l, 0);
 			return;
 		}
@@ -789,6 +828,8 @@ checkidleinhibitor(struct wlr_surface *exclude)
 void
 cleanup(void)
 {
+	char **name;
+
 	cleanuplisteners();
 #ifdef XWAYLAND
 	wlr_xwayland_destroy(xwayland);
@@ -810,6 +851,14 @@ cleanup(void)
 	 * Destroy it until it's fixed on the wlroots side */
 	wlr_backend_destroy(backend);

+	if (transaction_idle)
+		wl_event_source_remove(transaction_idle);
+	wl_event_source_remove(transaction_timer);
+	wl_array_release(&ghosts);
+	wl_array_for_each(name, &offmons)
+		free(*name);
+	wl_array_release(&offmons);
+
 	wl_display_destroy(dpy);
 	/* Destroy after the wayland display (when the monitors are already destroyed)
 	   to avoid destroying them with an invalid scene output. */
@@ -877,8 +926,10 @@ cleanuplisteners(void)
 	wl_list_remove(&new_session_lock.link);
 	wl_list_remove(&new_foreign_toplevel_capture_request.link);
 #ifdef XWAYLAND
+	if (xwayland) {
 		wl_list_remove(&new_xwayland_surface.link);
 		wl_list_remove(&xwayland_ready.link);
+	}
 #endif
 }

@@ -989,6 +1040,8 @@ commitnotify(struct wl_listener *listener, void *data)
 		return;
 	}

+	transactioncommit(c, c->resize_serial && c->surface.xdg->current.configure_serial
+			>= c->resize_serial);
 	resize(c, c->geom, (c->isfloating && !c->isfullscreen));
 }

@@ -1015,8 +1068,8 @@ commitpopup(struct wl_listener *listener, void *data)
 		return;
 	}
 	box = type == LayerShell ? l->mon->m : c->mon->w;
-	box.x -= (type == LayerShell ? l->scene->node.x : c->geom.x);
-	box.y -= (type == LayerShell ? l->scene->node.y : c->geom.y);
+	box.x -= (type == LayerShell ? l->scene->node.x : c->geom.x - c->surface.xdg->geometry.x);
+	box.y -= (type == LayerShell ? l->scene->node.y : c->geom.y - c->surface.xdg->geometry.y);
 	wlr_xdg_popup_unconstrain_from_box(popup, &box);
 	wl_list_remove(&listener->link);
 	free(listener);
@@ -1185,14 +1238,17 @@ createmon(struct wl_listener *listener, void *data)
 	 * monitor supports only a specific set of modes. We just pick the
 	 * monitor's preferred mode; a more sophisticated compositor would let
 	 * the user configure it. */
-	wlr_output_state_set_mode(&state, wlr_output_preferred_mode(wlr_output));
-
 	/* Set up event listeners */
 	LISTEN(&wlr_output->events.frame, &m->frame, rendermon);
 	LISTEN(&wlr_output->events.destroy, &m->destroy, cleanupmon);
 	LISTEN(&wlr_output->events.request_state, &m->request_state, requestmonstate);

+	/* Some monitors disconnect when they are turned off and reconnect shortly
+	 * after, so keep outputs that were turned off disabled. */
+	if (!monoff(wlr_output)) {
+		wlr_output_state_set_mode(&state, wlr_output_preferred_mode(wlr_output));
 		wlr_output_state_set_enabled(&state, 1);
+	}
 	wlr_output_commit_state(wlr_output, &state);
 	wlr_output_state_finish(&state);

@@ -1218,6 +1274,12 @@ createmon(struct wl_listener *listener, void *data)
 	 * output (such as DPI, scale factor, manufacturer, etc).
 	 */
 	m->scene_output = wlr_scene_output_create(scene, wlr_output);
+
+	if (!wlr_output->enabled) {
+		updatemons(NULL, NULL);
+		return;
+	}
+
 	if (m->m.x == -1 && m->m.y == -1)
 		wlr_output_layout_add_auto(output_layout, wlr_output);
 	else
@@ -1362,7 +1424,6 @@ destroydragicon(struct wl_listener *listener, void *data)
 	focusclient(focustop(selmon), NULL, 1);
 	motionnotify(0, NULL, 0, 0, 0, 0);
 	wl_list_remove(&listener->link);
-	free(listener);
 }

 void
@@ -1518,7 +1579,7 @@ dirtomon(enum wlr_direction dir)
 void
 focusclient(Client *c, LayerSurface *l, int lift)
 {
-	struct wlr_surface *old = seat->keyboard_state.focused_surface;
+	struct wlr_surface *surface, *old = seat->keyboard_state.focused_surface;
 	int unused_lx, unused_ly, old_client_type;
 	Client *old_c = NULL;
 	LayerSurface *old_l = NULL;
@@ -1549,7 +1610,6 @@ focusclient(Client *c, LayerSurface *l, int lift)
 		/* Don't change border color if there is an exclusive focus or we are
 		 * handling a drag operation */
 		if (!(old_l && old_l->layer_surface->current.keyboard_interactive == ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_EXCLUSIVE)
-				&& !(old_c && client_wants_focus(old_c))
 				&& !seat->drag)
 			client_set_border_color(c, focuscolor);
 	}
@@ -1574,31 +1634,23 @@ focusclient(Client *c, LayerSurface *l, int lift)
 	}
 	printstatus();

-	if (l) {
-		/* Focus a layer surface and let the input method follow it */
-		input_method_relay_set_focus(input_method_relay, l->layer_surface->surface);
-		client_notify_enter(l->layer_surface->surface, wlr_seat_get_keyboard(seat));
-		return;
-	}
-
-	if (!c) {
+	if (!c && !l) {
 		/* With no client, all we have left is to clear focus */
 		input_method_relay_set_focus(input_method_relay, NULL);
 		wlr_seat_keyboard_notify_clear_focus(seat);
 		return;
 	}

-	/* Change cursor surface */
+	surface = c ? client_surface(c) : l->layer_surface->surface;
+	input_method_relay_set_focus(input_method_relay, surface);
+	client_notify_enter(surface, wlr_seat_get_keyboard(seat));
+
+	if (l)
+		return;
+
+	client_activate_surface(surface, 1);
 	motionnotify(0, NULL, 0, 0, 0, 0);

-	input_method_relay_set_focus(input_method_relay, client_surface(c));
-
-	/* Have a client, so focus its top-level wlr_surface */
-	client_notify_enter(client_surface(c), wlr_seat_get_keyboard(seat));
-
-	/* Activate the new client */
-	client_activate_surface(client_surface(c), 1);
-
 	if (!client_is_unmanaged(c))
 		focused_client = c;
 }
@@ -1924,8 +1976,15 @@ mapnotify(struct wl_listener *listener, void *data)
 	}

 	/* Initialize client geometry with room for border */
+	client_set_tiled(c, WLR_EDGE_TOP | WLR_EDGE_BOTTOM | WLR_EDGE_LEFT |
+			WLR_EDGE_RIGHT);
 	c->geom.width += 2 * c->bw;
 	c->geom.height += 2 * c->bw;
+	if (client_is_x11(c)) {
+		int x = c->geom.x - (int)c->bw, y = c->geom.y - (int)c->bw;
+		c->geom.x = c->geom.x < sgeom.x ? x : MAX(x, sgeom.x);
+		c->geom.y = c->geom.y < sgeom.y ? y : MAX(y, sgeom.y);
+	}

 	/* Insert this client into client lists. */
 	wl_list_insert(&clients, &c->link);
@@ -2019,6 +2078,17 @@ motionabsolute(struct wl_listener *listener, void *data)
 	motionnotify(event->time_msec, &event->pointer->base, dx, dy, dx, dy);
 }

+char **
+monoff(struct wlr_output *wlr_output)
+{
+	char **name;
+	wl_array_for_each(name, &offmons) {
+		if (!strcmp(*name, wlr_output->name))
+			return name;
+	}
+	return NULL;
+}
+
 void
 motionnotify(uint32_t time, struct wlr_input_device *device, double dx, double dy,
 		double dx_unaccel, double dy_unaccel)
@@ -2205,6 +2275,7 @@ outputmgrapplyortest(struct wlr_output_configuration_v1 *config, int test)
 		/* Ensure displays previously disabled by wlr-output-power-management-v1
 		 * are properly handled*/
 		m->asleep = 0;
+		setmonoff(wlr_output, !config_head->state.enabled);

 		/* Don't move monitors if position wouldn't change. This avoids
 		 * wlroots marking the output as manually configured.
@@ -2323,6 +2394,10 @@ powermgrsetmode(struct wl_listener *listener, void *data)

 	m->gamma_lut_changed = 1; /* Reapply gamma LUT when re-enabling the output */
 	wlr_output_state_set_enabled(&state, event->mode);
+	/* The output was reconnected while off and was never modeset */
+	if (event->mode && !m->wlr_output->current_mode)
+		wlr_output_state_set_mode(&state, wlr_output_preferred_mode(m->wlr_output));
+	setmonoff(m->wlr_output, !event->mode);
 	wlr_output_commit_state(m->wlr_output, &state);

 	m->asleep = !event->mode;
@@ -2385,7 +2460,7 @@ void
 resize(Client *c, struct wlr_box geo, int interact)
 {
 	struct wlr_box *bbox;
-	struct wlr_box clip;
+	uint32_t serial;

 	if (!c->mon || !client_surface(c)->mapped)
 		return;
@@ -2396,20 +2471,27 @@ resize(Client *c, struct wlr_box geo, int interact)
 	c->geom = geo;
 	applybounds(c, bbox);

-	/* Update scene-graph, including borders */
-	wlr_scene_node_set_position(&c->scene->node, c->geom.x, c->geom.y);
-	wlr_scene_node_set_position(&c->scene_surface->node, c->bw, c->bw);
-	wlr_scene_rect_set_size(c->border[0], c->geom.width, c->bw);
-	wlr_scene_rect_set_size(c->border[1], c->geom.width, c->bw);
-	wlr_scene_rect_set_size(c->border[2], c->bw, c->geom.height - 2 * c->bw);
-	wlr_scene_rect_set_size(c->border[3], c->bw, c->geom.height - 2 * c->bw);
-	wlr_scene_node_set_position(&c->border[1]->node, 0, c->geom.height - c->bw);
-	wlr_scene_node_set_position(&c->border[2]->node, 0, c->bw);
-	wlr_scene_node_set_position(&c->border[3]->node, c->geom.width - c->bw, c->bw);
+	if ((serial = client_set_size(c, c->geom.width - 2 * c->bw,
+			c->geom.height - 2 * c->bw)))
+		c->resize_serial = serial;

-	client_set_size(c, c->geom.width - 2 * c->bw, c->geom.height - 2 * c->bw);
-	client_get_clip(c, &clip);
-	wlr_scene_subsurface_tree_set_clip(&c->scene_surface->node, &clip);
+	if (interact || (!c->resize_serial && wlr_box_equal(&c->geom, &c->current))) {
+		c->resize_serial = 0;
+		applygeom(c);
+		return;
+	}
+
+	/* Until the transaction is applied, keep showing the current content
+	 * instead of buffers with the new size at the old position. */
+	if (c->resize_serial) {
+		if (!c->snapshot && c->scene->node.enabled
+				&& (c->snapshot = snapshot(&c->scene_surface->node, c->scene, c)))
+			wlr_scene_node_set_enabled(&c->scene_surface->node, 0);
+		/* The scene graph doesn't send frame done events to hidden
+		 * surfaces, but the client may be waiting for one to redraw */
+		client_send_frame_done(c);
+	}
+	transactionschedule();
 }

 void
@@ -2510,14 +2592,10 @@ setcursorshape(struct wl_listener *listener, void *data)
 void
 setfloating(Client *c, int floating)
 {
-	Client *p = client_get_parent(c);
 	c->isfloating = floating;
 	/* If in floating layout do not change the client's layer */
 	if (!c->mon || !client_surface(c)->mapped || !c->mon->lt[c->mon->sellt]->arrange)
 		return;
-	wlr_scene_node_reparent(&c->scene->node, layers[c->isfullscreen ||
-			(p && p->isfullscreen) ? LyrFS
-			: c->isfloating ? LyrFloat : LyrTile]);
 	arrange(c->mon);
 	printstatus();
 }
@@ -2530,8 +2608,6 @@ setfullscreen(Client *c, int fullscreen)
 		return;
 	c->bw = fullscreen ? 0 : borderpx;
 	client_set_fullscreen(c, fullscreen);
-	wlr_scene_node_reparent(&c->scene->node, layers[c->isfullscreen
-			? LyrFS : c->isfloating ? LyrFloat : LyrTile]);

 	if (fullscreen) {
 		c->prev = c->geom;
@@ -2597,6 +2673,22 @@ setmon(Client *c, Monitor *m, uint32_t newtags)
 	focusclient(focustop(selmon), NULL, 1);
 }

+void
+setmonoff(struct wlr_output *wlr_output, int off)
+{
+	char **name = monoff(wlr_output), **last;
+
+	if (off && !name && (name = wl_array_add(&offmons, sizeof(*name)))) {
+		if (!(*name = strdup(wlr_output->name)))
+			offmons.size -= sizeof(*name);
+	} else if (!off && name) {
+		free(*name);
+		last = (char **)((char *)offmons.data + offmons.size) - 1;
+		*name = *last;
+		offmons.size -= sizeof(*name);
+	}
+}
+
 void
 setpsel(struct wl_listener *listener, void *data)
 {
@@ -2735,6 +2827,10 @@ setup(void)
 	wl_list_init(&clients);
 	wl_list_init(&fstack);

+	transaction_timer = wl_event_loop_add_timer(event_loop, transactiontimeout, NULL);
+	wl_array_init(&ghosts);
+	wl_array_init(&offmons);
+
 	xdg_shell = wlr_xdg_shell_create(dpy, 6);
 	wl_signal_add(&xdg_shell->events.new_toplevel, &new_xdg_toplevel);
 	wl_signal_add(&xdg_shell->events.new_popup, &new_xdg_popup);
@@ -2856,6 +2952,57 @@ setup(void)
 #endif
 }

+struct wlr_scene_node *
+snapshot(struct wlr_scene_node *node, struct wlr_scene_tree *parent, void *data)
+{
+	/* Copy the visible part of a scene graph subtree, keeping references to
+	 * the buffers so that they can be shown after the client changes them */
+	struct wlr_scene_node *child, *copy;
+	struct wlr_scene_tree *tree;
+	struct wlr_scene_rect *rect;
+	struct wlr_scene_buffer *src, *buffer;
+
+	if (!node->enabled)
+		return NULL;
+
+	switch (node->type) {
+	case WLR_SCENE_NODE_TREE:
+		tree = wlr_scene_tree_create(parent);
+		wl_list_for_each(child, &wlr_scene_tree_from_node(node)->children, link)
+			snapshot(child, tree, data);
+		copy = &tree->node;
+		break;
+	case WLR_SCENE_NODE_RECT:
+		rect = wlr_scene_rect_from_node(node);
+		copy = &wlr_scene_rect_create(parent, rect->width, rect->height, rect->color)->node;
+		break;
+	case WLR_SCENE_NODE_BUFFER:
+		src = wlr_scene_buffer_from_node(node);
+		buffer = wlr_scene_buffer_create(parent, NULL);
+		wlr_scene_buffer_set_dest_size(buffer, src->dst_width, src->dst_height);
+		wlr_scene_buffer_set_opaque_region(buffer, &src->opaque_region);
+		wlr_scene_buffer_set_opacity(buffer, src->opacity);
+		wlr_scene_buffer_set_filter_mode(buffer, src->filter_mode);
+		wlr_scene_buffer_set_transfer_function(buffer, src->transfer_function);
+		wlr_scene_buffer_set_primaries(buffer, src->primaries);
+		wlr_scene_buffer_set_color_encoding(buffer, src->color_encoding);
+		wlr_scene_buffer_set_color_range(buffer, src->color_range);
+		wlr_scene_buffer_set_source_box(buffer, &src->src_box);
+		wlr_scene_buffer_set_transform(buffer, src->transform);
+		wlr_scene_buffer_set_buffer(buffer, src->buffer);
+		copy = &buffer->node;
+		break;
+	default:
+		return NULL;
+	}
+
+	copy->data = data;
+	wlr_scene_node_set_position(copy, node->x, node->y);
+	if (node->parent == parent)
+		wlr_scene_node_place_above(copy, node);
+	return copy;
+}
+
 void
 spawn(const Arg *arg)
 {
@@ -2875,7 +3022,7 @@ startdrag(struct wl_listener *listener, void *data)
 		return;

 	drag->icon->data = &wlr_scene_drag_icon_create(drag_icon, drag->icon)->node;
-	LISTEN_STATIC(&drag->icon->events.destroy, destroydragicon);
+	wl_signal_add(&drag->icon->events.destroy, &drag_icon_destroy);
 }

 void
@@ -2977,6 +3124,88 @@ toggleview(const Arg *arg)
 	printstatus();
 }

+void
+transactionapply(void)
+{
+	struct wlr_scene_node **ghost;
+	Client *c;
+	Monitor *m;
+
+	wl_event_source_timer_update(transaction_timer, 0);
+	transaction_waiting = 0;
+
+	wl_array_for_each(ghost, &ghosts)
+		wlr_scene_node_destroy(*ghost);
+	ghosts.size = 0;
+
+	wl_list_for_each(c, &clients, link) {
+		c->resize_serial = 0;
+		if (!c->mon)
+			continue;
+		if (c->mon->wlr_output->enabled)
+			wlr_scene_node_set_enabled(&c->scene->node, VISIBLEON(c, c->mon));
+		applygeom(c);
+	}
+
+	wl_list_for_each(m, &mons, link) {
+		if (m->wlr_output->enabled)
+			wlr_scene_node_set_enabled(&m->fullscreen_bg->node,
+					(c = focustop(m)) && c->isfullscreen);
+	}
+
+	motionnotify(0, NULL, 0, 0, 0, 0);
+	checkidleinhibitor(NULL);
+}
+
+void
+transactioncheck(void *data)
+{
+	Client *c;
+
+	transaction_idle = NULL;
+
+	/* Hidden clients don't have to redraw before the layout is shown */
+	wl_list_for_each(c, &clients, link) {
+		if (c->resize_serial && VISIBLEON(c, c->mon) && c->mon->wlr_output->enabled) {
+			if (!transaction_waiting) {
+				/* Don't restart the timer on updates of the pending
+				 * layout, so the delay is bounded */
+				wl_event_source_timer_update(transaction_timer, TRANSACTION_TIMEOUT);
+				transaction_waiting = 1;
+			}
+			return;
+		}
+	}
+
+	transactionapply();
+}
+
+void
+transactioncommit(Client *c, int ready)
+{
+	if (c->resize_serial && ready) {
+		c->resize_serial = 0;
+		transactionschedule();
+	} else if (c->snapshot) {
+		/* This buffer is not shown, let the client draw again */
+		client_send_frame_done(c);
+	}
+}
+
+void
+transactionschedule(void)
+{
+	if (!transaction_idle)
+		transaction_idle = wl_event_loop_add_idle(event_loop, transactioncheck, NULL);
+}
+
+int
+transactiontimeout(void *data)
+{
+	transactionapply();
+	return 0;
+}
+
 void
 unlocksession(struct wl_listener *listener, void *data)
 {
@@ -3003,6 +3232,7 @@ unmapnotify(struct wl_listener *listener, void *data)
 {
 	/* Called when the surface is unmapped, and should no longer be shown. */
 	Client *c = wl_container_of(listener, c, unmap);
+	struct wlr_scene_node *ghost, **slot;
 	if (c == grabc) {
 		cursor_mode = CurNormal;
 		grabc = NULL;
@@ -3011,6 +3241,15 @@ unmapnotify(struct wl_listener *listener, void *data)
 		focused_client = NULL;

 	if (!client_is_unmanaged(c)) {
+		/* Keep showing the client until the transaction rearranging the
+		 * remaining ones is applied, to not show a gap */
+		if ((ghost = snapshot(&c->scene->node, c->scene->node.parent, NULL))) {
+			if ((slot = wl_array_add(&ghosts, sizeof(ghost))))
+				*slot = ghost;
+			else
+				wlr_scene_node_destroy(ghost);
+			transactionschedule();
+		}
 		wl_list_remove(&c->link);
 		setmon(c, NULL, 0);
 		wl_list_remove(&c->flink);
@@ -3034,6 +3273,9 @@ unmapnotify(struct wl_listener *listener, void *data)
 	c->image_capture_source = NULL;
 	wlr_scene_node_destroy(&c->scene->node);
 	client_surface(c)->data = NULL;
+	c->snapshot = NULL;
+	c->resize_serial = 0;
+	c->current = (struct wlr_box){0};
 	printstatus();
 	motionnotify(0, NULL, 0, 0, 0, 0);
 }
@@ -3233,20 +3475,26 @@ xytonode(double x, double y, struct wlr_surface **psurface,
 		Client **pc, LayerSurface **pl, double *nx, double *ny)
 {
 	struct wlr_scene_node *node;
+	struct wlr_scene_surface *scene_surface;
 	struct wlr_surface *surface = NULL;
+	Client *c = NULL;
 	int layer;

-	for (layer = NUM_LAYERS - 1; !surface && layer >= (locked ? LyrBlock : 0); layer--) {
+	for (layer = NUM_LAYERS - 1; !surface && !c && layer >= (locked ? LyrBlock : 0); layer--) {
 		if (layer == LyrIMPopup ||
-				!(node = wlr_scene_node_at(&layers[layer]->node, x, y, nx, ny)))
+				!(node = wlr_scene_node_at(&layers[layer]->node, x, y, nx, ny))
+				|| node->type != WLR_SCENE_NODE_BUFFER)
 			continue;

-		if (node->type == WLR_SCENE_NODE_BUFFER)
-			surface = wlr_scene_surface_try_from_buffer(
-					wlr_scene_buffer_from_node(node))->surface;
+		if ((scene_surface = wlr_scene_surface_try_from_buffer(
+				wlr_scene_buffer_from_node(node))))
+			surface = scene_surface->surface;
+		else /* snapshot of a client during a transaction */
+			c = node->data;
 	}

 	if (psurface) *psurface = surface;
+	if (pc) *pc = c;
 	toplevel_from_wlr_surface(surface, pc, pl);
 }

@@ -3299,10 +3547,21 @@ associatex11(struct wl_listener *listener, void *data)
 {
 	Client *c = wl_container_of(listener, c, associate);

+	LISTEN(&client_surface(c)->events.commit, &c->commit, commitx11);
 	LISTEN(&client_surface(c)->events.map, &c->map, mapnotify);
 	LISTEN(&client_surface(c)->events.unmap, &c->unmap, unmapnotify);
 }

+void
+commitx11(struct wl_listener *listener, void *data)
+{
+	Client *c = wl_container_of(listener, c, commit);
+	struct wlr_surface *surface = client_surface(c);
+
+	transactioncommit(c, surface->current.width == c->geom.width - 2 * (int)c->bw
+			&& surface->current.height == c->geom.height - 2 * (int)c->bw);
+}
+
 void
 configurex11(struct wl_listener *listener, void *data)
 {
@@ -3351,6 +3610,7 @@ void
 dissociatex11(struct wl_listener *listener, void *data)
 {
 	Client *c = wl_container_of(listener, c, dissociate);
+	wl_list_remove(&c->commit.link);
 	wl_list_remove(&c->map.link);
 	wl_list_remove(&c->unmap.link);
 }