Improve CSD logic

This does the following:

* Removes the xdg-decoration surface_commit listener. I was under the
impression the client could ignore the server's preference and set
whatever decoration they like using this protocol, but I don't think
that's right.
* Adds a listener for the xdg-decoration request_mode signal. The
protocol states that the server should respond to this with its
preference. We'll always respond with SSD here.
* Makes it so tiled views which use CSD will still have sway decorations
rendered. To do this, using_csd had to be added back to the view struct,
and the border is changed when floating or unfloating a view.

include/sway/tree/view.h

@@ -76,8 +76,19 @@ struct sway_view {
 	int natural_width, natural_height;
 
 	char *title_format;
+
+	// Our border types are B_NONE, B_PIXEL, B_NORMAL and B_CSD. We normally
+	// just assign this to the border property and ignore the other two.
+	// However, when a view using CSD is tiled, we want to render our own
+	// borders as well. So in this case the border property becomes one of the
+	// first three, and using_csd is true.
+	// Lastly, views can change their decoration mode at any time. When an SSD
+	// view becomes CSD without our approval, we save the SSD border type so it
+	// can be restored if/when the view returns from CSD to SSD.
 	enum sway_container_border border;
 	enum sway_container_border saved_border;
+	bool using_csd;
+
 	int border_thickness;
 	bool border_top;
 	bool border_bottom;

include/sway/xdg_decoration.h

@@ -10,7 +10,7 @@ struct sway_xdg_decoration {
 	struct sway_view *view;
 
 	struct wl_listener destroy;
-	struct wl_listener surface_commit;
+	struct wl_listener request_mode;
 };
 
 struct sway_xdg_decoration *xdg_decoration_from_surface(

sway/commands/border.c

@@ -7,15 +7,49 @@
 #include "sway/tree/container.h"
 #include "sway/tree/view.h"
 
+// A couple of things here:
+// - view->border should never be B_CSD when the view is tiled, even when CSD is
+//   in use (we set using_csd instead and render a sway border).
+// - view->saved_border should be the last applied border when switching to CSD.
+// - view->using_csd should always reflect whether CSD is applied or not.
 static void set_border(struct sway_view *view,
 		enum sway_container_border new_border) {
-	if (view->border == B_CSD && new_border != B_CSD) {
+	if (view->using_csd && new_border != B_CSD) {
 		view_set_csd_from_server(view, false);
-	} else if (view->border != B_CSD && new_border == B_CSD) {
+	} else if (!view->using_csd && new_border == B_CSD) {
 		view_set_csd_from_server(view, true);
-	}
 		view->saved_border = view->border;
+	}
+	if (new_border != B_CSD || container_is_floating(view->container)) {
 		view->border = new_border;
+	}
+	view->using_csd = new_border == B_CSD;
+}
+
+static void border_toggle(struct sway_view *view) {
+	if (view->using_csd) {
+		set_border(view, B_NONE);
+		return;
+	}
+	switch (view->border) {
+	case B_NONE:
+		set_border(view, B_PIXEL);
+		break;
+	case B_PIXEL:
+		set_border(view, B_NORMAL);
+		break;
+	case B_NORMAL:
+		if (view->xdg_decoration) {
+			set_border(view, B_CSD);
+		} else {
+			set_border(view, B_NONE);
+		}
+		break;
+	case B_CSD:
+		// view->using_csd should be true so it would have returned above
+		sway_assert(false, "Unreachable");
+		break;
+	}
 }
 
 struct cmd_results *cmd_border(int argc, char **argv) {
@@ -44,8 +78,7 @@ struct cmd_results *cmd_border(int argc, char **argv) {
 		}
 		set_border(view, B_CSD);
 	} else if (strcmp(argv[0], "toggle") == 0) {
-		int num_available = view->xdg_decoration ? 4 : 3;
-		set_border(view, (view->border + 1) % num_available);
+		border_toggle(view);
 	} else {
 		return cmd_results_new(CMD_INVALID, "border",
 				"Expected 'border <none|normal|pixel|toggle>' "

sway/tree/container.c

@@ -669,6 +669,9 @@ void container_set_floating(struct sway_container *container, bool enable) {
 		container_init_floating(container);
 		if (container->view) {
 			view_set_tiled(container->view, false);
+			if (container->view->using_csd) {
+				container->view->border = B_CSD;
+			}
 		}
 		if (old_parent) {
 			container_reap_empty(old_parent);
@@ -695,6 +698,9 @@ void container_set_floating(struct sway_container *container, bool enable) {
 		}
 		if (container->view) {
 			view_set_tiled(container->view, true);
+			if (container->view->using_csd) {
+				container->view->border = container->view->saved_border;
+			}
 		}
 		container->is_sticky = false;
 	}

sway/tree/view.c

@@ -309,6 +309,7 @@ void view_request_activate(struct sway_view *view) {
 }
 
 void view_set_csd_from_server(struct sway_view *view, bool enabled) {
+	wlr_log(WLR_DEBUG, "Telling view %p to set CSD to %i", view, enabled);
 	if (view->xdg_decoration) {
 		uint32_t mode = enabled ?
 			WLR_XDG_TOPLEVEL_DECORATION_V1_MODE_CLIENT_SIDE :
@@ -316,15 +317,20 @@ void view_set_csd_from_server(struct sway_view *view, bool enabled) {
 		wlr_xdg_toplevel_decoration_v1_set_mode(
 				view->xdg_decoration->wlr_xdg_decoration, mode);
 	}
+	view->using_csd = enabled;
 }
 
 void view_update_csd_from_client(struct sway_view *view, bool enabled) {
+	wlr_log(WLR_DEBUG, "View %p updated CSD to %i", view, enabled);
 	if (enabled && view->border != B_CSD) {
 		view->saved_border = view->border;
+		if (container_is_floating(view->container)) {
 			view->border = B_CSD;
+		}
 	} else if (!enabled && view->border == B_CSD) {
 		view->border = view->saved_border;
 	}
+	view->using_csd = enabled;
 }
 
 void view_set_tiled(struct sway_view *view, bool tiled) {

sway/xdg_decoration.c

@@ -12,31 +12,22 @@ static void xdg_decoration_handle_destroy(struct wl_listener *listener,
 		wl_container_of(listener, deco, destroy);
 	deco->view->xdg_decoration = NULL;
 	wl_list_remove(&deco->destroy.link);
-	wl_list_remove(&deco->surface_commit.link);
+	wl_list_remove(&deco->request_mode.link);
 	wl_list_remove(&deco->link);
 	free(deco);
 }
 
-static void xdg_decoration_handle_surface_commit(struct wl_listener *listener,
+static void xdg_decoration_handle_request_mode(struct wl_listener *listener,
 		void *data) {
-	struct sway_xdg_decoration *decoration =
-		wl_container_of(listener, decoration, surface_commit);
-
-	bool csd = decoration->wlr_xdg_decoration->current_mode ==
-		WLR_XDG_TOPLEVEL_DECORATION_V1_MODE_CLIENT_SIDE;
-	struct sway_view *view = decoration->view;
-
-	view_update_csd_from_client(view, csd);
-
-	arrange_container(view->container);
-	transaction_commit_dirty();
+	struct sway_xdg_decoration *deco =
+		wl_container_of(listener, deco, request_mode);
+	wlr_xdg_toplevel_decoration_v1_set_mode(deco->wlr_xdg_decoration,
+			WLR_XDG_TOPLEVEL_DECORATION_V1_MODE_SERVER_SIDE);
 }
 
 void handle_xdg_decoration(struct wl_listener *listener, void *data) {
 	struct wlr_xdg_toplevel_decoration_v1 *wlr_deco = data;
 	struct sway_xdg_shell_view *xdg_shell_view = wlr_deco->surface->data;
-	struct wlr_xdg_surface *wlr_xdg_surface =
-		xdg_shell_view->view.wlr_xdg_surface;
 
 	struct sway_xdg_decoration *deco = calloc(1, sizeof(*deco));
 	if (deco == NULL) {
@@ -50,13 +41,8 @@ void handle_xdg_decoration(struct wl_listener *listener, void *data) {
 	wl_signal_add(&wlr_deco->events.destroy, &deco->destroy);
 	deco->destroy.notify = xdg_decoration_handle_destroy;
 
-	// Note: We don't listen to the request_mode signal here, effectively
-	// ignoring any modes the client asks to set. The client can still force a
-	// mode upon us, in which case we get upset but live with it.
-
-	deco->surface_commit.notify = xdg_decoration_handle_surface_commit;
-	wl_signal_add(&wlr_xdg_surface->surface->events.commit,
-		&deco->surface_commit);
+	wl_signal_add(&wlr_deco->events.request_mode, &deco->request_mode);
+	deco->request_mode.notify = xdg_decoration_handle_request_mode;
 
 	wl_list_insert(&server.xdg_decorations, &deco->link);
 }