Add CSD to border modes

This replaces view.using_csd with a new border mode: B_CSD. This also
removes sway_xdg_shell{_v6}_view.deco_mode and
view->has_client_side_decorations as we can now get these from the
border.

You can use `border toggle` to cycle through the modes including CSD, or
use `border csd` to set it directly. The client must support the
xdg-decoration protocol, and the only client I know of that does is the
example in wlroots.

If the client switches from SSD to CSD without us expecting it (via the
server-decoration protocol), we stash the previous border type into
view.saved_border so we can restore it if the client returns to SSD. I
haven't found a way to test this though.

4 files changed, 40 insertions, 7 deletions

diff --git a/include/sway/server.h b/include/sway/server.h
index 5dabb61f..3e1cbb33 100644
--- a/include/sway/server.h
+++ b/include/sway/server.h
@@ -54,6 +54,10 @@ struct sway_server {
 	struct wl_listener server_decoration;
 	struct wl_list decorations; // sway_server_decoration::link
 
+	struct wlr_xdg_decoration_manager_v1 *xdg_decoration_manager;
+	struct wl_listener xdg_decoration;
+	struct wl_list xdg_decorations; // sway_xdg_decoration::link
+
 	size_t txn_timeout_ms;
 	list_t *transactions;
 	list_t *dirty_nodes;
@@ -78,5 +82,6 @@ void handle_xdg_shell_surface(struct wl_listener *listener, void *data);
 void handle_xwayland_surface(struct wl_listener *listener, void *data);
 #endif
 void handle_server_decoration(struct wl_listener *listener, void *data);
+void handle_xdg_decoration(struct wl_listener *listener, void *data);
 
 #endif
diff --git a/include/sway/tree/container.h b/include/sway/tree/container.h
index 5e281a2f..6019602c 100644
--- a/include/sway/tree/container.h
+++ b/include/sway/tree/container.h
@@ -28,6 +28,7 @@ enum sway_container_border {
 	B_NONE,
 	B_PIXEL,
 	B_NORMAL,
+	B_CSD,
 };
 
 struct sway_root;
@@ -63,7 +64,6 @@ struct sway_container_state {
 	bool border_bottom;
 	bool border_left;
 	bool border_right;
-	bool using_csd;
 };
 
 struct sway_container {
diff --git a/include/sway/tree/view.h b/include/sway/tree/view.h
index d10251dd..49df7c88 100644
--- a/include/sway/tree/view.h
+++ b/include/sway/tree/view.h
@@ -11,6 +11,7 @@
 #include "sway/input/seat.h"
 
 struct sway_container;
+struct sway_xdg_decoration;
 
 enum sway_view_type {
 	SWAY_VIEW_XDG_SHELL_V6,
@@ -44,7 +45,6 @@ struct sway_view_impl {
 	void (*set_tiled)(struct sway_view *view, bool tiled);
 	void (*set_fullscreen)(struct sway_view *view, bool fullscreen);
 	bool (*wants_floating)(struct sway_view *view);
-	bool (*has_client_side_decorations)(struct sway_view *view);
 	void (*for_each_surface)(struct sway_view *view,
 		wlr_surface_iterator_func_t iterator, void *user_data);
 	void (*for_each_popup)(struct sway_view *view,
@@ -60,6 +60,7 @@ struct sway_view {
 
 	struct sway_container *container; // NULL if unmapped and transactions finished
 	struct wlr_surface *surface; // NULL for unmapped views
+	struct sway_xdg_decoration *xdg_decoration;
 
 	pid_t pid;
 
@@ -76,12 +77,12 @@ struct sway_view {
 
 	char *title_format;
 	enum sway_container_border border;
+	enum sway_container_border saved_border;
 	int border_thickness;
 	bool border_top;
 	bool border_bottom;
 	bool border_left;
 	bool border_right;
-	bool using_csd;
 
 	struct timespec urgent;
 	bool allow_request_urgent;
@@ -127,8 +128,6 @@ struct sway_view {
 struct sway_xdg_shell_v6_view {
 	struct sway_view view;
 
-	enum wlr_server_decoration_manager_mode deco_mode;
-
 	struct wl_listener commit;
 	struct wl_listener request_move;
 	struct wl_listener request_resize;
@@ -145,8 +144,6 @@ struct sway_xdg_shell_v6_view {
 struct sway_xdg_shell_view {
 	struct sway_view view;
 
-	enum wlr_server_decoration_manager_mode deco_mode;
-
 	struct wl_listener commit;
 	struct wl_listener request_move;
 	struct wl_listener request_resize;
@@ -175,6 +172,7 @@ struct sway_xwayland_view {
 	struct wl_listener set_role;
 	struct wl_listener set_window_type;
 	struct wl_listener set_hints;
+	struct wl_listener set_decorations;
 	struct wl_listener map;
 	struct wl_listener unmap;
 	struct wl_listener destroy;
@@ -268,6 +266,17 @@ void view_set_activated(struct sway_view *view, bool activated);
  */
 void view_request_activate(struct sway_view *view);
 
+/**
+ * If possible, instructs the client to change their decoration mode.
+ */
+void view_set_csd_from_server(struct sway_view *view, bool enabled);
+
+/**
+ * Updates the view's border setting when the client unexpectedly changes their
+ * decoration mode.
+ */
+void view_set_csd_from_client(struct sway_view *view, bool enabled);
+
 void view_set_tiled(struct sway_view *view, bool tiled);
 
 void view_close(struct sway_view *view);
diff --git a/include/sway/xdg_decoration.h b/include/sway/xdg_decoration.h
new file mode 100644
index 00000000..46fb8d34
--- /dev/null
+++ b/include/sway/xdg_decoration.h
@@ -0,0 +1,19 @@
+#ifndef _SWAY_XDG_DECORATION_H
+#define _SWAY_XDG_DECORATION_H
+
+#include <wlr/types/wlr_xdg_decoration_v1.h>
+
+struct sway_xdg_decoration {
+	struct wlr_xdg_toplevel_decoration_v1 *wlr_xdg_decoration;
+	struct wl_list link;
+
+	struct sway_view *view;
+
+	struct wl_listener destroy;
+	struct wl_listener surface_commit;
+};
+
+struct sway_xdg_decoration *xdg_decoration_from_surface(
+	struct wlr_surface *surface);
+
+#endif