gtk-primary-selection: refactor everything, untie from seat

This commits completely refactors wlr_gtk_primary_selection. The goal is to
remove gtk-primary-selection state from the seat and better handle inert
resources where it makes sense.

wlr_seat_client.primary_selection_devices has been removed and replaced by
wlr_gtk_primary_selection_device. This allows us to make offers inert when the
current selection is replaced.

wlr_seat_set_primary_selection has been removed because it relied on wlr_seat
instead of wlr_gtk_primary_selection_device_manager. A new function,
wlr_gtk_primary_selection_device_manager_set_selection (candidate for the
longest function name in wlroots) has been added. It doesn't take a serial
anymore as serial checking only makes sense for set_selection requests coming
from Wayland clients (serial checking is now done in the Wayland interface
implementation).

Since wlr_gtk_primary_selection_device_manager is now required to set the
selection, a new function wlr_xwayland_set_gtk_primary_selection_device_manager
(candidate number two for longest function name) has been added.

Devices are now made inert when the seat goes away.

Future work includes removing the last primary selection bits from the seat,
mainly wlr_seat.primary_selection_source and wlr_seat.events.primary_selection,
replacing those with new fields in wlr_gtk_primary_selection_device. Or maybe
we could keep those in the seat and replace them with a re-usable interface
(for future zwp_primary_selection_v1 support). We need to think how we'll sync
these three protocols (GTK, X11 and wayland-protocols).

See https://github.com/swaywm/wlroots/issues/1388

3 files changed, 52 insertions, 10 deletions

diff --git a/include/wlr/types/wlr_gtk_primary_selection.h b/include/wlr/types/wlr_gtk_primary_selection.h
index f3410f69..e2019123 100644
--- a/include/wlr/types/wlr_gtk_primary_selection.h
+++ b/include/wlr/types/wlr_gtk_primary_selection.h
@@ -14,7 +14,8 @@
 
 struct wlr_gtk_primary_selection_device_manager {
 	struct wl_global *global;
-	struct wl_list resources;
+	struct wl_list resources; // wl_resource_get_link
+	struct wl_list devices; // wlr_gtk_primary_selection_device::link
 
 	struct wl_listener display_destroy;
 
@@ -25,6 +26,28 @@ struct wlr_gtk_primary_selection_device_manager {
 	void *data;
 };
 
+/**
+ * A device is a per-seat object used to set and get the current selection.
+ */
+struct wlr_gtk_primary_selection_device {
+	struct wlr_gtk_primary_selection_device_manager *manager;
+	struct wlr_seat *seat;
+	struct wl_list link; // wlr_gtk_primary_selection_device_manager::devices
+	struct wl_list resources; // wl_resource_get_link
+
+	struct wlr_gtk_primary_selection_source *source;
+	struct wl_list offers; // wlr_gtk_primary_selection_offer::link
+
+	struct wl_listener seat_destroy;
+	struct wl_listener seat_focus_change;
+	struct wl_listener source_destroy;
+
+	void *data;
+};
+
+/**
+ * A source is the sending side of a selection.
+ */
 struct wlr_gtk_primary_selection_source {
 	// source metadata
 	struct wl_array mime_types;
@@ -34,9 +57,6 @@ struct wlr_gtk_primary_selection_source {
 		const char *mime_type, int32_t fd);
 	void (*cancel)(struct wlr_gtk_primary_selection_source *source);
 
-	// source status
-	struct wlr_seat_client *seat_client;
-
 	struct {
 		struct wl_signal destroy;
 	} events;
@@ -44,9 +64,15 @@ struct wlr_gtk_primary_selection_source {
 	void *data;
 };
 
+/**
+ * An offer is the receiving side of a selection. When the selection is set,
+ * offers are created for the currently focused client and can be used to
+ * initiate the data transfer.
+ */
 struct wlr_gtk_primary_selection_offer {
 	struct wl_resource *resource;
 	struct wlr_gtk_primary_selection_source *source;
+	struct wl_list link; // wlr_gtk_primary_selection_device::offers
 
 	struct wl_listener source_destroy;
 
@@ -58,9 +84,10 @@ struct wlr_gtk_primary_selection_device_manager *
 void wlr_gtk_primary_selection_device_manager_destroy(
 	struct wlr_gtk_primary_selection_device_manager *manager);
 
-void wlr_seat_client_send_gtk_primary_selection(struct wlr_seat_client *seat_client);
-void wlr_seat_set_gtk_primary_selection(struct wlr_seat *seat,
-	struct wlr_gtk_primary_selection_source *source, uint32_t serial);
+void wlr_gtk_primary_selection_device_manager_set_selection(
+	struct wlr_gtk_primary_selection_device_manager *manager,
+	struct wlr_seat *seat,
+	struct wlr_gtk_primary_selection_source *source);
 
 void wlr_gtk_primary_selection_source_init(
 	struct wlr_gtk_primary_selection_source *source);
diff --git a/include/wlr/types/wlr_seat.h b/include/wlr/types/wlr_seat.h
index 9670e6a5..f064c3bb 100644
--- a/include/wlr/types/wlr_seat.h
+++ b/include/wlr/types/wlr_seat.h
@@ -30,7 +30,6 @@ struct wlr_seat_client {
 	struct wl_list keyboards;
 	struct wl_list touches;
 	struct wl_list data_devices;
-	struct wl_list primary_selection_devices;
 
 	struct {
 		struct wl_signal destroy;
@@ -168,6 +167,10 @@ struct wlr_seat_keyboard_state {
 
 	struct wlr_seat_keyboard_grab *grab;
 	struct wlr_seat_keyboard_grab *default_grab;
+
+	struct {
+		struct wl_signal focus_change; // wlr_seat_keyboard_focus_change_event
+	} events;
 };
 
 struct wlr_seat_touch_state {
@@ -194,6 +197,7 @@ struct wlr_seat {
 	struct wlr_data_source *selection_source;
 	uint32_t selection_serial;
 
+	// not owned by the seat
 	struct wlr_gtk_primary_selection_source *primary_selection_source;
 	uint32_t primary_selection_serial;
 
@@ -208,7 +212,6 @@ struct wlr_seat {
 
 	struct wl_listener display_destroy;
 	struct wl_listener selection_source_destroy;
-	struct wl_listener primary_selection_source_destroy;
 	struct wl_listener drag_source_destroy;
 
 	struct {
@@ -248,6 +251,11 @@ struct wlr_seat_pointer_focus_change_event {
 	double sx, sy;
 };
 
+struct wlr_seat_keyboard_focus_change_event {
+	struct wlr_seat *seat;
+	struct wlr_surface *old_surface, *new_surface;
+};
+
 /**
  * Allocates a new wlr_seat and adds a wl_seat global to the display.
  */
diff --git a/include/wlr/xwayland.h b/include/wlr/xwayland.h
index 8247aa15..9a7f0f07 100644
--- a/include/wlr/xwayland.h
+++ b/include/wlr/xwayland.h
@@ -18,6 +18,7 @@
 
 struct wlr_xwm;
 struct wlr_xwayland_cursor;
+struct wlr_gtk_primary_selection_device_manager;
 
 struct wlr_xwayland {
 	pid_t pid;
@@ -42,13 +43,15 @@ struct wlr_xwayland {
 	struct wl_display *wl_display;
 	struct wlr_compositor *compositor;
 	struct wlr_seat *seat;
-	struct wl_listener seat_destroy;
+	struct wlr_gtk_primary_selection_device_manager *gtk_primary_selection;
 
 	struct {
 		struct wl_signal ready;
 		struct wl_signal new_surface;
 	} events;
 
+	struct wl_listener seat_destroy;
+
 	/**
 	 * Add a custom event handler to xwayland. Return 1 if the event was
 	 * handled or 0 to use the default wlr-xwayland handler. wlr-xwayland will
@@ -223,6 +226,10 @@ void wlr_xwayland_surface_set_fullscreen(struct wlr_xwayland_surface *surface,
 void wlr_xwayland_set_seat(struct wlr_xwayland *xwayland,
 	struct wlr_seat *seat);
 
+void wlr_xwayland_set_gtk_primary_selection_device_manager(
+	struct wlr_xwayland *xwayland,
+	struct wlr_gtk_primary_selection_device_manager *manager);
+
 bool wlr_surface_is_xwayland_surface(struct wlr_surface *surface);
 
 struct wlr_xwayland_surface *wlr_xwayland_surface_from_wlr_surface(