kiosk-shell: Add transform_handler to correctly position xwayland surfaces

When using xwayland surfaces and multiple outputs we need to notify
xwayland surface that the surface position has changed, otherwise we're
going to end up with pop-ups being displayed on other outputs rather
than the one were the main surface resides.

Stolen from desktop-shell.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Suggested-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>

kiosk-shell/kiosk-shell.c

@@ -35,6 +35,8 @@
 #include "shared/helpers.h"
 #include "util.h"
 
+#include <libweston/xwayland-api.h>
+
 static struct kiosk_shell_surface *
 get_kiosk_shell_surface(struct weston_surface *surface)
 {
@@ -63,6 +65,35 @@ get_kiosk_shell_seat(struct weston_seat *seat)
 			    struct kiosk_shell_seat, seat_destroy_listener);
 }
 
+static void
+transform_handler(struct wl_listener *listener, void *data)
+{
+	struct weston_surface *surface = data;
+	struct kiosk_shell_surface *shsurf = get_kiosk_shell_surface(surface);
+	const struct weston_xwayland_surface_api *api;
+	int x, y;
+
+	if (!shsurf)
+		return;
+
+	api = shsurf->shell->xwayland_surface_api;
+	if (!api) {
+		api = weston_xwayland_surface_get_api(shsurf->shell->compositor);
+		shsurf->shell->xwayland_surface_api = api;
+	}
+
+	if (!api || !api->is_xwayland_surface(surface))
+		return;
+
+	if (!weston_view_is_mapped(shsurf->view))
+		return;
+
+	x = shsurf->view->geometry.x;
+	y = shsurf->view->geometry.y;
+
+	api->send_position(surface, x, y);
+}
+
 /*
  * kiosk_shell_surface
  */
@@ -1015,6 +1046,7 @@ kiosk_shell_destroy(struct wl_listener *listener, void *data)
 	wl_list_remove(&shell->output_resized_listener.link);
 	wl_list_remove(&shell->output_moved_listener.link);
 	wl_list_remove(&shell->seat_created_listener.link);
+	wl_list_remove(&shell->transform_listener.link);
 
 	wl_list_for_each_safe(shoutput, tmp, &shell->output_list, link) {
 		kiosk_shell_output_destroy(shoutput);
@@ -1050,6 +1082,9 @@ wet_shell_init(struct weston_compositor *ec,
 		return 0;
 	}
 
+	shell->transform_listener.notify = transform_handler;
+	wl_signal_add(&ec->transform_signal, &shell->transform_listener);
+
 	weston_layer_init(&shell->background_layer, ec);
 	weston_layer_init(&shell->normal_layer, ec);
 

kiosk-shell/kiosk-shell.h

@@ -36,12 +36,15 @@ struct kiosk_shell {
 	struct wl_listener output_resized_listener;
 	struct wl_listener output_moved_listener;
 	struct wl_listener seat_created_listener;
+	struct wl_listener transform_listener;
 
 	struct weston_layer background_layer;
 	struct weston_layer normal_layer;
 
 	struct wl_list output_list;
 	struct wl_list seat_list;
+
+	const struct weston_xwayland_surface_api *xwayland_surface_api;
 };
 
 struct kiosk_shell_surface {