wayland: Add the xdg-foreign-unstable-v2 protocol

Add the xdg-foreign-unstable-v2 protocol and use it to create export handles for toplevel windows, which will be used when an external component, such as the file chooser portal, requires it.

src/video/wayland/SDL_waylandvideo.c

@@ -57,6 +57,7 @@
 #include "viewporter-client-protocol.h"
 #include "xdg-activation-v1-client-protocol.h"
 #include "xdg-decoration-unstable-v1-client-protocol.h"
+#include "xdg-foreign-unstable-v2-client-protocol.h"
 #include "xdg-output-unstable-v1-client-protocol.h"
 #include "xdg-shell-client-protocol.h"
 
@@ -1078,6 +1079,8 @@ static void display_handle_global(void *data, struct wl_registry *registry, uint
         if (d->input) {
             Wayland_CreateCursorShapeDevice(d->input);
         }
+    } else if (SDL_strcmp(interface, "zxdg_exporter_v2") == 0) {
+        d->zxdg_exporter_v2 = wl_registry_bind(d->registry, id, &zxdg_exporter_v2_interface, 1);
     } else if (SDL_strcmp(interface, "kde_output_order_v1") == 0) {
         d->kde_output_order = wl_registry_bind(d->registry, id, &kde_output_order_v1_interface, 1);
         kde_output_order_v1_add_listener(d->kde_output_order, &kde_output_order_listener, d);
@@ -1331,6 +1334,11 @@ static void Wayland_VideoCleanup(SDL_VideoDevice *_this)
         data->cursor_shape_manager = NULL;
     }
 
+    if (data->zxdg_exporter_v2) {
+        zxdg_exporter_v2_destroy(data->zxdg_exporter_v2);
+        data->zxdg_exporter_v2 = NULL;
+    }
+
     if (data->kde_output_order) {
         Wayland_FlushOutputOrder(data);
         kde_output_order_v1_destroy(data->kde_output_order);

src/video/wayland/SDL_waylandvideo.h

@@ -79,6 +79,7 @@ struct SDL_VideoData
     struct wp_viewporter *viewporter;
     struct wp_fractional_scale_manager_v1 *fractional_scale_manager;
     struct zwp_input_timestamps_manager_v1 *input_timestamps_manager;
+    struct zxdg_exporter_v2 *zxdg_exporter_v2;
     struct kde_output_order_v1 *kde_output_order;
 
     struct xkb_context *xkb_context;

src/video/wayland/SDL_waylandwindow.c

@@ -38,6 +38,7 @@
 #include "xdg-activation-v1-client-protocol.h"
 #include "viewporter-client-protocol.h"
 #include "fractional-scale-v1-client-protocol.h"
+#include "xdg-foreign-unstable-v2-client-protocol.h"
 
 #ifdef HAVE_LIBDECOR_H
 #include <libdecor.h>
@@ -1484,6 +1485,21 @@ static struct wl_callback_listener show_hide_sync_listener = {
     show_hide_sync_handler
 };
 
+static void exported_handle_handler(void *data, struct zxdg_exported_v2 *zxdg_exported_v2, const char *handle)
+{
+    SDL_WindowData *wind = (SDL_WindowData*)data;
+    SDL_PropertiesID props = SDL_GetWindowProperties(wind->sdlwindow);
+
+    SDL_free(wind->export_handle);
+    wind->export_handle = SDL_strdup(handle);
+
+    SDL_SetProperty(props, SDL_PROP_WINDOW_WAYLAND_XDG_TOPLEVEL_EXPORT_HANDLE_POINTER, wind->export_handle);
+}
+
+static struct zxdg_exported_v2_listener exported_v2_listener = {
+    exported_handle_handler
+};
+
 void Wayland_ShowWindow(SDL_VideoDevice *_this, SDL_Window *window)
 {
     SDL_VideoData *c = _this->driverdata;
@@ -1549,6 +1565,11 @@ void Wayland_ShowWindow(SDL_VideoDevice *_this, SDL_Window *window)
             libdecor_frame_set_app_id(data->shell_surface.libdecor.frame, data->app_id);
             libdecor_frame_map(data->shell_surface.libdecor.frame);
 
+            if (c->zxdg_exporter_v2) {
+                data->exported = zxdg_exporter_v2_export_toplevel(c->zxdg_exporter_v2, data->surface);
+                zxdg_exported_v2_add_listener(data->exported, &exported_v2_listener, data);
+            }
+
             SDL_SetProperty(props, SDL_PROP_WINDOW_WAYLAND_XDG_SURFACE_POINTER, libdecor_frame_get_xdg_surface(data->shell_surface.libdecor.frame));
             SDL_SetProperty(props, SDL_PROP_WINDOW_WAYLAND_XDG_TOPLEVEL_POINTER, libdecor_frame_get_xdg_toplevel(data->shell_surface.libdecor.frame));
         }
@@ -1623,6 +1644,12 @@ void Wayland_ShowWindow(SDL_VideoDevice *_this, SDL_Window *window)
             data->shell_surface.xdg.roleobj.toplevel = xdg_surface_get_toplevel(data->shell_surface.xdg.surface);
             xdg_toplevel_set_app_id(data->shell_surface.xdg.roleobj.toplevel, data->app_id);
             xdg_toplevel_add_listener(data->shell_surface.xdg.roleobj.toplevel, &toplevel_listener_xdg, data);
+
+            if (c->zxdg_exporter_v2) {
+                data->exported = zxdg_exporter_v2_export_toplevel(c->zxdg_exporter_v2, data->surface);
+                zxdg_exported_v2_add_listener(data->exported, &exported_v2_listener, data);
+            }
+
             SDL_SetProperty(props, SDL_PROP_WINDOW_WAYLAND_XDG_TOPLEVEL_POINTER, data->shell_surface.xdg.roleobj.toplevel);
         }
     }
@@ -1699,7 +1726,6 @@ void Wayland_ShowWindow(SDL_VideoDevice *_this, SDL_Window *window)
     Wayland_SetWindowResizable(_this, window, !!(window->flags & SDL_WINDOW_RESIZABLE));
     Wayland_SetWindowBordered(_this, window, !(window->flags & SDL_WINDOW_BORDERLESS));
 
-
     /* We're finally done putting the window together, raise if possible */
     if (c->activation_manager) {
         /* Note that we don't check for empty strings, as that is still
@@ -1798,6 +1824,17 @@ void Wayland_HideWindow(SDL_VideoDevice *_this, SDL_Window *window)
         wl_surface_commit(wind->surface);
     }
 
+    /* Clean up the export handle. */
+    if (wind->exported) {
+        zxdg_exported_v2_destroy(wind->exported);
+        wind->exported = NULL;
+
+        SDL_free(wind->export_handle);
+        wind->export_handle = NULL;
+
+        SDL_SetProperty(props, SDL_PROP_WINDOW_WAYLAND_XDG_TOPLEVEL_EXPORT_HANDLE_POINTER, NULL);
+    }
+
 #ifdef HAVE_LIBDECOR_H
     if (wind->shell_surface_type == WAYLAND_SURFACE_LIBDECOR) {
         if (wind->shell_surface.libdecor.frame) {

src/video/wayland/SDL_waylandwindow.h

@@ -95,6 +95,7 @@ struct SDL_WindowData
     struct xdg_activation_token_v1 *activation_token;
     struct wp_viewport *viewport;
     struct wp_fractional_scale_v1 *fractional_scale;
+    struct zxdg_exported_v2 *exported;
 
     SDL_AtomicInt swap_interval_ready;
 
@@ -104,6 +105,7 @@ struct SDL_WindowData
     SDL_Window *keyboard_focus;
 
     char *app_id;
+    char *export_handle;
     float windowed_scale_factor;
 
     struct