Implement keyboard grab support for Wayland

Use zwp_keyboard_shortcuts_inhibit_manager_v1 to allow SDL applications
to capture system keyboard shortcuts like Alt+Tab when keyboard grab is
enabled via SDL_HINT_GRAB_KEYBOARD.

src/video/wayland/SDL_waylandevents.c

@@ -41,6 +41,7 @@
 #include "relative-pointer-unstable-v1-client-protocol.h"
 #include "xdg-shell-client-protocol.h"
 #include "xdg-shell-unstable-v6-client-protocol.h"
+#include "keyboard-shortcuts-inhibit-unstable-v1-client-protocol.h"
 
 #ifdef SDL_INPUT_LINUXEV
 #include <linux/input.h>
@@ -1418,6 +1419,37 @@ int Wayland_input_unconfine_pointer(struct SDL_WaylandInput *input)
     return 0;
 }
 
+int Wayland_input_grab_keyboard(SDL_Window *window, struct SDL_WaylandInput *input)
+{
+    SDL_WindowData *w = window->driverdata;
+    SDL_VideoData *d = input->display;
+
+    if (!d->key_inhibitor_manager)
+        return -1;
+
+    if (w->key_inhibitor)
+        return 0;
+
+    w->key_inhibitor =
+        zwp_keyboard_shortcuts_inhibit_manager_v1_inhibit_shortcuts(d->key_inhibitor_manager,
+                                                                    w->surface,
+                                                                    input->seat);
+    
+    return 0;
+}
+
+int Wayland_input_ungrab_keyboard(SDL_Window *window)
+{
+    SDL_WindowData *w = window->driverdata;
+
+    if (w->key_inhibitor) {
+        zwp_keyboard_shortcuts_inhibitor_v1_destroy(w->key_inhibitor);
+        w->key_inhibitor = NULL;
+    }
+
+    return 0;
+}
+
 #endif /* SDL_VIDEO_DRIVER_WAYLAND */
 
 /* vi: set ts=4 sw=4 expandtab: */

src/video/wayland/SDL_waylandevents_c.h

@@ -49,6 +49,9 @@ extern int Wayland_input_unconfine_pointer(struct SDL_WaylandInput *input);
 extern void Wayland_display_add_relative_pointer_manager(SDL_VideoData *d, uint32_t id);
 extern void Wayland_display_destroy_relative_pointer_manager(SDL_VideoData *d);
 
+extern int Wayland_input_grab_keyboard(SDL_Window *window, struct SDL_WaylandInput *input);
+extern int Wayland_input_ungrab_keyboard(SDL_Window *window);
+
 #endif /* SDL_waylandevents_h_ */
 
 /* vi: set ts=4 sw=4 expandtab: */

src/video/wayland/SDL_waylandvideo.c

@@ -49,6 +49,7 @@
 #include "xdg-shell-unstable-v6-client-protocol.h"
 #include "xdg-decoration-unstable-v1-client-protocol.h"
 #include "org-kde-kwin-server-decoration-manager-client-protocol.h"
+#include "keyboard-shortcuts-inhibit-unstable-v1-client-protocol.h"
 
 #define WAYLANDVID_DRIVER_NAME "wayland"
 
@@ -393,6 +394,8 @@ display_handle_global(void *data, struct wl_registry *registry, uint32_t id,
         Wayland_display_add_relative_pointer_manager(d, id);
     } else if (strcmp(interface, "zwp_pointer_constraints_v1") == 0) {
         Wayland_display_add_pointer_constraints(d, id);
+    } else if (strcmp(interface, "zwp_keyboard_shortcuts_inhibit_manager_v1") == 0) {
+        d->key_inhibitor_manager = wl_registry_bind(d->registry, id, &zwp_keyboard_shortcuts_inhibit_manager_v1_interface, 1);
     } else if (strcmp(interface, "wl_data_device_manager") == 0) {
         d->data_device_manager = wl_registry_bind(d->registry, id, &wl_data_device_manager_interface, SDL_min(3, version));
     } else if (strcmp(interface, "zxdg_decoration_manager_v1") == 0) {
@@ -493,6 +496,9 @@ Wayland_VideoQuit(_THIS)
     Wayland_display_destroy_pointer_constraints(data);
     Wayland_display_destroy_relative_pointer_manager(data);
 
+    if (data->key_inhibitor_manager)
+        zwp_keyboard_shortcuts_inhibit_manager_v1_destroy(data->key_inhibitor_manager);
+
     if (data->xkb_context) {
         WAYLAND_xkb_context_unref(data->xkb_context);
         data->xkb_context = NULL;

src/video/wayland/SDL_waylandvideo.h

@@ -64,6 +64,7 @@ typedef struct {
     struct wl_data_device_manager *data_device_manager;
     struct zxdg_decoration_manager_v1 *decoration_manager;
     struct org_kde_kwin_server_decoration_manager *kwin_server_decoration_manager;
+    struct zwp_keyboard_shortcuts_inhibit_manager_v1 *key_inhibitor_manager;
 
     EGLDisplay edpy;
     EGLContext context;

src/video/wayland/SDL_waylandwindow.c

@@ -636,10 +636,15 @@ Wayland_SetWindowGrab(_THIS, SDL_Window *window, SDL_bool grabbed)
 {
     SDL_VideoData *data = (SDL_VideoData *) _this->driverdata;
 
-    if (grabbed)
+    if (grabbed) {
         Wayland_input_confine_pointer(window, data->input);
-    else
+
+        if (SDL_GetHintBoolean(SDL_HINT_GRAB_KEYBOARD, SDL_FALSE))
+            Wayland_input_grab_keyboard(window, data->input);
+    } else {
+        Wayland_input_ungrab_keyboard(window);
         Wayland_input_unconfine_pointer(data->input);
+    }
 }
 
 int Wayland_CreateWindow(_THIS, SDL_Window *window)

src/video/wayland/SDL_waylandwindow.h

@@ -65,6 +65,7 @@ typedef struct {
     struct zwp_locked_pointer_v1 *locked_pointer;
     struct zxdg_toplevel_decoration_v1 *server_decoration;
     struct org_kde_kwin_server_decoration *kwin_server_decoration;
+    struct zwp_keyboard_shortcuts_inhibitor_v1 *key_inhibitor;
 
 #ifdef SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH
     struct qt_extended_surface *extended_surface;