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

@@ -636,11 +636,16 @@ 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;

wayland-protocols/keyboard-shortcuts-inhibit-unstable-v1.xml

@@ -0,0 +1,143 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="keyboard_shortcuts_inhibit_unstable_v1">
+
+  <copyright>
+    Copyright © 2017 Red Hat Inc.
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice (including the next
+    paragraph) shall be included in all copies or substantial portions of the
+    Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+  </copyright>
+
+  <description summary="Protocol for inhibiting the compositor keyboard shortcuts">
+    This protocol specifies a way for a client to request the compositor
+    to ignore its own keyboard shortcuts for a given seat, so that all
+    key events from that seat get forwarded to a surface.
+
+    Warning! The protocol described in this file is experimental and
+    backward incompatible changes may be made. Backward compatible
+    changes may be added together with the corresponding interface
+    version bump.
+    Backward incompatible changes are done by bumping the version
+    number in the protocol and interface names and resetting the
+    interface version. Once the protocol is to be declared stable,
+    the 'z' prefix and the version number in the protocol and
+    interface names are removed and the interface version number is
+    reset.
+  </description>
+
+  <interface name="zwp_keyboard_shortcuts_inhibit_manager_v1" version="1">
+    <description summary="context object for keyboard grab_manager">
+      A global interface used for inhibiting the compositor keyboard shortcuts.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the keyboard shortcuts inhibitor object">
+	Destroy the keyboard shortcuts inhibitor manager.
+      </description>
+    </request>
+
+    <request name="inhibit_shortcuts">
+      <description summary="create a new keyboard shortcuts inhibitor object">
+	Create a new keyboard shortcuts inhibitor object associated with
+	the given surface for the given seat.
+
+	If shortcuts are already inhibited for the specified seat and surface,
+	a protocol error "already_inhibited" is raised by the compositor.
+      </description>
+      <arg name="id" type="new_id" interface="zwp_keyboard_shortcuts_inhibitor_v1"/>
+      <arg name="surface" type="object" interface="wl_surface"
+	   summary="the surface that inhibits the keyboard shortcuts behavior"/>
+      <arg name="seat" type="object" interface="wl_seat"
+	   summary="the wl_seat for which keyboard shortcuts should be disabled"/>
+    </request>
+
+    <enum name="error">
+      <entry name="already_inhibited"
+	     value="0"
+	     summary="the shortcuts are already inhibited for this surface"/>
+    </enum>
+  </interface>
+
+  <interface name="zwp_keyboard_shortcuts_inhibitor_v1" version="1">
+    <description summary="context object for keyboard shortcuts inhibitor">
+      A keyboard shortcuts inhibitor instructs the compositor to ignore
+      its own keyboard shortcuts when the associated surface has keyboard
+      focus. As a result, when the surface has keyboard focus on the given
+      seat, it will receive all key events originating from the specified
+      seat, even those which would normally be caught by the compositor for
+      its own shortcuts.
+
+      The Wayland compositor is however under no obligation to disable
+      all of its shortcuts, and may keep some special key combo for its own
+      use, including but not limited to one allowing the user to forcibly
+      restore normal keyboard events routing in the case of an unwilling
+      client. The compositor may also use the same key combo to reactivate
+      an existing shortcut inhibitor that was previously deactivated on
+      user request.
+
+      When the compositor restores its own keyboard shortcuts, an
+      "inactive" event is emitted to notify the client that the keyboard
+      shortcuts inhibitor is not effectively active for the surface and
+      seat any more, and the client should not expect to receive all
+      keyboard events.
+
+      When the keyboard shortcuts inhibitor is inactive, the client has
+      no way to forcibly reactivate the keyboard shortcuts inhibitor.
+
+      The user can chose to re-enable a previously deactivated keyboard
+      shortcuts inhibitor using any mechanism the compositor may offer,
+      in which case the compositor will send an "active" event to notify
+      the client.
+
+      If the surface is destroyed, unmapped, or loses the seat's keyboard
+      focus, the keyboard shortcuts inhibitor becomes irrelevant and the
+      compositor will restore its own keyboard shortcuts but no "inactive"
+      event is emitted in this case.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the keyboard shortcuts inhibitor object">
+	Remove the keyboard shortcuts inhibitor from the associated wl_surface.
+      </description>
+    </request>
+
+    <event name="active">
+      <description summary="shortcuts are inhibited">
+	This event indicates that the shortcut inhibitor is active.
+
+	The compositor sends this event every time compositor shortcuts
+	are inhibited on behalf of the surface. When active, the client
+	may receive input events normally reserved by the compositor
+	(see zwp_keyboard_shortcuts_inhibitor_v1).
+
+	This occurs typically when the initial request "inhibit_shortcuts"
+	first becomes active or when the user instructs the compositor to
+	re-enable and existing shortcuts inhibitor using any mechanism
+	offered by the compositor.
+      </description>
+    </event>
+
+    <event name="inactive">
+      <description summary="shortcuts are restored">
+	This event indicates that the shortcuts inhibitor is inactive,
+	normal shortcuts processing is restored by the compositor.
+       </description>
+    </event>
+  </interface>
+</protocol>