Wayland: Implement KDE's SSD protocol

If the compositor prefers server-side decorations and the client doesn't
customize the title bar, we disable client-side decorations and let the
compositor know. Otherwise, we continue to use client-side decorations.

Signed-off-by: Drew DeVault <sir@cmpwn.com>

https://bugzilla.gnome.org/show_bug.cgi?id=781909

1 files changed, 39 insertions, 0 deletions

diff --git a/gdk/wayland/gdkdisplay-wayland.c b/gdk/wayland/gdkdisplay-wayland.c
index 2154e5101e..ab1aa72a02 100644
--- a/gdk/wayland/gdkdisplay-wayland.c
+++ b/gdk/wayland/gdkdisplay-wayland.c
@@ -49,6 +49,7 @@
 #include "tablet-unstable-v2-client-protocol.h"
 #include <wayland/xdg-shell-unstable-v6-client-protocol.h>
 #include <wayland/xdg-foreign-unstable-v1-client-protocol.h>
+#include <wayland/server-decoration-client-protocol.h>
 
 /**
  * SECTION:wayland_interaction
@@ -337,6 +338,35 @@ static const struct wl_shm_listener wl_shm_listener = {
 };
 
 static void
+server_decoration_manager_default_mode (void                                          *data,
+                                        struct org_kde_kwin_server_decoration_manager *manager,
+                                        uint32_t                                       mode)
+{
+  g_assert (mode <= ORG_KDE_KWIN_SERVER_DECORATION_MANAGER_MODE_SERVER);
+  const char *modes[] = {
+    [ORG_KDE_KWIN_SERVER_DECORATION_MANAGER_MODE_NONE]   = "none",
+    [ORG_KDE_KWIN_SERVER_DECORATION_MANAGER_MODE_CLIENT] = "client",
+    [ORG_KDE_KWIN_SERVER_DECORATION_MANAGER_MODE_SERVER] = "server",
+  };
+  GdkWaylandDisplay *display_wayland = data;
+  g_debug ("Compositor prefers decoration mode '%s'", modes[mode]);
+  display_wayland->server_decoration_mode = mode;
+}
+
+static const struct org_kde_kwin_server_decoration_manager_listener server_decoration_listener = {
+  .default_mode = server_decoration_manager_default_mode
+};
+
+gboolean
+gdk_wayland_display_prefers_ssd (GdkDisplay *display)
+{
+  GdkWaylandDisplay *display_wayland = GDK_WAYLAND_DISPLAY (display);
+  if (display_wayland->server_decoration_manager)
+    return display_wayland->server_decoration_mode == ORG_KDE_KWIN_SERVER_DECORATION_MANAGER_MODE_SERVER;
+  return FALSE;
+}
+
+static void
 gdk_registry_handle_global (void               *data,
                             struct wl_registry *registry,
                             uint32_t            id,
@@ -459,6 +489,15 @@ gdk_registry_handle_global (void               *data,
         wl_registry_bind (display_wayland->wl_registry, id,
                           &zwp_keyboard_shortcuts_inhibit_manager_v1_interface, 1);
     }
+  else if (strcmp (interface, "org_kde_kwin_server_decoration_manager") == 0)
+    {
+      display_wayland->server_decoration_manager =
+        wl_registry_bind (display_wayland->wl_registry, id,
+                          &org_kde_kwin_server_decoration_manager_interface, 1);
+      org_kde_kwin_server_decoration_manager_add_listener (display_wayland->server_decoration_manager,
+                                                           &server_decoration_listener,
+                                                           display_wayland);
+    }
   else
     handled = FALSE;