wayland: Implement make_center (#1942)

Co-authored-by: Danielle Foré <danielle@elementary.io>

protocol/pantheon-desktop-shell-v1.xml

@@ -111,5 +111,21 @@
         Tell the shell to keep the surface above on all workspaces
       </description>
     </request>
+
+    <request name="make_centered">
+      <description summary="requests to keep the surface centered">
+        Request to keep the surface centered. This will cause keyboard focus
+        to not be granted automatically but having to be requested via focus.
+      </description>
+    </request>
+
+    <request name="focus">
+      <description summary="request keyboard focus">
+        Request keyboard focus, taking it away from any other window.
+        Keyboard focus must always be manually be requested and is
+        - in contrast to normal windows - never automatically granted
+        by the compositor.
+      </description>
+    </request>
   </interface>
 </protocol>

protocol/pantheon-desktop-shell.vapi

@@ -56,6 +56,8 @@ namespace Pantheon.Desktop {
         public static Wl.Interface iface;
         public Destroy destroy;
         public SetKeepAbove set_keep_above;
+        public MakeCentered make_centered;
+        public Focus focus;
     }
 
     [CCode (has_target = false, has_typedef = false)]
@@ -75,5 +77,7 @@ namespace Pantheon.Desktop {
     [CCode (has_target = false, has_typedef = false)]
     public delegate void SetKeepAbove (Wl.Client client, Wl.Resource resource);
     [CCode (has_target = false, has_typedef = false)]
+    public delegate void MakeCentered (Wl.Client client, Wl.Resource resource);
+    [CCode (has_target = false, has_typedef = false)]
     public delegate void Destroy (Wl.Client client, Wl.Resource resource);
 }

src/PantheonShell.vala

@@ -55,7 +55,7 @@ namespace Gala {
         wayland_pantheon_panel_interface = {
             destroy_panel_surface,
             set_anchor,
-            focus,
+            focus_panel,
             set_size,
             set_hide_mode,
         };
@@ -67,9 +67,13 @@ namespace Gala {
         wayland_pantheon_extended_behavior_interface = {
             destroy_extended_behavior_surface,
             set_keep_above,
+            make_centered,
+            focus_extended_behavior,
         };
 
         PanelSurface.quark = GLib.Quark.from_string ("-gala-wayland-panel-surface-data");
+        WidgetSurface.quark = GLib.Quark.from_string ("-gala-wayland-widget-surface-data");
+        ExtendedBehaviorSurface.quark = GLib.Quark.from_string ("-gala-wayland-extended-behavior-surface-data");
 
         shell_global = Wl.Global.create (wl_disp, ref Pantheon.Desktop.ShellInterface.iface, 1, (client, version, id) => {
             unowned var resource = client.create_resource (ref Pantheon.Desktop.ShellInterface.iface, (int) version, id);
@@ -260,15 +264,29 @@ namespace Gala {
         ShellClientsManager.get_instance ().set_anchor (window, side);
     }
 
-    internal static void focus (Wl.Client client, Wl.Resource resource) {
+    internal static void focus_panel (Wl.Client client, Wl.Resource resource) {
         unowned PanelSurface? panel_surface = resource.get_user_data<PanelSurface> ();
         if (panel_surface.wayland_surface == null) {
             warning ("Window tried to focus but wayland surface is null.");
             return;
         }
 
+        focus (panel_surface.wayland_surface);
+    }
+
+    internal static void focus_extended_behavior (Wl.Client client, Wl.Resource resource) {
+        unowned ExtendedBehaviorSurface? extended_behavior_surface = resource.get_user_data<ExtendedBehaviorSurface> ();
+        if (extended_behavior_surface.wayland_surface == null) {
+            warning ("Window tried to focus but wayland surface is null.");
+            return;
+        }
+
+        focus (extended_behavior_surface.wayland_surface);
+    }
+
+    internal static void focus (Object wayland_surface) {
         Meta.Window? window;
-        panel_surface.wayland_surface.get ("window", out window, null);
+        wayland_surface.get ("window", out window, null);
         if (window == null) {
             warning ("Window tried to focus but wayland surface had no associated window.");
             return;
@@ -326,6 +344,21 @@ namespace Gala {
         window.make_above ();
     }
 
+    internal static void make_centered (Wl.Client client, Wl.Resource resource) {
+        unowned ExtendedBehaviorSurface? eb_surface = resource.get_user_data<ExtendedBehaviorSurface> ();
+        if (eb_surface.wayland_surface == null) {
+            return;
+        }
+
+        Meta.Window? window;
+        eb_surface.wayland_surface.get ("window", out window, null);
+        if (window == null) {
+            return;
+        }
+
+        ShellClientsManager.get_instance ().make_centered (window);
+    }
+
     internal static void destroy_panel_surface (Wl.Client client, Wl.Resource resource) {
         resource.destroy ();
     }

src/ShellClients/CenteredWindow.vala

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2024 elementary, Inc. (https://elementary.io)
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * Authored by: Leonhard Kargl <leo.kargl@proton.me>
+ */
+
+public class Gala.CenteredWindow : Object {
+    public WindowManager wm { get; construct; }
+    public Meta.Window window { get; construct; }
+
+    public CenteredWindow (WindowManager wm, Meta.Window window) {
+        Object (wm: wm, window: window);
+    }
+
+    construct {
+        window.size_changed.connect (position_window);
+        window.stick ();
+
+        var monitor_manager = wm.get_display ().get_context ().get_backend ().get_monitor_manager ();
+        monitor_manager.monitors_changed.connect (() => position_window ());
+
+        position_window ();
+
+        window.shown.connect (() => window.focus (wm.get_display ().get_current_time ()));
+    }
+
+    private void position_window () {
+        var display = wm.get_display ();
+        var monitor_geom = display.get_monitor_geometry (display.get_primary_monitor ());
+        var window_rect = window.get_frame_rect ();
+
+        var x = monitor_geom.x + (monitor_geom.width - window_rect.width) / 2;
+        var y = monitor_geom.y + (monitor_geom.height - window_rect.height) / 2;
+
+        Idle.add (() => {
+            window.move_frame (false, x, y);
+            return Source.REMOVE;
+        });
+    }
+}

src/ShellClients/ShellClientsManager.vala

@@ -26,6 +26,7 @@ public class Gala.ShellClientsManager : Object {
     private ManagedClient[] protocol_clients = {};
 
     private GLib.HashTable<Meta.Window, PanelWindow> windows = new GLib.HashTable<Meta.Window, PanelWindow> (null, null);
+    private GLib.HashTable<Meta.Window, CenteredWindow> centered_windows = new GLib.HashTable<Meta.Window, CenteredWindow> (null, null);
 
     private ShellClientsManager (WindowManager wm) {
         Object (wm: wm);
@@ -97,20 +98,22 @@ public class Gala.ShellClientsManager : Object {
         }
     }
 
-    public void set_anchor (Meta.Window window, Meta.Side side) {
-        if (window in windows) {
-            windows[window].update_anchor (side);
-            return;
-        }
-
-#if HAS_MUTTER46
+    private void make_dock (Meta.Window window) {
         foreach (var client in protocol_clients) {
             if (client.wayland_client.owns_window (window)) {
                 client.wayland_client.make_dock (window);
                 break;
             }
         }
-#endif
+    }
+
+    public void set_anchor (Meta.Window window, Meta.Side side) {
+        if (window in windows) {
+            windows[window].update_anchor (side);
+            return;
+        }
+
+        make_dock (window);
         // TODO: Return if requested by window that's not a trusted client?
 
         windows[window] = new PanelWindow (wm, window, side);
@@ -143,4 +146,14 @@ public class Gala.ShellClientsManager : Object {
 
         windows[window].set_hide_mode (hide_mode);
     }
+
+    public void make_centered (Meta.Window window) {
+        if (window in centered_windows) {
+            return;
+        }
+
+        make_dock (window);
+
+        centered_windows[window] = new CenteredWindow (wm, window);
+    }
 }

src/meson.build

@@ -40,6 +40,7 @@ gala_bin_sources = files(
     'HotCorners/Barrier.vala',
     'HotCorners/HotCorner.vala',
     'HotCorners/HotCornerManager.vala',
+    'ShellClients/CenteredWindow.vala',
     'ShellClients/HideTracker.vala',
     'ShellClients/ManagedClient.vala',
     'ShellClients/NotificationsClient.vala',