lib: add inhibitor helper

This is an object which is meant to be acquired/released in response to
user input. Currently, it will inhibit the shortcuts in the display server
if possible.

Some additional things may be added eventually like relative pointers or
similar (by grabbing pointer input).

lib/meson.build

@@ -29,6 +29,7 @@ libmks_private_sources = [
   'mks-display-picture.c',
   'mks-css.c',
   'mks-gl-context.c',
+  'mks-inhibitor.c',
   'mks-read-only-list-model.c',
   'mks-util.c',
 

lib/mks-inhibitor-private.h

@@ -0,0 +1,35 @@
+/* mks-inhibitor.h
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+G_BEGIN_DECLS
+
+#define MKS_TYPE_INHIBITOR (mks_inhibitor_get_type())
+
+G_DECLARE_FINAL_TYPE (MksInhibitor, mks_inhibitor, MKS, INHIBITOR, GObject)
+
+MksInhibitor *mks_inhibitor_new       (GtkWidget    *widget,
+                                       GdkEvent     *event);
+void          mks_inhibitor_uninhibit (MksInhibitor *self);
+
+G_END_DECLS

lib/mks-inhibitor.c

@@ -0,0 +1,157 @@
+/* mks-inhibitor.c
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "config.h"
+
+#include "mks-inhibitor-private.h"
+
+struct _MksInhibitor
+{
+  GObject parent_instance;
+  GdkToplevel *toplevel;
+  guint shortcuts_inhibited : 1;
+};
+
+G_DEFINE_FINAL_TYPE (MksInhibitor, mks_inhibitor, G_TYPE_OBJECT)
+
+static void
+notify_cb (GdkToplevel *toplevel,
+           GParamSpec  *pspec,
+           gpointer     user_data)
+{
+  gboolean shortcuts_inhibited;
+
+  g_object_get (toplevel,
+                "shortcuts-inhibited", &shortcuts_inhibited,
+                NULL);
+
+  g_debug ("Toplevel %p shortcuts-inhibited: %s\n",
+           toplevel,
+           shortcuts_inhibited ? "YES" : "NO");
+}
+
+static void
+inhibit_shortcuts (MksInhibitor *self,
+                   GdkEvent     *event)
+{
+  guint count;
+
+  g_assert (MKS_IS_INHIBITOR (self));
+  g_assert (GDK_IS_EVENT (event));
+  g_assert (GDK_IS_TOPLEVEL (self->toplevel));
+  g_assert (self->shortcuts_inhibited == FALSE);
+
+  count = GPOINTER_TO_UINT (g_object_get_data (G_OBJECT (self->toplevel), "MKS_INHIBITOR_COUNT"));
+  count++;
+  g_object_set_data (G_OBJECT (self->toplevel), "MKS_INHIBITOR_COUNT", GUINT_TO_POINTER (count));
+
+  if (count == 1)
+    {
+      g_signal_connect (self->toplevel,
+                        "notify::shortcuts-inhibited",
+                        G_CALLBACK (notify_cb),
+                        NULL);
+      gdk_toplevel_inhibit_system_shortcuts (self->toplevel, event);
+      notify_cb (self->toplevel, NULL, NULL);
+    }
+
+  self->shortcuts_inhibited = TRUE;
+}
+
+static void
+uninhibit_shortcuts (MksInhibitor *self)
+{
+  guint count;
+
+  g_assert (MKS_IS_INHIBITOR (self));
+  g_assert (GDK_IS_TOPLEVEL (self->toplevel));
+  g_assert (self->shortcuts_inhibited == TRUE);
+
+  count = GPOINTER_TO_UINT (g_object_get_data (G_OBJECT (self->toplevel), "MKS_INHIBITOR_COUNT"));
+  count--;
+  g_object_set_data (G_OBJECT (self->toplevel), "MKS_INHIBITOR_COUNT", GUINT_TO_POINTER (count));
+
+  if (count == 0)
+    {
+      g_signal_handlers_disconnect_by_func (self->toplevel,
+                                            G_CALLBACK (notify_cb),
+                                            NULL);
+      gdk_toplevel_restore_system_shortcuts (self->toplevel);
+    }
+
+  self->shortcuts_inhibited = FALSE;
+}
+
+static void
+mks_inhibitor_dispose (GObject *object)
+{
+  MksInhibitor *self = (MksInhibitor *)object;
+
+  if (self->shortcuts_inhibited)
+    uninhibit_shortcuts (self);
+
+  G_OBJECT_CLASS (mks_inhibitor_parent_class)->dispose (object);
+}
+
+static void
+mks_inhibitor_class_init (MksInhibitorClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose = mks_inhibitor_dispose;
+}
+
+static void
+mks_inhibitor_init (MksInhibitor *self)
+{
+}
+
+MksInhibitor *
+mks_inhibitor_new (GtkWidget *widget,
+                   GdkEvent  *event)
+{
+  MksInhibitor *self;
+  GdkSurface *surface;
+  GtkNative *native;
+
+  g_return_val_if_fail (GTK_IS_WIDGET (widget), NULL);
+  g_return_val_if_fail (GDK_IS_EVENT (event), NULL);
+
+  self = g_object_new (MKS_TYPE_INHIBITOR, NULL);
+
+  if ((native = gtk_widget_get_native (widget)) &&
+      (surface = gtk_native_get_surface (native)) &&
+      GDK_IS_TOPLEVEL (surface))
+    {
+      if (g_set_object (&self->toplevel, GDK_TOPLEVEL (surface)))
+        inhibit_shortcuts (self, event);
+    }
+
+  return self;
+}
+
+void
+mks_inhibitor_uninhibit (MksInhibitor *self)
+{
+  g_return_if_fail (MKS_IS_INHIBITOR (self));
+
+  if (self->shortcuts_inhibited)
+    uninhibit_shortcuts (self);
+}