backends: Add MetaA11yManager

This a11y manager will handle key event emission to screen
readers and other ATs. This initial commit only introduces
the object.

Carlos Garnacho: Make the object take a ::backend property

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4217>

src/backends/meta-a11y-manager.c

@@ -0,0 +1,102 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright 2024 GNOME Foundation
+ *
+ * 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 2 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/>.
+ *
+ */
+
+#include "config.h"
+
+#include "backends/meta-a11y-manager.h"
+#include "meta/meta-backend.h"
+#include "meta/meta-context.h"
+#include "meta/util.h"
+
+#include "meta-dbus-a11y.h"
+
+enum
+{
+  A11Y_MODIFIERS_CHANGED,
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS];
+
+enum
+{
+  PROP_0,
+  PROP_BACKEND,
+  N_PROPS,
+};
+
+static GParamSpec *props[N_PROPS];
+
+typedef struct _MetaA11yManager
+{
+  GObject parent;
+  MetaBackend *backend;
+} MetaA11yManager;
+
+G_DEFINE_TYPE (MetaA11yManager, meta_a11y_manager, G_TYPE_OBJECT)
+
+static void
+meta_a11y_manager_set_property (GObject      *object,
+                                guint         prop_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  MetaA11yManager *a11y_manager = META_A11Y_MANAGER (object);
+
+  switch (prop_id)
+    {
+    case PROP_BACKEND:
+      a11y_manager->backend = g_value_get_object (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+meta_a11y_manager_class_init (MetaA11yManagerClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->set_property = meta_a11y_manager_set_property;
+
+  props[PROP_BACKEND] =
+    g_param_spec_object ("backend", NULL, NULL,
+                         META_TYPE_BACKEND,
+                         G_PARAM_WRITABLE |
+                         G_PARAM_CONSTRUCT_ONLY |
+                         G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (object_class, N_PROPS, props);
+}
+
+static void
+meta_a11y_manager_init (MetaA11yManager *a11y_manager)
+{
+}
+
+MetaA11yManager *
+meta_a11y_manager_new (MetaBackend *backend)
+{
+  return g_object_new (META_TYPE_A11Y_MANAGER,
+                       "backend", backend,
+                       NULL);
+}

src/backends/meta-a11y-manager.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2024 GNOME Foundation
+ *
+ * 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 2 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/>.
+ *
+ */
+
+#pragma once
+
+#include <glib-object.h>
+
+#include "backends/meta-backend-types.h"
+#include "clutter/clutter.h"
+
+#define META_TYPE_A11Y_MANAGER (meta_a11y_manager_get_type ())
+G_DECLARE_FINAL_TYPE (MetaA11yManager, meta_a11y_manager, META, A11Y_MANAGER, GObject)
+
+MetaA11yManager * meta_a11y_manager_new (MetaBackend *backend);

src/meson.build

@@ -186,6 +186,8 @@ mutter_sources = [
   'backends/edid.h',
   'backends/edid-parse.c',
   'backends/gsm-inhibitor-flag.h',
+  'backends/meta-a11y-manager.c',
+  'backends/meta-a11y-manager.h',
   'backends/meta-backend.c',
   'backends/meta-backend-private.h',
   'backends/meta-barrier.c',