compositor: Introduce MetaCompositorView

MetaCompositorView is a class which contains compositor logic
specific to ClutterStageViews.

Each MetaCompositorView is "attached" to a ClutterStageView as an
opaque pointer using g_object_set_qdata_full (), and is freed when
the ClutterStageView is destroyed. This ensures that the lifetime of
the MetaCompositorView can't extend beyond the lifetime of its
ClutterStageView.

In a following commit, MetaCompositorView will be expanded to allow
keeping track of the top MetaWindowActor located on each
ClutterStageView.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2526>

4 files changed, 229 insertions, 0 deletions

diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index 8c11f74dc..92732c635 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -61,6 +61,7 @@
 #include "backends/x11/meta-stage-x11.h"
 #include "clutter/clutter-mutter.h"
 #include "cogl/cogl.h"
+#include "compositor/meta-compositor-view.h"
 #include "compositor/meta-later-private.h"
 #include "compositor/meta-window-actor-x11.h"
 #include "compositor/meta-window-actor-private.h"
@@ -108,6 +109,7 @@ typedef struct _MetaCompositorPrivate
   gulong before_paint_handler_id;
   gulong after_paint_handler_id;
   gulong window_visibility_updated_id;
+  gulong monitors_changed_internal_id;
 
   int64_t server_time_query_time;
   int64_t server_time_offset;
@@ -137,6 +139,8 @@ typedef struct _MetaCompositorPrivate
 G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (MetaCompositor, meta_compositor,
                                      G_TYPE_OBJECT)
 
+static GQuark quark_compositor_view;
+
 static void
 on_presented (ClutterStage     *stage,
               ClutterStageView *stage_view,
@@ -927,6 +931,35 @@ meta_compositor_sync_window_geometry (MetaCompositor *compositor,
 }
 
 static void
+meta_compositor_ensure_compositor_views (MetaCompositor *compositor)
+{
+  MetaCompositorPrivate *priv =
+    meta_compositor_get_instance_private (compositor);
+  ClutterStage *stage =
+    CLUTTER_STAGE (meta_backend_get_stage (priv->backend));
+  GList *l;
+
+  for (l = clutter_stage_peek_stage_views (stage); l; l = l->next)
+    {
+      ClutterStageView *stage_view = l->data;
+      MetaCompositorView *compositor_view;
+
+      compositor_view = g_object_get_qdata (G_OBJECT (stage_view),
+                                            quark_compositor_view);
+
+      if (compositor_view)
+        continue;
+
+      compositor_view = meta_compositor_view_new (stage_view);
+
+      g_object_set_qdata_full (G_OBJECT (stage_view),
+                               quark_compositor_view,
+                               compositor_view,
+                               g_object_unref);
+    }
+}
+
+static void
 on_presented (ClutterStage     *stage,
               ClutterStageView *stage_view,
               ClutterFrameInfo *frame_info,
@@ -1054,6 +1087,13 @@ on_window_visibility_updated (MetaDisplay    *display,
 }
 
 static void
+on_monitors_changed_internal (MetaMonitorManager *monitor_manager,
+                              MetaCompositor     *compositor)
+{
+  meta_compositor_ensure_compositor_views (compositor);
+}
+
+static void
 meta_compositor_set_property (GObject      *object,
                               guint         prop_id,
                               const GValue *value,
@@ -1113,6 +1153,8 @@ meta_compositor_constructed (GObject *object)
   ClutterBackend *clutter_backend =
     meta_backend_get_clutter_backend (priv->backend);
   ClutterActor *stage = meta_backend_get_stage (priv->backend);
+  MetaMonitorManager *monitor_manager =
+    meta_backend_get_monitor_manager (priv->backend);
 
   priv->context = clutter_backend->cogl_context;
 
@@ -1133,9 +1175,17 @@ meta_compositor_constructed (GObject *object)
                       G_CALLBACK (on_window_visibility_updated),
                       compositor);
 
+  priv->monitors_changed_internal_id =
+    g_signal_connect (monitor_manager,
+                      "monitors-changed-internal",
+                      G_CALLBACK (on_monitors_changed_internal),
+                      compositor);
+
   priv->laters = meta_laters_new (compositor);
 
   G_OBJECT_CLASS (meta_compositor_parent_class)->constructed (object);
+
+  meta_compositor_ensure_compositor_views (compositor);
 }
 
 static void
@@ -1190,6 +1240,9 @@ meta_compositor_class_init (MetaCompositorClass *klass)
                          G_PARAM_CONSTRUCT_ONLY |
                          G_PARAM_STATIC_STRINGS);
   g_object_class_install_properties (object_class, N_PROPS, obj_props);
+
+  quark_compositor_view =
+    g_quark_from_static_string ("-meta-compositor-view");
 }
 
 /**
diff --git a/src/compositor/meta-compositor-view.c b/src/compositor/meta-compositor-view.c
new file mode 100644
index 000000000..5bc16de3b
--- /dev/null
+++ b/src/compositor/meta-compositor-view.c
@@ -0,0 +1,129 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2022 Dor Askayo
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Written by:
+ *     Dor Askayo <dor.askayo@gmail.com>
+ */
+
+#include "config.h"
+
+#include "compositor/meta-compositor-view.h"
+
+enum
+{
+  PROP_0,
+
+  PROP_STAGE_VIEW,
+
+  N_PROPS
+};
+
+static GParamSpec *obj_props[N_PROPS];
+
+typedef struct _MetaCompositorViewPrivate
+{
+  ClutterStageView *stage_view;
+} MetaCompositorViewPrivate;
+
+G_DEFINE_TYPE_WITH_PRIVATE (MetaCompositorView, meta_compositor_view,
+                            G_TYPE_OBJECT)
+
+MetaCompositorView *
+meta_compositor_view_new (ClutterStageView *stage_view)
+{
+  g_assert (stage_view);
+
+  return g_object_new (META_TYPE_COMPOSITOR_VIEW,
+                       "stage-view", stage_view,
+                       NULL);
+}
+
+ClutterStageView *
+meta_compositor_view_get_stage_view (MetaCompositorView *compositor_view)
+{
+  MetaCompositorViewPrivate *priv =
+    meta_compositor_view_get_instance_private (compositor_view);
+
+  return priv->stage_view;
+}
+
+static void
+meta_compositor_view_set_property (GObject      *object,
+                                   guint         prop_id,
+                                   const GValue *value,
+                                   GParamSpec   *pspec)
+{
+  MetaCompositorView *compositor_view = META_COMPOSITOR_VIEW (object);
+  MetaCompositorViewPrivate *priv =
+    meta_compositor_view_get_instance_private (compositor_view);
+
+  switch (prop_id)
+    {
+    case PROP_STAGE_VIEW:
+      priv->stage_view = g_value_get_object (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+meta_compositor_view_get_property (GObject    *object,
+                                   guint       prop_id,
+                                   GValue     *value,
+                                   GParamSpec *pspec)
+{
+  MetaCompositorView *compositor_view = META_COMPOSITOR_VIEW (object);
+  MetaCompositorViewPrivate *priv =
+    meta_compositor_view_get_instance_private (compositor_view);
+
+  switch (prop_id)
+    {
+    case PROP_STAGE_VIEW:
+      g_value_set_object (value, priv->stage_view);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+meta_compositor_view_class_init (MetaCompositorViewClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->set_property = meta_compositor_view_set_property;
+  object_class->get_property = meta_compositor_view_get_property;
+
+  obj_props[PROP_STAGE_VIEW] =
+    g_param_spec_object ("stage-view",
+                         "stage-view",
+                         "ClutterStageView",
+                         CLUTTER_TYPE_STAGE_VIEW,
+                         G_PARAM_READWRITE |
+                         G_PARAM_CONSTRUCT_ONLY |
+                         G_PARAM_STATIC_STRINGS);
+  g_object_class_install_properties (object_class, N_PROPS, obj_props);
+}
+
+static void
+meta_compositor_view_init (MetaCompositorView *compositor_view)
+{
+}
diff --git a/src/compositor/meta-compositor-view.h b/src/compositor/meta-compositor-view.h
new file mode 100644
index 000000000..bed3404f7
--- /dev/null
+++ b/src/compositor/meta-compositor-view.h
@@ -0,0 +1,45 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2022 Dor Askayo
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Written by:
+ *     Dor Askayo <dor.askayo@gmail.com>
+ */
+
+#ifndef META_COMPOSITOR_VIEW_H
+#define META_COMPOSITOR_VIEW_H
+
+#include <glib-object.h>
+
+#include "clutter/clutter-mutter.h"
+
+struct _MetaCompositorViewClass
+{
+  GObjectClass parent_class;
+};
+
+#define META_TYPE_COMPOSITOR_VIEW (meta_compositor_view_get_type ())
+G_DECLARE_FINAL_TYPE (MetaCompositorView, meta_compositor_view,
+                      META, COMPOSITOR_VIEW, GObject)
+
+MetaCompositorView *meta_compositor_view_new (ClutterStageView *stage_view);
+
+ClutterStageView *meta_compositor_view_get_stage_view (MetaCompositorView *compositor_view);
+
+#endif /* META_COMPOSITOR_VIEW_H */
diff --git a/src/meson.build b/src/meson.build
index 6dda94b69..504dc20ee 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -268,6 +268,8 @@ mutter_sources = [
   'compositor/meta-background-private.h',
   'compositor/meta-compositor-server.c',
   'compositor/meta-compositor-server.h',
+  'compositor/meta-compositor-view.c',
+  'compositor/meta-compositor-view.h',
   'compositor/meta-cullable.c',
   'compositor/meta-cullable.h',
   'compositor/meta-dnd-actor.c',