[mutter] compositor: Expose the MetaCompositorView in before_paint () vfunc

[Marge Bot <marge-bot src gnome org>]

commit 2ead3874f5d6fd5b5cbf85d71271b0fa8b5897f6
Author: Dor Askayo <dor askayo gmail com>
Date:   Mon Jul 11 12:23:24 2022 +0300

    compositor: Expose the MetaCompositorView in before_paint () vfunc
    
    The idea is that the state of the MetaCompositorView shall be
    up-to-date only in specific scenarios, thus allowing operations
    performed on it to be queued and aggregated to be handled in the
    right time, and only if they are still necessary.
    
    For example, in a following commit, the top window actor in each
    view will be planned (if needed) only once before painting a frame,
    rendering the top window actor in the MetaCompositorView potentially
    stale in all other times.
    
    Similarly, if a MetaCompositorView is destroyed before the beginning
    of the frame, a queued operation to update its top window actor can be
    discarded.
    
    As an interface segragation measure, and as part of an attempt to
    avoid the use of g_return_if_fail () to check the validity of the
    MetaCompositorView's state in multiple places (which is still prone to
    human error), the interfaces through which a MetaCompositorView is
    made available would only ones where it's state is gurenteed to be
    up-to-date.
    
    Specifically, this commit gurentees that the state of the
    MetaCompositorView would be up-to-date during the before_paint () and
    after_paint () vfuncs exposed to child classes of the MetaCompositor.
    
    The frame_in_progress variable will be used in a following commit to
    guarantee that the MetaCompositorView's state is not invalidated during
    this time.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2526>

 src/compositor/compositor-private.h     |  9 ++---
 src/compositor/compositor.c             | 58 +++++++++++++++++++++++++--------
 src/compositor/meta-compositor-native.c |  6 ++--
 src/compositor/meta-compositor-x11.c    |  6 ++--
 4 files changed, 56 insertions(+), 23 deletions(-)
---
diff --git a/src/compositor/compositor-private.h b/src/compositor/compositor-private.h
index d3b3145a35..6d62af8558 100644
--- a/src/compositor/compositor-private.h
+++ b/src/compositor/compositor-private.h
@@ -7,6 +7,7 @@
 
 #include "clutter/clutter-mutter.h"
 #include "clutter/clutter.h"
+#include "compositor/meta-compositor-view.h"
 #include "compositor/meta-plugin-manager.h"
 #include "compositor/meta-window-actor-private.h"
 #include "meta/compositor.h"
@@ -24,10 +25,10 @@ struct _MetaCompositorClass
   gboolean (* manage) (MetaCompositor  *compositor,
                        GError         **error);
   void (* unmanage) (MetaCompositor *compositor);
-  void (* before_paint) (MetaCompositor   *compositor,
-                         ClutterStageView *stage_view);
-  void (* after_paint) (MetaCompositor   *compositor,
-                        ClutterStageView *stage_view);
+  void (* before_paint) (MetaCompositor     *compositor,
+                         MetaCompositorView *compositor_view);
+  void (* after_paint) (MetaCompositor     *compositor,
+                        MetaCompositorView *compositor_view);
   void (* remove_window) (MetaCompositor *compositor,
                           MetaWindow     *window);
   int64_t (* monotonic_to_high_res_xserver_time) (MetaCompositor *compositor,
diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index 92732c635b..53db2df4a6 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -61,7 +61,6 @@
 #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"
@@ -131,6 +130,8 @@ typedef struct _MetaCompositorPrivate
 
   int switch_workspace_in_progress;
 
+  gboolean frame_in_progress;
+
   MetaPluginManager *plugin_mgr;
 
   MetaLaters *laters;
@@ -986,34 +987,44 @@ on_presented (ClutterStage     *stage,
 }
 
 static void
-meta_compositor_real_before_paint (MetaCompositor   *compositor,
-                                   ClutterStageView *stage_view)
+meta_compositor_real_before_paint (MetaCompositor     *compositor,
+                                   MetaCompositorView *compositor_view)
 {
   MetaCompositorPrivate *priv =
     meta_compositor_get_instance_private (compositor);
+  ClutterStageView *stage_view;
   GList *l;
 
+  stage_view = meta_compositor_view_get_stage_view (compositor_view);
+
   for (l = priv->windows; l; l = l->next)
     meta_window_actor_before_paint (l->data, stage_view);
 }
 
 static void
-meta_compositor_before_paint (MetaCompositor   *compositor,
-                              ClutterStageView *stage_view)
+meta_compositor_before_paint (MetaCompositor     *compositor,
+                              MetaCompositorView *compositor_view)
 {
+  MetaCompositorPrivate *priv =
+    meta_compositor_get_instance_private (compositor);
+
   COGL_TRACE_BEGIN_SCOPED (MetaCompositorPrePaint,
                            "Compositor (before-paint)");
-  META_COMPOSITOR_GET_CLASS (compositor)->before_paint (compositor, stage_view);
+
+  priv->frame_in_progress = TRUE;
+
+  META_COMPOSITOR_GET_CLASS (compositor)->before_paint (compositor, compositor_view);
 }
 
 static void
-meta_compositor_real_after_paint (MetaCompositor   *compositor,
-                                  ClutterStageView *stage_view)
+meta_compositor_real_after_paint (MetaCompositor     *compositor,
+                                  MetaCompositorView *compositor_view)
 {
   MetaCompositorPrivate *priv =
     meta_compositor_get_instance_private (compositor);
   ClutterActor *stage_actor = meta_backend_get_stage (priv->backend);
   CoglGraphicsResetStatus status;
+  ClutterStageView *stage_view;
   GList *l;
 
   status = cogl_get_graphics_reset_status (priv->context);
@@ -1040,6 +1051,8 @@ meta_compositor_real_after_paint (MetaCompositor   *compositor,
       break;
     }
 
+  stage_view = meta_compositor_view_get_stage_view (compositor_view);
+
   for (l = priv->windows; l; l = l->next)
     {
       ClutterActor *actor = l->data;
@@ -1052,12 +1065,17 @@ meta_compositor_real_after_paint (MetaCompositor   *compositor,
 }
 
 static void
-meta_compositor_after_paint (MetaCompositor   *compositor,
-                             ClutterStageView *stage_view)
+meta_compositor_after_paint (MetaCompositor     *compositor,
+                             MetaCompositorView *compositor_view)
 {
+  MetaCompositorPrivate *priv =
+    meta_compositor_get_instance_private (compositor);
+
   COGL_TRACE_BEGIN_SCOPED (MetaCompositorPostPaint,
                            "Compositor (after-paint)");
-  META_COMPOSITOR_GET_CLASS (compositor)->after_paint (compositor, stage_view);
+  META_COMPOSITOR_GET_CLASS (compositor)->after_paint (compositor, compositor_view);
+
+  priv->frame_in_progress = FALSE;
 }
 
 static void
@@ -1065,7 +1083,14 @@ on_before_paint (ClutterStage     *stage,
                  ClutterStageView *stage_view,
                  MetaCompositor   *compositor)
 {
-  meta_compositor_before_paint (compositor, stage_view);
+  MetaCompositorView *compositor_view;
+
+  compositor_view = g_object_get_qdata (G_OBJECT (stage_view),
+                                        quark_compositor_view);
+
+  g_assert (compositor_view != NULL);
+
+  meta_compositor_before_paint (compositor, compositor_view);
 }
 
 static void
@@ -1073,7 +1098,14 @@ on_after_paint (ClutterStage     *stage,
                 ClutterStageView *stage_view,
                 MetaCompositor   *compositor)
 {
-  meta_compositor_after_paint (compositor, stage_view);
+  MetaCompositorView *compositor_view;
+
+  compositor_view = g_object_get_qdata (G_OBJECT (stage_view),
+                                        quark_compositor_view);
+
+  g_assert (compositor_view != NULL);
+
+  meta_compositor_after_paint (compositor, compositor_view);
 }
 
 static void
diff --git a/src/compositor/meta-compositor-native.c b/src/compositor/meta-compositor-native.c
index bc17704e1b..c268905014 100644
--- a/src/compositor/meta-compositor-native.c
+++ b/src/compositor/meta-compositor-native.c
@@ -156,8 +156,8 @@ done:
 #endif /* HAVE_WAYLAND */
 
 static void
-meta_compositor_native_before_paint (MetaCompositor   *compositor,
-                                     ClutterStageView *stage_view)
+meta_compositor_native_before_paint (MetaCompositor     *compositor,
+                                     MetaCompositorView *compositor_view)
 {
   MetaCompositorClass *parent_class;
 
@@ -166,7 +166,7 @@ meta_compositor_native_before_paint (MetaCompositor   *compositor,
 #endif
 
   parent_class = META_COMPOSITOR_CLASS (meta_compositor_native_parent_class);
-  parent_class->before_paint (compositor, stage_view);
+  parent_class->before_paint (compositor, compositor_view);
 }
 
 MetaCompositorNative *
diff --git a/src/compositor/meta-compositor-x11.c b/src/compositor/meta-compositor-x11.c
index 614bec674b..8145efb5dc 100644
--- a/src/compositor/meta-compositor-x11.c
+++ b/src/compositor/meta-compositor-x11.c
@@ -385,8 +385,8 @@ on_after_update (ClutterStage     *stage,
 }
 
 static void
-meta_compositor_x11_before_paint (MetaCompositor   *compositor,
-                                  ClutterStageView *stage_view)
+meta_compositor_x11_before_paint (MetaCompositor     *compositor,
+                                  MetaCompositorView *compositor_view)
 {
   MetaCompositorX11 *compositor_x11 = META_COMPOSITOR_X11 (compositor);
   MetaCompositorClass *parent_class;
@@ -394,7 +394,7 @@ meta_compositor_x11_before_paint (MetaCompositor   *compositor,
   maybe_unredirect_top_window (compositor_x11);
 
   parent_class = META_COMPOSITOR_CLASS (meta_compositor_x11_parent_class);
-  parent_class->before_paint (compositor, stage_view);
+  parent_class->before_paint (compositor, compositor_view);
 }
 
 static void