[gnome-shell] st: Only use clutter_actor_invalidate_paint_volume() if the API exists

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

commit 1cefd589da2edca84d19b285d553e2a68cda3e37
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Mon Apr 12 20:49:10 2021 +0200

    st: Only use clutter_actor_invalidate_paint_volume() if the API exists
    
    With commits fab39bbea5d9a7a0330a1be548f8ee26cd7e3131 and
    62e40a13506b4481a50944be886b36566c464dc0 we started depending on a new
    ClutterActor API: clutter_actor_invalidate_paint_volume()
    
    Given that this commit was applied to the 40 stable release, it broke
    ABI compatibility with mutter, which is something we guarantee between
    stable releases. So use GModule to dynamically find the symbol in our
    loaded libraries. If it exists, use it and invalidate the paint volume.
    If it doesn't exist, libmutter is still at version 40.0 and we don't
    need to invalidate the paint volume.
    
    This also adds a dependency on gmodule. We need to link against gmodule
    to use g_module_open() and g_module_symbol() APIs.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1807>

 meson.build          |  1 +
 src/st/meson.build   |  2 +-
 src/st/st-viewport.c | 16 +++++++++++++++-
 src/st/st-widget.c   | 14 +++++++++++++-
 4 files changed, 30 insertions(+), 3 deletions(-)
---
diff --git a/meson.build b/meson.build
index 14b75c1c9f..359fa2a35d 100644
--- a/meson.build
+++ b/meson.build
@@ -81,6 +81,7 @@ gi_dep = dependency('gobject-introspection-1.0', version: gi_req)
 gio_dep = dependency('gio-2.0', version: gio_req)
 gio_unix_dep = dependency('gio-unix-2.0', version: gio_req)
 gjs_dep = dependency('gjs-1.0', version: gjs_req)
+gmodule_dep = dependency('gmodule-2.0')
 gtk_dep = dependency('gtk+-3.0', version: gtk_req)
 libxml_dep = dependency('libxml-2.0')
 clutter_dep = dependency(clutter_pc, version: mutter_req)
diff --git a/src/st/meson.build b/src/st/meson.build
index 6b88af2952..a74581ff8a 100644
--- a/src/st/meson.build
+++ b/src/st/meson.build
@@ -180,7 +180,7 @@ st_cflags = [
 libst = shared_library('st-1.0',
   sources: st_gir_sources + st_nogir_sources + croco_sources,
   c_args: st_cflags,
-  dependencies: [clutter_dep, gtk_dep, mutter_dep, libxml_dep, m_dep],
+  dependencies: [clutter_dep, gmodule_dep, gtk_dep, mutter_dep, libxml_dep, m_dep],
   build_rpath: mutter_typelibdir,
   install_rpath: mutter_typelibdir,
   install_dir: pkglibdir,
diff --git a/src/st/st-viewport.c b/src/st/st-viewport.c
index 96b703b14f..8aaaad54ac 100644
--- a/src/st/st-viewport.c
+++ b/src/st/st-viewport.c
@@ -80,8 +80,22 @@ adjustment_value_notify_cb (StAdjustment *adjustment,
                             GParamSpec   *pspec,
                             StViewport   *viewport)
 {
+  static gboolean invalidate_paint_volume_valid = FALSE;
+  static void (* invalidate_paint_volume) (ClutterActor *) = NULL;
+
   clutter_actor_invalidate_transform (CLUTTER_ACTOR (viewport));
-  clutter_actor_invalidate_paint_volume (CLUTTER_ACTOR (viewport));
+
+  if (!invalidate_paint_volume_valid)
+    {
+      g_module_symbol (g_module_open (NULL, G_MODULE_BIND_LAZY),
+                       "clutter_actor_invalidate_paint_volume",
+                       (gpointer *)&invalidate_paint_volume);
+      invalidate_paint_volume_valid = TRUE;
+    }
+
+  if (invalidate_paint_volume)
+    invalidate_paint_volume (CLUTTER_ACTOR (viewport));
+
   clutter_actor_queue_relayout (CLUTTER_ACTOR (viewport));
 }
 
diff --git a/src/st/st-widget.c b/src/st/st-widget.c
index 47a84c5c2d..05a2dd134b 100644
--- a/src/st/st-widget.c
+++ b/src/st/st-widget.c
@@ -1722,7 +1722,19 @@ st_widget_recompute_style (StWidget    *widget,
 
   if (!paint_equal)
     {
-      clutter_actor_invalidate_paint_volume (CLUTTER_ACTOR (widget));
+      static gboolean invalidate_paint_volume_valid = FALSE;
+      static void (* invalidate_paint_volume) (ClutterActor *) = NULL;
+
+      if (!invalidate_paint_volume_valid)
+        {
+          g_module_symbol (g_module_open (NULL, G_MODULE_BIND_LAZY),
+                           "clutter_actor_invalidate_paint_volume",
+                           (gpointer *)&invalidate_paint_volume);
+          invalidate_paint_volume_valid = TRUE;
+        }
+
+      if (invalidate_paint_volume)
+        invalidate_paint_volume (CLUTTER_ACTOR (widget));
 
       next_paint_state (widget);