[gnome-shell/wip/exalm/gestures2: 7/10] workspaceAnimation: Use window clones

[Alexander Mikhaylenko <alexm src gnome org>]

commit 5b2cf8eeb1582198fdc4d9d904c7dbdb74591b7a
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Thu Jul 4 23:15:15 2019 +0500

    workspaceAnimation: Use window clones
    
    Instead of reparenting windows, clone them. This will allow to properly
    support multi-monitor setups in subsequent commits.
    
    Block window mapping animation while the animation is running to prevent
    new windows appearing during the animation from being visible at the same
    time as their clones.
    
    Fixes https://gitlab.gnome.org/GNOME/mutter/issues/929
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1326

 js/ui/workspaceAnimation.js | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)
---
diff --git a/js/ui/workspaceAnimation.js b/js/ui/workspaceAnimation.js
index 3c2148bda5..e7cbd9f9f6 100644
--- a/js/ui/workspaceAnimation.js
+++ b/js/ui/workspaceAnimation.js
@@ -38,12 +38,16 @@ class WorkspaceGroup extends Clutter.Actor {
     }
 
     _syncStacking() {
-        const windowActors = global.get_window_actors();
-        let lastSibling = null;
+        const windowActors = global.get_window_actors().filter(w =>
+            this._shouldShowWindow(w.meta_window));
+
+        let lastRecord;
 
         for (const windowActor of windowActors) {
-            this.set_child_above_sibling(windowActor, lastSibling);
-            lastSibling = windowActor;
+            const record = this._windowRecords.find(r => r.windowActor === windowActor);
+
+            this.set_child_above_sibling(record.clone, lastRecord ? lastRecord.clone : null);
+            lastRecord = record;
         }
     }
 
@@ -52,16 +56,18 @@ class WorkspaceGroup extends Clutter.Actor {
             this._shouldShowWindow(w.meta_window));
 
         for (const windowActor of windowActors) {
-            const record = {
-                windowActor,
-                parent: windowActor.get_parent(),
-            };
+            const clone = new Clutter.Clone({
+                source: windowActor,
+                x: windowActor.x,
+                y: windowActor.y,
+            });
+
+            this.add_child(clone);
 
-            record.parent.remove_child(windowActor);
-            this.add_child(windowActor);
-            windowActor.show();
+            const record = { windowActor, clone };
 
             record.windowDestroyId = windowActor.connect('destroy', () => {
+                clone.destroy();
                 this._windowRecords.splice(this._windowRecords.indexOf(record), 1);
             });
 
@@ -72,11 +78,7 @@ class WorkspaceGroup extends Clutter.Actor {
     _removeWindows() {
         for (const record of this._windowRecords) {
             record.windowActor.disconnect(record.windowDestroyId);
-            this.remove_child(record.windowActor);
-            record.parent.add_child(record.windowActor);
-
-            if (!this._workspace.active)
-                record.windowActor.hide();
+            record.clone.destroy();
         }
 
         this._windowRecords = [];