[gnome-shell/gnome-42] ControlsManagerLayout: Cache workAreaBox

[Florian Müllner <fmuellner src gnome org>]

commit dc933779681fc630ee2baf87fbbc72d162d68ec6
Author: Ivan Molodetskikh <yalterz gmail com>
Date:   Sat Jul 30 21:59:33 2022 -0700

    ControlsManagerLayout: Cache workAreaBox
    
    Allocation runs every frame during the overview animations, so we want
    to do as little work there as possible. Cache the work area box
    computation.
    
    Part-of:
    <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2395>
    (cherry picked from commit 8562606ad11b05435df78015ee4e8f6c4caff53a)

 js/ui/overviewControls.js | 39 ++++++++++++++++++++++++---------------
 1 file changed, 24 insertions(+), 15 deletions(-)
---
diff --git a/js/ui/overviewControls.js b/js/ui/overviewControls.js
index 2d58be7bb0..828463ef99 100644
--- a/js/ui/overviewControls.js
+++ b/js/ui/overviewControls.js
@@ -45,19 +45,34 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
         this._postAllocationCallbacks = [];
 
         stateAdjustment.connect('notify::value', () => this.layout_changed());
+
+        this._workAreaBox = new Clutter.ActorBox();
+        global.display.connectObject(
+            'workareas-changed', () => this._updateWorkAreaBox(),
+            this);
+        this._updateWorkAreaBox();
     }
 
-    _computeWorkspacesBoxForState(state, box, workAreaBox, searchHeight, dashHeight, thumbnailsHeight) {
+    _updateWorkAreaBox() {
+        const monitor = Main.layoutManager.primaryMonitor;
+        const workArea = Main.layoutManager.getWorkAreaForMonitor(monitor.index);
+        const startX = workArea.x - monitor.x;
+        const startY = workArea.y - monitor.y;
+        this._workAreaBox.set_origin(startX, startY);
+        this._workAreaBox.set_size(workArea.width, workArea.height);
+    }
+
+    _computeWorkspacesBoxForState(state, box, searchHeight, dashHeight, thumbnailsHeight) {
         const workspaceBox = box.copy();
         const [width, height] = workspaceBox.get_size();
-        const { y1: startY } = workAreaBox;
+        const { y1: startY } = this._workAreaBox;
         const { spacing } = this;
         const { expandFraction } = this._workspacesThumbnails;
 
         switch (state) {
         case ControlsState.HIDDEN:
-            workspaceBox.set_origin(...workAreaBox.get_origin());
-            workspaceBox.set_size(...workAreaBox.get_size());
+            workspaceBox.set_origin(...this._workAreaBox.get_origin());
+            workspaceBox.set_size(...this._workAreaBox.get_size());
             break;
         case ControlsState.WINDOW_PICKER:
             workspaceBox.set_origin(0,
@@ -80,9 +95,9 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
         return workspaceBox;
     }
 
-    _getAppDisplayBoxForState(state, box, workAreaBox, searchHeight, dashHeight, appGridBox) {
+    _getAppDisplayBoxForState(state, box, searchHeight, dashHeight, appGridBox) {
         const [width, height] = box.get_size();
-        const { y1: startY } = workAreaBox;
+        const { y1: startY } = this._workAreaBox;
         const appDisplayBox = new Clutter.ActorBox();
         const { spacing } = this;
 
@@ -135,13 +150,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
 
         const { spacing } = this;
 
-        const monitor = Main.layoutManager.primaryMonitor;
-        const workArea = Main.layoutManager.getWorkAreaForMonitor(monitor.index);
-        const startX = workArea.x - monitor.x;
-        const startY = workArea.y - monitor.y;
-        const workAreaBox = new Clutter.ActorBox();
-        workAreaBox.set_origin(startX, startY);
-        workAreaBox.set_size(workArea.width, workArea.height);
+        const startY = this._workAreaBox.y1;
         box.y1 += startY;
         const [width, height] = box.get_size();
         let availableHeight = height;
@@ -181,7 +190,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
         }
 
         // Workspaces
-        let params = [box, workAreaBox, searchHeight, dashHeight, thumbnailsHeight];
+        let params = [box, searchHeight, dashHeight, thumbnailsHeight];
         const transitionParams = this._stateAdjustment.getStateTransitionParams();
 
         // Update cached boxes
@@ -206,7 +215,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
             const workspaceAppGridBox =
                 this._cachedWorkspaceBoxes.get(ControlsState.APP_GRID);
 
-            params = [box, workAreaBox, searchHeight, dashHeight, workspaceAppGridBox];
+            params = [box, searchHeight, dashHeight, workspaceAppGridBox];
             let appDisplayBox;
             if (!transitionParams.transitioning) {
                 appDisplayBox =