[gnome-shell] iconGrid: Only animate items when we actually need it

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

commit 7f996550673ea417a1f0618a883d9275ae0e93cf
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Wed Feb 24 11:29:46 2021 +0100

    iconGrid: Only animate items when we actually need it
    
    Animating items of the iconGrid involves calling a few more C functions,
    which is quite slow. Especially calling ClutterActor.set_easing_delay()
    is slow because we override that function in JS to adjust for the
    animation slow-down factor. So add a small class variable to make sure
    we only animate the icons of the grid when we actually need it.
    
    This makes the average time spent in vfunc_allocate() of the iconGrid go
    down to about 0.7 ms.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1713>

 js/ui/iconGrid.js | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/js/ui/iconGrid.js b/js/ui/iconGrid.js
index 0fc37a49c5..0272c0e233 100644
--- a/js/ui/iconGrid.js
+++ b/js/ui/iconGrid.js
@@ -790,6 +790,7 @@ var IconGridLayout = GObject.registerClass({
         const pageHeight = this._pageHeight;
         const pageSizeChanged = this._pageSizeChanged;
         const lastRowAlign = this.lastRowAlign;
+        const shouldEaseItems = this._shouldEaseItems;
 
         this._pages.forEach((page, pageIndex) => {
             if (isRtl && orientation === Clutter.Orientation.HORIZONTAL)
@@ -826,8 +827,7 @@ var IconGridLayout = GObject.registerClass({
                     Math.max(childSize, naturalWidth),
                     Math.max(childSize, naturalHeight));
 
-                // Only ease icons when the page size didn't change
-                if (pageSizeChanged)
+                if (!shouldEaseItems || pageSizeChanged)
                     item.allocate(childBox);
                 else if (animateIconPosition(item, childBox, nChangedIcons))
                     nChangedIcons++;
@@ -835,6 +835,7 @@ var IconGridLayout = GObject.registerClass({
         });
 
         this._pageSizeChanged = false;
+        this._shouldEaseItems = false;
 
         this._runPostAllocation();
     }
@@ -863,6 +864,8 @@ var IconGridLayout = GObject.registerClass({
         if (!this._container)
             return;
 
+        this._shouldEaseItems = true;
+
         this._container.add_child(item);
         this._addItemToPage(item, page, index);
     }
@@ -889,6 +892,8 @@ var IconGridLayout = GObject.registerClass({
         if (!this._items.has(item))
             throw new Error(`Item ${item} is not part of the IconGridLayout`);
 
+        this._shouldEaseItems = true;
+
         this._removeItemData(item);
         this._addItemToPage(item, newPage, newPosition);
     }
@@ -906,6 +911,8 @@ var IconGridLayout = GObject.registerClass({
         if (!this._container)
             return;
 
+        this._shouldEaseItems = true;
+
         this._container.remove_child(item);
         this._removeItemData(item);
     }