[gnome-shell] iconGrid: Save class variables to local ones

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

commit 7771bf4437d236f69121f458273743fe7d565b69
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Wed Feb 24 12:07:03 2021 +0100

    iconGrid: Save class variables to local ones
    
    It's quite slow to access class variables in JS, especially when they're
    backed by GObject properties. To avoid accessing them in every iteration
    when we're looping through the children of iconGrid, store those values
    to another variable and reuse that inside the loop.
    
    This shaves off another 0.2 ms from iconGrids vfunc_allocate(), getting
    the average time spent in that function down from 1.3 ms to 1.1 ms.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1713>

 js/ui/iconGrid.js | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)
---
diff --git a/js/ui/iconGrid.js b/js/ui/iconGrid.js
index 8f6b547019..0fc37a49c5 100644
--- a/js/ui/iconGrid.js
+++ b/js/ui/iconGrid.js
@@ -662,9 +662,9 @@ var IconGridLayout = GObject.registerClass({
         return [leftEmptySpace, topEmptySpace, hSpacing, vSpacing];
     }
 
-    _getRowPadding(items, itemIndex, childSize, spacing) {
-        if (this.lastRowAlign === Clutter.ActorAlign.START ||
-            this.lastRowAlign === Clutter.ActorAlign.FILL)
+    _getRowPadding(align, items, itemIndex, childSize, spacing) {
+        if (align === Clutter.ActorAlign.START ||
+            align === Clutter.ActorAlign.FILL)
             return 0;
 
         const nRows = Math.ceil(items.length / this.columnsPerPage);
@@ -685,7 +685,7 @@ var IconGridLayout = GObject.registerClass({
         const isRtl =
             Clutter.get_default_text_direction() === Clutter.TextDirection.RTL;
 
-        switch (this.lastRowAlign) {
+        switch (align) {
         case Clutter.ActorAlign.CENTER:
             rowAlign = availableWidth / 2;
             break;
@@ -784,32 +784,38 @@ var IconGridLayout = GObject.registerClass({
         const childBox = new Clutter.ActorBox();
 
         let nChangedIcons = 0;
+        const columnsPerPage = this.columnsPerPage;
+        const orientation = this._orientation;
+        const pageWidth = this._pageWidth;
+        const pageHeight = this._pageHeight;
+        const pageSizeChanged = this._pageSizeChanged;
+        const lastRowAlign = this.lastRowAlign;
 
         this._pages.forEach((page, pageIndex) => {
-            if (isRtl && this._orientation === Clutter.Orientation.HORIZONTAL)
+            if (isRtl && orientation === Clutter.Orientation.HORIZONTAL)
                 pageIndex = swap(pageIndex, this._pages.length);
 
             page.visibleChildren.forEach((item, itemIndex) => {
-                const row = Math.floor(itemIndex / this.columnsPerPage);
-                let column = itemIndex % this.columnsPerPage;
+                const row = Math.floor(itemIndex / columnsPerPage);
+                let column = itemIndex % columnsPerPage;
 
                 if (isRtl)
-                    column = swap(column, this.columnsPerPage);
+                    column = swap(column, columnsPerPage);
 
-                const rowPadding = this._getRowPadding(page.visibleChildren,
-                    itemIndex, childSize, hSpacing);
+                const rowPadding = this._getRowPadding(lastRowAlign,
+                    page.visibleChildren, itemIndex, childSize, hSpacing);
 
                 // Icon position
                 let x = leftEmptySpace + rowPadding + column * (childSize + hSpacing);
                 let y = topEmptySpace + row * (childSize + vSpacing);
 
                 // Page start
-                switch (this._orientation) {
+                switch (orientation) {
                 case Clutter.Orientation.HORIZONTAL:
-                    x += pageIndex * this._pageWidth;
+                    x += pageIndex * pageWidth;
                     break;
                 case Clutter.Orientation.VERTICAL:
-                    y += pageIndex * this._pageHeight;
+                    y += pageIndex * pageHeight;
                     break;
                 }
 
@@ -821,7 +827,7 @@ var IconGridLayout = GObject.registerClass({
                     Math.max(childSize, naturalHeight));
 
                 // Only ease icons when the page size didn't change
-                if (this._pageSizeChanged)
+                if (pageSizeChanged)
                     item.allocate(childBox);
                 else if (animateIconPosition(item, childBox, nChangedIcons))
                     nChangedIcons++;