[gnome-shell] iconGrid/iconGrid: Wait for icon sizes before running spring animation

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

commit b730875012cabc4cf4ffecb869266b8a76ea64cc
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Wed Dec 2 17:43:13 2020 -0300

    iconGrid/iconGrid: Wait for icon sizes before running spring animation
    
    To run the spring animation, IconGrid uses the transformed position and size
    of the icons. This works okay when IconGridLayout doesn't need to update the
    icon sizes, but looks bad when IconGridLayout selects a different icon size.
    
    Wait for the icon sizes to be recalculated, and the icons  beallocated, before
    running the spring animation. If no icon size update is pending, run the spring
    animation directly.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1518>

 js/ui/iconGrid.js | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)
---
diff --git a/js/ui/iconGrid.js b/js/ui/iconGrid.js
index 093815922c..b7c8db5936 100644
--- a/js/ui/iconGrid.js
+++ b/js/ui/iconGrid.js
@@ -391,6 +391,9 @@ var IconGridLayout = GObject.registerClass({
 
         this._containerDestroyedId = 0;
         this._updateIconSizesLaterId = 0;
+
+        this._resolveOnIdleId = 0;
+        this._iconSizeUpdateResolveCbs = [];
     }
 
     _findBestIconSize() {
@@ -701,11 +704,28 @@ var IconGridLayout = GObject.registerClass({
         return isRtl ? rowAlign * -1 : rowAlign;
     }
 
+    _runPostAllocation() {
+        if (this._iconSizeUpdateResolveCbs.length > 0 &&
+            this._resolveOnIdleId === 0) {
+            this._resolveOnIdleId = GLib.idle_add(GLib.PRIORITY_DEFAULT, () => {
+                this._iconSizeUpdateResolveCbs.forEach(cb => cb());
+                this._iconSizeUpdateResolveCbs = [];
+                this._resolveOnIdleId = 0;
+                return GLib.SOURCE_REMOVE;
+            });
+        }
+    }
+
     _onDestroy() {
         if (this._updateIconSizesLaterId >= 0) {
             Meta.later_remove(this._updateIconSizesLaterId);
             this._updateIconSizesLaterId = 0;
         }
+
+        if (this._resolveOnIdleId > 0) {
+            GLib.source_remove(this._resolveOnIdleId);
+            delete this._resolveOnIdleId;
+        }
     }
 
     vfunc_set_container(container) {
@@ -820,6 +840,8 @@ var IconGridLayout = GObject.registerClass({
         });
 
         this._pageSizeChanged = false;
+
+        this._runPostAllocation();
     }
 
     /**
@@ -964,6 +986,14 @@ var IconGridLayout = GObject.registerClass({
         return itemData.pageIndex;
     }
 
+    ensureIconSizeUpdated() {
+        if (this._updateIconSizesLaterId === 0)
+            return Promise.resolve();
+
+        return new Promise(
+            resolve => this._iconSizeUpdateResolveCbs.push(resolve));
+    }
+
     adaptToSize(pageWidth, pageHeight) {
         if (this._pageWidth === pageWidth && this._pageHeight === pageHeight)
             return;
@@ -1617,7 +1647,7 @@ var IconGrid = GObject.registerClass({
         this.layout_manager.adaptToSize(width, height);
     }
 
-    animateSpring(animationDirection, sourceActor) {
+    async animateSpring(animationDirection, sourceActor) {
         this._resetAnimationActors();
 
         let actors = this._getChildrenToAnimate();
@@ -1626,6 +1656,8 @@ var IconGrid = GObject.registerClass({
             return;
         }
 
+        await this.layout_manager.ensureIconSizeUpdated();
+
         let [sourceX, sourceY] = sourceActor.get_transformed_position();
         let [sourceWidth, sourceHeight] = sourceActor.get_size();
         // Get the center