From 18234ea91a8eec06fc1c43a516ad2f42391e7ecb Mon Sep 17 00:00:00 2001
From: Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
Date: Tue, 26 May 2020 01:41:43 -0300
Subject: [PATCH] appDisplay: Use custom function to retrieve item page and
 position

It is important that '_loadApps()' return a sorted list -- adding the
same icons at the same positions but in different orders results in
a wrong icon grid.

Add support for using a custom positioning function, and implement it
in AppDisplay. Because FolderView doesn't implement a custom sorting
function, the items are still sorted alphabetically.

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1284
---
 js/ui/appDisplay.js | 49 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 38 insertions(+), 11 deletions(-)

diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index 01df5afe6..5f9a2df5f 100644
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -305,11 +305,24 @@ var BaseAppView = GObject.registerClass({
         this._grid.removeItem(item);
     }
 
+    _getItemPosition(item) {
+        const { itemsPerPage } = this._grid;
+
+        let iconIndex = this._orderedItems.indexOf(item);
+        if (iconIndex === -1)
+            iconIndex = this._orderedItems.length - 1;
+
+        const page = Math.floor(iconIndex / itemsPerPage);
+        const position = iconIndex % itemsPerPage;
+
+        return [page, position];
+    }
+
     _redisplay() {
         let oldApps = this._orderedItems.slice();
         let oldAppIds = oldApps.map(icon => icon.id);
 
-        let newApps = this._loadApps().sort(this._compareItems);
+        let newApps = this._loadApps().sort(this._compareItems.bind(this));
         let newAppIds = newApps.map(icon => icon.id);
 
         let addedApps = newApps.filter(icon => !oldAppIds.includes(icon.id));
@@ -322,16 +335,9 @@ var BaseAppView = GObject.registerClass({
         });
 
         // Add new app icons
-        const { itemsPerPage } = this._grid;
         addedApps.forEach(icon => {
-            let iconIndex = newApps.indexOf(icon);
-
-            this._orderedItems.splice(iconIndex, 0, icon);
-            this._items.set(icon.id, icon);
-
-            const page = Math.floor(iconIndex / itemsPerPage);
-            const position = iconIndex % itemsPerPage;
-            this._grid.addItem(icon, page, position);
+            const [page, position] = this._getItemPosition(icon, newApps);
+            this._addItem(icon, page, position);
         });
 
         this._viewIsReady = true;
@@ -754,7 +760,7 @@ class AppDisplay extends BaseAppView {
         // supposed to be and reinsert it where it's sorted.
         let oldIdx = this._orderedItems.indexOf(item);
         this._orderedItems.splice(oldIdx, 1);
-        let newIdx = Util.insertSorted(this._orderedItems, item, this._compareItems);
+        let newIdx = Util.insertSorted(this._orderedItems, item, this._compareItems.bind(this));
 
         this._grid.removeItem(item);
 
@@ -770,6 +776,27 @@ class AppDisplay extends BaseAppView {
         return this._appInfoList;
     }
 
+    _getItemPosition(item) {
+        return this._pageManager.getAppPosition(item.id);
+    }
+
+    _compareItems(a, b) {
+        const [aPage, aPosition] = this._pageManager.getAppPosition(a.id);
+        const [bPage, bPosition] = this._pageManager.getAppPosition(b.id);
+
+        if (aPage === -1 && bPage === -1)
+            return a.name.localeCompare(b.name);
+        else if (aPage === -1)
+            return 1;
+        else if (bPage === -1)
+            return -1;
+
+        if (aPage !== bPage)
+            return aPage - bPage;
+
+        return aPosition - bPosition;
+    }
+
     _loadApps() {
         let appIcons = [];
         this._appInfoList = Shell.AppSystem.get_default().get_installed().filter(appInfo => {