[gnome-shell/wip/exalm/gestures-part-2: 1/2] appDisplay: Add timeout for mouse scrolling

[Florian Müllner <fmuellner src gnome org>]

commit 08ebfa1acfd1261bb44853f0d8a94dfa58e76c28
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Wed Oct 16 12:30:14 2019 +0500

    appDisplay: Add timeout for mouse scrolling
    
    Prevent uncontrollably fast scrolling. Use the same duration as switching
    animation, but add a separate timeout to account for disabled animations.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/issues/1338
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/825

 js/ui/appDisplay.js | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
---
diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index 05d0ab3a4a..0156877e8f 100644
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -376,6 +376,9 @@ var AllView = GObject.registerClass({
         this._displayingPopup = false;
         this._currentPopupDestroyId = 0;
 
+        this._canScroll = true; // limiting scrolling speed
+        this._scrollTimeoutId = 0;
+
         this._availWidth = 0;
         this._availHeight = 0;
 
@@ -406,6 +409,15 @@ var AllView = GObject.registerClass({
 
         Main.overview.connect('item-drag-begin', this._onDragBegin.bind(this));
         Main.overview.connect('item-drag-end', this._onDragEnd.bind(this));
+
+        this.connect('destroy', this._onDestroy.bind(this));
+    }
+
+    _onDestroy() {
+        if (this._scrollTimeoutId !== 0) {
+            GLib.source_remove(this._scrollTimeoutId);
+            this._scrollTimeoutId = 0;
+        }
     }
 
     vfunc_map() {
@@ -638,11 +650,25 @@ var AllView = GObject.registerClass({
         if (this._displayingPopup || !this._scrollView.reactive)
             return Clutter.EVENT_STOP;
 
+        if (!this._canScroll)
+            return Clutter.EVENT_STOP;
+
         let direction = event.get_scroll_direction();
         if (direction == Clutter.ScrollDirection.UP)
             this.goToPage(this._grid.currentPage - 1);
         else if (direction == Clutter.ScrollDirection.DOWN)
             this.goToPage(this._grid.currentPage + 1);
+        else
+            return Clutter.EVENT_STOP;
+
+        this._canScroll = false;
+        this._scrollTimeoutId = GLib.timeout_add(GLib.PRIORITY_DEFAULT,
+            PAGE_SWITCH_TIME, () => {
+                this._canScroll = true;
+                this._scrollTimeoutId = 0;
+                return GLib.SOURCE_REMOVE;
+            }
+        );
 
         return Clutter.EVENT_STOP;
     }