[gnome-shell/gbsneto/custom-icon-positions: 5/20] appDisplay: Nudge target item towards its new position

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 0758cc593d2d20d775f40a8d78b2223d9f68bd26
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Mon Jun 22 18:46:59 2020 -0300

    appDisplay: Nudge target item towards its new position
    
    Make the icon being hovered slightly nudge towards its final
    position, some sort of "preview" of what will happen. This
    avoids a surprising change of the grid.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1284

 js/ui/appDisplay.js | 39 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)
---
diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index dbeac0967e..a611b88e48 100644
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -36,7 +36,7 @@ const FOLDER_DIALOG_ANIMATION_TIME = 200;
 const OVERSHOOT_THRESHOLD = 20;
 const OVERSHOOT_TIMEOUT = 1000;
 
-const DELAYED_MOVE_TIMEOUT = 1500;
+const DELAYED_MOVE_TIMEOUT = 750;
 
 let discreteGpuAvailable = false;
 
@@ -563,6 +563,7 @@ class AppDisplay extends BaseAppView {
         this._lastOvershootTimeoutId = 0;
         this._delayedMoveId = 0;
         this._targetDropPosition = null;
+        this._nudgedItem = null;
 
         Main.overview.connect('hidden', () => this.goToPage(0));
 
@@ -820,6 +821,37 @@ class AppDisplay extends BaseAppView {
         this._targetDropPosition = null;
     }
 
+    _nudgeItem(item, dragLocation) {
+        if (this._nudgedItem)
+            this._removeNudge();
+
+        const params = {
+            duration: DELAYED_MOVE_TIMEOUT,
+            mode: Clutter.AnimationMode.EASE_IN_OUT_CUBIC,
+        };
+
+        const rtl = this.get_text_direction() === Clutter.TextDirection.RTL;
+        const nudgeOffset = item.width / 4;
+        if (dragLocation === IconGrid.DragLocation.START_EDGE)
+            params.translation_x = nudgeOffset * (rtl ? -1 : 1);
+        else if (dragLocation === IconGrid.DragLocation.END_EDGE)
+            params.translation_x = -nudgeOffset * (rtl ? -1 : 1);
+
+        item.ease(params);
+        this._nudgedItem = item;
+    }
+
+    _removeNudge() {
+        if (!this._nudgedItem)
+            return;
+
+        this._nudgedItem.ease({
+            translation_x: 0,
+            mode: Clutter.AnimationMode.EASE_OUT_QUAD,
+        });
+        this._nudgedItem = null;
+    }
+
     _maybeMoveItem(dragEvent) {
         const [success, x, y] =
             this._grid.transform_stage_point(dragEvent.x, dragEvent.y);
@@ -835,6 +867,7 @@ class AppDisplay extends BaseAppView {
             item === source ||
             dragLocation === IconGrid.DragLocation.ON_ICON) {
             this._removeDelayedMove();
+            this._removeNudge();
             return;
         }
 
@@ -850,10 +883,13 @@ class AppDisplay extends BaseAppView {
             this._delayedMoveId = GLib.timeout_add(GLib.PRIORITY_DEFAULT,
                 DELAYED_MOVE_TIMEOUT, () => {
                     this.moveItem(source, page, position);
+                    this._removeNudge();
                     this._targetDropPosition = null;
                     this._delayedMoveId = 0;
                     return GLib.SOURCE_REMOVE;
                 });
+
+            this._nudgeItem(item, dragLocation);
         }
     }
 
@@ -942,6 +978,7 @@ class AppDisplay extends BaseAppView {
         }
 
         this._resetOvershoot();
+        this._removeNudge();
     }
 
     _canAccept(source) {