appIcon: Scale and fade itself when starting drag

As per design direction, scale and fade the app icon
when starting dragging it, and show it again if the
drop is accepted. Clutter takes care of animating the
rest of icon positions through implicit animations.

Scale and fade the dragged icon while it's being dragged.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/603

js/ui/appDisplay.js

@@ -894,6 +894,8 @@ var AllView = class AllView extends BaseAppView {
                 this._currentPopup.popdown();
         }
 
+        source.undoScaleAndFade();
+
         this.moveItem(source, index);
         this.removeNudges();
         return true;
@@ -1358,8 +1360,11 @@ var FolderView = class FolderView extends BaseAppView {
 
     acceptDrop(source, actor, x, y, time) {
         let [index, dragLocation] = this.canDropAt(x, y);
+        let sourceIndex = this._allItems.indexOf(source);
         let success = index != -1;
 
+        source.undoScaleAndFade();
+
         if (success)
             this.moveItem(source, index);
 
@@ -1569,8 +1574,10 @@ var FolderIcon = class FolderIcon {
     }
 
     acceptDrop(source, actor, x, y, time) {
-        if (!this._canDropAt(source))
+        if (!this._canDropAt(source)) {
+            source.undoScaleAndFade();
             return true;
+        }
 
         let app = source.app;
         let folderApps = this._folder.get_strv('apps');
@@ -1848,6 +1855,7 @@ var AppIcon = class AppIcon {
         this._view = view;
 
         this.actor = new St.Button({ style_class: 'app-well-app',
+                                     pivot_point: new Clutter.Point({x: 0.5, y: 0.5}),
                                      reactive: true,
                                      button_mask: St.ButtonMask.ONE | St.ButtonMask.TWO,
                                      can_focus: true,
@@ -1894,6 +1902,7 @@ var AppIcon = class AppIcon {
             this._draggable = DND.makeDraggable(this.actor);
             this._draggable.connect('drag-begin', () => {
                 this._dragging = true;
+                this.scaleAndFade();
                 this._removeMenuTimeout();
                 Main.overview.beginItemDrag(this);
             });
@@ -1903,6 +1912,7 @@ var AppIcon = class AppIcon {
             });
             this._draggable.connect('drag-end', () => {
                 this._dragging = false;
+                this.undoScaleAndFade();
                 Main.overview.endItemDrag(this);
             });
         }
@@ -2126,6 +2136,24 @@ var AppIcon = class AppIcon {
         return this.actor.hover && (!this._menu || !this._menu.isOpen);
     }
 
+    scaleAndFade() {
+        this.actor.save_easing_state();
+        this.actor.reactive = false;
+        this.actor.scale_x = 0.75;
+        this.actor.scale_y = 0.75;
+        this.actor.opacity = 128;
+        this.actor.restore_easing_state();
+    }
+
+    undoScaleAndFade() {
+        this.actor.save_easing_state();
+        this.actor.reactive = true;
+        this.actor.scale_x = 1.0;
+        this.actor.scale_y = 1.0;
+        this.actor.opacity = 255;
+        this.actor.restore_easing_state();
+    }
+
     get view() {
         return this._view;
     }

js/ui/dash.js

@@ -478,16 +478,6 @@ var Dash = class Dash {
         let appIcon = new AppDisplay.AppIcon(app, null,
                                              { setSizeManually: true,
                                                showLabel: false });
-        if (appIcon._draggable) {
-            appIcon._draggable.connect('drag-begin',
-                                       () => {
-                                           appIcon.actor.opacity = 50;
-                                       });
-            appIcon._draggable.connect('drag-end',
-                                       () => {
-                                           appIcon.actor.opacity = 255;
-                                       });
-        }
 
         appIcon.connect('menu-state-changed',
                         (appIcon, opened) => {