[gnome-shell/gbsneto/icon-grid-part2: 42/48] folderIcon: Allow dropping application icons

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

commit 2122e0dc006313c6711ff61327a1632187ccec03
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Fri Jun 28 19:47:32 2019 -0300

    folderIcon: Allow dropping application icons
    
    Connect to the overview signals related to Drag n' Drop, and
    allow dropping application icons in it. Dropping an icon
    appends the application id to the folder's GSettings key.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/664

 js/ui/appDisplay.js | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
---
diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index 6bd3b1398..e6b599a75 100644
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -1220,6 +1220,11 @@ var FolderIcon = class FolderIcon {
 
         this.view = new FolderView(this._folder, parentView);
 
+        Main.overview.connect('item-drag-begin',
+                              this._onDragBegin.bind(this));
+        Main.overview.connect('item-drag-end',
+                              this._onDragEnd.bind(this));
+
         this.actor.connect('clicked', this.open.bind(this));
         this.actor.connect('destroy', this.onDestroy.bind(this));
         this.actor.connect('notify::mapped', () => {
@@ -1253,6 +1258,44 @@ var FolderIcon = class FolderIcon {
         return this.view.getAllItems().map(item => item.id);
     }
 
+    _onDragBegin() {
+        this._parentView.inhibitEventBlocker();
+    }
+
+    _onDragEnd() {
+        this._parentView.uninhibitEventBlocker();
+    }
+
+    _canAccept(source) {
+        if (!(source instanceof AppIcon))
+            return false;
+
+        if (this._folder.get_strv('apps').includes(source.id))
+            return false;
+
+        return true;
+    }
+
+    handleDragOver(source) {
+        if (!this._canAccept(source))
+            return DND.DragMotionResult.NO_DROP;
+
+        return DND.DragMotionResult.MOVE_DROP;
+    }
+
+    acceptDrop(source) {
+        if (!this._canAccept(source))
+            return true;
+
+        let app = source.app;
+        let folderApps = this._folder.get_strv('apps');
+        folderApps.push(app.id);
+
+        this._folder.set_strv('apps', folderApps);
+
+        return true;
+    }
+
     _updateName() {
         let name = _getFolderName(this._folder);
         if (this.name == name)