[gnome-shell/gbsneto/icon-grid-part2: 4/10] folderIcon: Allow dropping application icons

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

commit 55898dd1d4652cd807bf92b759e5cc2ff3d0c05a
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 | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
---
diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index 6bd3b1398b..5ec15c1f27 100644
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -81,6 +81,13 @@ function clamp(value, min, max) {
     return Math.max(min, Math.min(max, value));
 }
 
+function _getViewFromIcon(icon) {
+    let parent = icon.actor.get_parent();
+    if (!parent._delegate)
+        return null;
+    return parent._delegate;
+}
+
 class BaseAppView {
     constructor(params, gridParams) {
         if (this.constructor === BaseAppView)
@@ -240,6 +247,7 @@ var AllView = class AllView extends BaseAppView {
         this.actor = new St.Widget({ layout_manager: new Clutter.BinLayout(),
                                      x_expand: true, y_expand: true });
         this.actor.add_actor(this._scrollView);
+        this._grid._delegate = this;
 
         this._scrollView.set_policy(St.PolicyType.NEVER,
                                     St.PolicyType.EXTERNAL);
@@ -1048,6 +1056,7 @@ var FolderView = class FolderView extends BaseAppView {
         this._grid.x_expand = true;
         this._folder = folder;
         this._parentView = parentView;
+        this._grid._delegate = this;
 
         this.actor = new St.ScrollView({ overlay_scrollbars: true });
         this.actor.set_policy(St.PolicyType.NEVER, St.PolicyType.AUTOMATIC);
@@ -1220,6 +1229,11 @@ 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 +1267,57 @@ 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;
+
+        let view = _getViewFromIcon(source);
+        if (!view || !(view instanceof AllView))
+            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);
+
+        // Also remove from 'excluded-apps' if the app id is listed
+        // there. This is only possible on categories-based folders.
+        let excludedApps = this._folder.get_strv('excluded-apps');
+        let index = excludedApps.indexOf(app.id);
+        if (index >= 0) {
+            excludedApps.splice(index, 1);
+            this._folder.set_strv('excluded-apps', excludedApps);
+        }
+
+        return true;
+    }
+
     _updateName() {
         let name = _getFolderName(this._folder);
         if (this.name == name)