[gnome-maps/wip/mlundblad/fix-drag-n-drop-routes] sidebar: Fix drag-and-dropping route entries

[Marcus Lundblad <mlundblad src gnome org>]

commit 73796ec4b479dd35d110cfec41da13f9f4c0ac53
Author: Marcus Lundblad <ml dfupdate se>
Date:   Thu Sep 29 22:43:57 2022 +0200

    sidebar: Fix drag-and-dropping route entries
    
    This was not working since the GTK4 port.

 src/sidebar.js | 51 ++++++++++++++-------------------------------------
 1 file changed, 14 insertions(+), 37 deletions(-)
---
diff --git a/src/sidebar.js b/src/sidebar.js
index 5a44c2a8..fc722194 100644
--- a/src/sidebar.js
+++ b/src/sidebar.js
@@ -559,51 +559,25 @@ export class Sidebar extends Gtk.Revealer {
         return true;
     }
 
-    _dragHighlightRow(row) {
-        row.opacity = 0.6;
-    }
-
-    _dragUnhighlightRow(row) {
-        row.opacity = 1.0;
-    }
-
-    // Set the opacity of the row we are currently dragging above
-    // to semi transparent.
-    _onDragMotion(row, context, x, y, time) {
-        let routeEntry = row.get_child();
-
-        if (this._draggedPoint && this._draggedPoint !== routeEntry.point) {
-            this._dragHighlightRow(row);
-            Gdk.drag_status(context, Gdk.DragAction.MOVE, time);
-        } else
-            Gdk.drag_status(context, 0, time);
-        return true;
-    }
-
     // Drag ends, show the dragged row again.
     _onDragEnd(row) {
         this._draggedPoint = null;
+        row.opacity = 1.0;
+    }
 
-        // Restore to natural height
-        row.height_request = -1;
-        row.get_child().show();
+    _onDragPrepare(routeEntry, source, x, y) {
+        return Gdk.ContentProvider.new_for_value(routeEntry);
     }
 
-    // Drag begins, set the correct drag icon and hide the dragged row.
+    // Drag begins, set the correct drag icon and dim the dragged row.
     _onDragBegin(source, row) {
         let routeEntry = row.get_child();
         let {x, y, width, height} = row.get_allocation();
-
-        this._draggedPoint = routeEntry.point;
-
-        // Set a fixed height on the row to prevent the sidebar height
-        // to shrink while dragging a row.
-        row.height_request = height;
-        row.get_child().hide();
-
-        let paintable = new Gtk.WidgetPaintable(row);
+        let paintable = new Gtk.WidgetPaintable({ widget: routeEntry });
 
         source.set_icon(paintable, 0, 0);
+        this._draggedPoint = routeEntry.point;
+        row.opacity = 0.6;
     }
 
     // Set up drag and drop between RouteEntrys. The drag source is from a
@@ -616,17 +590,20 @@ export class Sidebar extends Gtk.Revealer {
 
         dragIcon.add_controller(dragSource);
 
+        dragSource.connect('prepare',
+                           this._onDragPrepare.bind(this, routeEntry));
         dragSource.connect('drag-begin',
-                           (source, drag, widget) => this._onDragBegin(source, row));
+                           (source, drag, widget) =>
+                           this._onDragBegin(source, row));
         dragSource.connect('drag-end',
                            (source, dele, data) => this._onDragEnd(row));
 
-        let dropTarget = Gtk.DropTarget.new(RouteEntry, Gdk.DragAction.MOVE);
+        let dropTarget = Gtk.DropTarget.new(RouteEntry, Gdk.DragAction.COPY);
 
         row.add_controller(dropTarget);
 
         dropTarget.connect('drop',
-                           (target, value, x, y, data) => this._onDragDrop(target));
+                           (target, value, x, y, data) => this._onDragDrop(row));
     }
 }