drag and drop basics

src/ui/play_queue.vala

@@ -10,6 +10,16 @@ class Ui.PlayQueueSong : Gtk.ListBoxRow {
     [GtkCallback] private string star_button_icon_name (DateTime? starred) {
         return starred == null ? "non-starred" : "starred";
     }
+
+    [GtkCallback] private Gdk.ContentProvider? on_drag_prepare (double x, double y) {
+        return new Gdk.ContentProvider.for_value (this);
+    }
+
+    [GtkCallback] private bool on_drop (Value value, double x, double y) {
+        var source = value as PlayQueueSong;
+        print ("dropped %u on %u", source.position, this.position);
+        return false;
+    }
 }
 
 [GtkTemplate (ui = "/eu/callcc/audrey/ui/play_queue.ui")]

src/ui/play_queue_song.blp

@@ -8,7 +8,7 @@ template $UiPlayQueueSong: ListBoxRow {
     spacing: 6;
 
     Image {
-      visible: false;
+      //visible: false;
       icon-name: "list-drag-handle";
       styles [ "drag-handle" ]
     }
@@ -113,6 +113,21 @@ template $UiPlayQueueSong: ListBoxRow {
       styles [ "flat" ]
     }
   }
+
+  DragSource {
+    actions: move;
+    propagation-phase: capture;
+
+    prepare => $on_drag_prepare ();
+  }
+
+  DropTarget {
+    actions: move;
+    formats: UiPlayQueueSong;
+    preload: true;
+
+    drop => $on_drop ();
+  }
 }
 
 SizeGroup {