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Source/Editor/CustomEditors/GUI/DraggablePropertyNameLabel.cs

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+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+using FlaxEngine;
+using FlaxEngine.GUI;
+
+namespace FlaxEditor.CustomEditors.GUI
+{
+    /// <summary>
+    /// Custom property name label that fires mouse events for label and supports dragging.
+    /// </summary>
+    /// <seealso cref="FlaxEditor.CustomEditors.GUI.PropertyNameLabel" />
+    [HideInEditor]
+    public class DraggablePropertyNameLabel : ClickablePropertyNameLabel
+    {
+        private bool _isLeftMouseButtonDown;
+
+        /// <summary>
+        /// Mouse drag action delegate.
+        /// </summary>
+        /// <param name="label">The label.</param>
+        /// <returns>The drag data or null if not use drag.</returns>
+        public delegate DragData DragDelegate(DraggablePropertyNameLabel label);
+
+        /// <summary>
+        /// The mouse starts the drag. Callbacks gets the drag data.
+        /// </summary>
+        public DragDelegate Drag;
+
+        /// <inheritdoc />
+        public DraggablePropertyNameLabel(string name)
+        : base(name)
+        {
+        }
+
+        /// <inheritdoc />
+        public override bool OnMouseUp(Vector2 location, MouseButton button)
+        {
+            if (button == MouseButton.Left)
+            {
+                _isLeftMouseButtonDown = false;
+            }
+
+            base.OnMouseUp(location, button);
+            return true;
+        }
+
+        /// <inheritdoc />
+        public override bool OnMouseDown(Vector2 location, MouseButton button)
+        {
+            if (button == MouseButton.Left)
+            {
+                _isLeftMouseButtonDown = true;
+            }
+
+            base.OnMouseDown(location, button);
+            return true;
+        }
+
+        /// <inheritdoc />
+        public override void OnMouseLeave()
+        {
+            base.OnMouseLeave();
+
+            if (_isLeftMouseButtonDown)
+            {
+                _isLeftMouseButtonDown = false;
+
+                var data = Drag?.Invoke(this);
+                if (data != null)
+                {
+                    DoDragDrop(data);
+                }
+            }
+        }
+
+        /// <inheritdoc />
+        public override void OnDestroy()
+        {
+            // Unlink event
+            Drag = null;
+
+            base.OnDestroy();
+        }
+    }
+}