chore: initial commit

Packages/com.kybernetik.animancer/Editor/GUI/DragAndDropHandler.cs

@@ -0,0 +1,127 @@
+// Animancer // https://kybernetik.com.au/animancer // Copyright 2018-2026 Kybernetik //
+
+#if UNITY_EDITOR
+
+using System;
+using System.Collections;
+using UnityEditor;
+using UnityEngine;
+
+namespace Animancer.Editor
+{
+    /// <summary>[Editor-Only]
+    /// Delegate for validating and responding to <see cref="DragAndDrop"/> operations.
+    /// </summary>
+    /// <remarks>
+    /// 
+    /// <strong>Example:</strong>
+    /// <code>
+    /// private DragAndDropHandler&lt;AnimationClip&gt; _AnimationDropHandler;
+    /// 
+    /// void OnGUI(Rect area)
+    /// {
+    ///     _AnimationDropHandler ??= (clip, isDrop) =>
+    ///     {
+    ///         if (clip.legacy)// Reject legacy animations
+    ///             return false;
+    ///             
+    ///         if (isDrop)// Only act when dropping.
+    ///             Debug.Log(clip + " was dropped");
+    ///     
+    ///         return true;// Drag or drop is accepted.
+    ///     };
+    ///     
+    ///     _AnimationDropHandler.Handle(area);
+    /// }
+    /// </code></remarks>
+    /// https://kybernetik.com.au/animancer/api/Animancer.Editor/DragAndDropHandler_1
+    public delegate bool DragAndDropHandler<T>(
+        T dragging,
+        bool isDrop)
+        where T : class;
+
+    /// https://kybernetik.com.au/animancer/api/Animancer.Editor/AnimancerGUI
+    public static partial class AnimancerGUI
+    {
+        /************************************************************************************************************************/
+
+        /// <summary>Handles the current event.</summary>
+        /// <remarks>See <see cref="DragAndDropHandler{T}"/> for a usage example.</remarks>
+        public static bool Handle<T>(
+            this DragAndDropHandler<T> handler,
+            Rect area,
+            DragAndDropVisualMode mode = DragAndDropVisualMode.Link)
+            where T : class
+        {
+            var currentEvent = Event.current;
+
+            bool isDrop;
+            switch (currentEvent.type)
+            {
+                case EventType.DragUpdated:
+                    isDrop = false;
+                    break;
+
+                case EventType.DragPerform:
+                    isDrop = true;
+                    break;
+
+                default:
+                    return false;
+            }
+
+            if (!area.Contains(currentEvent.mousePosition))
+                return false;
+
+            return handler.Handle(DragAndDrop.objectReferences, isDrop, mode);
+        }
+
+        /************************************************************************************************************************/
+
+        /// <summary>Handles the current event.</summary>
+        /// <remarks>See <see cref="DragAndDropHandler{T}"/> for a usage example.</remarks>
+        public static bool Handle<T>(
+            this DragAndDropHandler<T> handler,
+            IEnumerable dragging,
+            bool isDrop,
+            DragAndDropVisualMode mode = DragAndDropVisualMode.Link)
+            where T : class
+        {
+            if (dragging == null)
+                return false;
+
+            var droppedAny = false;
+
+            foreach (var obj in dragging)
+            {
+                if (obj is not T t ||
+                    !handler(t, isDrop))
+                    continue;
+
+                Deselect();
+                Event.current.Use();
+
+                if (isDrop)
+                {
+                    droppedAny = true;
+                }
+                else
+                {
+                    DragAndDrop.visualMode = mode;
+                    return true;
+                }
+            }
+
+            if (!droppedAny)
+                return false;
+
+            DragAndDrop.AcceptDrag();
+            return true;
+        }
+
+        /************************************************************************************************************************/
+    }
+}
+
+#endif
+