Merge pull request #268 from Unity-Technologies/zxw/support_editor_dragdrop

Add support to Editor Drag&Drop

Author: zhuxingwei

Samples/UIWidgetsSamples_2019_4/Assets/Editor/EditorWindowSample/UnityObjectDragging.cs

@@ -0,0 +1,63 @@
+using System.Collections.Generic;
+using uiwidgets;
+using Unity.UIWidgets.Editor;
+using Unity.UIWidgets.gestures;
+using Unity.UIWidgets.widgets;
+using UnityEditor;
+using UnityEngine;
+
+namespace UIWidgetsEditorWindowSample
+{
+    public class UnityObjectDraggingWindow : UIWidgetsEditorPanel
+    {
+        [MenuItem("UIWidgets/EditorSample/UnityObjectDragging")]
+        public static void CountDemo()
+        {
+            CreateWindow<UnityObjectDraggingWindow>();
+        }
+
+        protected override void onEnable()
+        {
+            AddFont("Material Icons", new List<string> {"MaterialIcons-Regular.ttf"}, new List<int> {0});
+            AddFont("CupertinoIcons", new List<string> {"CupertinoIcons.ttf"}, new List<int> {0});
+            AddFont("GalleryIcons", new List<string> {"gallery/GalleryIcons.ttf"}, new List<int> {0});
+        }
+
+        protected override void main()
+        {
+            editor_ui_.runEditorApp(new MyApp());
+        }
+        
+        public class MyApp : StatelessWidget
+        {
+            public override Widget build(BuildContext context)
+            {
+                return 
+                    new Container(color: Colors.green, child:
+                    new Center(child: 
+                        new UnityObjectDetector(
+                            child: new Container(color: Colors.blue, width: 200f, height: 200f, 
+                                child: new Center(child: new Text("Drag UnityObject or file to me"))),
+                                onEnter: (details) =>
+                                {
+                                    Debug.Log("enter");
+                                },
+                                onHover: (details =>
+                                {
+                                    Debug.Log("position = " + details.position);
+                                }),
+                                onExit: () =>
+                                {
+                                    Debug.Log("on exit");
+                                },
+                                onRelease: (details) =>
+                                {
+                                    Debug.Log("on release");
+                                }
+                        )
+                        )
+                    );
+            }
+    }
+    }
+}

Samples/UIWidgetsSamples_2019_4/Assets/Editor/EditorWindowSample/UnityObjectDragging.cs.meta

@@ -158,6 +158,14 @@ void Input_OnGUIEvent(Event evt) {
                 var pos = _getPointerPosition(position: evt.mousePosition);
                 _wrapper.OnMouseScroll(delta: delta, pos: pos);
             }
+            else if (evt.type == EventType.DragUpdated) {
+                var pos = _getPointerPosition(position: evt.mousePosition);
+                _wrapper.OnDragUpdateInEditor(pos: pos);
+            }
+            else if (evt.type == EventType.DragPerform || evt.type == EventType.DragExited) {
+                var pos = _getPointerPosition(position: evt.mousePosition);
+                _wrapper.OnDragReleaseInEditor(pos: pos);
+            }
             else if (evt.isKey) {
                 _wrapper.OnKeyDown(e: evt);
                 Event.current.Use();

com.unity.uiwidgets/Editor/UIWidgetsEditorPanel.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections.Generic;
+using Unity.UIWidgets.gestures;
+using Unity.UIWidgets.ui;
+
+namespace Unity.UIWidgets.widgets {
+    public class UiWidgetsEditorBinding : UiWidgetsBinding {
+        public new static UiWidgetsEditorBinding instance {
+            get { return (UiWidgetsEditorBinding) UiWidgetsBinding.instance; }
+            set { UiWidgetsBinding.instance = value; }
+        }
+        
+        public static UiWidgetsEditorBinding ensureInitializedForEditor() {
+            if (UiWidgetsEditorBinding.instance == null) {
+                return new UiWidgetsEditorBinding();
+            }
+            
+            return UiWidgetsEditorBinding.instance;
+        }
+        
+        public EditorMouseTracker editorMouseTracker {
+            get { return _editorMouseTracker; }
+        }
+
+        EditorMouseTracker _editorMouseTracker;
+
+        private void initEditorMouseTracker(EditorMouseTracker tracker  = null) {
+            _editorMouseTracker?.dispose();
+            _editorMouseTracker = tracker ?? new EditorMouseTracker(pointerRouter, hitTestMouseTrackers);
+        }
+
+        public EditorMouseTrackerAnnotation hitTestMouseTrackers(Offset position) {
+            List<EditorMouseTrackerAnnotation> annotations = 
+                new List<EditorMouseTrackerAnnotation>(renderView.layer.findAllAnnotations<EditorMouseTrackerAnnotation>(
+                position * renderView.configuration.devicePixelRatio
+            ).annotations);
+
+            if (annotations is null || annotations.Count == 0) {
+                return null;
+            }
+
+            return annotations[0];
+        }
+
+        protected override void initInstances() {
+            base.initInstances();
+            
+            addPersistentFrameCallback(_handlePersistentFrameCallbackForEditor);
+            initEditorMouseTracker();
+        }
+
+        private void _handlePersistentFrameCallbackForEditor(TimeSpan timeStamp) {
+            _editorMouseTracker.schedulePostFrameCheck();
+        }
+    }
+    
+    public static class editor_ui_ {
+        public static void runEditorApp(Widget app) {
+            var instance = UiWidgetsEditorBinding.ensureInitializedForEditor();
+            instance.scheduleAttachRootWidget(app);
+            instance.scheduleWarmUpFrame();
+        }
+    }
+}