diff --git a/packages/core/example/main.js b/packages/core/example/main.js
index 217a090..99cbca6 100644
--- a/packages/core/example/main.js
+++ b/packages/core/example/main.js
@@ -22,6 +22,9 @@ const core = new Core(mount, {
   height: 400,
   devicePixelRatio: 4
 });
+
+console.log('core ===', core);
+
 core.setData(data);
 doScale(core, defaultConf.scale);
 doScroll(core, defaultConf);
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index 4725355..38bef8b 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -18,41 +18,54 @@ enum Mode {
   PAINTING = 'painting',
 }
 
+const _board = Symbol('_board');
+const _data = Symbol('_data');
+const _opts = Symbol('_opts');
+const _config = Symbol('_config');
+const _renderer = Symbol('_renderer');
+const _element = Symbol('_element');
+const _helper = Symbol('_helper');
+const _hasInited = Symbol('_hasInited');
+const _mode = Symbol('_mode');
+const _selectedUUID = Symbol('_selectedUUID');
+const _prevPoint = Symbol('_prevPoint');
+const _selectedDotDirection = Symbol('_selectedDotDirection');
+
 class Core {
 
-  private _board: Board;
-  private _data: TypeData;
-  private _opts: Options;
-  private _config: TypeConfigStrict;
-  private _renderer: Renderer;
-  private _element: Element;
-  private _helper: Helper;
-  private _hasInited: boolean = false; 
-  private _mode: Mode = Mode.NULL;
+  private [_board]: Board;
+  private [_data]: TypeData;
+  private [_opts]: Options;
+  private [_config]: TypeConfigStrict;
+  private [_renderer]: Renderer;
+  private [_element]: Element;
+  private [_helper]: Helper;
+  private [_hasInited]: boolean = false; 
+  private [_mode]: Mode = Mode.NULL;
 
-  private _selectedUUID: string | null = null;
-  private _prevPoint: TypePoint | null = null;
-  private _selectedDotDirection: TypeHelperWrapperDotDirection | null = null;
+  private [_selectedUUID]: string | null = null;
+  private [_prevPoint]: TypePoint | null = null;
+  private [_selectedDotDirection]: TypeHelperWrapperDotDirection | null = null;
 
   constructor(mount: HTMLDivElement, opts: Options, config: TypeConfig) {
-    this._data = { elements: [] };
-    this._opts = opts;
-    this._config = mergeConfig(config);
-    this._board = new Board(mount, this._opts);
-    this._renderer = new Renderer(this._board); 
-    this._element = new Element(this._board.getContext());
-    this._helper = new Helper(this._board.getContext(), this._config);
+    this[_data] = { elements: [] };
+    this[_opts] = opts;
+    this[_config] = mergeConfig(config);
+    this[_board] = new Board(mount, this[_opts]);
+    this[_renderer] = new Renderer(this[_board]); 
+    this[_element] = new Element(this[_board].getContext());
+    this[_helper] = new Helper(this[_board].getContext(), this[_config]);
     this._initEvent();
-    this._hasInited = true;
+    this[_hasInited] = true;
   }
 
   draw() {
-    this._helper.updateConfig(this._data, {
-      selectedUUID: this._selectedUUID,
-      devicePixelRatio: this._opts.devicePixelRatio,
-      scale: this._board.getTransform().scale // TODO
+    this[_helper].updateConfig(this[_data], {
+      selectedUUID: this[_selectedUUID],
+      devicePixelRatio: this[_opts].devicePixelRatio,
+      scale: this[_board].getTransform().scale // TODO
     });
-    this._renderer.render(this._data, this._helper.getConfig());
+    this[_renderer].render(this[_data], this[_helper].getConfig());
   }
 
   // TODO
@@ -62,78 +75,78 @@ class Core {
   }
 
   scale(ratio: number) {
-    this._board.scale(ratio);
+    this[_board].scale(ratio);
   }
 
   scrollX(x: number) {
-    this._board.scrollX(x);
+    this[_board].scrollX(x);
   }
 
   scrollY(y: number) {
-    this._board.scrollY(y);
+    this[_board].scrollY(y);
   }
 
   getData(): TypeData {
-    return JSON.parse(JSON.stringify(this._data));
+    return JSON.parse(JSON.stringify(this[_data]));
   }
 
   setData(data: TypeData) {
-    return this._data = this._element.initData(data);
+    return this[_data] = this[_element].initData(data);
   }
 
   private _initEvent() {
-    if (this._hasInited === true) {
+    if (this[_hasInited] === true) {
       return;
     }
-    this._board.on('point', this._handlePoint.bind(this));
-    this._board.on('moveStart', this._handleMoveStart.bind(this));
-    this._board.on('move', this._handleMove.bind(this));
-    this._board.on('moveEnd', this._handleMoveEnd.bind(this));
+    this[_board].on('point', this._handlePoint.bind(this));
+    this[_board].on('moveStart', this._handleMoveStart.bind(this));
+    this[_board].on('move', this._handleMove.bind(this));
+    this[_board].on('moveEnd', this._handleMoveEnd.bind(this));
   }
 
   private _handlePoint(point: TypePoint) {
-    const [uuid, direction] = this._helper.isPointInElementWrapperDot(point);
+    const [uuid, direction] = this[_helper].isPointInElementWrapperDot(point);
     if (uuid && direction) {
-      this._mode = Mode.SELECT_ELEMENT_WRAPPER_DOT;
-      this._selectedDotDirection = direction;
-      this._selectedUUID = uuid;
+      this[_mode] = Mode.SELECT_ELEMENT_WRAPPER_DOT;
+      this[_selectedDotDirection] = direction;
+      this[_selectedUUID] = uuid;
     } else {
-      const [index, uuid] = this._element.isPointInElement(point, this._data);
+      const [index, uuid] = this[_element].isPointInElement(point, this[_data]);
       if (index >= 0) {
-        this._mode = Mode.SELECT_ELEMENT;
-        this._selectedUUID = uuid;
+        this[_mode] = Mode.SELECT_ELEMENT;
+        this[_selectedUUID] = uuid;
         this.draw();
       }
     }
   }
 
   private _handleMoveStart(point: TypePoint) {
-    this._prevPoint = point;
+    this[_prevPoint] = point;
   }
 
   private _handleMove(point: TypePoint) {
-    if (this._selectedUUID) {
-      if (this._mode === Mode.SELECT_ELEMENT) {
-        this._dragElement(this._selectedUUID, point, this._prevPoint);
+    if (typeof this[_selectedUUID] === 'string') {
+      if (this[_mode] === Mode.SELECT_ELEMENT) {
+        this._dragElement(this[_selectedUUID] as string, point, this[_prevPoint]);
         this.draw();
-      } else if (this._mode === Mode.SELECT_ELEMENT_WRAPPER_DOT && this._selectedDotDirection) {
-        this._transfromElement(this._selectedUUID, point, this._prevPoint, this._selectedDotDirection);
+      } else if (this[_mode] === Mode.SELECT_ELEMENT_WRAPPER_DOT && this[_selectedDotDirection]) {
+        this._transfromElement(this[_selectedUUID] as string, point, this[_prevPoint], this[_selectedDotDirection] as TypeHelperWrapperDotDirection);
       }
     }
     
-    this._prevPoint = point;
+    this[_prevPoint] = point;
   }
 
   private _handleMoveEnd(point: TypePoint) {
-    this._selectedUUID = null;
-    this._prevPoint = null;
+    this[_selectedUUID] = null;
+    this[_prevPoint] = null;
   }
 
   private _dragElement(uuid: string, point: TypePoint, prevPoint: TypePoint|null) {
     if (!prevPoint) {
       return;
     }
-    this._element.dragElement(this._data, uuid, point, prevPoint, this._board.getContext().getTransform().scale);
+    this[_element].dragElement(this[_data], uuid, point, prevPoint, this[_board].getContext().getTransform().scale);
     this.draw();
   }
 
@@ -141,7 +154,7 @@ class Core {
     if (!prevPoint) {
       return;
     }
-    this._element.transformElement(this._data, uuid, point, prevPoint, this._board.getContext().getTransform().scale, direction);
+    this[_element].transformElement(this[_data], uuid, point, prevPoint, this[_board].getContext().getTransform().scale, direction);
     this.draw();
   }
 }
diff --git a/packages/idraw/src/index.ts b/packages/idraw/src/index.ts
index 62deb52..82407e1 100644
--- a/packages/idraw/src/index.ts
+++ b/packages/idraw/src/index.ts
@@ -1,21 +1,21 @@
-import { TypeData } from '@idraw/types';
+// import { TypeData } from '@idraw/types';
 
-const data: TypeData = {
-  elements: [
-    {
-      x: 0,
-      y: 0,
-      w: 0,
-      h: 0,
-      type: 'circle',
-      desc: {
-        color: '#f0f0f0',
-      }
-    }
-  ]
-}
+// const data: TypeData = {
+//   elements: [
+//     {
+//       x: 0,
+//       y: 0,
+//       w: 0,
+//       h: 0,
+//       type: 'circle',
+//       desc: {
+//         color: '#f0f0f0',
+//       }
+//     }
+//   ]
+// }
 
-console.log('data =', data)
+// console.log('data =', data)
 
 class IDraw {
   render() {