From 0672f3b8cc22b34e6a1662526e0341b91b7e1565 Mon Sep 17 00:00:00 2001
From: "lihao.ylh" <lihao.ylh@alibaba-inc.com>
Date: Thu, 16 Sep 2021 16:11:40 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20=E6=96=B0=E5=A2=9E=20onDetectingChange?=
 =?UTF-8?q?=20=E4=BA=8B=E4=BB=B6=E7=9B=91=E5=90=AC,=20=E5=8F=AF=E7=9B=91?=
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---
 packages/designer/src/designer/detecting.ts | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/packages/designer/src/designer/detecting.ts b/packages/designer/src/designer/detecting.ts
index 92f0ceb17..e818d1379 100644
--- a/packages/designer/src/designer/detecting.ts
+++ b/packages/designer/src/designer/detecting.ts
@@ -1,6 +1,9 @@
 import { makeObservable, obx } from '@ali/lowcode-editor-core';
+import { EventEmitter } from 'events';
 import { Node, DocumentModel } from '../document';
 
+const DETECTING_CHANGE_EVENT = 'detectingChange';
+
 export class Detecting {
   @obx.ref private _enable = true;
 
@@ -19,6 +22,8 @@ export class Detecting {
 
   @obx.ref private _current: Node | null = null;
 
+  private emitter: EventEmitter = new EventEmitter();
+
   constructor() {
     makeObservable(this);
   }
@@ -28,12 +33,16 @@ export class Detecting {
   }
 
   capture(node: Node | null) {
-    this._current = node;
+    if (this._current !== node) {
+      this._current = node;
+      this.emitter.emit(DETECTING_CHANGE_EVENT, this.current);
+    }
   }
 
   release(node: Node) {
     if (this._current === node) {
       this._current = null;
+      this.emitter.emit(DETECTING_CHANGE_EVENT, this.current);
     }
   }
 
@@ -42,4 +51,11 @@ export class Detecting {
       this._current = null;
     }
   }
+
+  onDetectingChange(fn: () => void) {
+    this.emitter.on(DETECTING_CHANGE_EVENT, fn);
+    return () => {
+      this.emitter.off(DETECTING_CHANGE_EVENT, fn);
+    };
+  }
 }