update zh-cn/application-dev/reference/arkui-ts/ts-basic-gestures-pinchgesture.md.

Signed-off-by: Nluoying_ace <luoying19@huawei.com>

zh-cn/application-dev/reference/arkui-ts/ts-basic-gestures-pinchgesture.md

@@ -16,7 +16,7 @@ PinchGesture(value?: { fingers?: number, distance?: number })
 | 参数名称 | 参数类型 | 必填 | 参数描述 |
 | -------- | -------- | -------- | -------- |
 | fingers | number | 否 | 触发捏合的最少手指数,&nbsp;最小为2指，最大为5指。<br/>默认值：2 |
-| distance | number | 否 | 最小识别距离，单位为vp。<br/>默认值：3.0 |
+| distance | number | 否 | 最小识别距离，单位为vp。<br/>默认值：3 |
 
 
 ## 事件
@@ -36,26 +36,40 @@ PinchGesture(value?: { fingers?: number, distance?: number })
 @Entry
 @Component
 struct PinchGestureExample {
-  @State scaleValue: number = 1
+  @State scaleValue: number = 1;
+  @State pinchValue: number = 1;
+  @State pinchX: number = 0;
+  @State pinchY: number = 0;
 
   build() {
-    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.SpaceBetween }) {
-      Text('PinchGesture scale:' + this.scaleValue)
-    }
-    .height(100).width(200).padding(20).border({ width: 1 }).margin(80)
-    .scale({ x: this.scaleValue, y: this.scaleValue, z: this.scaleValue })
-    .gesture(
-      PinchGesture()
+    Column() {
+      Column() {
+        Text('PinchGesture scale:\n' + this.scaleValue)
+        Text('PinchGesture center:\n(' + this.pinchX + ',' + this.pinchY + ')')
+      }
+      .height(200)
+      .width(300)
+      .padding(20)
+      .border({ width: 3 })
+      .margin({ top: 100 })
+      .scale({ x: this.scaleValue, y: this.scaleValue, z: 1 })
+      // 三指捏合触发该手势事件
+      .gesture(
+      PinchGesture({ fingers: 3 })
         .onActionStart((event: GestureEvent) => {
-          console.info('Pinch start')
+          console.info('Pinch start');
         })
         .onActionUpdate((event: GestureEvent) => {
-          this.scaleValue = event.scale
+          this.scaleValue = this.pinchValue * event.scale;
+          this.pinchX = event.pinchCenterX;
+          this.pinchY = event.pinchCenterY;
         })
         .onActionEnd(() => {
-          console.info('Pinch end')
+          this.pinchValue = this.scaleValue;
+          console.info('Pinch end');
         })
-    )
+      )
+    }.width('100%')
   }
 }
 ```