【每日学点 HarmonyOS Next 知识】状态变量、公共 Page、可见区域变化回调、接收参数、拖拽排序控件

2025-03-11
北京
本文字数：3732 字
阅读完需：约 12 分钟

1、HarmonyOS 在定时器里面改变 @state 修饰的变量，无法更新 UI 吗？

将函数 function 写成了封装函数的形式就可以了

@Entry@Componentstruct Index {  @State acSetValve: number = 0;
  aboutToAppear(): void {    setInterval(() => {      this.acSetValve += 200;      console.log('hahhah' + this.acSetValve)    } ,100)  }
  build() {    Row() {      Column() {        Text(this.acSetValve.toString())          .fontSize(50)          .fontWeight(FontWeight.Bold)      }      .width('100%')    }    .height('100%')  }}

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2、HarmonyOS 写一个公共的 page，然后其他具体的 page 继承它，在公共 page 的做一些处理？

demo 参考：

//主页面  FirstTest.etsimport { FirstTest2 } from "./FirstTest2"
@Entry@Componentstruct FirstTest {  @State message1: string = 'Hello World';  // 显隐控制设置为不占用
  build() {    Column() {      Text("FirstTest：" + this.message1)        .fontSize(25)        .fontWeight(FontWeight.Bold)      //FirstTest2页面数据传递参考API：https://developer.huawei.com/consumer/cn/doc/harmonyos-guides/ArkTS-link-0000001820999565#ZH-CN_TOPIC_0000001857916041__%E6%A6%82%E8%BF%B0      //FirstTest2为Component修饰的组件，并且进行export，然后在FirstTest进行导入直接使用即可，可以多个页面复用      FirstTest2({message2:this.message1});    }  }}
//复用组件  FirstTest2.ets@Componentexport struct FirstTest2 {  @State test:string = "FirstTest2"  @Link message2: string ;
  build() {    Row() {      Column() {        Text("FirstTest2:" + this.test)          .fontSize(25)          .fontWeight(FontWeight.Bold)
        Text("FirstTest2:" + this.message2)          .fontSize(25)          .fontWeight(FontWeight.Bold)      }      .width('100%')    }    .height('100%')  }}

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3、HarmonyOS onVisibleAreaChange 事件没有触发？

添加 onVisibleAreaChange 事件监听，只有第一屏可以触发，切到第二屏没有触发。影响埋点上报

onVisibleAreaChange 规格上不支持监控由改变 offset 引起的组件区域变化。若要实现切屏监控，请使用 swiper 组件。

文档参考：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/ts-container-swiper-V5

4、HarmonyOS router.pushNamedRoute 参数传递在接收页面怎么接收？

可以通过 router.getParams();接收参数，API 链接：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-router-V5#ZH-CN_TOPIC_0000001884917590__routergetparams

参考 demo 如下:

import router from '@ohos.router';class innerParams {  array:number[]  constructor(tuple:number[]) {    this.array = tuple  }}
class routerParams {  text:string  data:innerParams  constructor(str:string, tuple:number[]) {    this.text = str    this.data = new innerParams(tuple)  }}
@Entry@Componentstruct Router1 {
  build() {
    Column(){      Column(){        Text("我是页面1").fontSize(50)      }      Column(){
        Button("跳转")          .onClick(()=>{            router.pushUrl({              url: 'pages/Router11',              params: new routerParams('message' ,[123,456,789])            })          })      }    }    .width('100%')    .height('100%')  }}import router from '@ohos.router';
class innerParams {  array:number[]
  constructor(tuple:number[]) {    this.array = tuple  }}
class routerParams {  text:string  data:innerParams  constructor(str:string, tuple:number[]) {    this.text = str    this.data = new innerParams(tuple)  }}
@Entry@Componentstruct Router11 {
  aboutToAppear(): void {    let s:number[]=((router.getParams() as routerParams).data as innerParams).array    console.log("*********:"+s);  }  build() {    Column(){      Text("123").fontSize(50)      Row(){        Text("33333").fontSize(50)      }    }    .width('100%')    .height('100%')    .opacity(0.5)    .backgroundColor(Color.Pink)
  }}

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5、HarmonyOS 拖拽排序以及控件平移效果是否有工具类可以用，当前控件数据数量上限无法满足？

拖拽排序以及控件平移效果是否有工具类可以用，当前控件数据数量上限无法满足

动画效果可以参考以下 demo：

@Entry@Componentstruct AnimationPage {  @Provide desX: number = 0;  @Provide desY: number = 0;
  @Builder  TabBar(index: number) {    Column() {      Image($r("app.media.icon"))        .width(38)        .height(38)      Text(index == 1 ? "分类" : index.toString())    }    .onAreaChange((oldValue: Area, newValue: Area) => {      if (index == 1) {        console.log("onAreaChange========= newValue:" + JSON.stringify(newValue))        this.desX = newValue.globalPosition.x as number        this.desY = newValue.globalPosition.y as number      }    })  }
  build() {    Column() {      Category()      Column() {        Image($r("app.media.icon"))          .width(38)          .height(38)      }      .onAreaChange((oldValue: Area, newValue: Area) => {        console.log("onAreaChange========= newValue:" + JSON.stringify(newValue))        this.desX = newValue.globalPosition.x as number        this.desY = newValue.globalPosition.y as number      })    }    .width("100%")    .height("100%")  }}
@Componentstruct Category {
  @State dataList:number[] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
  build() {    Column() {      Flex({direction:FlexDirection.Row, justifyContent: FlexAlign.SpaceBetween, wrap: FlexWrap.Wrap}) {        ForEach(this.dataList, (item:number) => {          ListItemComponent()        })      }      .width('100%')      .height('80%')      .backgroundColor(Color.White)    }  }}
@Observedclass AnimationBean {  animationAppear: Boolean = false;  id:number = -1;}
@Componentstruct ListItemComponent {  @State animationList: AnimationBean[] = []  static index: number = 0;  @Consume desX: number;  @Consume desY: number;
  @Provide orgX: number = 0;  @Provide orgY: number = 0;

  @Builder  BuildAnimationItem() {    Image($r("app.media.app_icon"))      .width(41)      .height(41)      .id("test")      .onClick(() => {        this.startAnimation();      })      .onAreaChange((oldValue:Area, newValue:Area) => {        this.orgX = newValue.globalPosition.x as number        this.orgY = newValue.globalPosition.y as number        console.log("onAreaChage==========" + JSON.stringify(newValue))      })  }
  startAnimation() {    const animation = new AnimationBean();    animation.id = ListItemComponent.index++    this.animationList.push(animation)    animateTo({      duration: 800,      curve: Curve.FastOutLinearIn,      onFinish: () => {        animation.animationAppear = false;        this.animationList = this.animationList.filter((item: AnimationBean) => {          return item.animationAppear        })      }    }, () => {      animation.animationAppear = true;    })  }
  @Builder  BuildItem() {    Row() {      Stack() {        this.BuildAnimationItem()
        ForEach(this.animationList, (item: AnimationBean) => {          AnimationChild({ item: item , AnimationView:this.BuildAnimationItem})        }, (item: AnimationBean, index: number) => {          return item.id.toLocaleString()        })      }    }    .width("20%")    .height(60)  }
  build() {    this.BuildItem()  }}

@Componentstruct AnimationChild {  @ObjectLink item: AnimationBean;  @Consume desX: number;  @Consume desY: number;  @Consume orgX: number;  @Consume orgY: number;
  @BuilderParam  AnimationView:() => void;
  build() {    Row() {      this.AnimationView()    }    .zIndex(5)    .translate(this.item.animationAppear ? { x: (this.desX - this.orgX -20), y: (this.desY - this.orgY) } : { x: 0 })  }}