class二次刷新渲染数组

当我们更新class类中的数据时，会使数组对应的属性及相应的样式刷新。

HarmonyOS

vclearner

2024-05-26 15:32:36

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回答 1

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回答 1

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FengTianYa

使用的核心API

@Observed装饰器和@ObjectLink装饰器：嵌套类对象属性变化

核心代码解释

核心代码如下：

@Entry 
@Component 
struct Index { 
@State section: Setion = new Setion() 
 
build() { 
  Row(){ 
    Row() { 
      Column() { 
        Text('reset ui '+this.section.data.count) 
          .margin({ top: 40 }) 
          .fontSize(25) 
          .fontWeight(FontWeight.Bold) 
          .onClick(() => { 
            this.section = new Setion(); 
            this.section.data = new Param(); 
            this.section.data.setCount(1); 
          }) 
 
        if (this.section.data) { 
          Header({ currentIndex: this.section.data.count, callback: (idx: number) => { 
            this.section = new Setion() 
            this.section.data.count = idx 
          } }) 
            .margin({ top: 120 }) 
        } 
      } 
      .width('100%') 
    } 
    .height('100%') 
  } 
} 
} 
 
@Component 
struct Header { 
@Prop currentIndex: number 
callback?: (index: number) => void 
 
build() { 
  List() { 
    ForEach(['1', '2', '3'], (content: string, index: number) => { 
      this.tabItem(content, index, () => { 
        this.currentIndex = index 
        if (this.callback) { 
          this.callback(index) 
        } 
      }) 
    }) 
  } 
  .height(28) 
  .listDirection(Axis.Horizontal) 
  .scrollBar(BarState.Off) 
  .edgeEffect(EdgeEffect.Spring, { alwaysEnabled: false }) 
} 
 
@Builder 
tabItem(item: string, index: number, click: () => void) { 
  Text(item) 
    .fontSize(12) 
    .fontColor(index == this.currentIndex ? '0x3377ff': 
      '0x222222') 
    .fontWeight(FontWeight.Medium) 
    .padding({ left: 12, right: 12, top: 7, bottom: 7 }) 
    .borderRadius(2) 
    .height(28) 
    .margin({ left: 8, bottom: 8 }) 
    .borderWidth(index == this.currentIndex ? 1 : 0) 
    .borderColor('0x4d3377ff') 
    .onClick(click) 
} 
} 
 
@Observed 
export class Setion { 
data: Param = new Param() 
 
 
} 
 
@Observed 
export class Param { 
count: number = 0 
 
setCount(count: number){ 
  this.count =count; 
} 
}

实现效果