HarmonyOS @Extend 的使用问题

import { ImageModifier } from “@ohos.arkui.modifer”; 
class MyImageModifier extends ImageModifier { 
  public syncModeValue?: boolean 
  public cacheModeValue?: boolean 
  override applyNormalAttribute(instance: ImageAttribute): void { 
    super.applyNormalAttribute(instance) 
    // extend logics 
  } 
  syncMode(isSync: boolean) : MyImageModifier { 
    this.syncModeValue = isSync 
    return this 
  } 
  cacheMode(isCached: boolean) : MyImageModifier { 
    this.cacheModeValue = isCached 
    return this 
  } 
} 
//封装自定义组件@Component 
struct MyImage { 
  @Link modifier: MyImageModifier 
  @State src: string 
  build() { 
    Image(this.src) 
      .attributeModifier(this.modifier) 
  } 
  aboutToAppear() { 
    if (this.modifier.syncModeValue) { 
      // do something 
    } 
    if (this.modifier.cacheModeValue) { 
      // do something 
    } 
  } 
} 
//使用自定义组件 
@Entry @Component 
struct Index { 
  @State myImageModifier: MyImageModifier = 
    new MyImageModifier() 
      .syncMode(true) 
      .cacheMode(true) 
      .autoResize(true) 
      .renderMode(ImageRenderMode.Template) 
      .width(100) 
  isSync: boolean = false 
 
  build() { 
    Row() { 
      MyImage({ modifier: this.myImageModifier, src: $r(‘xxxx’) }) 
      Button(“Click”).onClick(() => { 
        isSync = !isSync 
        this.myImageModifier.syncMode(isSync) 
      }) 
    } 
  } 
}