HarmonyOS 关于使用获取屏幕截图接口异常的问题

import { componentSnapshot, window } from '@kit.ArkUI' 
import { BusinessError } from '@kit.BasicServicesKit' 
import { image } from '@kit.ImageKit' 
import { common } from '@kit.AbilityKit' 
import { util } from '@kit.ArkTS' 
 
@Entry 
@Component 
export struct ScreenImageTest { 
  @State pixmap: image.PixelMap | undefined = undefined 
 
  build() { 
    Column() { 
      Image($r('app.media.food')) 
        .width('100%') 
        .aspectRatio(ImageFit.Contain) 
        .id("root") 
      Text("截图保存") 
        .fontColor(Color.Black) 
        .fontSize(28) 
        .fontWeight(FontWeight.Bold) 
        .onClick(() => { 
          this.screenImageClick() 
        }) 
    } 
    .height("100%") 
  } 
 
  screenImageClick() { 
    componentSnapshot.get("root", (error: Error, pixmap: image.PixelMap) => { 
      if (error) { 
        console.log("error: " + JSON.stringify(error)) 
        return; 
      } 
      this.pixmap = pixmap 
 
      let buffer: ArrayBuffer = new ArrayBuffer(pixmap.getPixelBytesNumber()); 
      pixmap.readPixelsToBuffer(buffer).then(() => { 
        let imageBase64 = new util.Base64Helper().encodeToStringSync(new Uint8Array(buffer)); 
        console.log("test",imageBase64) 
      }).catch((err: BusinessError) => { 
        console.log("base encode error: " + JSON.stringify(err)) 
      }).finally(() => { 
        pixmap.release() 
      }); 
    }) 
  } 
 
}