HarmonyOS 鸿蒙Next中为什么expandSafeArea只有上半部分有效

HarmonyOS 鸿蒙Next中为什么expandSafeArea只有上半部分有效

@Entry
@Component
struct IndexPage{
  private canvasContext = new CanvasRenderingContext2D(new RenderingContextSettings(true))

  build() {
    RelativeContainer() {
      Canvas(this.canvasContext)
        .onReady(() => {
          this.canvasContext.beginPath()
          this.canvasContext.moveTo(0, 0)
          this.canvasContext.lineTo(0, this.canvasContext.height)
          this.canvasContext.lineTo(this.canvasContext.width, this.canvasContext.height)
          this.canvasContext.lineTo(this.canvasContext.width, 0)
          this.canvasContext.fillStyle = '#AA000000'
          this.canvasContext.fill()
          this.canvasContext.closePath()
        })
      .expandSafeArea([SafeAreaType.SYSTEM])
    }
    .width('100%')
    .height('100%')
    .expandSafeArea([SafeAreaType.SYSTEM])
  }
}