HarmonyOS 有没有自定义视图绘制的案例, 绘制渐变曲线？

// xxx.ets  
@Entry  
@Component  
struct CreateLinearGradient {  
  private settings: RenderingContextSettings = new RenderingContextSettings(true)  
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)  
  build() {  
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {  
      Canvas(this.context)  
        .width('100%')  
        .height('100%')  
        .backgroundColor('#ffff00')  
        .onReady(() =>{  
          let grad = this.context.createLinearGradient(50,0, 300,100)  
          grad.addColorStop(0.0, '#ff0000')  
          grad.addColorStop(0.5, '#ffffff')  
          grad.addColorStop(1.0, '#00ff00')  
          this.context.fillStyle = grad  
          this.context.fillRect(0, 0, 400, 400)  
        })  
    }  
    .width('100%')  
    .height('100%')  
  }  
}