HarmonyOS 鸿蒙Next 关于绘图逻辑接口的咨询

问题一：

参考链接：https://developer.huawei.com/consumer/cn/forum/topic/0201146249389568290?fid=0109140870620153026

问题二：绘制水印参考demo

@Entry

@Component

struct PageWatermark {

  private settings: RenderingContextSettings = new RenderingContextSettings(true)

  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)

  @Builder Watermark() {

    Canvas(this.context)

      .width("100%") .height("100%")

      .hitTestBehavior(HitTestMode.Transparent)

      .onReady(() => {

        this.context.fillStyle = '#10000000'

        this.context.font = "16vp"

        this.context.textAlign = "center"

        this.context.textBaseline = "middle"

        // 在这里绘制文字水印，也可以是图片水印

        for (let i = 0; i < this.context.width / 120; i++) {

          this.context.translate(120, 0)

          let j = 0

          for (; j < this.context.height / 120; j++) {

            this.context.rotate(-Math.PI / 180 * 30)

            // 此处水印数据是写死的，具体请替换为自己的水印

            this.context.fillText("水印水印水印", -60, -60)

            this.context.rotate(Math.PI / 180 * 30)

            this.context.translate(0, 120) }

          this.context.translate(0, -120 * j)

        }

      })

  }

  build() {

    Column() {

      Text("没有数据哦").fontColor("#495057")

      Image($r("app.media.startIcon"))

        .width(300)

        .layoutWeight(1)

        .overlay(this.Watermark())

        .width("100%")

    }

    .height('100%')

    .width('100%')

  }

}