HarmonyOS 图片染色api

参考文档：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/ts-universal-attributes-gradient-color-V5#lineargradient

demo如下：

// xxx.ets
@Entry
@Component
struct ColorGradientExample {
  @State posX: number = 0.5;

  build() {
    Column({ space: 5 }) {
      Image($r('app.media.function_guide_01'))
        .width(100)
        .height(100)
        .borderRadius(20)
        .clip(true)
        .linearGradient({
          direction: GradientDirection.Right,
          repeating: false,
          colors: [[0xff0000, 0.0], [0xff0000, this.posX],[0xffffff, this.posX], [0xffffff, 1.0]]
        })

      Slider({
        value: $$this.posX,
        min: 0,
        max: 1,
        step: 0.1,
      })

    }
    .width('100%')
    .padding({ top: 5 })
  }
}