harmony 鸿蒙CanvasPattern

2023-06-24
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CanvasPattern

CanvasPattern represents an object, created by the createPattern API, describing an image filling pattern based on the image and repetition mode.

NOTE

The APIs of this module are supported since API version 8. Updates will be marked with a superscript to indicate their earliest API version.

Methods

setTransform

setTransform(transform?: Matrix2D): void

Uses a Matrix2D object as a parameter to perform matrix transformation on the current CanvasPattern object.

Since API version 9, this API is supported in ArkTS widgets.

Parameters

Name	Type	Mandatory	Default Value	Description
transform	Matrix2D	No	null	Transformation matrix.

Example

// xxx.ets
@Entry
@Component
struct CanvasPatternPage {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private matrix: Matrix2D = new Matrix2D()
  private img: ImageBitmap = new ImageBitmap("common/pattern.jpg")
  private pattern : CanvasPattern|null = null

  build() {
      Column() {
        Button("Click to set transform")
          .onClick(() => {
            this.matrix.scaleY = 1
            this.matrix.scaleX = 1
            this.matrix.translateX = 50
            this.matrix.translateY = 200
            if (this.pattern) {
              this.pattern.setTransform(this.matrix)
            }
            this.context.fillRect(0, 0, 480, 720)
          })
          .width("45%")
          .margin("5px")
        Canvas(this.context)
          .width('100%')
          .height('80%')
          .backgroundColor('#FFFFFF')
          .onReady(() => {
            this.pattern = this.context.createPattern(this.img, 'no-repeat')
            this.matrix.scaleY = 0.5
            this.matrix.scaleX = 0.5
            this.matrix.translateX = 50
            this.matrix.translateY = 50
            if (this.pattern) {
              this.context.fillStyle = this.pattern
              this.pattern.setTransform(this.matrix)
            }
            this.context.fillRect(0, 0, 480, 720)
          })
      }
      .width('100%')
      .height('100%')
  }
}

CanvasPattern