OffscreenCanvasRenderingContext2D

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.

Use OffscreenCanvasRenderingContext2D to draw rectangles, images, and text offscreen onto a canvas. Drawing offscreen onto a canvas is a process where content to draw onto the canvas is first drawn in the buffer, and then converted into a picture, and finally the picture is drawn on the canvas. This process increases the drawing efficiency.

APIs

OffscreenCanvasRenderingContext2D(width: number, height: number, setting: RenderingContextSettings)

• Parameters

Attributes

Name	Type	Default Value	Description
fillStyle	<color> | CanvasGradient | CanvasPattern	-	Style used to fill an area. - When the type is <color>, this attribute indicates the fill color. - When the type is CanvasGradient, this attribute indicates a gradient object, which is created using the createLinearGradient method. - When the type is CanvasPattern, this attribute indicates a pattern, which is created using the createPattern method.
lineWidth	number	-	Line width.
strokeStyle	<color> | CanvasGradient | CanvasPattern	-	Stroke style. - When the type is <color>, this attribute indicates the stroke color. - When the type is CanvasGradient, this attribute indicates a gradient object, which is created using the createLinearGradient method. - When the type is CanvasPattern, this attribute indicates a pattern, which is created using the createPattern method.
lineCap	string	'butt'	Style of the line endpoints. The options are as follows: - 'butt': The endpoints of the line are squared off. - 'round': The endpoints of the line are rounded. - 'square': The endpoints of the line are squared off by adding a box with an equal width and half the height of the line's thickness.
lineJoin	string	'miter'	Style of the shape used to join line segments. The options are as follows: - 'round': The shape used to join line segments is a rounded corner with the radius equal to the line width. - 'bevel': The shape used to join line segments is a beveled corner. The rectangular corner of each line is independent. - 'miter': The shape used to join line segments is a mitered corner. The corner is formed by extending the outside edges of the lines until they meet. You can adjust the effect of this attribute using miterLimit.
miterLimit	number	10	Maximum miter length. The miter length is the distance between the inner corner and the outer corner where two lines meet.
font	string	'normal normal 14px sans-serif'	Font style. Syntax: ctx.font='font-size font-family' - (Optional) font-size: font size and row height. The unit can only be px. - (Optional) font-family: font family. Syntax: ctx.font='font-style font-weight font-size font-family' - (Optional) font-style: specifies the font style. Available values are 'normal' and 'italic'. - (Optional) font-weight: font weight. Available values are as follows: 'normal', 'bold', 'bolder', 'lighter', 100, 200, 300, 400, 500, 600, 700, 800, 900 - (Optional) font-size: font size and row height. The unit can only be px. - (Optional) font-family: font family. Available values are 'sans-serif', 'serif', and 'monospace'.
textAlign	string	'left'	Text alignment mode. Available values are as follows: - 'left': The text is left-aligned. - 'right': The text is right-aligned. - 'center': The text is center-aligned. - 'start': The text is aligned with the start bound. - 'end': The text is aligned with the end bound. > NOTE > In the ltr layout mode, the value start equals left. In the rtl layout mode, the value start equals right.
textBaseline	string	'alphabetic'	Horizontal alignment mode of text. Available values are as follows: - 'alphabetic': The text baseline is the normal alphabetic baseline. - 'top': The text baseline is on the top of the text bounding box. - 'hanging': The text baseline is a hanging baseline over the text. - 'middle': The text baseline is in the middle of the text bounding box. - 'ideographic': The text baseline is the ideographic baseline. If a character exceeds the alphabetic baseline, the ideographic baseline is located at the bottom of the excess character. - 'bottom': The text baseline is at the bottom of the text bounding box. Its difference from the ideographic baseline is that the ideographic baseline does not consider letters in the next line.
globalAlpha	number	-	Opacity. 0.0: completely transparent; 1.0: completely opaque.
lineDashOffset	number	0.0	Offset of the dashed line. The precision is float.
globalCompositeOperation	string	'source-over'	Composition operation type. Available values are as follows: 'source-over', 'source-atop', 'source-in', 'source-out', 'destination-over', 'destination-atop', 'destination-in', 'destination-out', 'lighter', 'copy', and 'xor'.
shadowBlur	number	0.0	Blur level during shadow drawing. A larger value indicates a more blurred effect. The precision is float.
shadowColor	<color>	-	Shadow color.
shadowOffsetX	number	-	X-axis shadow offset relative to the original object.
shadowOffsetY	number	-	Y-axis shadow offset relative to the original object.
imageSmoothingEnabled	boolean	true	Whether to adjust the image smoothness during image drawing. The value true means to enable this feature, and false means the opposite.
imageSmoothingQuality	string	'low'	Image smoothness. The value can be 'low', 'medium', or 'high'.

NOTE The value of the <color> type can be in 'rgb(255, 255, 255)', 'rgba(255, 255, 255, 1.0)', or '#FFFFFF' format.

fillStyle

// xxx.ets
@Entry
@Component
struct FillStyleExample {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.fillStyle = '#0000ff'
          this.offContext.fillRect(20, 160, 150, 100)
          var image = this.offContext.transferToImageBitmap();
          this.context.transferFromImageBitmap(image);
        })
    }
    .width('100%')
    .height('100%')
  }
}

lineWidth

// xxx.ets
@Entry
@Component
struct LineWidthExample {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.lineWidth = 5
          this.offContext.strokeRect(25, 25, 85, 105)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

strokeStyle

// xxx.ets
@Entry
@Component
struct StrokeStyleExample {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.lineWidth = 10
          this.offContext.strokeStyle = '#0000ff'
          this.offContext.strokeRect(25, 25, 155, 105)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

lineCap

// xxx.ets
@Entry
@Component
struct LineCapExample {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.lineWidth = 8
          this.offContext.beginPath()
          this.offContext.lineCap = 'round'
          this.offContext.moveTo(30, 50)
          this.offContext.lineTo(220, 50)
          this.offContext.stroke()
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

lineJoin

// xxx.ets
@Entry
@Component
struct LineJoinExample {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.beginPath()
          this.offContext.lineWidth = 8
          this.offContext.lineJoin = 'miter'
          this.offContext.moveTo(30, 30)
          this.offContext.lineTo(120, 60)
          this.offContext.lineTo(30, 110)
          this.offContext.stroke()
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

miterLimit

// xxx.ets
@Entry
@Component
struct MiterLimit {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.lineWidth = 8
          this.offContext.lineJoin = 'miter'
          this.offContext.miterLimit = 3
          this.offContext.moveTo(30, 30)
          this.offContext.lineTo(60, 35)
          this.offContext.lineTo(30, 37)
          this.offContext.stroke()
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

font

// xxx.ets
@Entry
@Component
struct Font {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.font = '30px sans-serif'
          this.offContext.fillText("Hello World", 20, 60)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

textAlign

// xxx.ets
@Entry
@Component
struct CanvasExample {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
        this.offContext.strokeStyle = '#0000ff'
        this.offContext.moveTo(140, 10)
        this.offContext.lineTo(140, 160)
        this.offContext.stroke()

        this.offContext.font = '18px sans-serif'

        this.offContext.textAlign = 'start'
        this.offContext.fillText('textAlign=start', 140, 60)
        this.offContext.textAlign = 'end'
        this.offContext.fillText('textAlign=end', 140, 80)
        this.offContext.textAlign = 'left'
        this.offContext.fillText('textAlign=left', 140, 100)
        this.offContext.textAlign = 'center'
        this.offContext.fillText('textAlign=center',140, 120)
        this.offContext.textAlign = 'right'
        this.offContext.fillText('textAlign=right',140, 140)
        var image = this.offContext.transferToImageBitmap()
        this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

textBaseline

// xxx.ets
@Entry
@Component
struct TextBaseline {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.strokeStyle = '#0000ff'
          this.offContext.moveTo(0, 120)
          this.offContext.lineTo(400, 120)
          this.offContext.stroke()

          this.offContext.font = '20px sans-serif'

          this.offContext.textBaseline = 'top'
          this.offContext.fillText('Top', 10, 120)
          this.offContext.textBaseline = 'bottom'
          this.offContext.fillText('Bottom', 55, 120)
          this.offContext.textBaseline = 'middle'
          this.offContext.fillText('Middle', 125, 120)
          this.offContext.textBaseline = 'alphabetic'
          this.offContext.fillText('Alphabetic', 195, 120)
          this.offContext.textBaseline = 'hanging'
          this.offContext.fillText('Hanging', 295, 120)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

globalAlpha

// xxx.ets
@Entry
@Component
struct GlobalAlpha {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.fillStyle = 'rgb(255,0,0)'
          this.offContext.fillRect(0, 0, 50, 50)
          this.offContext.globalAlpha = 0.4
          this.offContext.fillStyle = 'rgb(0,0,255)'
          this.offContext.fillRect(50, 50, 50, 50)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

lineDashOffset

// xxx.ets
@Entry
@Component
struct LineDashOffset {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.arc(100, 75, 50, 0, 6.28)
          this.offContext.setLineDash([10,20])
          this.offContext.stroke();
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

globalCompositeOperation

// xxx.ets
@Entry
@Component
struct GlobalCompositeOperation {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.fillStyle = 'rgb(255,0,0)'
          this.offContext.fillRect(20, 20, 50, 50)
          this.offContext.globalCompositeOperation = 'source-over'
          this.offContext.fillStyle = 'rgb(0,0,255)'
          this.offContext.fillRect(50, 50, 50, 50)
          this.offContext.fillStyle = 'rgb(255,0,0)'
          this.offContext.fillRect(120, 20, 50, 50)
          this.offContext.globalCompositeOperation = 'destination-over'
          this.offContext.fillStyle = 'rgb(0,0,255)'
          this.offContext.fillRect(150, 50, 50, 50)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

shadowBlur

// xxx.ets
@Entry
@Component
struct ShadowBlur {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.shadowBlur = 30
          this.offContext.shadowColor = 'rgb(0,0,0)'
          this.offContext.fillStyle = 'rgb(255,0,0)'
          this.offContext.fillRect(20, 20, 100, 80)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

shadowColor

// xxx.ets
@Entry
@Component
struct ShadowColor {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.shadowBlur = 30
          this.offContext.shadowColor = 'rgb(0,0,255)'
          this.offContext.fillStyle = 'rgb(255,0,0)'
          this.offContext.fillRect(30, 30, 100, 100)
          var image = this.offContext.transferToImageBitmap
()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

shadowOffsetX

// xxx.ets
@Entry
@Component
struct ShadowOffsetX {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.shadowBlur = 10
          this.offContext.shadowOffsetX = 20
          this.offContext.shadowColor = 'rgb(0,0,0)'
          this.offContext.fillStyle = 'rgb(255,0,0)'
          this.offContext.fillRect(20, 20, 100, 80)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

shadowOffsetY

// xxx.ets
@Entry
@Component
struct ShadowOffsetY {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.shadowBlur = 10
          this.offContext.shadowOffsetY = 20
          this.offContext.shadowColor = 'rgb(0,0,0)'
          this.offContext.fillStyle = 'rgb(255,0,0)'
          this.offContext.fillRect(30, 30, 100, 100)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

imageSmoothingEnabled

// xxx.ets
@Entry
@Component
struct ImageSmoothingEnabled {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private img:ImageBitmap = new ImageBitmap("common/images/icon.jpg")
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.imageSmoothingEnabled = false
          this.offContext.drawImage( this.img,0,0,400,200)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

Methods

fillRect

fillRect(x: number, y: number, w: number, h: number): void

Fills a rectangle on the canvas.

• Parameters

• Example

// xxx.ets @Entry @Component struct FillRect { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)

build() {
  Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
    Canvas(this.context)
      .width('100%')
      .height('100%')
      .backgroundColor('#ffff00')
      .onReady(() =>{
        this.offContext.fillRect(0,30,100,100)
        var image = this.offContext.transferToImageBitmap()
        this.context.transferFromImageBitmap(image)
     })
    }
  .width('100%')
  .height('100%')
}

}

![en-us_image_0000001257138375](figures/en-us_image_0000001257138375.png)


### strokeRect

strokeRect(x: number, y: number, w: number, h: number): void

Draws an outlined rectangle on the canvas.

- Parameters
| Name   | Type   | Mandatory | Default Value | Description                              |
| ------ | ------ | --------- | ------------- | ---------------------------------------- |
| x      | number | Yes       | 0             | X-coordinate of the upper left corner of the rectangle. |
| y      | number | Yes       | 0             | Y-coordinate of the upper left corner of the rectangle. |
| width  | number | Yes       | 0             | Width of the rectangle.                  |
| height | number | Yes       | 0             | Height of the rectangle.                 |

- Example

@Entry @Component struct StrokeRect { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.strokeRect(30, 30, 200, 150) var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001212378436](figures/en-us_image_0000001212378436.png)


### clearRect

clearRect(x: number, y: number, w: number, h: number): void

Clears the content in a rectangle on the canvas.

- Parameters
| Name   | Type   | Mandatory | Default Value | Description                              |
| ------ | ------ | --------- | ------------- | ---------------------------------------- |
| x      | number | Yes       | 0             | X-coordinate of the upper left corner of the rectangle. |
| y      | number | Yes       | 0             | Y-coordinate of the upper left corner of the rectangle. |
| width  | number | Yes       | 0             | Width of the rectangle.                  |
| height | number | Yes       | 0             | Height of the rectangle.                 |

- Example

```ts
// xxx.ets
@Entry
@Component
struct ClearRect {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.fillStyle = 'rgb(0,0,255)'
          this.offContext.fillRect(0,0,500,500)
          this.offContext.clearRect(20,20,150,100)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

fillText

fillText(text: string, x: number, y: number): void

Draws filled text on the canvas.

• Parameters

• Example

// xxx.ets @Entry @Component struct FillText { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.font = '30px sans-serif' this.offContext.fillText("Hello World!", 20, 100) var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001257058437](figures/en-us_image_0000001257058437.png)


### strokeText

strokeText(text: string, x: number, y: number): void

Draws a text stroke on the canvas.

- Parameters
| Name | Type   | Mandatory | Default Value | Description                              |
| ---- | ------ | --------- | ------------- | ---------------------------------------- |
| text | string | Yes       | ""            | Text to draw.                            |
| x    | number | Yes       | 0             | X-coordinate of the lower left corner of the text. |
| y    | number | Yes       | 0             | Y-coordinate of the lower left corner of the text. |

- Example

@Entry @Component struct StrokeText { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.font = '55px sans-serif' this.offContext.strokeText("Hello World!", 20, 60) var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001212218466](figures/en-us_image_0000001212218466.png)


### measureText

measureText(text: string): TextMetrics

Returns a **TextMetrics** object used to obtain the width of specified text.

- Parameters
| Name | Type   | Mandatory | Default Value | Description          |
| ---- | ------ | --------- | ------------- | -------------------- |
| text | string | Yes       | ""            | Text to be measured. |

- Return value
| Type        | Description             |
| ----------- | ----------------------- |
| TextMetrics | **TextMetrics** object. |

- **TextMetrics** attributes
| Name  | Type   | Description        |
| ----- | ------ | ------------------ |
| width | number | Width of the text. |

- Example

```ts
// xxx.ets
@Entry
@Component
struct MeasureText {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.font = '50px sans-serif'
          this.offContext.fillText("Hello World!", 20, 100)
          this.offContext.fillText("width:" + this.context.measureText("Hello World!").width, 20, 200)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

stroke

stroke(path?: Path2D): void

Strokes a path.

• Parameters

• Example

  @Entry
  @Component
  struct Stroke {
    private settings: RenderingContextSettings = new RenderingContextSettings(true)
    private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
    private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
    build() {
      Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
        Canvas(this.context)
          .width('100%')
          .height('100%')
          .backgroundColor('#ffff00')
          .onReady(() =>{
            this.offContext.moveTo(25, 25)
            this.offContext.lineTo(25, 105)
            this.offContext.strokeStyle = 'rgb(0,0,255)'
            this.offContext.stroke()
            var image = this.offContext.transferToImageBitmap()
            this.context.transferFromImageBitmap(image)
          })
      }
      .width('100%')
      .height('100%')
    }
  }
  

  

beginPath

beginPath(): void

Creates a drawing path.

• Example

// xxx.ets @Entry @Component struct BeginPath { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.beginPath() this.offContext.lineWidth = 6 this.offContext.strokeStyle = '#0000ff' this.offContext.moveTo(15, 80) this.offContext.lineTo(280, 160) this.offContext.stroke() var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001212378440](figures/en-us_image_0000001212378440.png)


### moveTo

moveTo(x: number, y: number): void

Moves a drawing path to a target position on the canvas.

- Parameters
| Name | Type   | Mandatory | Default Value | Description                          |
| ---- | ------ | --------- | ------------- | ------------------------------------ |
| x    | number | Yes       | 0             | X-coordinate of the target position. |
| y    | number | Yes       | 0             | Y-coordinate of the target position. |

- Example

```ts
// xxx.ets
@Entry
@Component
struct MoveTo {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.beginPath()
          this.offContext.moveTo(10, 10)
          this.offContext.lineTo(280, 160)
          this.offContext.stroke()
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

lineTo

lineTo(x: number, y: number): void

Connects the current point to a target position using a straight line.

• Parameters

• Example

// xxx.ets @Entry @Component struct LineTo { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.beginPath() this.offContext.moveTo(10, 10) this.offContext.lineTo(280, 160) this.offContext.stroke() var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001257058435](figures/en-us_image_0000001257058435.png)


### closePath

closePath(): void

Draws a closed path.

- Example

```ts
// xxx.ets
@Entry
@Component
struct ClosePath {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
            this.offContext.beginPath()
            this.offContext.moveTo(30, 30)
            this.offContext.lineTo(110, 30)
            this.offContext.lineTo(70, 90)
            this.offContext.closePath()
            this.offContext.stroke()
            var image = this.offContext.transferToImageBitmap()
            this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

createPattern

createPattern(image: ImageBitmap, repetition: string): CanvasPattern

Creates a pattern for image filling based on a specified source image and repetition mode.

• Parameters

• Example

// xxx.ets @Entry @Component struct CreatePattern { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private img:ImageBitmap = new ImageBitmap("common/images/icon.jpg") private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ var pattern = this.offContext.createPattern(this.img, 'repeat') this.offContext.fillStyle = pattern this.offContext.fillRect(0, 0, 200, 200) var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001257138387](figures/en-us_image_0000001257138387.png)


### bezierCurveTo

bezierCurveTo(cp1x: number, cp1y: number, cp2x: number, cp2y: number, x: number, y: number): void

Draws a cubic bezier curve on the canvas.

- Name
| Name | Type   | Mandatory | Default Value | Description                              |
| ---- | ------ | --------- | ------------- | ---------------------------------------- |
| cp1x | number | Yes       | 0             | X-coordinate of the first parameter of the bezier curve. |
| cp1y | number | Yes       | 0             | Y-coordinate of the first parameter of the bezier curve. |
| cp2x | number | Yes       | 0             | X-coordinate of the second parameter of the bezier curve. |
| cp2y | number | Yes       | 0             | Y-coordinate of the second parameter of the bezier curve. |
| x    | number | Yes       | 0             | X-coordinate of the end point on the bezier curve. |
| y    | number | Yes       | 0             | Y-coordinate of the end point on the bezier curve. |

- Example

```ts
// xxx.ets
@Entry
@Component
struct BezierCurveTo {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.beginPath()
          this.offContext.moveTo(10, 10)
          this.offContext.bezierCurveTo(20, 100, 200, 100, 200, 20)
          this.offContext.stroke()
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

quadraticCurveTo

quadraticCurveTo(cpx: number, cpy: number, x: number, y: number): void

Draws a quadratic curve on the canvas.

• Parameters

• Example

// xxx.ets @Entry @Component struct QuadraticCurveTo { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.beginPath(); this.offContext.moveTo(20, 20); this.offContext.quadraticCurveTo(100, 100, 200, 20); this.offContext.stroke(); var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001256978383](figures/en-us_image_0000001256978383.png)


### arc

arc(x: number, y: number, radius: number, startAngle: number, endAngle: number, anticlockwise?: boolean): void

Draws an arc on the canvas.

- Parameters
| Name          | Type    | Mandatory | Default Value | Description                              |
| ------------- | ------- | --------- | ------------- | ---------------------------------------- |
| x             | number  | Yes       | 0             | X-coordinate of the center point of the arc. |
| y             | number  | Yes       | 0             | Y-coordinate of the center point of the arc. |
| radius        | number  | Yes       | 0             | Radius of the arc.                       |
| startAngle    | number  | Yes       | 0             | Start radian of the arc.                 |
| endAngle      | number  | Yes       | 0             | End radian of the arc.                   |
| anticlockwise | boolean | No        | false         | Whether to draw the arc counterclockwise. |

- Example

```ts
// xxx.ets
@Entry
@Component
struct Arc {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.beginPath()
          this.offContext.arc(100, 75, 50, 0, 6.28)
          this.offContext.stroke()
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

arcTo

arcTo(x1: number, y1: number, x2: number, y2: number, radius: number): void

Draws an arc based on the radius and points on the arc.

• Parameters

• Example

// xxx.ets @Entry @Component struct ArcTo { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.moveTo(100, 20); this.offContext.arcTo(150, 20, 150, 70, 50); this.offContext.stroke(); var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001257138383](figures/en-us_image_0000001257138383.png)


### ellipse

ellipse(x: number, y: number, radiusX: number, radiusY: number, rotation: number, startAngle: number, endAngle: number, anticlockwise?: boolean): void

Draws an ellipse in the specified rectangular region.

- Parameters
| Name          | Type    | Mandatory | Default Value | Description                              |
| ------------- | ------- | --------- | ------------- | ---------------------------------------- |
| x             | number  | Yes       | 0             | X-coordinate of the ellipse center.      |
| y             | number  | Yes       | 0             | Y-coordinate of the ellipse center.      |
| radiusX       | number  | Yes       | 0             | Ellipse radius on the x-axis.            |
| radiusY       | number  | Yes       | 0             | Ellipse radius on the y-axis.            |
| rotation      | number  | Yes       | 0             | Rotation angle of the ellipse, in radians. |
| startAngle    | number  | Yes       | 0             | Angle of the start point for drawing the ellipse, in radians. |
| endAngle      | number  | Yes       | 0             | Angle of the end point for drawing the ellipse, in radians. |
| anticlockwise | boolean | No        | false         | Whether to draw the ellipse in the counterclockwise direction. |

- Example


```ts
// xxx.ets
@Entry
@Component
struct CanvasExample {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.beginPath()
          this.offContext.ellipse(200, 200, 50, 100, Math.PI * 0.25, Math.PI * 0.5, Math.PI)
          this.offContext.stroke()
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

rect

rect(x: number, y: number, width: number, height: number): void

Creates a rectangle.

• Parameters

• Example

// xxx.ets @Entry @Component struct CanvasExample { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.rect(20, 20, 100, 100) // Create a 100*100 rectangle at (20, 20) this.offContext.stroke() var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001257138381](figures/en-us_image_0000001257138381.png)


### fill

fill(): void

Fills the area inside a closed path.

- Example

```ts
// xxx.ets
@Entry
@Component
struct Fill {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.rect(20, 20, 100, 100) // Create a 100*100 rectangle at (20, 20)
          this.offContext.fill()
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

clip

clip(): void

Sets the current path to a clipping path.

• Example

// xxx.ets @Entry @Component struct Clip { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.rect(0, 0, 200, 200) this.offContext.stroke() this.offContext.clip() this.offContext.fillStyle = "rgb(255,0,0)" this.offContext.fillRect(0, 0, 150, 150) var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001257058441](figures/en-us_image_0000001257058441.png)


### rotate

rotate(rotate: number): void

Rotates a canvas clockwise around its coordinate axes.

- Parameters
| Name   | Type   | Mandatory | Default Value | Description                              |
| ------ | ------ | --------- | ------------- | ---------------------------------------- |
| rotate | number | Yes       | 0             | Clockwise rotation angle. You can use **Math.PI / 180** to convert the angle to a radian. |

- Example

```ts
// xxx.ets
@Entry
@Component
struct Rotate {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.rotate(45 * Math.PI / 180) // Rotate the rectangle 45 degrees
          this.offContext.fillRect(70, 20, 50, 50)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

scale

scale(x: number, y: number): void

Scales a canvas based on scale factors.

• Parameters

• Example

// xxx.ets @Entry @Component struct Scale { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.strokeRect(10, 10, 25, 25) this.offContext.scale(2, 2) // Scale to 200% this.offContext.strokeRect(10, 10, 25, 25) var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001211898516](figures/en-us_image_0000001211898516.png)


### transform

transform(scaleX: number, skewX: number, skewY: number, scaleY: number, translateX: number, translateY: number): void

Defines a transformation matrix. To transform a graph, you only need to set parameters of the matrix. The coordinates of the graph are multiplied by the matrix values to obtain new coordinates of the transformed graph. You can use the matrix to implement multiple transform effects.

> **NOTE**
> The following formulas calculate coordinates of the transformed graph. **x** and **y** represent coordinates before transformation, and **x'** and **y'** represent coordinates after transformation.
>
> - x' = scaleX \* x + skewY \* y + translateX
>
> - y' = skewX \* x + scaleY \* y + translateY

- Parameters
| Name       | Type   | Mandatory | Default Value | Description         |
| ---------- | ------ | --------- | ------------- | ------------------- |
| scaleX     | number | Yes       | 0             | X-axis scale.       |
| skewX      | number | Yes       | 0             | X-axis skew.        |
| skewY      | number | Yes       | 0             | Y-axis skew.        |
| scaleY     | number | Yes       | 0             | Y-axis scale.       |
| translateX | number | Yes       | 0             | X-axis translation. |
| translateY | number | Yes       | 0             | Y-axis translation. |

- Example

```ts
// xxx.ets
@Entry
@Component
struct Transform {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.fillStyle = 'rgb(0,0,0)'
          this.offContext.fillRect(0, 0, 100, 100)
          this.offContext.transform(1, 0.5, -0.5, 1, 10, 10)
          this.offContext.fillStyle = 'rgb(255,0,0)'
          this.offContext.fillRect(0, 0, 100, 100)
          this.offContext.transform(1, 0.5, -0.5, 1, 10, 10)
          this.offContext.fillStyle = 'rgb(0,0,255)'
          this.offContext.fillRect(0, 0, 100, 100)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

setTransform

setTransform(scaleX: number, skewX: number, skewY: number, scale: number, translateX: number, translateY: number): void

Resets the existing transformation matrix and creates a new transformation matrix by using the same parameters as the transform() function.

• Parameters

• Example

// xxx.ets @Entry @Component struct SetTransform { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.fillStyle = 'rgb(255,0,0)' this.offContext.fillRect(0, 0, 100, 100) this.offContext.setTransform(1,0.5, -0.5, 1, 10, 10) this.offContext.fillStyle = 'rgb(0,0,255)' this.offContext.fillRect(0, 0, 100, 100) var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001211898518](figures/en-us_image_0000001211898518.png)


### translate

translate(x: number, y: number): void

Moves the origin of the coordinate system.

- Parameters
| Name | Type   | Mandatory | Default Value | Description         |
| ---- | ------ | --------- | ------------- | ------------------- |
| x    | number | Yes       | 0             | X-axis translation. |
| y    | number | Yes       | 0             | Y-axis translation. |

- Example

```ts
// xxx.ets
@Entry
@Component
struct Translate {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.fillRect(10, 10, 50, 50)
          this.offContext.translate(70, 70)
          this.offContext.fillRect(10, 10, 50, 50)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

drawImage

drawImage(image: ImageBitmap | PixelMap, dx: number, dy: number): void

drawImage(image: ImageBitmap | PixelMap, dx: number, dy: number, dWidth: number, dHeight: number): void

drawImage(image: ImageBitmap | PixelMap, sx: number, sy: number, sWidth: number, sHeight: number, dx: number, dy: number, dWidth: number, dHeight: number):void

Draws an image.

• Parameters

• Example

// xxx.ets @Entry @Component struct Index { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private img:ImageBitmap = new ImageBitmap("common/images/icon.jpg") private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() => { this.offContext.drawImage( this.img,0,0,400,200) var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

![en-us_image_0000001256978377](figures/en-us_image_0000001256978377.png)


### createImageData

createImageData(width: number, height: number): Object

Creates an **ImageData** object based on the specified width and height. For details, see [ImageData](ts-components-canvas-imagebitmap.md).

- Parameters
| Name   | Type   | Mandatory | Default Value | Description                         |
| ------ | ------ | --------- | ------------- | ----------------------------------- |
| width  | number | Yes       | 0             | Width of the **ImageData** object.  |
| height | number | Yes       | 0             | Height of the **ImageData** object. |


### createImageData

createImageData(imageData: ImageData): Object

Creates an **ImageData** object by copying an existing **ImageData** object. For details, see [ImageData](ts-components-canvas-imagebitmap.md).

- Parameters
| Name      | Type                                     | Mandatory | Default Value | Description                   |
| --------- | ---------------------------------------- | --------- | ------------- | ----------------------------- |
| imagedata | [ImageData](ts-components-canvas-imagebitmap.md) | Yes       | null          | **ImageData** object to copy. |

### getPixelMap

getPixelMap(sx: number, sy: number, sw: number, sh: number): PixelMap

Obtains the **[PixelMap](../apis/js-apis-image.md#pixelmap7)** object created with the pixels within the specified area on the canvas.
- Parameters
| Name | Type | Mandatory | Default Value | Description |
| -------- | -------- | -------- | -------- | -------- |
| sx | number | Yes | 0 | X-coordinate of the upper left corner of the output area. |
| sy | number | Yes | 0 | Y-coordinate of the upper left corner of the output area. |
| sw | number | Yes | 0 | Width of the output area. |
| sh | number | Yes | 0 | Height of the output area. |

### getImageData

getImageData(sx: number, sy: number, sw: number, sh: number): Object

Obtains the **[ImageData](ts-components-canvas-imagebitmap.md)** object created with the pixels within the specified area on the canvas.

- Parameters
| Name | Type   | Mandatory | Default Value | Description                              |
| ---- | ------ | --------- | ------------- | ---------------------------------------- |
| sx   | number | Yes       | 0             | X-coordinate of the upper left corner of the output area. |
| sy   | number | Yes       | 0             | Y-coordinate of the upper left corner of the output area. |
| sw   | number | Yes       | 0             | Width of the output area.                |
| sh   | number | Yes       | 0             | Height of the output area.               |


### putImageData

putImageData(imageData: Object, dx: number, dy: number, dirtyX?: number, dirtyY?: number, dirtyWidth?: number, dirtyHeight?: number): void

Puts the [ImageData](ts-components-canvas-imagebitmap.md) onto a rectangular area on the canvas.

- Parameters
| Name        | Type   | Mandatory | Default Value                      | Description                              |
| ----------- | ------ | --------- | ---------------------------------- | ---------------------------------------- |
| imagedata   | Object | Yes       | null                               | **ImageData** object with pixels to put onto the canvas. |
| dx          | number | Yes       | 0                                  | X-axis offset of the rectangular area on the canvas. |
| dy          | number | Yes       | 0                                  | Y-axis offset of the rectangular area on the canvas. |
| dirtyX      | number | No        | 0                                  | X-axis offset of the upper left corner of the rectangular area relative to that of the source image. |
| dirtyY      | number | No        | 0                                  | Y-axis offset of the upper left corner of the rectangular area relative to that of the source image. |
| dirtyWidth  | number | No        | Width of the **ImageData** object  | Width of the rectangular area to crop the source image. |
| dirtyHeight | number | No        | Height of the **ImageData** object | Height of the rectangular area to crop the source image. |

- Example

```ts
// xxx.ets
@Entry
@Component
struct PutImageData {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          var imageData = this.offContext.createImageData(100, 100)
          for (var i = 0; i < imageData.data.length; i += 4) {
            imageData.data[i + 0] = 255
            imageData.data[i + 1] = 0
            imageData.data[i + 2] = 255
            imageData.data[i + 3] = 255
          }
          this.offContext.putImageData(imageData, 10, 10)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

restore

restore(): void

Restores the saved drawing context.

• Example

// xxx.ets @Entry @Component struct CanvasExample { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings) private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings) build() { Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) { Canvas(this.context) .width('100%') .height('100%') .backgroundColor('#ffff00') .onReady(() =>{ this.offContext.restore() var image = this.offContext.transferToImageBitmap() this.context.transferFromImageBitmap(image) }) } .width('100%') .height('100%') } }

### save

save(): void

Saves the current drawing context.

- Example

```ts
// xxx.ets
@Entry
@Component
struct CanvasExample {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.offContext.save()
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
      })
    }
    .width('100%')
    .height('100%')
  }
}

createLinearGradient

createLinearGradient(x0: number, y0: number, x1: number, y1: number): void

Creates a linear gradient.

• Parameters

• Example

// xxx.ets @Entry @Component struct CreateLinearGradient { private settings: RenderingContextSettings = new RenderingContextSettings(true) private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)

private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
build() {
  Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
    Canvas(this.context)
      .width('100%')
      .height('100%')
      .backgroundColor('#ffff00')
      .onReady(() =>{
        var grad = this.offContext.createLinearGradient(50,0, 300,100)
        grad.addColorStop(0.0, 'red')
        grad.addColorStop(0.5, 'white')
        grad.addColorStop(1.0, 'green')
        this.offContext.fillStyle = grad
        this.offContext.fillRect(0, 0, 500, 500)
        var image = this.offContext.transferToImageBitmap()
        this.context.transferFromImageBitmap(image)
      })
  }
  .width('100%')
  .height('100%')
}

}

![en-us_image_0000001212378434](figures/en-us_image_0000001212378434.png)


### createRadialGradient

createRadialGradient(x0: number, y0: number, r0: number, x1: number, y1: number, r1: number): void

Creates a linear gradient.

- Parameters
| Name | Type   | Mandatory | Default Value | Description                              |
| ---- | ------ | --------- | ------------- | ---------------------------------------- |
| x0   | number | Yes       | 0             | X-coordinate of the center of the start circle. |
| y0   | number | Yes       | 0             | Y-coordinate of the center of the start circle. |
| r0   | number | Yes       | 0             | Radius of the start circle, which must be a non-negative finite number. |
| x1   | number | Yes       | 0             | X-coordinate of the center of the end circle. |
| y1   | number | Yes       | 0             | Y-coordinate of the center of the end circle. |
| r1   | number | Yes       | 0             | Radius of the end circle, which must be a non-negative finite number. |

- Example

```ts
// xxx.ets
@Entry
@Component
struct CreateRadialGradient {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  
  private offContext: OffscreenCanvasRenderingContext2D = new OffscreenCanvasRenderingContext2D(600, 600, this.settings)
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          var grad = this.offContext.createRadialGradient(200,200,50, 200,200,200)
          grad.addColorStop(0.0, 'red')
          grad.addColorStop(0.5, 'white')
          grad.addColorStop(1.0, 'green')
          this.offContext.fillStyle = grad
          this.offContext.fillRect(0, 0, 500, 500)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

CanvasPattern

Defines an object created by using the createPattern method.