OpenHarmony应用开发-组件CanvasRenderingContext2D对象（上篇）

// xxx.ets
@Entry
@Component
struct FillStyleExample {
  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(() =>{
          this.context.fillStyle = '#0000ff'
          this.context.fillRect(20, 20, 150, 100)
        })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct LineWidthExample {
  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(() =>{
        this.context.lineWidth = 5
        this.context.strokeRect(25, 25, 85, 105)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct StrokeStyleExample {
  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(() =>{
          this.context.lineWidth = 10
          this.context.strokeStyle = '#0000ff'
          this.context.strokeRect(25, 25, 155, 105)
        })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct LineCapExample {
  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(() =>{
          this.context.lineWidth = 8
          this.context.beginPath()
          this.context.lineCap = 'round'
          this.context.moveTo(30, 50)
          this.context.lineTo(220, 50)
          this.context.stroke()
        })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct LineJoinExample {
  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(() =>{
        this.context.beginPath()
        this.context.lineWidth = 8
        this.context.lineJoin = 'miter'
        this.context.moveTo(30, 30)
        this.context.lineTo(120, 60)
        this.context.lineTo(30, 110)
        this.context.stroke()
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct MiterLimit {
  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(() =>{
          this.context.lineWidth = 8
          this.context.lineJoin = 'miter'
          this.context.miterLimit = 3
          this.context.moveTo(30, 30)
          this.context.lineTo(60, 35)
          this.context.lineTo(30, 37)
          this.context.stroke()
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct Fonts {
  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(() =>{
          this.context.font = '30px sans-serif'
          this.context.fillText("Hello World", 20, 60)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct CanvasExample {
  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(() =>{
        this.context.strokeStyle = '#0000ff'
        this.context.moveTo(140, 10)
        this.context.lineTo(140, 160)
        this.context.stroke()
        this.context.font = '18px sans-serif'
        this.context.textAlign = 'start'
        this.context.fillText('textAlign=start', 140, 60)
        this.context.textAlign = 'end'
        this.context.fillText('textAlign=end', 140, 80)
        this.context.textAlign = 'left'
        this.context.fillText('textAlign=left', 140, 100)
        this.context.textAlign = 'center'
        this.context.fillText('textAlign=center',140, 120)
        this.context.textAlign = 'right'
        this.context.fillText('textAlign=right',140, 140)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct TextBaseline {
  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(() =>{
          this.context.strokeStyle = '#0000ff'
          this.context.moveTo(0, 120)
          this.context.lineTo(400, 120)
          this.context.stroke()
          this.context.font = '20px sans-serif'
          this.context.textBaseline = 'top'
          this.context.fillText('Top', 10, 120)
          this.context.textBaseline = 'bottom'
          this.context.fillText('Bottom', 55, 120)
          this.context.textBaseline = 'middle'
          this.context.fillText('Middle', 125, 120)
          this.context.textBaseline = 'alphabetic'
          this.context.fillText('Alphabetic', 195, 120)
          this.context.textBaseline = 'hanging'
          this.context.fillText('Hanging', 295, 120)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct GlobalAlpha {
  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(() =>{
          this.context.fillStyle = 'rgb(0,0,255)'
          this.context.fillRect(0, 0, 50, 50)
          this.context.globalAlpha = 0.4
          this.context.fillStyle = 'rgb(0,0,255)'
          this.context.fillRect(50, 50, 50, 50)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct LineDashOffset {
  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(() =>{
          this.context.arc(100, 75, 50, 0, 6.28)
          this.context.setLineDash([10,20])
          this.context.lineDashOffset = 10.0
          this.context.stroke()
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct GlobalCompositeOperation {
  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(() =>{
          this.context.fillStyle = 'rgb(255,0,0)'
          this.context.fillRect(20, 20, 50, 50)
          this.context.globalCompositeOperation = 'source-over'
          this.context.fillStyle = 'rgb(0,0,255)'
          this.context.fillRect(50, 50, 50, 50)
          this.context.fillStyle = 'rgb(255,0,0)'
          this.context.fillRect(120, 20, 50, 50)
          this.context.globalCompositeOperation = 'destination-over'
          this.context.fillStyle = 'rgb(0,0,255)'
          this.context.fillRect(150, 50, 50, 50)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct ShadowBlur {
  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(() =>{
          this.context.shadowBlur = 30
          this.context.shadowColor = 'rgb(0,0,0)'
          this.context.fillStyle = 'rgb(255,0,0)'
          this.context.fillRect(20, 20, 100, 80)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct ShadowColor {
  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(() =>{
          this.context.shadowBlur = 30
          this.context.shadowColor = 'rgb(0,0,255)'
          this.context.fillStyle = 'rgb(255,0,0)'
          this.context.fillRect(30, 30, 100, 100)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct ShadowOffsetX {
  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(() =>{
          this.context.shadowBlur = 10
          this.context.shadowOffsetX = 20
          this.context.shadowColor = 'rgb(0,0,0)'
          this.context.fillStyle = 'rgb(255,0,0)'
          this.context.fillRect(20, 20, 100, 80)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct ShadowOffsetY {
  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(() =>{
          this.context.shadowBlur = 10
          this.context.shadowOffsetY = 20
          this.context.shadowColor = 'rgb(0,0,0)'
          this.context.fillStyle = 'rgb(255,0,0)'
          this.context.fillRect(30, 30, 100, 100)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// 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")
  
  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() =>{
          this.context.imageSmoothingEnabled = false
          this.context.drawImage( this.img,0,0,400,200)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct FillRect {
  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(() =>{
          this.context.fillRect(30,30,100,100)
       })
      }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct StrokeRect {
  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(() =>{
          this.context.strokeRect(30, 30, 200, 150)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct ClearRect {
  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(() =>{
          this.context.fillStyle = 'rgb(0,0,255)'
          this.context.fillRect(20,20,200,200)
          this.context.clearRect(30,30,150,100)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct FillText {
  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(() =>{
          this.context.font = '30px sans-serif'
          this.context.fillText("Hello World!", 20, 100)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct StrokeText {
  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(() =>{
          this.context.font = '55px sans-serif'
          this.context.strokeText("Hello World!", 20, 60)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct MeasureText {
  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(() =>{
          this.context.font = '50px sans-serif'
          this.context.fillText("Hello World!", 20, 100)
          this.context.fillText("width:" + this.context.measureText("Hello World!").width, 20, 200)
      })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct Stroke {
  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(() =>{
          this.context.moveTo(25, 25)
          this.context.lineTo(25, 105)
          this.context.lineTo(75, 105)
          this.context.lineTo(75, 25)
          this.context.strokeStyle = 'rgb(0,0,255)'
          this.context.stroke()
        })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct BeginPath {
  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(() =>{
          this.context.beginPath()
          this.context.lineWidth = 6
          this.context.strokeStyle = '#0000ff'
          this.context.moveTo(15, 80)
          this.context.lineTo(280, 160)
          this.context.stroke()
        })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct MoveTo {
  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(() =>{
          this.context.beginPath()
          this.context.moveTo(10, 10)
          this.context.lineTo(280, 160)
          this.context.stroke()
        })
    }
    .width('100%')
    .height('100%')
  }
}

// xxx.ets
@Entry
@Component
struct LineTo {
  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(() =>{
          this.context.beginPath()
          this.context.moveTo(10, 10)
          this.context.lineTo(280, 160)
          this.context.stroke()
        })
    }
    .width('100%')
    .height('100%')
  }
}