/**
   * 微信小程序canvas繪制圓覺圓角角片
   * @param 圖片寬 imageWidth 
   * @param 圖片高 imageHeight 
   * @param x坐標 pointX 
   * @param y坐標 pointY 
   * @param 圖片路徑 iamgePath 
   */
  drawRoundImage(imageWidth,imageHeight,pointX,pointY,imageCorner,iamgePath,ctx){
     
    console.log(imageWidth)
    console.log(imageHeight)
    console.log(pointX)
    console.log(pointY)
    console.log(imageCorner)
    console.log(iamgePath)

    // 繪制海報背景圖片圓角
     ctx.save()
     ctx.beginPath()
     ctx.arc(pointX + imageCorner, pointY + imageCorner, imageCorner, Math.PI, Math.PI * 1.5)
     ctx.arc(pointX + imageWidth - imageCorner, pointY + imageCorner, imageCorner, Math.PI * 1.5, Math.PI * 2)
     ctx.arc(pointX + imageWidth - imageCorner, pointY + imageHeight - imageCorner, imageCorner, 0, Math.PI * 0.5)
     ctx.arc(pointX + imageCorner, pointY + imageHeight - imageCorner, imageCorner, Math.PI * 0.5, Math.PI)
     ctx.clip()
     ctx.drawImage(iamgePath, pointX, pointY, imageWidth, imageHeight)
     // 恢復(fù)之前保存的繪圖上下文
     ctx.restore()
  }

示例：

 //繪制頂部頭像 4個像素的圖片圓角
this.drawRoundImage(40,40, baseLeft, baseTop,5,this.data.avatarPath,ctx)