Canvas/18_canvas_线条帽子.html

<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <title>Page Title</title>
  <meta name="viewport" content="width=device-width, initial-scale=1">
</head>

<body>
  <canvas id="myCanvas" style="border:1px solid red;">
    当前浏览器不支持canvas，请更换浏览器后再试
  </canvas>
  <script>
    window.onload = function () {
      var canvas = document.getElementById('myCanvas')

      canvas.width = 800
      canvas.height = 800

      var ctx = canvas.getContext('2d')

      ctx.beginPath()
      ctx.moveTo(100, 100)
      ctx.lineTo(600, 100)

      ctx.lineWidth = 50
      ctx.lineCap = 'butt' // 默认值，无帽子，lineCap样式只能用在线条开始和结束处，无法使用在线条连接处

      ctx.stroke()

      ctx.beginPath()
      ctx.moveTo(100, 200)
      ctx.lineTo(600, 200)

      ctx.lineWidth = 50
      ctx.lineCap = 'round' // 圆形

      ctx.stroke()

      ctx.beginPath()
      ctx.moveTo(100, 300)
      ctx.lineTo(600, 300)

      ctx.lineWidth = 50
      ctx.lineCap = 'square' // 方形

      ctx.stroke()

      // baseLine
      ctx.beginPath()
      ctx.moveTo(100, 0)
      ctx.lineTo(100, 800)

      ctx.lineWidth = 1
      ctx.stroke()

      ctx.beginPath()
      ctx.moveTo(600, 0)
      ctx.lineTo(600, 800)

      ctx.lineWidth = 1
      ctx.stroke()


    }

  </script>
</body>

</html>