椭圆形

代码运行

<!DOCTYPE HTML>
<html>
  <head>
    <title>椭圆形</title>
    <style>
      body {
        margin: 0px;
        padding: 0px;
      }
    </style>
  </head>
  <body>
    <canvas id="myCanvas" width="578" height="200"></canvas>
    <script>
      var canvas = document.getElementById('myCanvas');
      var context = canvas.getContext('2d');
      var centerX = 0;
      var centerY = 0;
      var radius = 50;

// save state
      context.save();

// translate context
      context.translate(canvas.width / 2, canvas.height / 2);

// scale context horizontally
      context.scale(2, 1);

// draw circle which will be stretched into an oval
      context.beginPath();
      context.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);

// restore to original state
      context.restore();

// apply styling
      context.fillStyle = '#8ED6FF';
      context.fill();
      context.lineWidth = 5;
      context.strokeStyle = 'black';
      context.stroke();
    </script>
  </body>
</html>