如何使用HTML5 canvas绘制一个矩形(2)-木庄网络博客

代码如下

<!DOCTYPE html>
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <title></title>
  <meta charset="utf-8" />
  <style type="text/css">
    <!--
    /*背景色和背景图*/
    .canvas{
      background-color:#FFFFFF;
      background-image: url("img/t.jpg");
    }
    -->
  </style>
  <script type="text/javascript">
  function draw() {
    var canvas = document.getElementById('SimpleCanvas');
    if ( ! canvas || ! canvas.getContext ) {
      return false;
    }
    var cx = 360;
    var cy = 400;
    var radius = 36;
    var context = canvas.getContext('2d');
    context.beginPath();
    context.rect(240, 80, 160, 80);
    context.lineWidth = 4;
    context.strokeStyle = 'coral';
    context.stroke();
}
  </script>
</head>
<body onload="draw()" style="background-color:#D0D0D0;">
  <canvas id="SimpleCanvas" width="640" height="480" class="canvas"></canvas>
  <div>Canvas Demo</div>
</body>
</html>

说明：在绘制图像时，如果不调用fill（）方法，只执行stroke（）方法，就能绘制内部不填充的矩形。

运行结果

在浏览器上显示如下效果

HTML5 canvas

最后我们来看直接填充内部的矩形绘制

<!DOCTYPE html>
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <title></title>
  <meta charset="utf-8" />
  <script type="text/javascript">
  function draw() {
    var canvas = document.getElementById('SimpleCanvas');
    if ( ! canvas || ! canvas.getContext ) {
      return false;
    }
    var cx = 360;
    var cy = 400;
    var radius = 36;
    var context = canvas.getContext('2d');
    context.beginPath();
    context.rect(260, 120, 220, 120);
    context.fillStyle = 'burlywood';
    context.fill();
}
  </script>
</head>
<body onload="draw()" style="background-color:#D0D0D0;">
  <canvas id="SimpleCanvas" width="640" height="480" style="background-color:#FFFFFF;"></canvas>
  <div>Canvas Demo</div>
</body>
</html>