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高洛峰원래의: 2016-11-03 16:58:411077검색

<canvas id="tutorial" width="150" height="150"></canvas>

替换内容

<canvas id="stockGraph" width="150"    style="max-width:90%">
  current stock price: $3.15 +0.15
</canvas>

<canvas id="clock" width="150" height="150">
  <img src="images/clock.png" width="150"    style="max-width:90%" alt=""/>
</canvas>

标签不可省

2.渲染上下文（The rendering context）

WebGL 使用了基于OpenGL ES的3D上下文 ("experimental-webgl")

我们将会将注意力放在2D渲染上下文中

canvas起初是空白的。为了展示，首先脚本需要找到渲染上下文，然后在它的上面绘制。

var canvas = document.getElementById(&#39;tutorial&#39;);
var ctx = canvas.getContext(&#39;2d&#39;);

3.检查支持性

var canvas = document.getElementById(&#39;tutorial&#39;);

if (canvas.getContext){
  var ctx = canvas.getContext(&#39;2d&#39;);
  // drawing code here
} else {
  // canvas-unsupported code here
}

4.一个模板骨架


  
    Canvas tutorial
    
    
  
  
    <canvas id="tutorial" width="150" height="150"></canvas>

5.一个简单例子

<html>
 <head>
  <script type="application/javascript">
    function draw() {
      var canvas = document.getElementById("canvas");
      if (canvas.getContext) {
        var ctx = canvas.getContext("2d");

        ctx.fillStyle = "rgb(200,0,0)";
        ctx.fillRect (10, 10, 55, 50);

        ctx.fillStyle = "rgba(0, 0, 200, 0.5)";
        ctx.fillRect (30, 30, 55, 50);
      }
    }
  </script>
 </head>
 <body onload="draw();">
   <canvas id="canvas" width="150" height="150"></canvas>
 </body>
</html>

성명：

이전 기사：HTML 테이블 요소다음 기사：HTML 테이블 요소

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