html5学习二（canvas）

添加画布

 <canvas id="myCanvas" width="200" height="100"></canvas>

通过javascript来绘制

 <script type="text/javascript">

 var c=document.getElementById("myCanvas");

 var cxt=c.getContext("2d");

 cxt.fillStyle="#FF0000";

 cxt.fillRect(0,0,150,75);

 </script>

getContext("2d") 对象是内建的 HTML5 对象，拥有多种绘制路径、矩形、圆形、字符以及添加图像的方法。

下面的两行代码绘制一个红色的矩形：

 cxt.fillStyle="#FF0000";
2 cxt.fillRect(0,0,150,75); 

 下面代码画线

 1 <script type="text/javascript">
 2 
 3 var c=document.getElementById("myCanvas");
 4 var cxt=c.getContext("2d");
 5 cxt.moveTo(10,10);
 6 cxt.lineTo(150,50);
 7 cxt.lineTo(10,50);
 8 cxt.stroke();
 9 
10 </script>

 圆形

 1 <script type="text/javascript">
 2 
 3 var c=document.getElementById("myCanvas");
 4 var cxt=c.getContext("2d");
 5 cxt.fillStyle="#FF0000";
 6 cxt.beginPath();
 7 cxt.arc(70,18,15,0,Math.PI*2,true);
 8 cxt.closePath();
 9 cxt.fill();
10 
11 </script>

 渐变

 1 <script type="text/javascript">
 2 
 3 var c=document.getElementById("myCanvas");
 4 var cxt=c.getContext("2d");
 5 var grd=cxt.createLinearGradient(0,0,175,50);
 6 grd.addColorStop(0,"#FF0000");
 7 grd.addColorStop(1,"#00FF00");
 8 cxt.fillStyle=grd;
 9 cxt.fillRect(0,0,175,50);
10 
11 </script>

 图片

 <script type="text/javascript">
2 
3 var c=document.getElementById("myCanvas");
4 var cxt=c.getContext("2d");
5 var img=new Image()
6 img.src="flower.png"
7 cxt.drawImage(img,0,0);
8 
9 </script>