效果展示：
查看效果可点击下载源文件 http://i.cnblogs.com/Files.aspx
html完整代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>canvas鼠标画图</title>
<style>
body { background-color:yellow;}
#c1 { background-color: white; }
</style>
<script>
window.onload = function() {
var oC = document.getElementById('c1');
var oCG = oC.getContext('2d');
oC.onmousedown = function(ev) {
var ev = ev || window.event;
oCG.moveTo(ev.clientX-oC.offsetLeft,ev.clientY-oC.offsetTop); //ev.clientX-oC.offsetLeft,ev.clientY-oC.offsetTop鼠标在当前画布上X,Y坐标
document.onmousemove = function(ev) {
var ev = ev || window.event;//获取event对象
oCG.lineTo(ev.clientX-oC.offsetLeft,ev.clientY-oC.offsetTop);
oCG.stroke();
};
oC.onmouseup = function() {
document.onmousemove = null;
document.onmouseup = null;
};
};
};
</script>
</head>
<body>
<canvas id="c1" width="400px" height="400px"> <!--宽高写在html里，写在css里有问题-->
<span>该浏览器不支持canvas内容</span> <!--对于不支持canvas的浏览器显示-->
</canvas>
</body>
</html>
年级1