canvas绘图
1 绘制五角星
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>五角星绘制</title>
<style type="text/css">
#canvas{
border: 1px solid #ADACB0;
display: block;
margin: 20px auto;
}
</style>
</head>
<body>
<canvas id="canvas" width="500" height="500">
你的浏览器还不支持canvas
</canvas>
</body>
<script type="text/javascript">
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
context.fillStyle = "#F6F152";
context.strokeStyle = "#F5270B";
context.beginPath();
//设置是个顶点的坐标，根据顶点制定路径
for (var i = 0; i < 5; i++) {
context.lineTo(Math.cos((18+i*72)/180*Math.PI)*200+230,
-Math.sin((18+i*72)/180*Math.PI)*200+230);
context.lineTo(Math.cos((54+i*72)/180*Math.PI)*80+230,
-Math.sin((54+i*72)/180*Math.PI)*80+230);
}//Math.PI返回圆周率
context.shadowBlur=10;
context.shadowColor="blue";
context.closePath();
//设置边框样式以及填充颜色
context.lineWidth="3";
context.fill();
context.stroke();
</script>
</html>
2 绘制半圆
<!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>半圆</title>
</head>
<body>
<canvas id="demo" width="300" height="300" style="border:1px solid #ccc"></canvas>
<script type="text/javascript">
var canvas=document.getElementById("demo");
var ctx=canvas.getContext("2d");
ctx.fillStyle="red";
ctx.strokeStyle="black";
ctx.lineWidth=5;
ctx.beginPath();
ctx.arc(150,150,130,0,Math.PI,true);
ctx.closePath();
ctx.fill();
ctx.stroke();
</script>
</body>
</html>
3 渐变文字
<!DOCTYPE html>
<html>
<head>
<title>渐变文字</title>
<meta charset="utf-8">
</head>
<body>
<canvas id="demo" width="800" height="600">你的浏览器不支持canvas</canvas>
<script type="text/javascript">
var canvas=document.getElementById('demo');
ctx=canvas.getContext('2d');
grd=ctx.createLinearGradient(0, 0, canvas.width, 0);
grd.addColorStop('0','black');
grd.addColorStop('0.3','green');
grd.addColorStop('0.6','yellow');
grd.addColorStop('1','red');
ctx.font = '80px yahei';
ctx.fillStyle= grd;
ctx.fillText('我喜欢Web前端', 100, 100);
</script>
</body>
</html>
4 图文混排
<!DOCTYPE html>
<html>
<head>
<title>图文混排</title>
<meta charset="utf-8">
</head>
<body>
<canvas id="demo" width="1000" height="800"></canvas>
<script type="text/javascript">
var canvas=document.getElementById("demo");
var ctx=canvas.getContext("2d");
ctx.fillStyle='#99f';
ctx.fillRect(0,0,800,600);
var image=new Image();
image.src="1.jpg";
image.onload=function(){
ctx.drawImage(image,20,20,300,560);
}
ctx.fillStyle = '#fff'; // 文字填充颜色
ctx.font = '33px 微软雅黑';
ctx.fillText('小朋友观看长颈鹿',390,100);
ctx.fillStyle = '#fff';
ctx.font = '66px 微软雅黑';
ctx.fillText('大家很开心!',390,200);
ctx.stroke();
</script>
</body>
</html>
