<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
#canvas{
display: block;
margin: 50px auto;
box-shadow: 4px 4px 5px #8e8e8e;
-webkit-box-shadow: 8px 8px 5px #8e8e8e;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
</body>
</html>
<script>
window.onload = function()
{
var canvas = document.getElementById('canvas');
canvas.width = 288;
canvas.height = 192;
var ctx = canvas.getContext('2d');
ctx.beginPath();
ctx.rect(0,0,288,192);
ctx.closePath();
ctx.fillStyle = "red";
ctx.fill();
//大的星星
drawStar(ctx,12,30,48,48,0);
//四个小星星
drawStar(ctx, 4, 10, 96, 19, 18);
drawStar(ctx, 4, 10, 115, 38, 126);
drawStar(ctx, 4, 10, 115, 68, 72);
drawStar(ctx, 4, 10, 96, 96, 180);
}
//https://segmentfault.com/a/1190000005982536
function drawStar(ctx,r,R,x,y,rote)
{
ctx.beginPath();//开始路径
for(var i =0;i<5;i++)
{
//顶点
ctx.lineTo(Math.cos((18 + i * 72 - rote) / 180 * Math.PI) * R + x,
-Math.sin((18 + i * 72 - rote) / 180 * Math.PI) * R + y);
//凹点
ctx.lineTo(Math.cos((54 + i * 72 - rote) / 180 * Math.PI) * r + x,
-Math.sin((54 + i * 72 - rote) / 180 * Math.PI) * r + y);
}
ctx.closePath();
ctx.fillStyle = "yellow";
ctx.fill();
}
</script>