Html五+JavaScript 在Canvas上绘制伍星Red Banner，具体思路如下图所示：
绘制思路在上海体育场合中已有证实，具体代码如下：
1 <script type="text/javascript">
2
3 //绘制五角星，其中一点垂直向上，相隔的点相连，即可绘制。
4 function drawStar(ctx,starCenterX,starCenterY,starRadius) {
5 var aX = starCenterX;
6 var aY = starCenterY - starRadius;
7 var bX = starCenterX - Math.cos(18 * Math.PI / 180) * starRadius;
8 var bY = starCenterY - Math.sin(18 * Math.PI / 180) * starRadius;
9 var cX = starCenterX - Math.cos(54 * Math.PI / 180) * starRadius;
10 var cY = starCenterY + Math.sin(54 * Math.PI / 180) * starRadius;
11 var dX = starCenterX + Math.cos(54 * Math.PI / 180) * starRadius;
12 var dY = starCenterY + Math.sin(54 * Math.PI / 180) * starRadius;
13 var eX = starCenterX + Math.cos(18 * Math.PI / 180) * starRadius;
14 var eY = starCenterY - Math.sin(18 * Math.PI / 180) * starRadius;
15 ctx.beginPath();
16 ctx.fillStyle = "yellow";
17 ctx.moveTo(aX, aY);
18 ctx.lineTo(cX, cY);
19 ctx.lineTo(eX, eY);
20 ctx.lineTo(bX, bY);
21 ctx.lineTo(dX, dY);
22 ctx.lineTo(aX, aY);
23 ctx.fill();
24 ctx.closePath();
25 }
26
27 window.onload = function () {
28 var c = document.getElementById("myCanvas");
29 var ctx = c.getContext("2d");
30 ctx.clearRect(0, 0, c.width, c.height);
31 var width = 300*1.5;
32 var height = 200*1.5;
33 var sX = 50; //其实坐标
34 var sY = 50; //其实坐标
35 var step = 10*1.5;
36 //绘制矩形
37 ctx.beginPath();
38 ctx.lineWidth = 1;
39 ctx.fillStyle = "red";
40 ctx.fillRect(sX, sY, width, height);
41 ctx.closePath();
42 //绘制大五角星
43 var bigStarCenterX = sX + 5 * step;
44 var bigStarCenterY = sY + 5 * step;
45 var bigStarRadius = (height * 3 / 10) / 2; //外接圆直径为旗高3/10，半径要再除以2
46 drawStar(ctx, bigStarCenterX, bigStarCenterY, bigStarRadius);
47 //绘制小五角星
48 var smallStarRadius = (height * 1 / 10) / 2; //外接圆直径为旗高1/10，半径要再除以2
49
50 var smallStarCenterX_1 = sX + 10 * step;
51 var smallStarCenterY_1 = sY + 2 * step;
52 drawStar(ctx, smallStarCenterX_1, smallStarCenterY_1, smallStarRadius);
53 var smallStarCenterX_2 = sX + 12 * step;
54 var smallStarCenterY_2 = sY + 4 * step;
55 drawStar(ctx, smallStarCenterX_2, smallStarCenterY_2, smallStarRadius);
56 var smallStarCenterX_3 = sX + 12 * step;
57 var smallStarCenterY_3 = sY + 7 * step;
58 drawStar(ctx, smallStarCenterX_3, smallStarCenterY_3, smallStarRadius);
59 var smallStarCenterX_4 = sX + 10 * step;
60 var smallStarCenterY_4 = sY + 9 * step;
61 drawStar(ctx, smallStarCenterX_4, smallStarCenterY_4, smallStarRadius);
62 };
63 </script>
View Code