-
Notifications
You must be signed in to change notification settings - Fork 0
/
2.html
88 lines (87 loc) · 2.3 KB
/
2.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<title>document</title>
<style>
*{
padding:0;
margin:0;
}
html,body{
width:100%;
height:100%;
overflow: hidden;
}
canvas{
}
span{
font-size: 50px;
}
</style>
<script>
function rnd(n,m){
return parseInt(Math.random()*(m-n)+n);
}
function d2a(n){
return n*Math.PI/180;
}
window.onload=function(){
var c=document.getElementsByTagName('canvas')[0];
var W=document.documentElement.clientWidth;
var H=document.documentElement.clientHeight;
c.width=W;
c.height=H;
var posX = 0;
var posY = 0;
var iSpeedX = 8;
var iSpeedY = 8;
function draw(){
// console.log(rnd(0,100));
//准备画笔
var gd=c.getContext('2d');
gd.fillStyle='red';
gd.clearRect(0,0,W,H);
gd.beginPath();
posX+= iSpeedX;
posY+= iSpeedY;
if(posX+50>W){//注意arc是从圆心画的所以是50不是100
iSpeedX*=-1;
}
if(posY+50>H){
iSpeedY*=-1;
}
if(posX<50&&iSpeedX!=8){//注意arc是从圆心画的所以是50不是100
iSpeedX*=-1;
}
if(posY<50&&iSpeedY!=8){
iSpeedY*=-1;
}
gd.arc(posX,posY,50,d2a(0),d2a(360),false);
gd.fill();
window.requestAnimationFrame(draw);//这里用递归不然循环不起来，不用担心性能问题，我说没问题就没问题
}
window.requestAnimationFrame(draw);
//不处理requesAnimationFrame的兼容性就没法在实际项目中使用，因为兼容性太操蛋了
//使用了一个IIFEs,你不懂也没事 拿过去用就行了
window.requestAnimationFrame = (function(){
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(callback){
window.setTimeout(callback, 1000 / 60);//低版本保险刷新频率
};
})();
};
</script>
</head>
<body>
<canvas width="800" height="500">
<span>你的浏览器不支持canvas</span>
</canvas>
</body>
</html>