使用html5制作loading图的示例

复制代码代码如下:
!DOCTYPE htML>
html>
head>
tITle> /title>
/head>
body>
canvas id = "canvas"> /canvas> /p> p> script>
VAR Loading = function (canvas, options) {
this.canvas = document.getElementById(canvas);
this.options = options;
} ; /p> p> Loading.PRototype = {
constructor: Loading,
show: function () {
var canvas = this.canvas,
begin = this.options.begin,
old = this.options.old,
lineWidth = this.options.lineWidth,
canvascenter = { x: canvas.width / 2, y: canvas.height / 2} ,
ctx = canvas.getContext("2d"),
color = this.options.color,
num = this.options.num,
angle = 0,
lineCap = this.options.lineCap,
CONST_PI = Math.PI * (360 / num) / 180;
window.timer = setInterval(function () {
ctx.clearRect(0, 0, canvas.width, canvas.height);
for (var i = 0; i num; i += 1) {
ctx.beginPath();
ctx.strokeStyle = color[num - 1 - i];
ctx.lineWidth = lineWidth;
ctx.lineCap= lineCap;
ctx.moveTo(canvasCenter.x + Math.cos(CONST_PI * i + angle) * begin, canvasCenter.y + Math.sin(CONST_PI * i + angle) * begin);
ctx.lineto(canvasCenter.x + Math.cos(CONST_PI * i + angle) * old, canvasCenter.y + Math.sin(CONST_PI * i + angle) * old);
ctx.stroke();
ctx.closePath();
}
angle += CONST_PI;
console.LOG(angle)
} ,50);
} ,
hide: function () {
clearInterval(window.timer);
}
} ; /p> p> (function () {
var options = {
num : 8,
begin: 20,
old: 40,
lineWidth: 10,
lineCap: "round",
color: ["rgb(0, 0, 0)", "rgb(20, 20, 20)","rgb(40, 40, 40)", "rgb(60, 60, 60)","rgb(80, 80, 80)", "rgb(100, 100, 100)", "rgb(120, 120, 120)", "rgb(140, 140, 140)"]
} ;
var loading = new Loading("canvas", options);
loading.show();
} ());
/script>
/body>
/html>


效果图：

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