昨天发了一篇使用HTML5 canvas写的时钟的文章，今天发一篇关于使用HTML5制作loading图的文章。
<!DOCTYPE html> <html> <head> <title></title> </head> <body> <canvas id = "canvas"></canvas> <script> var Loading = function (canvas, options) { this.canvas = document.getElementById(canvas); this.options = options; }; 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); } }; (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>
这是效果图：
这一篇也是没有注释，但这一篇比上一篇更容易理解。后面还会有一些关于HTML5 canvas的文章，都是去年写的。