这篇文章将为大家详细讲解有关HTML 5中怎么实现缓冲效果，文章内容质量较高，因此小编分享给大家做个参考，希望大家阅读完这篇文章后对相关知识有一定的了解。
这里是案例的演示代码：
<!doctype html> <html> <head> <meta http-equiv="content-type" content="GBK"/> <title>loading</title> <script type="text/javascript"> function loading(canvas,options){ this.canvas = canvas; if(options){ this.radius = options.radius||12; this.circleLineWidth = options.circleLineWidth||4; this.circleColor = options.circleColor||'lightgray'; this.dotColor = options.dotColor||'gray'; }else{ this.radius = 12; this.circelLineWidth = 4; this.circleColor = 'lightgray'; this.dotColor = 'gray'; } } loading.prototype = { show:function (){ var canvas = this.canvas; if(!canvas.getContext)return; if(canvas.__loading)return; canvas.__loading = this; var ctx = canvas.getContext('2d'); var radius = this.radius; var rotators = [{angle:0,radius:1.5},{angle:3/radius,radius:2},{angle:7/radius,radius:2.5},{angle:12/radius,radius:3}]; var me = this; canvas.loadingInterval = setInterval(function(){ ctx.clearRect(0,0,canvas.width,canvas.height); var lineWidth = me.circleLineWidth; var center = {x:canvas.width/2 - radius,y:canvas.height/2-radius}; ctx.beginPath(); ctx.lineWidth = lineWidth; ctx.strokeStyle = me.circleColor; ctx.arc(center.x,center.y,radius,0,Math.PI*2); ctx.closePath(); ctx.stroke(); for(var i=0;i<rotators.length;i++){ var rotatorAngle = rotators[i].currentAngle||rotators[i].angle; //在圆圈上面画小圆 var rotatorCenter = {x:center.x-(radius)*Math.cos(rotatorAngle) ,y:center.y-(radius)*Math.sin(rotatorAngle)}; var rotatorRadius = rotators[i].radius; ctx.beginPath(); ctx.fillStyle = me.dotColor; ctx.arc(rotatorCenter.x,rotatorCenter.y,rotatorRadius,0,Math.PI*2); ctx.closePath(); ctx.fill(); rotators[i].currentAngle = rotatorAngle+4/radius; } },50); }, hide:function(){ var canvas = this.canvas; canvas.__loading = false; if(canvas.loadingInterval){ window.clearInterval(canvas.loadingInterval); } var ctx = canvas.getContext('2d'); if(ctx)ctx.clearRect(0,0,canvas.width,canvas.height); } }; </script> </head> <body> <canvas id="canvas" width="300" height="100" style="border:1px solid #69c"></canvas> <p> <input type="button" onclick="loadingObj.hide()" value="HideLoading"/> <input type="button" onclick="loadingObj.show()" value="showLoading"/> </style> <p> <script> var loadingObj = new loading(document.getElementById('canvas'),{radius:8,circleLineWidth:3}); loadingObj.show(); </script> </body> </html>第二个较为简单，在一个圆环上有一个相同圆心相同半径的圆弧在不停的转动。画图的步骤是首先画一个圆环，然后画一个不同颜色相同圆心半径的圆弧，在每次刷新画布时改变圆弧的起始角度。
这里是案例的演示代码：
<!doctype html> <html> <head> <meta http-equiv="content-type" content="text/html;charset=gbk"/> <title>loading</title> <script> function loading(canvas,options){ this.canvas = canvas; if(options){ this.radius = options.radius||12; this.circleLineWidth = options.circleLineWidth||4; this.circleColor = options.circleColor||'lightgray'; this.moveArcColor = options.moveArcColor||'gray'; }else{ this.radius = 12; this.circelLineWidth = 4; this.circleColor = 'lightgray'; this.moveArcColor = 'gray'; } } loading.prototype = { show:function (){ var canvas = this.canvas; if(!canvas.getContext)return; if(canvas.__loading)return; canvas.__loading = this; var ctx = canvas.getContext('2d'); var radius = this.radius; var me = this; var rotatorAngle = Math.PI*1.5; var step = Math.PI/6; canvas.loadingInterval = setInterval(function(){ ctx.clearRect(0,0,canvas.width,canvas.height); var lineWidth = me.circleLineWidth; var center = {x:canvas.width/2 - radius,y:canvas.height/2-radius}; ctx.beginPath(); ctx.lineWidth = lineWidth; ctx.strokeStyle = me.circleColor; ctx.arc(center.x,center.y,radius,0,Math.PI*2); ctx.closePath(); ctx.stroke(); //在圆圈上面画小圆 ctx.beginPath(); ctx.strokeStyle = me.moveArcColor; ctx.arc(center.x,center.y,radius,rotatorAngle,rotatorAngle+Math.PI*.45); ctx.stroke(); rotatorAngle+=step; },50); }, hide:function(){ var canvas = this.canvas; canvas.__loading = false; if(canvas.loadingInterval){ window.clearInterval(canvas.loadingInterval); } var ctx = canvas.getContext('2d'); if(ctx)ctx.clearRect(0,0,canvas.width,canvas.height); } }; </script> </head> <body> <canvas id="canvas" width="300" height="100" style="border:1px solid #69c">您的浏览器不支持html5哟</canvas> <p> <input type="button" onclick="loadingObj.hide()" value="HideLoading"/> <input type="button" onclick="loadingObj.show()" value="showLoading"/> </p> <script> var loadingObj = new loading(document.getElementById('canvas'),{radius:8,circleLineWidth:3}); loadingObj.show(); </script> </body> </html>关于HTML 5中怎么实现缓冲效果就分享到这里了，希望以上内容可以对大家有一定的帮助，可以学到更多知识。如果觉得文章不错，可以把它分享出去让更多的人看到。
