canvas实现圆形进度条动画的示例代码HTML5 Canvas 实现圆形进度条并显示数字百分比效果示例

 70% 

 var canvas = document.getElementById("mycanvas"); var context = canvas.getContext("2d"); function draw(i){ // 大圆框 context.beginPath(); context.lineWidth = 1; context.arc(50,50,46,0,Math.PI*2); context.strokeStyle = "grey"; context.stroke(); // 大圆 context.beginPath(); var grd = context.createLinearGradient(15,15,80,80); grd.addColorStop(0,"red"); grd.addColorStop(0.5,"yellow"); grd.addColorStop(1,"blue"); context.arc(50,50,38,0,Math.PI*2*(i/100)); context.lineWidth = 16; context.strokeStyle = grd; context.stroke(); // context.fillStyle = grd; // context.fill(); // 小圆 context.beginPath(); context.arc(50,50,30,0,Math.PI*2); context.lineWidth = 1; context.strokeStyle = "grey"; context.stroke(); context.fillStyle = "white"; context.fill(); // 字 context.beginPath(); context.textBaseline = "middle"; context.textAlign = "center"; context.font = "20px Arial"; context.fillStyle = "black"; context.fillText(i+"%",50,50); } 

 var i = 0; var progress = parseInt(canvas.innerHTML); // console.log(progress); var timer = setInterval(function(){ if(i >= progress){ clearInterval(timer); } context.clearRect(0,0,canvas.width,canvas.height); draw(i); i++; },50);