canvas圆形进度条

时间：2021-09-07 21:12:54

通过定义一个canvas标签， new方法传进ID值，和旋转角度值，即可生成圆形进度条

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>圆进度条</title>

</head>

<body>

    <canvas id="yuan" width="200" height="200"></canvas>

</body>

<script src="jquery-1.11.1.min.js"></script>

<script type="text/javascript">

    window.chart =function(ID){

        var canvas = document.getElementById(ID);

        var ctx = canvas.getContext("2d");

        // 画布宽高

        var W = canvas.width;

        var H = canvas.height;

         //度角

         var degrees = 0;

         var new_degrees = 0;

         // 差额

         var difference = 0;

         var text,text_w;                   // 文字

         var R =W < H ? W:H;             //先默认环半径为canvas宽度

         var outW =parseInt(R / 14);        //环宽度

         var outR = (R/2) -outW;           //环半径=canvas宽度半径 -外环宽度

         var $this = this;

         console.log("canvas宽度:"+R);

         console.log(outW);

         console.log(outR);

         $this.ratePieNoAnimation = function (number){

             degrees =360*number/100;

             // 园弧底图

             ctx.clearRect(0,0,W,H);//先清画布

             ctx.beginPath();

             ctx.strokeStyle ="green";

            // 园弧线的宽度

             ctx.lineWidth = outW;

             ctx.arc(W / 2, H / 2, outR, 0, Math.PI * 2, false);

             ctx.stroke();

            //圆弧动画

            var r = degrees * Math.PI / 180;

            ctx.beginPath();

            ctx.strokeStyle = "#994746";

            ctx.lineWidth = outW;

            // 弧将从最顶端开始

            ctx.arc(W / 2, H / 2, outR, 0 - 90 * Math.PI / 180, r - 90 * Math.PI / 180, false);

            ctx.stroke();

            // 文字添加

            ctx.fillStyle = "#63d2ef";

            ctx.shadowColor = "#eee";

            ctx.font = "bold " + R / 6 + "px hanyi";

            text = Math.floor(degrees / 360 * 100) + "%";

            text_w = ctx.measureText(text).width;

            ctx.fillText(text, W / 2 - text_w / 2, H / 2 + R / 10);

        };

        $this.ratePie = function(number){

            var i=0;

            var time=setInterval(function(){

                if( i==number){

                    clearInterval(time);

                }else{

                    number >0 ? i++ : i--;

                }

                $this.ratePieNoAnimation(i);

                if( i>100 || i<-100){

                    $this.ratePieNoAnimation(number);

                    clearInterval(time);

                }

            }, 2000 / (number > 0 ? number : -number));

        };

    }

    new chart("yuan").ratePie(50);

</script>

</html>

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