JS implements circular progress bar drag and slide

This article example shares the specific code of JS to realize the drag and slide of circular progress bar for your reference. The specific content is as follows

Effect display

Semicircular progress bar effect

Circular progress bar

Code Implementation

<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
  <title> Drag and slide the circular progress bar</title>
</head>
<body>
<canvas id="canvasId" width="400" height="400"></canvas>
<script type="text/javascript">
    var canvas = document.getElementById("canvasId");
    var ctx = canvas.getContext("2d");
    var ox = 200;
    var oy = 200;
    var or = 180;
    var br = 15;
    var moveFlag = false;

    function offset(r,d) {//Calculate the offset coordinates based on radians and distance return {x: -Math.sin(r)*d, y: Math.cos(r)*d};
    };

    function draw(n) {
        ctx.clearRect(0,0,canvas.width,canvas.height);
        ctx.strokeStyle = "#99a";
        ctx.lineWidth = 5;
        ctx.beginPath();
        ctx.arc(ox,oy,or,0,Math.PI,true);//semicircle// ctx.arc(ox,oy,or,0,2*Math.PI,true);//full circlectx.stroke();
        ctx.strokeStyle = "#69f";
        ctx.lineWidth = 5;
        ctx.beginPath();
        ctx.arc(ox,oy,or,Math.PI,(n*2+0.5)*Math.PI,false);
        // ctx.arc(ox,oy,or,0.5*Math.PI,(n*2+0.5)*Math.PI,false);
        ctx.stroke();
        ctx.fillStyle = "#69f";
        ctx.font = "80px Arial";
        ctx.textAlign = "center";
        ctx.textBaseline = "middle";
        ctx.fillText(Math.round(n*100-25)+"%",ox,oy);
        ctx.fillStyle = "#00f";
        ctx.beginPath();
        var d = offset(n*2*Math.PI,or);
        ctx.arc(ox+dx,oy+dy,br,0,2*Math.PI,true);
        ctx.fill();
    }

    var on = ("ontouchstart" in document)? {
        start: "touchstart", move: "touchmove", end: "touchend"
    } : {
        start: "mousedown", move: "mousemove", end: "mouseup"
    };

    function getXY(e,obj) {
        var et = e.touches? e.touches[0] : e;
        var x = et.clientX;
        var y = et.clientY;
        return {
            x : x - obj.offsetLeft + (document.body.scrollLeft || document.documentElement.scrollLeft),
            y : y - obj.offsetTop + (document.body.scrollTop || document.documentElement.scrollTop)
        }
    }

    canvas.addEventListener(on.start, function(e) {
        moveFlag = true;
    }, false);

    canvas.addEventListener(on.move, function(e) {
        if (moveFlag) {
            var k = getXY(e,canvas);
            var r = Math.atan2(kx-ox, oy-ky);
            var hd = (Math.PI+r)/(2*Math.PI);

            // Determine the sliding range of the semicircle if (hd <= 0.75 && hd >= 0.25) {
                draw(hd);
            }
        }
    }, false);

    canvas.addEventListener(on.end, function(e) {
        moveFlag = false;
    }, false);

    draw(0.25);
</script>

</body>
</html>

The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM.

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