canvas-2arcTo.html

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Document</title>

</head>

<body>

    <canvas id="canvas" style="margin:0 auto;border:1px #ddd solid;">

        The current browser does not support Canvas, can replace the browser a try!

    </canvas>

    <script>

        window.onload = function(){

            var canvas = document.getElementById('canvas');

            canvas.width = 1024;

            canvas.height = 768;

            if(canvas.getContext('2d')){

                var context = canvas.getContext('2d');

                context.beginPath();

                context.moveTo(150,150);

                context.arcTo(650,150,650,650,300);

                context.lineWidth = 6;

                context.strokeStyle = "red";

                context.stroke();

                // baseline

                context.beginPath();

                context.moveTo(150,150);

                context.lineTo(650,150);

                context.lineTo(650,650);

                context.lineWidth = 2;

                context.strokeStyle = "gray"

                context.stroke();

            }else{

                alert('当前游览器不支持Canvas，请更换游览器后再试！');

            }

        }

        function arcToTest(cxt,x0,y0,x1,y1,x2,y2,R){

            cxt.beginPath();

            cxt.moveTo(x0,y0);

            cxt.arcTo(x1,y1,x2,y2,R);

            cxt.lineWidth = 6;

            cxt.strokeStyle = "red";

            cxt.stroke();

            // baseline

            cxt.beginPath();

            cxt.moveTo(x0,y0);

            cxt.lineTo(x1,y1);

            cxt.lineTo(x2,y2);

            cxt.lineWidth = 2;

            cxt.strokeStyle = "gray"

            cxt.stroke();

        }

    </script>

</body>

<script>

    /*总结

        context.arc(x1,y1,x2,y2,r)

    */

</script>

</html>