canvas-3radialGradient.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 = 800;

            canvas.height = 800;

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

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

                // begin

                var radialGrad = context.createRadialGradient(400,400,0,400,400,500);

                radialGrad.addColorStop(0.0,'white');

                radialGrad.addColorStop(0.25,'yellow');

                radialGrad.addColorStop(0.5,'green');

                radialGrad.addColorStop(0.75,'blue');

                radialGrad.addColorStop(1.0,'black');

                context.fillStyle = radialGrad;

                context.fillRect(0,0,800,800)

            }else{

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

            }

        }

    </script>

</body>

<script>

    /*总结

    step 1

        // 内圆的圆心（x0,y0） 内圆半径r0

        var grd = context.creatRadialGradient(x0,y0,r0,x1,x1,r1)

    step 2

        //stop的值域[0,1]

        grd.addColorStop(stop,color)

    */

</script>

</html>
巴特西

canvas-3radialGradient.html

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