h5 canvas绘制的旋转小球

最新推荐文章于 2024-05-06 07:24:40 发布

ITzhongzi

最新推荐文章于 2024-05-06 07:24:40 发布

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本文介绍了一个使用HTML5 Canvas实现的旋转球动画效果。该动画包括一个大圆和围绕其旋转的小圆，每个小圆上还标记了不同的文本，如'php'、'前端'等。通过不断更新Canvas的内容，实现了流畅的动画效果。

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>$</title>
</head>
<body>
<canvas id="canvas" width="800" height="600" style="border:1px solid red"></canvas>
</body>
<script>


    function RotateBall(opt) {

        for (var key in opt) {
            this[key] = opt[key];
        }

        this.init()
    }
    RotateBall.prototype = {
        init: function () {


            this.loop();
        },

        loop:function(){
            var self = this;
            this.timer = setInterval(function () {
                self.ctx.clearRect(0,0,self.ctx.canvas.width,self.ctx.canvas.height);
                self.ctx.font = '20px 微软雅黑';
                self.ctx.textAlign = 'center';
                self.ctx.textBaseline = 'middle';

                self.start += 0.01 * Math.PI;
                //绘制
                self.drawBigCircle();
                self.drawSmallCircles();
            }, 20);
        },
        drawBigCircle: function () {
            var ctx = this.ctx;
            ctx.beginPath();
            ctx.arc(this.bigX, this.bigY, this.bigRadius, 0, 2 * Math.PI);
            ctx.stroke();
        },
        drawSmallCircles: function () {
            var dataL = this.data.length;
            var radian = 2 * Math.PI / dataL;
            var bigRadius = this.bigRadius;
            var bigX = this.bigX;
            var bigY = this.bigY;
            var datas = this.data;
            for (var i = 0; i < dataL; i++) {
                var startRadian = radian * i + this.start;

                var b = bigRadius * Math.cos(startRadian);
                var h = bigRadius * Math.sin(startRadian);

                var smallX = bigX + b;
                var smallY = bigY + h;

                this.drawSmallCircle(smallX, smallY);

                this.drawSmallCircle(startRadian);
                this.drawText(datas[i], smallX, smallY);
            }
        },
        drawSmallCircle: function (smallX, smallY) {

            var ctx = this.ctx;
            ctx.save()
            ctx.beginPath();
            ctx.arc(smallX, smallY, this.smallRadius, 0, 2 * Math.PI);
            ctx.fillStyle = 'skyblue';
            ctx.fill();
            ctx.restore();
        },
        drawText: function (data, smallX, smallY) {
            ctx.save()
            ctx.beginPath();
            ctx.fillStyle = 'orange';
            ctx.fillText(data, smallX, smallY);
            ctx.restore();
        }
    };

    var canvas = document.getElementById("canvas");
    var ctx = canvas.getContext("2d");
    var data = ['php', '前端', 'ios', '安卓', 'python', 'java'];

    var obj = {
        ctx: ctx,
        bigX: 300,
        bigY: 300,
        bigRadius: 150,
        data: data,
        smallRadius: 30,
        start: 0
    }
    var rball = new RotateBall(obj);
</script>
</html>