(网页)HTML5 Canvas ( 事件交互, 点击事件为例 ) isPointInPath(转)

<!DOCTYPE html>

<html>

<head>

    <meta charset="UTF-8">

    <title>canvas</title>

    <script type="text/javascript" src="../js/jQuery.js"></script>

    <style type="text/css">

        #canvas{

            width: 7rem;

            margin: .25rem   .5rem;

            border: 1px solid black;

            display: block;

        }

    </style>

</head>

<body>

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

</body>

</html>

<script type="text/javascript">

    /**

     * rem 布局初始化

     */

    $('html').css('font-size', $(window).width()/);

    /**

     * 获取 canvas 画布

     * 获取 canvas 绘图上下文环境

     */

    var canvas = $('#canvas')[];

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

    var balls = [];

    /**

     * 事件交互, 点击事件为例

     * isPointInPath(横坐标, 纵坐标)

     */

    for(var i = ; i < ; i++){

        var ball = {

            X: Math.random()*canvas.width,

            Y: Math.random()*canvas.height,

            R: Math.random()* +

        }

        balls[i] = ball;

    }

    draw();

    $("#canvas").click(function(){

        //标准的获取鼠标点击相对于canvas画布的坐标公式

        var x = event.pageX - canvas.getBoundingClientRect().left;

        var y = event.pageY - canvas.getBoundingClientRect().top;

        for(var i = ; i < balls.length; i++){

            cxt.beginPath();

            cxt.arc(balls[i].X, balls[i].Y, balls[i].R, , Math.PI*);

            if(cxt.isPointInPath(x, y)){

                cxt.fillStyle = "red";

                cxt.fill();

            }

        }

    });

    function draw(){

        cxt.fillStyle = "blue";

        for(var i = ; i < balls.length; i++){

            cxt.beginPath();

            cxt.arc(balls[i].X, balls[i].Y, balls[i].R, , Math.PI*);

            cxt.fill();

        }

    }

</script>
原文地址:https://www.cnblogs.com/lovling/p/6657966.html