js canvas-CFANZ编程社区

js canvas
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">

    <style type="text/css">
        * {
            margin: 0;
            padding: 0;
        }

        .canvas-box {
            position: relative;
        }

        canvas {
            box-shadow: 0 0 10px rgba(0, 0, 0, 0.2)
        }
    </style>

    <title>Document</title>
</head>

<body>
    <!-- <canvas id="canvas"></canvas>
    <script>
        var canvas = document.getElementById("canvas");
        var ctx = canvas.getContext("2d");
        ctx.fillStyle = "red";
        ctx.fillRect(0, 0, 100, 500);
        ctx.fillRect(100, 100, 600, 600);

        ctx.fillStyle = "blue";

        // ctx.stroke();
        console.log(ctx.isPointInPath(5, 5)); // true
    </script> -->





    <div class="canvas-box">
        <canvas id="cvs" width="500" height="400">不支持canvas</canvas>
    </div>

    <script>
        var cvs = document.getElementById('cvs');
        var ctx = cvs.getContext('2d');
        // 封装绘制的图形
        function draw() {
            ctx.fillStyle = '#000';
            ctx.beginPath();
            ctx.moveTo(100, 100);
            ctx.bezierCurveTo(110, 110, 199, 278, 300, 379);
            ctx.lineTo(400, 100)
            ctx.closePath();
        }
        function circle() {
            ctx.fillStyle = '#000';
            ctx.beginPath();
            ctx.arc(100, 200, 50, 0, Math.PI * 2)
            ctx.closePath();
        }
        // 初始化绘制图形
        draw();
        ctx.fill()
        circle();
        ctx.fill()
        var fns = [draw, circle];
        // 监听鼠标事件
        cvs.onmousemove = function (e) {
            // 得到鼠标的坐标
            var x = e.pageX, y = e.pageY;
            ctx.clearRect(0, 0, 400, 300)
            // 遍历绘制图形
            for (var i = fns.length; i--;) {
                fns[i]();
                // 每绘制一个图形就判断一次当前鼠标的坐标是否在这个图形上，然后进行自定义操作
                if (ctx.isPointInPath(x, y)) {
                    ctx.fillStyle = "#f00"
                } else {
                    ctx.fillStyle = "#000"
                }
                ctx.fill()
            }
        }
    </script>


</body>

</html>
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