怎样用canvas来绘制彩色七巧板-H5教程-PHP中文网

怎样用canvas来绘制彩色七巧板

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发布： 2018-03-14 09:41:37

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这次给大家带来怎样用canvas来绘制彩色七巧板，用canvas来绘制彩色七巧板的注意事项有哪些，下面就是实战案例，一起来看一下。

HTML代码

<!DOCTYPE html><html lang="en">
<head>
    <meta charset="UTF-8"/>
    <title>Canvas绘制七巧板</title>
</head>
    <body>
        <style>
            #canvas{        border: 1px solid #aaa;        text-align: center;}
        </style>
        <canvas id="canvas" width="800" height="800">
            当用户浏览器不支持Canvas,请更换浏览器重试！
        </canvas>
    </body>
</html>

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js代码如下所示：

var tangram = [
    {p: [{x: 0, y: 0}, {x: 800, y: 0}, {x: 400, y: 400}], color: "#caff67"},
    {p: [{x: 0, y: 0}, {x: 400, y: 400}, {x: 0, y: 800}], color: "#67becf"},
    {p: [{x: 800, y: 0}, {x: 800, y: 400}, {x: 600, y: 600}, {x: 600, y: 200}], color: "#ef3d61"},
    {p: [{x: 600, y: 200}, {x: 600, y: 600}, {x: 400, y: 400}], color: "#f9f51a"},
    {p: [{x: 400, y: 400}, {x: 600, y: 600}, {x: 400, y: 800}, {x: 200, y: 600}], color: "#a594c0"},
    {p: [{x: 200, y: 600}, {x: 400, y: 800}, {x: 0, y: 800}], color: "#fa8ecc"},
    {p: [{x: 800, y: 400}, {x: 800, y: 800}, {x: 400, y: 800}], color: "#f6ca29"}
];//七巧板的七块图形，p为各顶点坐标，color为颜色window.onload = function () {    var canvas = document.getElementById("canvas");    if (canvas.getContext("2d")) {//判断浏览器是否支持canvas
        var context = canvas.getContext("2d");        for (var i = 0; i < tangram.length; i++) {
            draw(tangram[i], context);
        }        function draw(piece, cxt) {
            cxt.beginPath();
            cxt.moveTo(piece.p[0].x, piece.p[0].y);            for (var i = 1; i < piece.p.length; i++) {
                cxt.lineTo(piece.p[i].x, piece.p[i].y);
            }
            cxt.closePath();
            cxt.fillStyle = piece.color;
            cxt.fill();
            cxt.strokeStyle = "black";
            cxt.lineWidth = 5;
            cxt.stroke();
        }
    } else {
        alert("不支持canvas,请更换浏览器！")
    }
};

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