怎样用canvas来绘制彩色七巧板

来源：无忧教育

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>

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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