標籤：fun init function charset csharp 繪製 span var html
demo.html
<!DOCTYPE html><html lang="zh"><head> <meta charset="UTF-8"> <title>arc</title> <script> function init() { var canvas=document.getElementById(‘canvas‘); var ctx=canvas.getContext("2d"); ctx.beginPath(); ctx.arc(100,100,80,0,1.5*Math.PI,false); ctx.closePath(); ctx.fillStyle="#ccc"; ctx.fill(); } </script></head><body onload="init();"><canvas id="canvas" width="400" height="300" style="border:2px blueviolet solid"></canvas></body></html>
效果：
定義和用法
arc() 方法建立弧/曲線（用於建立圓或部分圓）。
提示：如需通過 arc() 來建立圓，請把起始角設定為 0，結束角設定為 2*Math.PI。
提示：請使用 stroke() 或 fill() 方法在畫布上繪製實際的弧。
2017-09-08 12:54:48
HTML5 arc的例子
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