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js+canvas繪製五角星的方法，jscanvas繪製五角星
本文執行個體講述了js+canvas繪製五角星的方法。分享給大家供大家參考，具體如下：
運行效果如下：
具體代碼如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head> <title>canvas繪製五角星 </title> <script type="text/javascript" > window.onload = function () { var canvas = document.getElementById("canvas"); if (canvas) { var context = canvas.getContext("2d"); drawStar(context, 50, 100, 100); } else { document.writeln("瀏覽器不支援canvas組件"); } } function drawStar(context, r, x, y) { context.lineWidth = 5; context.beginPath(); var dit = Math.PI * 4 / 5; var sin = Math.sin(0) * r + y; var cos = Math.cos(0) * r + x; console.log(0+":"+0); context.moveTo(cos, sin); for (var i = 0; i < 5; i++) { var tempDit = dit * i; sin = Math.sin(tempDit) * r + y; cos = Math.cos(tempDit) * r + x; context.lineTo(cos, sin); console.log(sin+":"+sin+":"+tempDit); } context.closePath(); context.strokeStyle = "red"; context.fillStyle = "#DDDDDD"; context.fill(); } </script></head><body><canvas id="canvas" ></canvas></body></html>
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