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在上一篇中我们了解html5的Canvas ,在这一篇中不用多说,写一个html5的时钟应用程序试手。在这里主要设置了坐标变换的平移(translate)和旋转变换(ratate),以及html5 Canvas的路径绘图,beginPath,closePath,rect,arc等,还有就是html5 Canvas路径绘图重要的绘图状态的保存和恢复机制,save,restore。 多的也不说了,直接上代码,有不解的欢迎提问,以及对我的建议指教都可以。 ff下效果图: 代码: 复制代码 代码如下:<html> <head> </head> <body> <canvas id="myCanvas" width="600" height="300">你的浏览器还不支持哦</canvas> <script type="text/javascript"> var c = document.getElementById("myCanvas"); var cxt = c.getContext("2d"); var slen = 60; var mlen = 50; var hlen = 40; cxt.strokeRect(0, 0, c.width, c.height); cxt.beginPath(); cxt.strokeStyle = "#00f"; cxt.fillStyle = "#00f"; cxt.arc(200, 150, 5, 0, 2 * Math.PI, true); cxt.fill(); cxt.closePath(); cxt.beginPath(); cxt.strokeStyle = "#00f"; cxt.arc(200, 150, 100, 0, 2 * Math.PI, true); cxt.stroke(); cxt.closePath(); cxt.beginPath(); cxt.translate(200, 150); //平移原点; cxt.rotate(-Math.PI / 2); cxt.save(); for (var i = 0; i < 60; i++) { if (i % 5 == 0) { // cxt.fillStyle = "#ff0000"; cxt.fillRect(80, 0, 20, 5); cxt.fillText("" + (i / 5 == 0 ? 12 : i / 5), 70, 0); } else { // cxt.strokeStyle = "#00f"; cxt.fillRect(90, 0, 10, 2); } //document.getElementById("div1").innerText += " " + i; cxt.rotate(Math.PI / 30); } cxt.closePath(); var ls = 0, lm = 0, lh = 0; function Refresh() { cxt.restore(); cxt.save(); cxt.rotate(ls * Math.PI / 30); cxt.clearRect(5, -1, slen+1, 2+2); cxt.restore(); cxt.save(); cxt.rotate(lm * Math.PI / 30); cxt.clearRect(5, -1, mlen+1, 3+2); cxt.restore(); cxt.save(); cxt.rotate(lh * Math.PI / 6); cxt.clearRect(5, -3, hlen+1, 4+2); var time = new Date(); var s = ls=time.getSeconds(); var m = lm=time.getMinutes(); var h = lh=time.getHours(); cxt.restore(); cxt.save(); cxt.rotate(s * Math.PI / 30); cxt.fillRect(5, 0, slen, 2); cxt.restore(); cxt.save(); cxt.rotate(m * Math.PI / 30); cxt.fillRect(5, 0, mlen, 3); cxt.restore(); cxt.save(); cxt.rotate(h * Math.PI / 6); cxt.fillRect(5, -2, hlen, 4); } var MyInterval = setInterval("Refresh();", 1000); </script> <div id="div1" style=" background:#00f;"></div> </body> </html> |
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