html5 canvas 画的简易时钟
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>時鐘</title>
<script type="text/javascript">
//開始之前必須懂得時針各指針的弧度計算公式。
var canvas,context;
function window_onload(){
??? canvas = document.getElementById("myCanvas");
??? context = canvas.getContext("2d");
??? setInterval("draw()",1000);
}
function draw(){
??? ?///得到當前系統(tǒng)時間的：時、分、秒
????? var now_date=new Date();
????? var radius = Math.min(canvas.width/2,canvas.height/2),
??? ?????? sec=now_date.getSeconds(),
??? ?????? min=now_date.getMinutes(),
??? ??? ?? hour=now_date.getHours();
?????????? hour=hour>=12?hour-12:hour;
?????
??? ? //初始化畫布
????? context.save();
????? context.clearRect(0,0,canvas.width,canvas.height);???
????? context.translate(canvas.width/2,canvas.height/2);???????
????? context.scale(0.9,0.9);
????? context.rotate(-Math.PI/2);
????? context.save();
??? ? //小時刻度
????? context.strokeStyle="black";
????? context.fillStyle="black";
????? context.lineWidth=3;
????? context.lineCap="round";
????? context.beginPath();
????? for(var i=0;i<12;i++){
??????? context.rotate(Math.PI/6);
??????? context.moveTo(radius-30,0);
??????? context.lineTo(radius-10,0);
????? }
????? context.stroke();
????? context.restore();
????? context.save();
?????
??? ? //分鐘刻度
????? context.lineWidth=2;
????? context.beginPath();
????? for(var i=0;i<60;i++){
??????? if(i%5!=0){
????????? context.moveTo(radius-15,0);
????????? context.lineTo(radius-10,0);
??????? }
??????? context.rotate(Math.PI/30);
????? }
????? context.stroke();
????? context.restore();
????? context.save();
?????
??? ? //畫上時針
????? context.rotate((Math.PI/6)*hour+(Math.PI/360)*min+(Math.PI/21600)*sec);
????? context.lineWidth=6;
????? context.lineCap="butt";
????? context.beginPath();
????? context.moveTo(-10,0);
????? context.lineTo(radius*0.5,0);
????? context.stroke();
????? context.restore();
????? context.save();
?????
??? ? //分針
????? context.rotate((Math.PI/30)*min+(Math.PI/1800)*sec);
????? context.strokeStyle="#29A8DE";
????? context.lineWidth=4;
????? context.lineCap="butt";
????? context.beginPath();
????? context.moveTo(-20,0);
????? context.lineTo(radius*0.7,0);
????? context.stroke();
????? context.restore();
????? context.save();
?????
??? ? //秒針
????? context.rotate(sec*Math.PI/30);
????? context.strokeStyle="red";
????? context.lineWidth=2;
????? context.lineCap="butt";
????? context.beginPath();
????? context.moveTo(-30,0);
????? context.lineTo(radius*0.9,0);
????? context.stroke();
????? context.restore();
????? context.save();
??? ?
????? ///表框?????
????? context.lineWidth=4;
????? context.strokeStyle="gray";
????? context.beginPath();
????? context.arc(0,0,radius,0,Math.PI*2,true);
????? context.stroke();
??? ? context.restore();
????? context.restore();
}
</script>
</head>
<body onLoad="window_onload()">
??? <canvas width="300" height="300" id="myCanvas"></canvas>
</body>
</html>
?
據(jù)博友要求，現(xiàn)補上效果圖：
?
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轉(zhuǎn)載于:https://blog.51cto.com/chenjinfei/770655
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