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<style>
canvas{
border:1px solid #ccc;
}
</style>
</head>
<body>
<canvas id="myCanvas" width=500 height=500></canvas>
</body>
<script>
var canvas = document.getElementById(‘myCanvas‘);
var ctx = canvas.getContext(‘2d‘);
var originX = 250;
var originY = 250;
var radius = 100;
setInterval(function() {
ctx.clearRect(0,0,500,500);
ctx.beginPath();
ctx.shadowColor = "black";
ctx.shadowBlur = 5;
ctx.shadowOffsetX = 1;
ctx.shadowOffsetY = 1;
ctx.lineWidth = 2;
var gradient = ctx.createRadialGradient(250, 250, 1, 250, 250, 100);
gradient.addColorStop(0, "#f5f5f5");
gradient.addColorStop(1, "#dfdfdf");
ctx.fillStyle = gradient;
ctx.arc(250, 250, 100, 0, 2 * Math.PI, true);
ctx.stroke();
ctx.fill();
ctx.shadowBlur = 0;
ctx.shadowOffsetX = 0;
ctx.shadowOffsetY = 0;
ctx.strokeStyle = "#333";
drawScale();
var date = new Date();
var ha = date.getHours() * 12 + (date.getMinutes() * 6 / 12) - 90;
var ma = date.getMinutes() * 6 - 90;
var sa = date.getSeconds() * 6 - 90;
drawPointer(55, ha, 4, "#333");
drawPointer(65, ma, 3, "#777");
drawPointer(75, sa, 2, "red");
ctx.beginPath();
ctx.fillStyle = "red";
ctx.arc(originX, originY, 2.5, 0, 2 * Math.PI, true);
ctx.fill();
}, 1000);
function drawPointer(radius,angle,width,color){
ctx.lineWidth = width;
ctx.strokeStyle = color;
ctx.beginPath();
ctx.moveTo(originX,originY);
ctx.lineTo(originX+radius*Math.cos(angle*Math.PI/180),originY+radius*Math.sin(angle*Math.PI/180));
ctx.stroke();
}
function drawScale() {
var dig = Math.PI / 30;
for (var i = 0; i < 60; i++) {
var r = radius - 6;
var lw = 3;
if (i % 5 == 0) {
r = radius - 10;
lw = 4;
}
ctx.lineWidth = lw;
ctx.beginPath();
ctx.moveTo(originX + radius * Math.cos(i * dig), originY + radius * Math.sin(i * dig));
ctx.lineTo(originX + r * Math.cos(i * dig), originY + r * Math.sin(i * dig));
ctx.stroke();
}
}
</script>标签：
原文地址：http://www.cnblogs.com/wangwei1234/p/4641596.html
