HTML特效代碼 - 時鐘
<!DOCTYPE html>
<html>
<head>
<title>時鐘</title>
</head>
<body>
<canvas id="myCanvas"></canvas>
<script>
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var radius = canvas.height / 2;
ctx.translate(radius, radius);
radius = radius * 0.9;
setInterval(drawClock, 1000);
function drawClock() {
drawFace(ctx, radius);
drawNumbers(ctx, radius);
drawTime(ctx, radius);
}
function drawFace(ctx, radius) {
ctx.beginPath();
ctx.arc(0, 0, radius, 0, 2*Math.PI);
ctx.fillStyle = "white";
ctx.fill();
ctx.lineWidth = radius*0.1;
ctx.strokeStyle = "#333";
ctx.stroke();
ctx.beginPath();
ctx.arc(0, 0, radius*0.05, 0, 2*Math.PI);
ctx.fillStyle = "#333";
ctx.fill();
}
function drawNumbers(ctx, radius) {
var angle;
var num;
ctx.font = radius*0.15 + "px arial";
ctx.textBaseline = "middle";
ctx.textAlign = "center";
for(num = 1; num< 13; num++){
angle = num * Math.PI / 6;
ctx.rotate(angle);
ctx.translate(0, -radius*0.85);
ctx.rotate(-angle);
ctx.fillText(num.toString(), 0, 0);
ctx.rotate(angle);
ctx.translate(0, radius*0.85);
ctx.rotate(-angle);
}
}
function drawTime(ctx, radius){
var now = new Date();
var hour = now.getHours();
var minute = now.getMinutes();
var second = now.getSeconds();
//hour
hour = hour%12;
hour = (hour*Math.PI/6)+
(minute*Math.PI/(6*60))+
(second*Math.PI/(360*60));
drawHand(ctx, hour, radius*0.5, radius*0.07);
//minute
minute = (minute*Math.PI/30)+(second*Math.PI/(30*60));
drawHand(ctx, minute, radius*0.8, radius*0.07);
// second
second = (second*Math.PI/30);
drawHand(ctx, second, radius*0.9, radius*0.02);
}
function drawHand(ctx, pos, length, width) {
ctx.beginPath();
ctx.lineWidth = width;
ctx.lineCap = "round";
ctx.moveTo(0,0);
ctx.rotate(pos);
ctx.lineTo(0, -length);
ctx.stroke();
ctx.rotate(-pos);
}
</script>
</body>
</html>使用上述代碼可以制作一個簡單的時鐘，其中包含了繪制表盤、表盤數(shù)字和指針的函數(shù)，通過設(shè)置定時器不斷更新時間和指針位置來實(shí)現(xiàn)時鐘的實(shí)時顯示效果。