介绍一个用HTML5Canvas制作的时钟-

用HTML5 Canvas 制作的时钟，看着挺简单的，但其中写起来还是有很多小的问题的，感兴趣的小伙伴们可以参考一下

    
        
        
        
        
      
    
    
        
            
HTML5 时钟
        
        

            
        
    

[Javascript]代码

// inner variables
var canvas, ctx;
var clockRadius = 250;
var clockImage;

// draw functions :
function clear() { // clear canvas function
    ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
}

function drawScene() { // main drawScene function
    clear(); // clear canvas

    // get current time
    var date = new Date();
    var hours = date.getHours();
    var minutes = date.getMinutes();
    var secOnds= date.getSeconds();
    hours = hours > 12 ? hours - 12 : hours;
    var hour = hours + minutes / 60;
    var minute = minutes + seconds / 60;

    // save current context
    ctx.save();

    // draw clock image (as background)
    ctx.drawImage(clockImage, 0, 0, 500, 500);

    ctx.translate(canvas.width / 2, canvas.height / 2);
    ctx.beginPath();

    // draw numbers
    ctx.fOnt= &＃39;36px Arial&＃39;;
    ctx.fillStyle = &＃39;#000&＃39;;
    ctx.textAlign = &＃39;center&＃39;;
    ctx.textBaseline = &＃39;middle&＃39;;
    for (var n = 1; n <= 12; n++) {
        var theta = (n - 3) * (Math.PI * 2) / 12;
        var x = clockRadius * 0.7 * Math.cos(theta);
        var y = clockRadius * 0.7 * Math.sin(theta);
        ctx.fillText(n, x, y);
    }

    // draw hour
    ctx.save();
    var theta = (hour - 3) * 2 * Math.PI / 12;
    ctx.rotate(theta);
    ctx.beginPath();
    ctx.moveTo(-15, -5);
    ctx.lineTo(-15, 5);
    ctx.lineTo(clockRadius * 0.5, 1);
    ctx.lineTo(clockRadius * 0.5, -1);
    ctx.fill();
    ctx.restore();

    // draw minute
    ctx.save();
    var theta = (minute - 15) * 2 * Math.PI / 60;
    ctx.rotate(theta);
    ctx.beginPath();
    ctx.moveTo(-15, -4);
    ctx.lineTo(-15, 4);
    ctx.lineTo(clockRadius * 0.8, 1);
    ctx.lineTo(clockRadius * 0.8, -1);
    ctx.fill();
    ctx.restore();

    // draw second
    ctx.save();
    var theta = (seconds - 15) * 2 * Math.PI / 60;
    ctx.rotate(theta);
    ctx.beginPath();
    ctx.moveTo(-15, -3);
    ctx.lineTo(-15, 3);
    ctx.lineTo(clockRadius * 0.9, 1);
    ctx.lineTo(clockRadius * 0.9, -1);
    ctx.fillStyle = &＃39;#0f0&＃39;;
    ctx.fill();
    ctx.restore();

    ctx.restore();
}
// initialization
$(function(){
    canvas = document.getElementById(&＃39;canvas&＃39;);
    ctx = canvas.getContext(&＃39;2d&＃39;);

    // var width = canvas.width;
    // var height = canvas.height;

clockImage = new Image();
clockImage.src = &＃39;http://static.oschina.net/uploads/space/2012/0712/125855_nnla_89964.png&＃39;;

    setInterval(drawScene, 1000); // loop drawScene
});

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