const endTime=new Date(2016,0,17,18,12,12);

var curShowTimeSeconds=0;

//加载页面

window.onload=function(){

var canvas=document.getElementById('canvas');

var context=canvas.getContext('2d');

canvas.width=WINDOW_WIDTH;

canvas.height=WINDOW_HEIGHT;

    //绘制canvas画布

    render(context);

    //获取当前时间

    curShowTimeSeconds=getCurrentShowTimeSeconds();

}

 //获取当前时间

function getCurrentShowTimeSeconds() {

var curTime=new Date();

var ret=endTime.getTime()-curTime.getTime();//得到的是毫秒数

ret=Math.round(ret/1000);

return ret>0?ret:0;

}

function render(ctx){

//绘制时钟

var hours=parseInt(curShowTimeSeconds/3600);

var minutes=parseInt((curShowTimeSeconds-hours*3600)/60);

var seconds=curShowTimeSeconds-hours*3600-minutes*60;

   //绘制小时