                        课程
                    
                        /前端开发
                        
                            /Html5
                        
                        /炫丽的倒计时效果Canvas绘图与动画基础

为什么时间是十秒刷新一次

/**
* Created by Administrator on 2016/5/25.
*/
var WINDOW_WIDTH=1200;
var WINDOW_HEIGHT=600;
var RADIUS=8;
var MARGIN_LEFT=30;
var MARGIN_TOP=60;
const endTime=new Date(2016,4,31,21,36,36);
var curShowTimeSeconds=0;

window.onload=function(){
var canvas=document.getElementById('canvas');
var context=canvas.getContext("2d");

canvas.width=WINDOW_WIDTH;
canvas.height=WINDOW_HEIGHT;

curShowTimeSeconds=getCurrentShowTimeSeconds();
//render(context);
setInterval(
function () {
render(context);
update();
}
,
50
);
};
function update() {
var nextShowTimeSeconds=getCurrentShowTimeSeconds();

var nextHours=parseInt(nextShowTimeSeconds/3600);
var nextMinutes=parseInt((nextShowTimeSeconds-nextHours*3600)/60);
var nextSeconds=nextShowTimeSeconds%60;

var curHours=parseInt(curShowTimeSeconds/3600);
var curMinutes=parseInt((curShowTimeSeconds-curHours*3600)/60);
var curSeconds=curShowTimeSeconds%60;

if(nextSeconds!=curSeconds){
curShowTimeSeconds=nextShowTimeSeconds;
}
}
function getCurrentShowTimeSeconds() {
var curTime=new Date();
var ret=endTime.getTime()-curTime.getTime();
ret=Math.round(ret/1000);

return ret>=0?ret:0;
}
function render(cxt) {

cxt.clearRect(0,0,WINDOW_WIDTH,WINDOW_HEIGHT);

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

renderDigit(MARGIN_LEFT,MARGIN_TOP,parseInt(hours/10),cxt);
renderDigit(MARGIN_LEFT+15*(RADIUS+1),MARGIN_TOP,parseInt(hours%10),cxt);
renderDigit(MARGIN_LEFT+30*(RADIUS+1),MARGIN_TOP,10,cxt);
renderDigit(MARGIN_LEFT+39*(RADIUS+1),MARGIN_TOP,parseInt(minutes/10),cxt);
renderDigit(MARGIN_LEFT+54*(RADIUS+1),MARGIN_TOP,parseInt(minutes%10),cxt);
renderDigit(MARGIN_LEFT+69*(RADIUS+1),MARGIN_TOP,10,cxt);
renderDigit(MARGIN_LEFT+78*(RADIUS+1),MARGIN_TOP,parseInt(seconds/10),cxt);
renderDigit(MARGIN_LEFT+93*(RADIUS+1),MARGIN_TOP,parseInt(minutes%10),cxt);
}

function renderDigit(x,y,num,cxt) {
cxt.fillStyle="rgb(0,102,153)";

for(var i=0;i<digit[num].length;i++)
for(var j=0;j<digit[num][i].length;j++)
if (digit[num][i][j] == 1) {
cxt.beginPath();
cxt.arc(x + j * 2 * (RADIUS + 1) + (RADIUS + 1), y + i * 2 * (RADIUS + 1) + (RADIUS + 1),
RADIUS, 0, 2 * Math.PI);
cxt.closePath();

cxt.fill();
}
}