canvas基础绘制-绚丽倒计时的实例

效果图：

html：

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>ball</title>
 <script src="digit_1.js"></script>
 <script src="countdown.js"></script>
</head>
<body >
<canvas id="canvas" ></canvas>
</body>
</html>

digit_1.js在之前的 canvas基础绘制-倒计时 中有贴

countdown.js:

var WINDOW_WIDTH = 1024;
var WINDOW_HEIGHT = 768;
var RADIUS = 8;
var MARGIN_TOP = 60;
var MARGIN_LEFT = 30;

var endTime = new Date();//const声明变量，不可修改，必须声明时赋值；
endTime.setTime( endTime.getTime() + 3600*1000);//当前时间向后一小时；
var curShowTimeSeconds = 0;

var balls =[];
const colors = ["#33B5E5","#0099CC","#AA66CC","#9933CC","#99CC00","#669900","#FFBB33","#FF8800","#FF4444","#CC0000"];

window.onload = function () {
 //屏幕自适应
 WINDOW_WIDTH = document.body.clientWidth;
 WINDOW_HEIGHT = document.body.clientHeight;

 RADIUS = Math.round(WINDOW_WIDTH*4/5/108)-1;

 MARGIN_TOP = Math.round(WINDOW_HEIGHT/5);
 MARGIN_LEFT = Math.round(WINDOW_WIDTH/10);

 var canvas = document.getElementById("canvas");
 var context = canvas.getContext("2d");

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

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

};

function getCurrentShowTimeSeconds() {
 var curTime = new Date();//获取目前时间；
 var ret = endTime.getTime()-curTime.getTime();
 ret = Math.round(ret/1000);//获取秒数差值；
 return ret>=0?ret:0;
}

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){
  if(parseInt(curHours/10)!=parseInt(nextHours/10)){
   addBalls(MARGIN_LEFT+0,MARGIN_TOP,parseInt(curHours/10));
  }
  if(parseInt(curHours%10)!=parseInt(nextHours%10)){
   addBalls(MARGIN_LEFT+15*(RADIUS+1),MARGIN_TOP,parseInt(curHours%10));
  }

  if(parseInt(curMinutes/10)!=parseInt(nextMinutes/10)){
   addBalls(MARGIN_LEFT+39*(RADIUS+1),MARGIN_TOP,parseInt(curMinutes/10));
  }
  if(parseInt(curMinutes%10)!=parseInt(nextMinutes%10)){
   addBalls(MARGIN_LEFT+54*(RADIUS+1),MARGIN_TOP,parseInt(curMinutes%10));
  }

  if(parseInt(curSeconds/10)!=parseInt(nextSeconds/10)){
   addBalls(MARGIN_LEFT+78*(RADIUS+1),MARGIN_TOP,parseInt(curSeconds/10));
  }
  if(parseInt(curSeconds%10)!=parseInt(nextSeconds%10)){
   addBalls(MARGIN_LEFT+93*(RADIUS+1),MARGIN_TOP,parseInt(curSeconds%10));
  }

  curShowTimeSeconds = nextShowTimeSeconds;
 }

 updateBalls();
}
function updateBalls() {

 //循环遍历每一个彩色动画小球
 for(var i=0;i<balls.length;i++){
  balls[i].x+=balls[i].vx;
  balls[i].y+=balls[i].vy;
  balls[i].vy+=balls[i].g;
  //落到画布最底部时反弹起来
  if(balls[i].y>=WINDOW_HEIGHT){
   balls[i].y = WINDOW_HEIGHT-RADIUS;
   balls[i].vy = -balls[i].vy*0.75;
  }
 }

 // 如果小球出了画布，就清除小球,性能优化
 var cnt = 0;
 for(var i=0;i<balls.length;i++){
  if(balls[i].x-RADIUS>0&&balls[i].x+RADIUS<WINDOW_WIDTH){
   balls[cnt++] = balls[i];
  }
 }

 while (balls.length>Math.min(300,cnt)){
  balls.pop();
 }
}

function addBalls(x,y,num) {

 for (var i = 0; i < digit[num].length; i++) {//数组行
  for (var j = 0; j < digit[num][i].length; j++) {//数组列
   if (digit[num][i][j] == 1) {
    var aBall = {
     x: x + j * 2 * (RADIUS + 1) + (RADIUS + 1),
     y: y + i * 2 * (RADIUS + 1) + (RADIUS + 1),
     g: 1.5 + Math.random(),
     vx: Math.pow(-1, Math.ceil(Math.random() * 1000)) * 4,//pow(x,y),x 的 y 次幂;ceil()可对一个数进行上舍入;
     vy: -5,
     color: colors[Math.floor(Math.random() * colors.length)]//floor()对一个数进行下舍入
    };
    balls.push(aBall);
   }
  }
 }
}
function render(cxt) {
 //每一帧都要对动画进行刷新，不然就会新的旧的叠在一起；
 cxt.clearRect(0,0,WINDOW_WIDTH,WINDOW_HEIGHT);//对一个矩形空间里的动画进行刷新；
 //倒计时的时间绘制
 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(seconds%10),cxt);
 //彩色动画小球的绘制
 for(var i=0;i<balls.length;i++){
  cxt.fillStyle = balls[i].color;

  cxt.beginPath();
  cxt.arc(balls[i].x,balls[i].y,RADIUS,0,2*Math.PI,true);
  cxt.closePath();

  cxt.fill();
 }
}

function renderDigit(x,y,num,cxt) {

 cxt.fillStyle = "rgb(0,102,153)";

 for (var i = 0; i < digit[num].length; i++) {//数组行
  for (var j = 0; j < digit[num][i].length; j++) {//数组列
   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();
   }
  }
 }
}

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