canvas基础绘制-绚丽倒计时

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 style="height: 100%;">
<canvas id="canvas" style="height: 100%"></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();
            }
        }
    }
}