【Canvas 03】 Canvas时钟效果

在前一篇文章中，我已经写了canvas如何制作一个百行代码Canvas酷炫倒计时

下面由此衍生出canvas动画时钟效果

代码下载：Github
视频地址：慕课·canvas小球倒计时

function getCurShowTimeSecond() {
    var curTime = new Date(); // 获取当前的时间是多少
    var ret =curTime.getHours()*3600+curTime.getMinutes()*60+curTime.getSeconds();//今天一共走了多少秒
    return ret ; // 判断 ret，倒计时结束，函数返回0.
}

完整的clock.js代码

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

//限制： 小时二位数 不超过4天
//var endTime = new Date(); // 注意！！！：data中的参数第二个表示月份，是由0-11表示的。0 - 一月；11- 十二月
//endTime.setTime(endTime.getTime() + 3600 * 1000) //距离 1小时倒计时
var curShowTimeSecond = 0; // 现在倒计时需要多少毫秒

var balls = [];
const colors = ["#FFFF00", "#FF69B4", '#FF4500', '#EE82EE', '#B3EE3A', '#BFEFFF', '#A020F0', '#8470FF', '#7A67EE', '#00FFFF', '#EE7AE9'] //设置颜色

window.onload = function() {
    var canvas = document.getElementById("canvas")
    var context = canvas.getContext("2d")
    canvas.width = WINDOW_WIDTH
    canvas.height = WINDOW_HEIGHT
    curShowTimeSecond = getCurShowTimeSecond(); //curShowTimeSecond：当前总共的毫秒数

    // 动画效果

    curShowTimeSecond = getCurShowTimeSecond()
    setInterval(
        function() {
            render(context);
            update(); //负责数据改变
        },
        50 //单位ms，每50ms变化一次
    );
}

function getCurShowTimeSecond() {
    var curTime = new Date(); // 获取当前的时间是多少
    var ret =curTime.getHours()*3600+curTime.getMinutes()*60+curTime.getSeconds();//今天一共走了多少秒
    return ret ; // 判断 ret，倒计时结束，函数返回0.
}

function update() {
    var nextShowTimeSeconds = getCurShowTimeSecond();
    var nextHours = parseInt(nextShowTimeSeconds / 3600); // 一共需要多少个小时
    var nextMinute = parseInt((nextShowTimeSeconds - nextHours * 3600) / 60);
    var nextSecond = nextShowTimeSeconds % 60;

    var curHours = parseInt(curShowTimeSecond / 3600); // 一共需要多少个小时
    var curMinute = parseInt((curShowTimeSecond - curHours * 3600) / 60);
    var curSecond = curShowTimeSecond % 60;

    if (nextSecond != curSecond) {
        if (parseInt(curHours / 10) != parseInt(nextHours / 10)) {
            addBalls(MARGIN_LEFT, 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(curMinute / 10) != parseInt(nextMinute / 10)) {
            addBalls(MARGIN_LEFT + 39 * (RADIUS + 1), MARGIN_TOP, parseInt(curMinute / 10))
        }
        if (parseInt(curMinute % 10) != parseInt(nextMinute % 10)) {
            addBalls(MARGIN_LEFT + 54 * (RADIUS + 1), MARGIN_TOP, parseInt(curMinute % 10))
        }
        if (parseInt(curSecond / 10) != parseInt(nextSecond / 10)) {
            addBalls(MARGIN_LEFT + 78 * (RADIUS + 1), MARGIN_TOP, parseInt(curSecond / 10))
        }
        if (parseInt(curSecond % 10) != parseInt(nextSecond % 10)) {
            addBalls(MARGIN_LEFT + 93 * (RADIUS + 1), MARGIN_TOP, parseInt(nextSecond % 10))
        }
        curShowTimeSecond = nextShowTimeSeconds
    }

    updateBalls()
}

function updateBalls() {
    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

        if (balls[i].y >= WINDOW_HEIGHT + RADIUS) {
            balls[i].y = WINDOW_HEIGHT + RADIUS
            balls[i].vy = -balls[i].vy * 0.75
        }
    }
    //让弹出屏幕的小球消失，以免内存过大
    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 > cnt) {
        balls.pop()

    }
}

function addBalls(x, y, num) {
    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) {
                var aBall = {
                    x: x + j * 2 * (RADIUS + 1) + (RADIUS + 1),
                    y: y + i * 2 * (RADIUS + 1) + (RADIUS + 1),
                    g: 1.5 + Math.random(), //加速度
                    vx: Math.pow(-1, Math.ceil(Math.random() * 1000)) * 4, //使初始速度随机化，小球变化更加灵活
                    vy: -6, //小球初始y速度
                    color: colors[Math.floor(Math.random() * colors.length)]
                }
                balls.push(aBall)
            }
        }
    }

}
// 时间更新函数

function render(cxt) {
    cxt.clearRect(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT)
    var hours = parseInt(curShowTimeSecond / 3600); // 一共需要多少个小时
    var minute = parseInt((curShowTimeSecond - hours * 3600) / 60);
    var second = curShowTimeSecond % 60;
    renderDigit(MARGIN_LEFT, MARGIN_TOP, parseInt(hours / 10), cxt); // 小时   
    renderDigit(MARGIN_LEFT + 15 * (RADIUS + 1), MARGIN_TOP, parseInt(hours % 10), cxt); // 每个字水平位置直径7,7*2 = 14半径+1 = 15          
    renderDigit(MARGIN_LEFT + 30 * (RADIUS + 1), MARGIN_TOP, 10, cxt); // 冒号 （4*2+1）= 9  digit.js中 10代表 ：    
    renderDigit(MARGIN_LEFT + 39 * (RADIUS + 1), MARGIN_TOP, parseInt(minute / 10), cxt); // 分钟 
    renderDigit(MARGIN_LEFT + 54 * (RADIUS + 1), MARGIN_TOP, parseInt(minute % 10), cxt);
    renderDigit(MARGIN_LEFT + 69 * (RADIUS + 1), MARGIN_TOP, 10, cxt); // 冒号 （4*2+1）= 9  digit.js中 10代表 ：
    renderDigit(MARGIN_LEFT + 78 * (RADIUS + 1), MARGIN_TOP, parseInt(second / 10), cxt); // 秒
    renderDigit(MARGIN_LEFT + 93 * (RADIUS + 1), MARGIN_TOP, parseInt(second % 10), cxt);

    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 = "#005588";
    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();
                // 圆心位置公式
                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();
            }
        }
    }
}