canvas基础绘制-倒计时(上)

效果：

html:

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>digit</title>

</head>

<body>

<canvas id="canvas"></canvas>

<script src="digit_1.js"></script>

<script src="countdown.js"></script>

</body>

</html>

countdown.js:

var WINDOW_WIDTH = 1024;

var WINDOW_HEIGHT = 768;

var RADIUS = 8;

var MARGIN_TOP = 60;

var MARGIN_LEFT = 30;

const endTime = new Date(2017,8,17,18,30,00);//const声明变量，不可修改，必须声明时赋值；

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();

    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){

        curShowTimeSeconds = nextShowTimeSeconds;

    }

}

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；

    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);

}

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();

            }

        }

    }

}

巴特西

canvas基础绘制-倒计时(上)

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