canvas基础绘制-倒计时(上)

Posted 喵嘻嘻

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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();
            }
        }
    }
}

 

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