妙味课堂HTML5视频资料分享

2014年10月29日，万维网联盟宣布，经过接近8年的艰苦努力，该标准规范终于制定完成。

《妙味课堂HTML5视频教程》 将会介绍超文本标记语言（HTML）的第五次重大修改，即最新版本；它比原来的标准又增加了一些新的标签，实现更多功能，更标准化，更适用于移动互联网。

视频播放地址：http://www.php.cn/course/418.html

本视频学习难点在于canvas的用法：

!DOCTYPE html>
    html>
    head>
    meta charset="UTF-8">
    tITle>
    仿知乎背景canvas特效/title>
    meta name="keywords" content="" />
    meta name="description" content="" />
    style type="text/css">
body{
    text-align: center;
    background: #F7FAfc;
    overflow: hidden;
    background: #fff;
}
    /style>
    /head>
    body>
    canvas id="Mycanvas">
    /canvas>
    script>
    //定义画布宽高和生成点的个数VAR WIDTH = window.innerWidth, HeiGHT = window.innerHeight, POINT = 35;
    var canvas = document.getElementById('Mycanvas');
    canvas.width = WIDTH,canvas.height = HEIGHT;
    var context = canvas.getContext('2d');
    context.strokeStyle = 'rgba(0,0,0,0.2)',context.strokeWidth = 1,context.fillStyle = 'rgba(0,0,0,0.1)';
    var circleArr = [];
//线条：开始xy坐标，结束xy坐标，线条透明度function Line (x, y, _x, _y, o) {
    this.beginX = x,this.beginY = y,this.closeX = _x,this.closeY = _y,this.o = o;
}
//点：圆心xy坐标，半径，每帧移动xy的距离function Circle (x, y, r, moveX, moveY) {
    this.x = x,this.y = y,this.r = r,this.moveX = moveX,this.moveY = moveY;
}
//生成max和min之间的随机数function num (max, _min) {
    var min = arguments[1] || 0;
    return Math.floor(Math.random()*(max-min+1)+min);
}
// 绘制原点function drawCricle (cxt, x, y, r, moveX, moveY) {
    var circle = new Circle(x, y, r, moveX, moveY)cxt.beginPath()cxt.arc(circle.x, circle.y, circle.r, 0, 2*Math.PI)cxt.closePath()cxt.fill();
    return circle;
}
//绘制线条function drawLine (cxt, x, y, _x, _y, o) {
    var line = new Line(x, y, _x, _y, o)cxt.beginPath()cxt.strokeStyle = 'rgba(0,0,0,'+ o +')'cxt.moveTo(line.beginX, line.beginY)cxt.lineto(line.closeX, line.closeY)cxt.closePath()cxt.stroke();
}
//每帧绘制function draw () {
    context.clearRect(0,0,canvas.width, canvas.height);
    for (var i = 0;
     i  POINT;
 i++) {
    drawCricle(context, circleArr[i].x, circleArr[i].y, circleArr[i].r);
}
    for (var i = 0;
     i  POINT;
 i++) {
    for (var j = 0;
     j  POINT;
 j++) {
if (i + j  POINT) {
    var A = Math.abs(circleArr[i+j].x - circleArr[i].x),B = Math.abs(circleArr[i+j].y - circleArr[i].y);
    var lineLength = Math.sqrt(A*A + B*B);
    var C = 1/lineLength*7-0.009;
    var lineopacity = C >
     0.03 ? 0.03 : C;
    if (lineOpacity >
 0) {
    drawLine(context, circleArr[i].x, circleArr[i].y, circleArr[i+j].x, circleArr[i+j].y, lineOpacity);
}
}
}
}
}
//初始化生成原点function init () {
    circleArr = [];
    for (var i = 0;
     i  POINT;
 i++) {
    circleArr.push(drawCricle(context, num(WIDTH), num(HEIGHT), num(15, 2), num(10, -10)/40, num(10, -10)/40));
}
    draw();
}
//调用执行window.onload = function () {
    init();
setInterval(function () {
    for (var i = 0;
     i  POINT;
 i++) {
    var cir = circleArr[i];
    cir.x += cir.moveX;
    cir.y += cir.moveY;
    if (cir.x >
     WIDTH) cir.x = 0;
    else if (cir.x  0) cir.x = WIDTH;
    if (cir.y >
     HEIGHT) cir.y = 0;
    else if (cir.y  0) cir.y = HEIGHT;
}
    draw();
}
    , 10);
}
    /script>
    /body>
    /html>
    

以上就是妙味课堂HTML5视频资料分享的详细内容，更多请关注其它相关文章！

声明：本文内容由网友自发贡献，本站不承担相应法律责任。对本内容有异议或投诉，请联系2913721942#qq.com核实处理，我们将尽快回复您，谢谢合作！