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HTML5中与页面显示相关的API

文章作者:前端 上传时间:2019-10-11

HTML5中与页面显示相关的API

2015/05/15 · HTML5 · HTML5

原稿出处: 涂根华的博客   

在HTML5中,扩充了2个与页面展现相关的API,分别是Page Visibility API与Fullscreen API; 功效分别如下:

Page Visibility API  是指当页面变为最小化状态或许客户将浏览器标签切换来任何标签时会触发。

Fullscreen API 是将页面全体或页面中有个别局地区域设为全屏。

Page Visibility API的应用场地如下:

  1. 三个应用程序中有所多幅图片的幻灯片式的一而再播放效果,当页面变为不可知状态(最小化状态可能将顾客浏览器标签切换成其余标签时),图片停播,当页面变为可以知道状态时,图片继续播放。
  2. 在二个实时呈现服务器端音信的应用程序中,当页面处于不可以预知状态(最小化状态只怕将客商浏览器标签切换成其余标签时),结束定时向劳动器端必要数据的管理,当页面变为可知状态,继续试行按期向劳动器端央浼数据的拍卖。
  3. 在贰个全数播放录像效果的应用程序中,当页面处于不可以见到状态(最小化状态或许将顾客浏览器标签切换来任何标签时),暂停播放录像,当页面变为可以看到状态时,继续播放录制。

浏览器协助程度:Firefox10+,chrome14+,IE10+;

实现Page Visibility API

在运用Page Visibility API时,大家首先需求判断当前顾客所利用的浏览器以至该浏览器是不是扶持。代码如下推断:

JavaScript

if(typeof document.hidden !== 'undefined') { hidden = 'hidden'; visibilityChange = 'visibilitychange'; }else if(typeof document.mozHidden !== 'undefined') { hidden = 'mozHidden'; visibilityChange = 'mozvisibilitychange'; }else if(typeof document.msHidden !== 'undefined') { hidden = 'msHidden'; visibilityChange = 'msvisibilitychange'; }else if(typeof document.webkitHidden !== 'undefined') { hidden = 'webkitHidden'; visibilityChange = 'webkitvisibilitychange'; }

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if(typeof document.hidden !== 'undefined') {
    hidden = 'hidden';
    visibilityChange = 'visibilitychange';
}else if(typeof document.mozHidden !== 'undefined') {
    hidden = 'mozHidden';
    visibilityChange = 'mozvisibilitychange';
}else if(typeof document.msHidden !== 'undefined') {
    hidden = 'msHidden';
    visibilityChange = 'msvisibilitychange';
}else if(typeof document.webkitHidden !== 'undefined') {        
    hidden = 'webkitHidden';
    visibilityChange = 'webkitvisibilitychange';
}

如上,在Page Visibility  API中,能够透过document对象的hidden属性值来判断页面是或不是处在可以看到状态,当页面处于可以知道状态时属性值为false,当页面处于不可知状态时属性值为true。

在Page Visibility中,能够经过document对象的visibilityState属性值来决断页面包车型大巴可知状态。该属性值为三个字符串,其含义如下所示:

    visible: 页面内容部分可以看到,当前页面位于客户正在查阅的浏览器标签窗口中,且浏览器窗口未被最小化。

    hidden: 页面内容对客商不可以知道。当前页面不在顾客正在查看的浏览器标签窗口中,或浏览器窗口已被最小化。

    prerender: 页面内容已被预渲染,不过对客商不可以知道。

于今大家来看二个demo,页面中有一个video成分与四个”播放”按键,顾客单击”播放”开关时 按键文字变为 ’暂停”,同一时间开班播报video成分的录像,当页面变为最小化状态或客商浏览器标签切换成另外标签时候,摄像被搁浅播放,当页面复苏平常状态或客商将浏览器标签切回页面所在标签时,录制持续播放。

HTML代码如下:

JavaScript

<video id="videoElement" controls width=640 height=360 autoplay> <source src="Wildlife/Wildlife.ogv" type='video/ogg; codecs="theora, vorbis"'/> <source src="Wildlife/Wildlife.webm" type='video/webm' > <source src="Wildlife/Wildlife.mp4" type='video/mp4'> </video> <button id="btnPlay" onclick="PlayOrPause()">播放</button> <div style="height:1500px;"></div>

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<video id="videoElement" controls width=640 height=360 autoplay>
    <source src="Wildlife/Wildlife.ogv" type='video/ogg; codecs="theora, vorbis"'/>
    <source src="Wildlife/Wildlife.webm" type='video/webm' >
    <source src="Wildlife/Wildlife.mp4" type='video/mp4'>
</video>
<button id="btnPlay" onclick="PlayOrPause()">播放</button>
<div style="height:1500px;"></div>

JS代码如下:

JavaScript

var hidden, visibilityChange, videoElement; if(typeof document.hidden !== 'undefined') { hidden = 'hidden'; visibilityChange = 'visibilitychange'; }else if(typeof document.mozHidden !== 'undefined') { hidden = 'mozHidden'; visibilityChange = 'mozvisibilitychange'; }else if(typeof document.msHidden !== 'undefined') { hidden = 'msHidden'; visibilityChange = 'msvisibilitychange'; }else if(typeof document.webkitHidden !== 'undefined') { hidden = 'webkitHidden'; visibilityChange = 'webkitvisibilitychange'; } document.addEventListener(visibilityChange,handle,false); videoElement = document.getElementById("videoElement"); videoElement.add伊夫ntListener('ended',videoEnded,false); videoElement.add伊夫ntListener('play',videoPlay,false); videoElement.add伊夫ntListener('pause',videoPause,false); // 借使页面变为不可以预知状态 则暂停摄像播放 // 假使页面变为可知状态,则连续摄像播放 function handle() { // 通过visibilityState属性值推断页面包车型大巴可以知道状态 console.log(document.visibilityState); if(document[hidden]) { videoElement.pause(); }else { videoElement.play(); } } // 播放视频function play() { videoElement.play(); } // 暂停止播放放 function pause() { videoElement.pause(); } function PlayOrPause() { if(videoElement.paused) { videoElement.play(); }else { videoElement.pause(); } } function videoEnded(e) { videoElement.currentTime = 0; this.pause(); } function videoPlay(e) { var btnPlay = document.getElementById("btnPlay"); btnPlay.innerHTML = "暂停"; } function videoPause(e) { var btnPlay = document.getElementById("btnPlay"); btnPlay.innerHTML = "播放"; }

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var hidden,
visibilityChange,
videoElement;
if(typeof document.hidden !== 'undefined') {
    hidden = 'hidden';
    visibilityChange = 'visibilitychange';
}else if(typeof document.mozHidden !== 'undefined') {
    hidden = 'mozHidden';
    visibilityChange = 'mozvisibilitychange';
}else if(typeof document.msHidden !== 'undefined') {
    hidden = 'msHidden';
    visibilityChange = 'msvisibilitychange';
}else if(typeof document.webkitHidden !== 'undefined') {
    hidden = 'webkitHidden';
    visibilityChange = 'webkitvisibilitychange';
}
document.addEventListener(visibilityChange,handle,false);
videoElement = document.getElementById("videoElement");
videoElement.addEventListener('ended',videoEnded,false);
videoElement.addEventListener('play',videoPlay,false);
videoElement.addEventListener('pause',videoPause,false);
// 如果页面变为不可见状态 则暂停视频播放
// 如果页面变为可见状态,则继续视频播放
function handle() {
    // 通过visibilityState属性值判断页面的可见状态
    console.log(document.visibilityState);
    if(document[hidden]) {
        videoElement.pause();    
    }else {
        videoElement.play();
    }
}
// 播放视频
function play() {
    videoElement.play();
}
// 暂停播放
function pause() {
    videoElement.pause();
}
function PlayOrPause() {
    if(videoElement.paused) {
        videoElement.play();
    }else {
        videoElement.pause();
    }
}
function videoEnded(e) {
    videoElement.currentTime = 0;
    this.pause();
}
function videoPlay(e) {
    var btnPlay = document.getElementById("btnPlay");
    btnPlay.innerHTML = "暂停";
}
function videoPause(e) {
    var btnPlay = document.getElementById("btnPlay");
    btnPlay.innerHTML = "播放";
}

实现Fullscreen API

在HTML5中,新扩张了二个Fullscreen API,其职能是将页面全体或页面中某些局地区域设为全屏展现状态。

浏览器辅助程度:Firefox10+,chrome16+,Safari5.1+

在Fullscreen API中,能够通过DOM对象的根节点目的或有个别成分的requestFullscreen属性值和执行相呼应的艺术来决断浏览器是或不是扶持Fullscreen API。代码如下:

JavaScript

var docElm = document.documentElement; if(docElm.requestFullscreen) { docElm.requestFullscreen(); }else if(docElm.mozRequestFullScreen) { docElm.mozRequestFullScreen(); }else if(docElm.webkitRequestFullScreen) { docElm.webkitRequestFullScreen(); }

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var docElm = document.documentElement;
if(docElm.requestFullscreen) {
        docElm.requestFullscreen();
}else if(docElm.mozRequestFullScreen) {
        docElm.mozRequestFullScreen();
}else if(docElm.webkitRequestFullScreen) {
        docElm.webkitRequestFullScreen();
}

在Fullscreen API中,也得以因而DOM对象或有些成分的exitFullscreen与CanvelFullScreen属性和章程将前段时间页面或有些元素设定为非全屏展现状态。

正如代码:

JavaScript

if(document.exitFullscreen) { document.exitFullscreen(); }else if(document.mozCancelFullScreen) { document.mozCancelFullScreen(); }else if(document.webkitCancelFullScreen) { document.webkitCancelFullScreen(); }

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if(document.exitFullscreen) {
    document.exitFullscreen();
}else if(document.mozCancelFullScreen) {
    document.mozCancelFullScreen();
}else if(document.webkitCancelFullScreen) {
    document.webkitCancelFullScreen();
}

在Fullscreen API中,能够由此监听DOM对象或某些元素的fullscreenchange事件(当页面或因素从非全屏显示状态变为全屏突显状态,或从全屏显示状态成为非全屏展现状态时触发)。代码如下:

JavaScript

document.addEventListener('fullscreenchange',function(){},false); document.addEventListener('mozfullscreenchange',function(){},false); document.addEventListener('webkitfullscreenchange',function(){},false);

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document.addEventListener('fullscreenchange',function(){},false);
document.addEventListener('mozfullscreenchange',function(){},false);
document.addEventListener('webkitfullscreenchange',function(){},false);

在css样式代码中,我们能够利用伪类选拔器来单独内定处于全屏展现状态的页面或因素样式:

JavaScript

html:-moz-full-screen { background:red; } html:-webkit-full-screen { background:red; } html:fullscreen { background:red; }

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html:-moz-full-screen {
    background:red;
}
html:-webkit-full-screen {
    background:red;
}
html:fullscreen {
    background:red;
}

末段我们来看一个demo,在页面中有二个按键,点击后,页面会形成全屏状态,再点击后,页面会退出全屏;

HTML代码如下:

JavaScript

<input type="button" id="btnFullScreen" value="页面全屏呈现" onclick="toggleFullScreen();"/> <div style="width:百分百;" id="fullscreentState">非全屏显示</div>

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<input type="button" id="btnFullScreen" value="页面全屏显示" onclick="toggleFullScreen();"/>
<div style="width:100%;" id="fullscreentState">非全屏显示</div>

Javascript如下:

JavaScript

var docElm = document.documentElement; var fullscreentState = document.getElementById("fullscreentState"); var btnFullScreen = document.getElementById("btnFullScreen"); fullscreentState.style.height = docElm.clientHeight + 'px'; document.add伊夫ntListener('fullscreenchange',function(){ fullscreentState.innerHTML = (document.fullscreen) ? "全屏突显" : "非全屏呈现"; },false); document.add伊芙ntListener('mozfullscreenchange',function(){ fullscreentState.innerHTML = (document.mozFullscreen) ? "全屏彰显" : "非全屏展现"; },false); document.add伊芙ntListener('webkitfullscreenchange',function(){ fullscreentState.innerHTML = (document.webkitFullscreen) ? "全屏展现" : "非全屏展现"; },false); function toggleFullScreen() { if(btnFullScreen.value == '页面全屏突显') { btnFullScreen.value = '页面非全屏展现'; if(docElm.requestFullscreen) { docElm.requestFullscreen(); }else if(docElm.mozRequestFullScreen) { docElm.mozRequestFullScreen(); }else if(docElm.webkitRequestFullScreen) { docElm.webkitRequestFullScreen(); } }else { if(document.exitFullscreen) { document.exitFullscreen(); }else if(document.mozCancelFullScreen) { document.mozCancelFullScreen(); }else if(document.webkitCancelFullScreen) { document.webkitCancelFullScreen(); } btnFullScreen.value = "页面全屏呈现"; } }

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var docElm = document.documentElement;
var fullscreentState = document.getElementById("fullscreentState");
var btnFullScreen = document.getElementById("btnFullScreen");
fullscreentState.style.height = docElm.clientHeight + 'px';
document.addEventListener('fullscreenchange',function(){
    fullscreentState.innerHTML = (document.fullscreen) ? "全屏显示" : "非全屏显示";
},false);
document.addEventListener('mozfullscreenchange',function(){
    fullscreentState.innerHTML = (document.mozFullscreen) ? "全屏显示" : "非全屏显示";
},false);
document.addEventListener('webkitfullscreenchange',function(){
    fullscreentState.innerHTML = (document.webkitFullscreen) ? "全屏显示" : "非全屏显示";
},false);
function toggleFullScreen() {
    if(btnFullScreen.value == '页面全屏显示') {
        btnFullScreen.value = '页面非全屏显示';
        if(docElm.requestFullscreen) {
            docElm.requestFullscreen();
        }else if(docElm.mozRequestFullScreen) {
            docElm.mozRequestFullScreen();
        }else if(docElm.webkitRequestFullScreen) {
            docElm.webkitRequestFullScreen();
        }
    }else {
        if(document.exitFullscreen) {
            document.exitFullscreen();
        }else if(document.mozCancelFullScreen) {
            document.mozCancelFullScreen();
        }else if(document.webkitCancelFullScreen) {
            document.webkitCancelFullScreen();
        }
        btnFullScreen.value = "页面全屏显示";
    }
}

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