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Fullscreen API

HTML 5 新增了一个 Fullscreen API ，即全屏显示。

基础​

Fullscreen API 可以通过编程的交互向用户请求全屏显示。如果交互完成，随时可以退出全屏模式。用户可以通过 DOM 的根节点（ document.documentElement ）或某个元素的 requestFullscreen() 方法请求 Fullscreen API 。

function launchFullscreen(e) {
  return (
    (e.requestFullscreen && e.requestFullscreen) ||
    (e.mozRequestFullscreen && e.mozRequestFullscreen) ||
    (e.msRequestFullscreen && e.msRequestFullscreen) ||
    (e.WebkitRequestFullscreen && e.WebkitRequestFullscreen)
  );
}

使用时，可以针对某个元素，也可以是整个页面:

launchFullscreen(document.documentElement);
launchFullscreen(document.querySelector('#id'));

取消全屏​

使用 exitFullscreen() 或 CanvelFullScreen() 方法可以取消 全屏：

function exitFullscreen() {
  return (
    (document.exitFullscreen && document.exitFullscreen()) ||
    (document.msExitFullscreen && document.msExitFullscreen()) ||
    (document.mozCancelFullscreen && document.mozCancelFullscreen()) ||
    (document.WebkitExitFullscreen && document.WebkitExitFullscreen())
  );
}

属性​

  • document.fullscreenElement ： 返回正在处于全屏的元素
  • document.fullscreenEnabled : 返回一个布尔值，表示当前是否处于全屏
let fsEn =
  document.fullscreenEnabled ||
  document.mozFullScreenEnabled ||
  document.WebkitFullscreenEnabled ||
  document.msFullscreenEnabled;
let fsEl =
  document.fullscreenElement ||
  document.mozFullScreenElement ||
  document.WebkitFullscreenElement;

css​

在全屏模式下，大多数浏览器都支持 :full-screen 伪类，而 IE 11 支持 :fullscreen 伪类。使用这个伪类，可以对全屏状态下设置单独的 CSS 样式：

_:-webkit-full-screen {
  width: auto;
}
_:-moz-full-screen {
  width: auto;
}
_:-ms-fullscreen {
  width: auto;
}
_:fullscreen {
  width: auto;
}
:-webkit-full-screen {
  width: 100%;
  height: 100%;
}

事件​

当退出或是进入全屏，会触发 fullscreenchange 事件。利用该事件可以监控全屏状态的变化，以便及时做出各种页面的响应：

document.addEventListener(
  'fullscreenchange',
  function () {
    fsState.innerHTML = document.fullscreen ? '全屏？' : '非全屏';
    btnFS.value = document.fullscreen ? '退出' : '全屏';
  },
  false,
);
document.addEventListener(
  'mozfullscreenchange',
  function () {
    fsState.innerHTML = document.mozFullscreen ? '全屏？' : '非全屏';
    btnFS.value = document.mozFullscreen ? '退出' : '全屏';
  },
  false,
);
document.addEventListener(
  'Webkitfullscreenchange',
  function () {
    fsState.innerHTML = document.WebkitIsFullScreen ? '全屏？' : '非全屏';
    btnFS.value = document.WebkitIsFullScreen ? '退出' : '全屏';
  },
  false,
);

案例 1​

<style>
  html:-moz-full-screen {
    background-color: #0ff;
  }
  html:-webkit-full-screen {
    background-color: #a0f;
  }
  html:fullscreen {
    background-color: #0f0;
  }
  div {
    width: 100%;
  }
</style>
<body>
  <input
    type="button"
    id="btnFullScreen"
    value="全屏"
    onclick="toggleFullscreen();"
  />
  <div id="fullscreenState">非全屏显示</div>
</body>
<script>
  let dEl = document.documentElement;
  let fsState = document.querySelector('#fullscreenState');
  let btnFS = document.querySelector('#btnFullScreen');
  fsState.style.height = dEl.clientHeight + 'px';
  document.addEventListener(
    'fullscreenchange',
    function () {
      fsState.innerHTML = document.fullscreen ? '全屏？' : '非全屏';
      btnFS.value = document.fullscreen ? '退出' : '全屏';
    },
    false,
  );
  document.addEventListener(
    'mozfullscreenchange',
    function () {
      fsState.innerHTML = document.mozFullscreen ? '全屏？' : '非全屏';
      btnFS.value = document.mozFullscreen ? '退出' : '全屏';
    },
    false,
  );
  document.addEventListener(
    'Webkitfullscreenchange',
    function () {
      fsState.innerHTML = document.WebkitIsFullScreen ? '全屏？' : '非全屏';
      btnFS.value = document.WebkitIsFullScreen ? '退出' : '全屏';
    },
    false,
  );
  function toggleFullscreen() {
    if (btnFS.value == '全屏') {
      (dEl.requestFullscreen && dEl.requestFullscreen()) ||
        (dEl.mozRequestFullscreen && dEl.mozRequestFullscreen()) ||
        (dEl.msRequestFullscreen && dEl.msRequestFullscreen()) ||
        (dEl.WebkitRequestFullscreen && dEl.WebkitRequestFullscreen());
    } else {
      (document.exitFullscreen && document.exitFullscreen()) ||
        (document.msExitFullscreen && document.msExitFullscreen()) ||
        (document.mozCancelFullscreen && document.mozCancelFullscreen()) ||
        (document.WebkitCancelFullscreen && document.WebkitCancelFullscreen());
    }
  }
</script>

经检测：在 Edge 、 Chrome 、 Firefox 、 IE 能够进入全屏， Edge 、 Chrome 、 Firefox 能够按钮退出， IE 只能通过按 Esc 键退出， Safari 手机端和平板不能点击按钮进入全屏。

例 2​

<body>
  <video id="videoElement" autoplay controls width="480" height="270">
    <source src="video/chrome.webm" type="video/webm" />
    <source src="video/chrome.ogv" type="video/ogg" />
    <source
      src="video/chrome.mp4"
      type="video/mp4; codecs='avc1.42E01E, mp4a.40.2'"
    />
  </video>
</body>
<script>
  var videoElement = document.getElementById('videoElement');
  function toggleFullScreen() {
    if (!document.mozFullScreen && !document.webkitFullScreen) {
      if (videoElement.mozRequestFullScreen) {
        videoElement.mozRequestFullScreen();
      } else {
        videoElement.webkitRequestFullScreen(Element.ALLOW_KEYBOARD_INPUT);
      }
    } else {
      if (document.mozCancelFullScreen) {
        document.mozCancelFullScreen();
      } else {
        document.webkitCancelFullScreen();
      }
    }
  }
  document.addEventListener(
    'keydown',
    function (e) {
      if (e.keyCode == 13) {
        toggleFullScreen();
      }
    },
    false,
  );
</script>