//判断全屏模式是否是可用 
export function isFullscreenEnabled() {
    return document.fullscreenEnabled ||
        document.mozFullScreenEnabled ||
        document.webkitFullscreenEnabled ||
        document.msFullscreenEnabled || false;
}

//判断浏览器是否全屏 
export function isFullscreen() {
    return document.fullscreenElement ||
        document.msFullscreenElement ||
        document.mozFullScreenElement ||
        document.webkitFullscreenElement || false;
}

//启动全屏
export function launchFullscreen() {
    if (isFullscreenEnabled()) {
        let element = document.documentElement;
        if (element.requestFullScreen) {
            element.requestFullScreen();
        } else if (element.mozRequestFullScreen) {
            element.mozRequestFullScreen();
        } else if (element.msRequestFullscreen) {
            element.msRequestFullscreen();
        } else if (element.oRequestFullscreen) {
            element.oRequestFullscreen();
        } else if (element.webkitRequestFullScreen) {
            element.webkitRequestFullScreen();
        }
    }
}

//退出全屏
export function exitFullscreen() {
    if (isFullscreen()) {
        if (document.exitFullscreen) {
            document.exitFullscreen();
        } else if (document.msExitFullscreen) {
            document.msExitFullscreen();
        } else if (document.mozCancelFullScreen) {
            document.mozCancelFullScreen();
        } else if (document.mozExitFullScreen) {
            document.mozExitFullScreen();
        } else if (document.webkitExitFullscreen) {
            document.webkitExitFullscreen();
        }
    }
}