这个问题分为两部分:

当你不知道模态的确切高度时,你如何将模态垂直地放置在中心? 是否有可能有模态居中,并有溢出:auto在模态体,但只有当模态超过屏幕高度?

我试过用这个:

.modal-dialog {
  height: 80% !important;
  padding-top:10%;
}

.modal-content {
  height: 100% !important;
  overflow:visible;
}

.modal-body {
  height: 80%;
  overflow: auto;
}

当内容远远大于垂直屏幕尺寸时,这给了我所需要的结果,但对于较小的模式内容,这几乎是不可用的。


当前回答

$('#myModal').on('shown.bs.modal', function() {
    var initModalHeight = $('#modal-dialog').outerHeight(); //give an id to .mobile-dialog
    var userScreenHeight = $(document).outerHeight();
    if (initModalHeight > userScreenHeight) {
        $('#modal-dialog').css('overflow', 'auto'); //set to overflow if no fit
    } else {
        $('#modal-dialog').css('margin-top', 
        (userScreenHeight / 2) - (initModalHeight/2)); //center it if it does fit
    }
});

其他回答

下面是另一个css方法,它的工作原理非常好: http://zerosixthree.se/vertical-align-anything-with-just-3-lines-of-css/

萨斯:

.modal {
    height: 100%;

    .modal-dialog {
        top: 50% !important;
        margin-top:0;
        margin-bottom:0;
    }

    //keep proper transitions on fade in
    &.fade .modal-dialog {
        transform: translateY(-100%) !important;
    }
    &.in .modal-dialog {
        transform: translateY(-50%) !important;
    }
}

没那么复杂。

请试试这个:

$(document).ready(function(){
    var modalId = "#myModal";
    resize: function(){
            var new_margin = Math.ceil(($(window).height() - $(modalId).find('.modal-dialog').height()) / 2);
            $(modalId).find('.modal-dialog').css('margin-top', new_margin + 'px');
    }
    $(window).resize(function(){
        resize();
    });
    $(modalId).on('shown.bs.modal', function(){
        resize();
    });
});

我的解决方案

.modal-dialog-center {
    margin-top: 25%;
}

    <div id="waitForm" class="modal">
        <div class="modal-dialog modal-dialog-center">
            <div class="modal-content">
                <div class="modal-header">
                    <button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
                    <h4 id="headerBlock" class="modal-title"></h4>
                </div>
                <div class="modal-body">
                    <span id="bodyBlock"></span>
                    <br/>
                    <p style="text-align: center">
                        <img src="@Url.Content("~/Content/images/progress-loader.gif")" alt="progress"/>
                    </p>   
                </div>
            </div>
        </div>
    </div>

.modal { } .vertical-alignment-helper { display:table; height: 100%; width: 100%; } .vertical-align-center { /* To center vertically */ display: table-cell; vertical-align: middle; } .modal-content { /* Bootstrap sets the size of the modal in the modal-dialog class, we need to inherit it */ width:inherit; height:inherit; /* To center horizontally */ margin: 0 auto; } <head> <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script> <link href="http://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css" rel="stylesheet"/> </head> <body> <!-- Button trigger modal --> <button class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal">Launch demo modal</button> <!-- Modal --> <div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true"> <div class="vertical-alignment-helper"> <div class="modal-dialog vertical-align-center"> <div class="modal-content"> <div class="modal-header"> <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">Close</span> </button> <h4 class="modal-title" id="myModalLabel">Modal title</h4> </div> <div class="modal-body">...</div> <div class="modal-footer"> <button type="button" class="btn btn-default" data-dismiss="modal">Close</button> <button type="button" class="btn btn-primary">Save changes</button> </div> </div> </div> </div> </div> </body>

CSS:

.modal {
}
.vertical-alignment-helper {
    display:table;
    height: 100%;
    width: 100%;
}
.vertical-align-center {
    /* To center vertically */
    display: table-cell;
    vertical-align: middle;
}
.modal-content {
    /* Bootstrap sets the size of the modal in the modal-dialog class, we need to inherit it */
    width:inherit;
    height:inherit;
    /* To center horizontally */
    margin: 0 auto;
}

HTML:

<!-- Button trigger modal -->
<button class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal">Launch demo modal</button>
<!-- Modal -->
<div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
    <div class="vertical-alignment-helper">
        <div class="modal-dialog vertical-align-center">
            <div class="modal-content">
                <div class="modal-header">
                    <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">Close</span>

                    </button>
                     <h4 class="modal-title" id="myModalLabel">Modal title</h4>

                </div>
                <div class="modal-body">...</div>
                <div class="modal-footer">
                    <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
                    <button type="button" class="btn btn-primary">Save changes</button>
                </div>
            </div>
        </div>
    </div>
</div>

参考:http://jsfiddle.net/rensdenobel/sRmLV/13/

从这里找到了完美的解决方案

$(function() {
    function reposition() {
        var modal = $(this),
            dialog = modal.find('.modal-dialog');
        modal.css('display', 'block');

        // Dividing by two centers the modal exactly, but dividing by three 
        // or four works better for larger screens.
        dialog.css("margin-top", Math.max(0, ($(window).height() - dialog.height()) / 2));
    }
    // Reposition when a modal is shown
    $('.modal').on('show.bs.modal', reposition);
    // Reposition when the window is resized
    $(window).on('resize', function() {
        $('.modal:visible').each(reposition);
    });
});