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
还有另一种解决方案，它将为窗口上的每个可见模态设置有效的位置。调整大小事件和show.bs.modal:
(function ($) {
"use strict";
function centerModal() {
$(this).css('display', 'block');
var $dialog = $(this).find(".modal-dialog"),
offset = ($(window).height() - $dialog.height()) / 2,
bottomMargin = parseInt($dialog.css('marginBottom'), 10);
// Make sure you don't hide the top part of the modal w/ a negative margin if it's longer than the screen height, and keep the margin equal to the bottom margin of the modal
if(offset < bottomMargin) offset = bottomMargin;
$dialog.css("margin-top", offset);
}
$(document).on('show.bs.modal', '.modal', centerModal);
$(window).on("resize", function () {
$('.modal:visible').each(centerModal);
});
})(jQuery);
其他回答
我已经从bellow link下载了bootstrap3-dialog，并修改了bootstrap-dialog.js中的open函数
https://github.com/nakupanda/bootstrap3-dialog
Code
open: function () {
!this.isRealized() && this.realize();
this.updateClosable();
//Custom To Vertically centering Bootstrap
var $mymodal = this.getModal();
$mymodal = $mymodal.append('<table border="0" cellpadding="0" cellspacing="0" width="100%" height="100%"><tr><td align="center" valign="middle" class="centerModal"></td></tr></table>');
$mymodal = $mymodal.find(".modal-dialog").appendTo($mymodal.find(".centerModal"));
//END
this.getModal().modal('show');
return this;
}
Css
.centerModal .modal-header{
text-align:left;
}
.centerModal .modal-body{
text-align:left;
}
这是相当老的，并特别要求使用Bootstrap 3的解决方案，但任何人都想知道:从Bootstrap 4有一个内置的解决方案称为.modal-dialog-centered。问题是:https://github.com/twbs/bootstrap/issues/23638
所以使用v4，你只需要添加.modal-dialog- centric到.modal-dialog来垂直居中模态:
<!-- Button trigger modal -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModalCenter">
Launch demo modal
</button>
<!-- Modal -->
<div class="modal fade" id="exampleModalCenter" tabindex="-1" role="dialog" aria-labelledby="exampleModalCenterTitle" aria-hidden="true">
<div class="modal-dialog modal-dialog-centered" role="document">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="exampleModalCenterTitle">Modal title</h5>
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<div class="modal-body">
...
</div>
<div class="modal-footer">
<button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
<button type="button" class="btn btn-primary">Save changes</button>
</div>
</div>
</div>
</div>
Demo
1. 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?
为了在不声明高度的情况下绝对居中Bootstrap 3 Modal，你首先需要覆盖Bootstrap CSS，将其添加到你的样式表中:
.modal-dialog-center { /* Edited classname 10/03/2014 */
margin: 0;
position: absolute;
top: 50%;
left: 50%;
}
这将使模态对话框位于窗口中心的左上角。
我们必须添加这个媒体查询，否则在小型设备上模式左边距是错误的:
@media (max-width: 767px) {
.modal-dialog-center { /* Edited classname 10/03/2014 */
width: 100%;
}
}
现在我们需要用JavaScript调整它的位置。要做到这一点，我们给元素一个负的上距和左距，等于它的高和宽的一半。在这个例子中，我们将使用jQuery，因为它是可用的Bootstrap。
$('.modal').on('shown.bs.modal', function() {
$(this).find('.modal-dialog').css({
'margin-top': function () {
return -($(this).outerHeight() / 2);
},
'margin-left': function () {
return -($(this).outerWidth() / 2);
}
});
});
更新(01/10/2015):
加上Finik的答案。归功于在未知的中心。
.modal {
text-align: center;
padding: 0!important;
}
.modal:before {
content: '';
display: inline-block;
height: 100%;
vertical-align: middle;
margin-right: -4px; /* Adjusts for spacing */
}
.modal-dialog {
display: inline-block;
text-align: left;
vertical-align: middle;
}
注意到这个负边距了吧?这将删除由内联块添加的空间。这个空格会导致模式跳转到页面底部@media width < 768px。
2. 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?
这可以通过给模态体一个overflow-y:auto和max-height来实现。这需要更多的工作才能使其正常工作。开始添加到你的样式表:
.modal-body {
overflow-y: auto;
}
.modal-footer {
margin-top: 0;
}
我们将再次使用jQuery来获取窗口高度，并首先设置modal-content的max-height。然后我们必须设置模态体的最大高度，通过用模态标题和模态页脚减去模态内容:
$('.modal').on('shown.bs.modal', function() {
var contentHeight = $(window).height() - 60;
var headerHeight = $(this).find('.modal-header').outerHeight() || 2;
var footerHeight = $(this).find('.modal-footer').outerHeight() || 2;
$(this).find('.modal-content').css({
'max-height': function () {
return contentHeight;
}
});
$(this).find('.modal-body').css({
'max-height': function () {
return (contentHeight - (headerHeight + footerHeight));
}
});
$(this).find('.modal-dialog').css({
'margin-top': function () {
return -($(this).outerHeight() / 2);
},
'margin-left': function () {
return -($(this).outerWidth() / 2);
}
});
});
你可以在这里找到Bootstrap 3.0.3的工作演示:http://cdpn.io/GwvrJ 编辑:我建议使用更新版本，以获得响应更快的解决方案:http://cdpn.io/mKfCc
更新(30/11/2015):
function setModalMaxHeight(element) {
this.$element = $(element);
this.$content = this.$element.find('.modal-content');
var borderWidth = this.$content.outerHeight() - this.$content.innerHeight();
var dialogMargin = $(window).width() < 768 ? 20 : 60;
var contentHeight = $(window).height() - (dialogMargin + borderWidth);
var headerHeight = this.$element.find('.modal-header').outerHeight() || 0;
var footerHeight = this.$element.find('.modal-footer').outerHeight() || 0;
var maxHeight = contentHeight - (headerHeight + footerHeight);
this.$content.css({
'overflow': 'hidden'
});
this.$element
.find('.modal-body').css({
'max-height': maxHeight,
'overflow-y': 'auto'
});
}
$('.modal').on('show.bs.modal', function() {
$(this).show();
setModalMaxHeight(this);
});
$(window).resize(function() {
if ($('.modal.in').length != 0) {
setModalMaxHeight($('.modal.in'));
}
});
(更新于2015年11月30日http://cdpn.io/mKfCc，有以上编辑)
.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">×</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">×</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/
它可以简单地可以固定显示:伸缩
.modal-dialog {
margin-top: 0;
margin-bottom: 0;
height: 100vh;
display: flex;
flex-direction: column;
justify-content: center;
}
.modal.fade .modal-dialog {
transform: translate(0, -100%);
}
.modal.in .modal-dialog {
transform: translate(0, 0);
}
与前缀
.modal-dialog {
margin-top: 0;
margin-bottom: 0;
height: 100vh;
display: -webkit-box;
display: -webkit-flex;
display: -ms-flexbox;
display: flex;
-webkit-box-orient: vertical;
-webkit-box-direction: normal;
-webkit-flex-direction: column;
-ms-flex-direction: column;
flex-direction: column;
-webkit-box-pack: center;
-webkit-justify-content: center;
-ms-flex-pack: center;
justify-content: center;
}
.modal.fade .modal-dialog {
-webkit-transform: translate(0, -100%);
transform: translate(0, -100%);
}
.modal.in .modal-dialog {
-webkit-transform: translate(0, 0);
transform: translate(0, 0);
}
