flex弹性布局 - 光年(Light Year Admin V4)后台管理系统模板

flex弹性布局

启用flex行为

使用 display 通用属性来创建一个flxbox容器，并将直属内部子元素转换为flex属性。 flex元素的容器和子项目可以通过额外的flex属性定义来实现进一步修改。

I'm a flexbox container!

<div class="d-flex p-2 border-highlight">I'm a flexbox container!</div>

border-highlight 类是为了标清楚div元素当前的范围演示使用

I'm an inline flexbox container!

<div class="d-inline-flex p-2 border-highlight">I'm an inline flexbox container!</div>

响应式变化也存在于 .d-flex 和 .d-inline-flex 这两个通用类上

.d-flex
.d-inline-flex
.d-sm-flex
.d-sm-inline-flex
.d-md-flex
.d-md-inline-flex
.d-lg-flex
.d-lg-inline-flex
.d-xl-flex
.d-xl-inline-flex

方向

基于系统提供的通用样式定义，可以设定flex的容器与内部flex元素的方向，在大多数情况下你可以忽略水平的class样式定义，因为浏览器的默认值是 row。但在比如响应式布局时，可能需要进行显式设定此值。

浏览器预默认值下，使用 .flex-row 可设置子元素水平方向排版呈现，或者使用.flex-row-reverse 可实现元素在水平上作反方向排列（右对齐、从右到左布局）。

Flex item 1

Flex item 2

Flex item 3

Flex item 1

Flex item 2

Flex item 3

<div class="d-flex flex-row border-highlight mb-3">
  <div class="p-2 border-highlight">Flex item 1</div>
  <div class="p-2 border-highlight">Flex item 2</div>
  <div class="p-2 border-highlight">Flex item 3</div>
</div>
<div class="d-flex flex-row-reverse border-highlight">
  <div class="p-2 border-highlight">Flex item 1</div>
  <div class="p-2 border-highlight">Flex item 2</div>
  <div class="p-2 border-highlight">Flex item 3</div>
</div>

使用 .flex-column 设置垂直方向布局，或使用 .flex-column-reverse 实现垂直方向的反转布局（从底向上铺开）。

Flex item 1

Flex item 2

Flex item 3

Flex item 1

Flex item 2

Flex item 3

<div class="d-flex flex-column border-highlight mb-3">
  <div class="p-2 border-highlight">Flex item 1</div>
  <div class="p-2 border-highlight">Flex item 2</div>
  <div class="p-2 border-highlight">Flex item 3</div>
</div>
<div class="d-flex flex-column-reverse border-highlight">
  <div class="p-2 border-highlight">Flex item 1</div>
  <div class="p-2 border-highlight">Flex item 2</div>
  <div class="p-2 border-highlight">Flex item 3</div>
</div>

flex-direction 的响应式属性规范：

.flex-row
.flex-row-reverse
.flex-column
.flex-column-reverse
.flex-sm-row
.flex-sm-row-reverse
.flex-sm-column
.flex-sm-column-reverse
.flex-md-row
.flex-md-row-reverse
.flex-md-column
.flex-md-column-reverse
.flex-lg-row
.flex-lg-row-reverse
.flex-lg-column
.flex-lg-column-reverse
.flex-xl-row
.flex-xl-row-reverse
.flex-xl-column
.flex-xl-column-reverse

内容对齐

使用flexbox弹性布局容器上的 justify-content-* 通用样式可以改变flx项目在主轴上的对齐（x轴开始，如果 flex-direction: column 则为y轴)，或选方向（值）包括： start (浏览器默认值),、end、 center、 between、 around。

Flex item

<div class="d-flex justify-content-start border-highlight mb-3">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex justify-content-end border-highlight mb-3">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex justify-content-center border-highlight mb-3">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex justify-content-between border-highlight mb-3">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex justify-content-around border-highlight">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>

justify-content-* 样式也通用存在响应式属性规范：

.justify-content-start
.justify-content-end
.justify-content-center
.justify-content-between
.justify-content-around
.justify-content-sm-start
.justify-content-sm-end
.justify-content-sm-center
.justify-content-sm-between
.justify-content-sm-around
.justify-content-md-start
.justify-content-md-end
.justify-content-md-center
.justify-content-md-between
.justify-content-md-around
.justify-content-lg-start
.justify-content-lg-end
.justify-content-lg-center
.justify-content-lg-between
.justify-content-lg-around
.justify-content-xl-start
.justify-content-xl-end
.justify-content-xl-center
.justify-content-xl-between
.justify-content-xl-around

对齐项目

使用 align-items-* 通用样式可以在flxbox容器上实现flex项目的对齐（y轴开始，如果选择 flex-direction: column 则从x轴开始)，可选参数有： start、end、 center、baseline、 stretch (浏览器默认值)。

Flex item

<div class="bd-example">
  <div class="d-flex align-items-start border-highlight mb-3" style="height: 100px">
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
  </div>
  <div class="d-flex align-items-end border-highlight mb-3" style="height: 100px">
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
  </div>
  <div class="d-flex align-items-center border-highlight mb-3" style="height: 100px">
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
  </div>
  <div class="d-flex align-items-baseline border-highlight mb-3" style="height: 100px">
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
  </div>
  <div class="d-flex align-items-stretch border-highlight" style="height: 100px">
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
    <div class="p-2 border-highlight">Flex item</div>
  </div>
</div>

align-items 的响应式属性规范：

.align-items-start
.align-items-end
.align-items-center
.align-items-baseline
.align-items-stretch
.align-items-sm-start
.align-items-sm-end
.align-items-sm-center
.align-items-sm-baseline
.align-items-sm-stretch
.align-items-md-start
.align-items-md-end
.align-items-md-center
.align-items-md-baseline
.align-items-md-stretch
.align-items-lg-start
.align-items-lg-end
.align-items-lg-center
.align-items-lg-baseline
.align-items-lg-stretch
.align-items-xl-start
.align-items-xl-end
.align-items-xl-center
.align-items-xl-baseline
.align-items-xl-stretch

自对齐

使用 align-self-* 通用样式可以使用flexbox上的项目单独改变在横轴上的对齐方式（y值开始，如果 flex-direction: column 则为x轴开始)，其拥有与 align-items 相同的可选子项: start、 end、center、 baseline、 or stretch (浏览器默认值)。

Flex item

Aligned flex item

Flex item

Aligned flex item

Flex item

Aligned flex item

Flex item

Aligned flex item

Flex item

Aligned flex item

Flex item

<div class="d-flex border-highlight mb-3" style="height: 100px">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="align-self-start p-2 border-highlight">Aligned flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex border-highlight mb-3" style="height: 100px">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="align-self-end p-2 border-highlight">Aligned flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex border-highlight mb-3" style="height: 100px">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="align-self-center p-2 border-highlight">Aligned flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex border-highlight mb-3" style="height: 100px">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="align-self-baseline p-2 border-highlight">Aligned flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex border-highlight" style="height: 100px">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="align-self-stretch p-2 border-highlight">Aligned flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>

align-self 的响应式属性规范：

.align-self-start
.align-self-end
.align-self-center
.align-self-baseline
.align-self-stretch
.align-self-sm-start
.align-self-sm-end
.align-self-sm-center
.align-self-sm-baseline
.align-self-sm-stretch
.align-self-md-start
.align-self-md-end
.align-self-md-center
.align-self-md-baseline
.align-self-md-stretch
.align-self-lg-start
.align-self-lg-end
.align-self-lg-center
.align-self-lg-baseline
.align-self-lg-stretch
.align-self-xl-start
.align-self-xl-end
.align-self-xl-center
.align-self-xl-baseline
.align-self-xl-stretch

填充

对一系列同级元素使用 .flex-fill 类，在占用所有可用水平空间的同时，将它们强制设置为与其内容相等的宽度（如果其内容不超过边框，则为相等的宽度）。

Flex item with a lot of content

Flex item

<div class="d-flex border-highlight">
  <div class="p-2 flex-fill border-highlight">Flex item with a lot of content</div>
  <div class="p-2 flex-fill border-highlight">Flex item</div>
  <div class="p-2 flex-fill border-highlight">Flex item</div>
</div>

flex-fill 也存在响应性变化。

.flex-fill
.flex-sm-fill
.flex-md-fill
.flex-lg-fill
.flex-xl-fill

扩大和收缩

使用 .flex-grow-* 实用程序切换flex项的增长能力以填充可用空间。在下面的示例中，.flex-grow-1 元素使用了它所能使用的所有可用空间，同时允许其余两个flex项使用它们所需的空间。

Flex item

Third flex item

<div class="d-flex border-highlight">
  <div class="p-2 flex-grow-1 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Third flex item</div>
</div>

使用 .flex-shrink-* 实用程序在必要时切换flex项的收缩能力。在下面的示例中，使用 .flex-shrink-1 的第二个flex项被强制将其内容包装到一个新行，“收缩”以允许使用 .w-100 的前一个flex项有更多空间。

Flex item

<div class="d-flex border-highlight">
  <div class="p-2 w-100 border-highlight">Flex item</div>
  <div class="p-2 flex-shrink-1 border-highlight">Flex item</div>
</div>

flex-grow 和 flex-shrink 也存在响应性变化。

.flex-{grow|shrink}-0
.flex-{grow|shrink}-1
.flex-sm-{grow|shrink}-0
.flex-sm-{grow|shrink}-1
.flex-md-{grow|shrink}-0
.flex-md-{grow|shrink}-1
.flex-lg-{grow|shrink}-0
.flex-lg-{grow|shrink}-1
.flex-xl-{grow|shrink}-0
.flex-xl-{grow|shrink}-1

自浮动

当你将flex对齐与auto margin混在一起的时候，flexbox也能正常运行。以下是通过自动manrgin来控制flex项目的三种示例，分别是预设（无margin）、向右推两个项目(.mr-auto)、向左推两个项目 (.ml-auto)：

不幸的是，IE10和IE11不能正确支持在父层具有非默认的 justify-content 值自边距浮动auto margin ，可查阅 StackOverflow对此现象的解答了解更多细节。

Flex item

<div class="d-flex border-highlight mb-3">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex border-highlight mb-3">
  <div class="mr-auto p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>
<div class="d-flex border-highlight mb-3">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="ml-auto p-2 border-highlight">Flex item</div>
</div>

结合align-items

结合 align-items、 flex-direction: column、 margin-top: auto 或 margin-bottom: auto，可以垂直移动一个flex子容器到顶部或底部。

Flex item

<div class="d-flex align-items-start flex-column border-highlight mb-3" style="height: 200px;">
  <div class="mb-auto p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
</div>

<div class="d-flex align-items-end flex-column border-highlight mb-3" style="height: 200px;">
  <div class="p-2 border-highlight">Flex item</div>
  <div class="p-2 border-highlight">Flex item</div>
  <div class="mt-auto p-2 border-highlight">Flex item</div>
</div>

包裹

改变flex项目在flex容器中的包裹方式（可以实现弹性布局），其中包括无包裹 .flex-nowrap（浏览器默认）、包裹 .flex-wrap,，或者反向包裹 .flex-wrap-reverse。

Flex item

<div class="d-flex flex-nowrap border-highlight" style="width: 8rem;">
  ...
</div>

Flex item

<div class="d-flex flex-wrap border-highlight">
  ...
</div>

Flex item

<div class="d-flex flex-wrap-reverse border-highlight">
  ...
</div>

flex-wrap 的响应式规范：

.flex-nowrap
.flex-wrap
.flex-wrap-reverse
.flex-sm-nowrap
.flex-sm-wrap
.flex-sm-wrap-reverse
.flex-md-nowrap
.flex-md-wrap
.flex-md-wrap-reverse
.flex-lg-nowrap
.flex-lg-wrap
.flex-lg-wrap-reverse
.flex-xl-nowrap
.flex-xl-wrap
.flex-xl-wrap-reverse

排序

使用一些 order 实用程序更改特定flex项的可视顺序。我们只提供了使一个项成为第一个或最后一个项的选项，以及使用DOM顺序的重置选项。当 order 接受任何整数值（例如5），因此对于需要的任何额外值需要自定义CSS。

First flex item

Second flex item

Third flex item

<div class="d-flex flex-nowrap border-highlight">
  <div class="order-3 p-2 border-highlight">First flex item</div>
  <div class="order-2 p-2 border-highlight">Second flex item</div>
  <div class="order-1 p-2 border-highlight">Third flex item</div>
</div>

order 也存在响应变化。

.order-0
.order-1
.order-2
.order-3
.order-4
.order-5
.order-6
.order-7
.order-8
.order-9
.order-10
.order-11
.order-12
.order-sm-0
.order-sm-1
.order-sm-2
.order-sm-3
.order-sm-4
.order-sm-5
.order-sm-6
.order-sm-7
.order-sm-8
.order-sm-9
.order-sm-10
.order-sm-11
.order-sm-12
.order-md-0
.order-md-1
.order-md-2
.order-md-3
.order-md-4
.order-md-5
.order-md-6
.order-md-7
.order-md-8
.order-md-9
.order-md-10
.order-md-11
.order-md-12
.order-lg-0
.order-lg-1
.order-lg-2
.order-lg-3
.order-lg-4
.order-lg-5
.order-lg-6
.order-lg-7
.order-lg-8
.order-lg-9
.order-lg-10
.order-lg-11
.order-lg-12
.order-xl-0
.order-xl-1
.order-xl-2
.order-xl-3
.order-xl-4
.order-xl-5
.order-xl-6
.order-xl-7
.order-xl-8
.order-xl-9
.order-xl-10
.order-xl-11
.order-xl-12

内容对齐

使用flexbox容器上的 align-content 通用样式定义，可以将flex物价于横轴上 一起对齐，可选方向有 start (浏览器默认值)、 end、 center、 between、 around、 stretch。为了展现这些效果，下面实例我们已经实施了flex-wrap: wrap定义并增加了很多子项目的数量，如下所示：

此属性对于单行的Flex项目没有影响。

Flex item

<div class="d-flex align-content-start flex-wrap">...</div>

Flex item

<div class="d-flex align-content-end flex-wrap">...</div>

Flex item

<div class="d-flex align-content-center flex-wrap">...</div>

Flex item

<div class="d-flex align-content-between flex-wrap">...</div>

Flex item

<div class="d-flex align-content-around flex-wrap">...</div>

Flex item

<div class="d-flex align-content-stretch flex-wrap">...</div>

align-content 也存在响应变化。

.align-content-start
.align-content-end
.align-content-center
.align-content-around
.align-content-stretch
.align-content-sm-start
.align-content-sm-end
.align-content-sm-center
.align-content-sm-around
.align-content-sm-stretch
.align-content-md-start
.align-content-md-end
.align-content-md-center
.align-content-md-around
.align-content-md-stretch
.align-content-lg-start
.align-content-lg-end
.align-content-lg-center
.align-content-lg-around
.align-content-lg-stretch
.align-content-xl-start
.align-content-xl-end
.align-content-xl-center
.align-content-xl-around
.align-content-xl-stretch