WeChat Mini Program Flex Layout

WeChat Mini ProgramPage layout adopts Flex Layout.
Flex layout is a new solution proposed by W3c in 2009, which can implement various page layouts in a simple, complete and responsive manner. Flex layout provides the alignment, direction and order of elements in the container, and they can even be dynamic or indefinitely sized.
The main feature of Flex layout is the ability to adjust its child elements to be used in different screen sizes. The most suitable method to fill the appropriate space

#flex layout

Features of Flex layout:

Telescopic in any direction, left, right, down, up
You can change and rearrange the order in the style layer
The main axis and side axis are convenient to configure
Space stretching and filling of child elements
Align along the container
WeChat mini program implements

Flex

layout. Let’s briefly introduce the use of Flex layout in WeChat mini program . An element whose container

has

display:flex<a href="http://www.php.cn/wiki/927.html" target="_blank"> or </a>display:block is a flex container (flexible container) , the child elements inside are called flex item (flexible items), and the child elements in flex container are laid out using Flex.

display:block

Specifies the block container mode, always starts displaying with a new line, the
• view

  container of the WeChat applet (view, scroll-view and swiper ) are dispaly:block by default. ##display:flex

  : Specifies the in-line container mode to display child elements in one line. You can use the
flex-wrap

• attribute to specify whether it should wrap. flex-wrap has three values: nowrap (no line wrap),wrap(line wrap),wrap-reverse(the first line of wrap is below)Code using display:block(default value):

  <view class="flex-row" style="display: block;">
        <view class="flex-view-item">1</view>
        <view class="flex-view-item">2</view>
        <view class="flex-view-item">3</view>
    </view>

  Display effect:
  

block

Change to

display:flex# The display effect of ##:

flex

You can see block
and

flex# from the renderings The difference between ## is whether the child element

view

is displayed in a new line (

block) or inline (flex). Main axis and cross axisFlexThe flex container of the layout can be laid out in any direction. The container has two axes by default:

main axis(

main

axis)

and cross axis(cross axis).
The starting position of the spindle is spindle starting point(main start), the end position of the spindle isspindle end point(main end), and the length of the spindle is
Spindle length(main size). Similarly, the starting point of the cross axis is the starting point of the cross axis (cross start), the end position is the end point of the cross axis (cross end), and the length is the length of the cross axis(cross size). See the picture below for details:
##Flex-direction

Note,
spindle

is not necessarily

from left to right, similarly side axis

is not necessarily

from top to bottom
, the direction of the main axis is flex-directionAttribute control, it has 4 optional values: row: The horizontal direction from left to right is the main axis

• row-reverse

  : The horizontal direction from right to left is the main axis

• column

  : From top The vertical direction from bottom to top is the main axis

• column-reverse

  The vertical direction from bottom to top is the main axis

If The horizontal direction is the main axis, the vertical direction is the side axis, and vice versa.
• Renderings of four main axis direction settings:

Example diagram

The example in the picture shows the use of different The

flex-direction

value is the difference in the arrangement direction. Example code:

<view >
    <view class="flex-row" style="display: flex;flex-direction: row;">
        <view class="flex-view-item">1</view>
        <view class="flex-view-item">2</view>
        <view class="flex-view-item">3</view>
    </view>
    <view class="flex-column" style="display:flex;flex-direction: column;" >
        <view class="flex-view-item">c1</view>
        <view class="flex-view-item">c2</view>
        <view class="flex-view-item">c3</view>
    </view>
</view>

Operation effect:

flex-direction

Alignment

There are two alignment methods for child elements:

just<a href="http://www.php.cn/wiki/109.html" target="_blank">if</a>y-conent Define the alignment of child elements on the main axis
align-items Define the alignment of child elements on the side axis

justify-contentThere are 5 optional alignment methods:

• ##flex-start Spindle starting point alignment (default Value)

• flex-end Spindle end point alignment

• center Centered in the spindle Alignment

• space-between Alignment at both ends, except that the child elements at both ends are leaning towards the containers at both ends, the intervals between other child elements are equal

• space-around The distance between each child element is equal, and the distance between the child elements at both ends of the container is also the same as the distance between other child elements The distance is the same. The alignment of
  justify-content is related to the direction of the main axis. In the figure below, flex-direction is row, and the main axis method is from the left. Go to the right and describe the display effect of js<a href="http://www.php.cn/wiki/48.html" target="_blank">tify-content</a>5 values:
  

  
  

  justify-content

align-items represents the alignment on the cross axis:

• stretch Fill the entire container (default value)

• flex-start Align the starting point of the cross axis

• flex-end Align the end of the cross axis

• center Align the center in the cross axis

• baseline Align the first line of text of the child element

align-tiems The alignment set is related to the direction of the cross-axis. The following figure is flex-direction is row, the side axis direction is from top to bottom, describing the display effect of the 5 values ​​of align-items:

aign-items

With the direction of the main axis and side axis and setting their alignment, most of the items can be realized The page is laid out.

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