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ui/Layout

A convenient tool for laying-out content using Layout, Cell, Row, and Column.

Layout is a powerful and versatile tool used for arranging content on the screen. On a conceptual level, it mixes the best parts of HTML tables wtih the best parts of HTML framesets, both of which were largely abandoned for their drawbacks, ignoring their strengths. A Layout is simply a container for Cell, the only "legal" child. Conversely, Cell may only be used in a Layout. Cells in a Layout can either be positioned next to each other (horizontally) or above/below each other (vertically) in what we refer to as a Row or Column, respectively.

The Row and Column layout presets describe the direction of layout for their children. This can sometimes cause confusion. A Row of children naturally forms a layout whose children can have the appearance of columns. To keep things clear, think about the layout rather than the what the children themselves represent.

Layout is an implementation of flex-box, but with built-in rails, properties, and features to help avoid common problems with flex-box; things like content overflowing, sizing quirks, and positioning problems regarding content of unknown or undefined dimension.

The following scenarios are some common cases where Layout can truly help out. A quality of Cell you'll see below is that when a Cell has no defined size, it automatically sizes to fill any remaining space in the Layout. If there are multiple auto-sizing Cell components, they share the space, subdividing it equally among themselves. It's great to leverage this and only apply sizes to Cells which must have defined sizes. shrink is one of the ways you can impose size guidelines on a Cell. It automatically fits the size of the Cell to the size of its content.

A row of cells where the last one should always attach to the right side, regardless of the size of the main "content" cell:

┌───────┬─┐
│Main   │R│
└───────┴─┘
<Row>
	<Cell>Main Content</Cell>
	<Cell shrink>Right Side</Cell>
</Row>

A "two-column" layout with equal sized cells using Row:

┌────┬────┐
│L   │R   │
└────┴────┘
<Row style={{height: '100%'}}>
	<Cell>Left Column</Cell>
	<Cell>Right Column</Cell>
</Row>

Remember: The cells of the Row are the columns in our layout. It's likely that in a complex layout Column would be used inside the left and right cells to arrange the components, as in the example below.

A full-height sidebar with a header and body to the right:

┌──┬──────┐
│S │HEADER│
│  ├──────┤
│  │Body  │
│  │      │
└──┴──────┘
<Row style={{height: '100%'}}>
	<Cell size="20%">Sidebar</Cell>
	<Cell>
		<Column>
			<Cell size={90} component="header">
				<h1>HEADER</h1>
			</Cell>
			<Cell>
				<p>Body area</p>
			</Cell>
		</Column>
	</Cell>
</Row>

Note: Here, we've set the height of Row so it fills the height of the screen, allowing the Sidebar Cell and content Cell to stretch from the top to the bottom. We've also leveraged the component prop on the header cell, which tells Cell to render itself as a "header" HTML tag rather than its usual "div" tag.

The example below produces a layout like the following:

┌─┬─────┬─┐
│o│Item │o│
└─┴─────┴─┘

You'll notice the use of some special classes in the example: "debug layout". Adding these on any element in your DOM hierarchy will enable borders in Layout and Cell to help visualize what is happening in the layout. They automatically change color the deeper in the stack they go.

import Layout from '@enact/ui/Layout';

Members

LayoutComponent

A container for Cells.

A stateless component that acts as a containing area for Cells to be positioned in a row or a column (horizontally or vertically, respectively. It supports an orientation property for laying-out its contents (Cells) in an organized, readable way.

Example:

import Input from '@enact/moonstone/Input';
import css from './LayoutExample.less';
...
<fieldset>
	<Layout align="center">
		<Cell component="label" size="40%" className={css.label} shrink>First Name</Cell>
		<Cell component={Input} placeholder="First" className={css.input} />
	</Layout>
	<Layout align="center">
		<Cell component="label" size="40%" className={css.label} shrink>Last Name</Cell>
		<Cell component={Input} placeholder="Last" className={css.input} />
	</Layout>
</fieldset>
import Layout from '@enact/ui/Layout';

CellComponent

A stateless component that provides a space for your content in a Layout.

import {Cell} from '@enact/ui/Layout';

CellBaseComponent

A stateless component that provides a space for your content in a Layout, without CellDecorator applied.

import {CellBase} from '@enact/ui/Layout';
Properties
align
String

The alignment of Cell.

Aligns this Cell vertically in the case of a horizontal layout or horizontally in the case of a vertical layout. "start", "center" and "end" are the most commonly used, although all values of align-self are supported. "start" refers to the top in a horizontal layout, and left in a vertical LTR layout "end" refers to the bottom in a horizontal layout, and right in a vertical LTR layout "start" and "end" reverse places when in a vertical layout in a RTL locale.

children
Any

Any valid Node that should be positioned in this Cell.

component
StringComponent

The type of component to use to render as the Cell. May be a DOM node name (e.g 'div', 'span', etc.) or a custom component.

Default: 'div'
componentRef
ObjectFunction

Called with a reference to the root component.

When using ui/Layout.Cell, the ref prop is forwarded to this component as componentRef.

shrink
Boolean

Sizes Cell to its contents.

A shrinkable cell will contract to its minimum size, according to the dimensions of its contents. This is used when you want the size of this Cell's content to influence the dimensions of this cell. shrink will not allow the contents of the Layout to be pushed beyond its boundaries (overflowing). See the size property for more details.

Default: false
size
StringNumber

Sets the desired size of the Cell using any valid CSS measurement value.

When used in conjunction with shrink, the size will be the maximum size, shrinking as necessary, to fit the content.

E.g.

  • size="400px" -> cell will be 400px, regardless of the dimensions of your content

  • size="400px" shrink -> cell will be 400px if your content is greater than 400px, and will match your contents size if it's smaller

This accepts any valid CSS measurement value string. If a numeric value is used, it will be treated as a pixel value and converted to a relative unit based on the rules of resolution independence.

CellDecoratorHigher-Order Component

Applies Cell behaviors.

import {CellDecorator} from '@enact/ui/Layout';

ColumnComponent

Shorthand for <Layout orientation="vertical">, which positions its Cells vertically.

┌────┐
├────┤
├────┤
├────┤
└────┘
import {Column} from '@enact/ui/Layout';

LayoutBaseComponent

A container for Cells.

A stateless component that acts as a containing area for Cells to be positioned in a row or a column (horizontally or vertically, respectively. It supports an orientation property for laying-out its contents (Cells) in an organized, readable way.

Example:

import Input from '@enact/moonstone/Input';
import css from './LayoutExample.less';
...
<fieldset>
	<Layout align="center">
		<Cell component="label" size="40%" className={css.label} shrink>First Name</Cell>
		<Cell component={Input} placeholder="First" className={css.input} />
	</Layout>
	<Layout align="center">
		<Cell component="label" size="40%" className={css.label} shrink>Last Name</Cell>
		<Cell component={Input} placeholder="Last" className={css.input} />
	</Layout>
</fieldset>
import {LayoutBase} from '@enact/ui/Layout';
Properties
align
String

The alignment of children.

Aligns the children Cells vertically in the case of a horizontal layout or horizontally in the case of a vertical layout. "start", "center" and "end" are the most commonly used, although all values of align-items are supported. "start" refers to the top in a horizontal layout, and left in a vertical LTR layout "end" refers to the bottom in a horizontal layout, and right in a vertical LTR layout "start" and "end" reverse places when in a vertical layout in a RTL locale. This includes support for align-parts which is shorthand for combining align-items and justify-content into a single property, separated by a space, in that order. This allows you to specify both the horizontal and vertical alignment in one property, separated by a space.

children
CellArrayCell

Only Cell components are supported as children.

component
StringComponent

The type of component to use to render as the Layout. May be a DOM node name (e.g 'div', 'span', etc.) or a custom component.

Default: 'div'
componentRef
ObjectFunction

Called with a reference to the root component.

When using ui/Layout.Layout, the ref prop is forwarded to this component as componentRef.

inline
Boolean

Allows this Layout to have following siblings drawn on the same line as itself instead of carving out the entire horizontal space for itself.

Default: false
orientation
String

The orientation of the Layout, i.e. how the children Cells are positioned on the screen. Must be either 'horizontal' or 'vertical'.

Default: 'horizontal'
wrap
BooleanString

Sets the Layout's flex-wrap values.

Determines how a Layout handles its cells if there are more than fit in the available space. This works like a normal Boolean prop, but also accepts strings for customization beyond the basic on/off support. In addition to true and false, the following strings are supported: 'wrap', 'nowrap', 'reverse'. 'reverse' performs standard line wrapping but additional lines are placed above/before the preceding line instead of below/after.

LayoutDecoratorHigher-Order Component

Applies Layout behaviors.

import {LayoutDecorator} from '@enact/ui/Layout';

RowComponent

Shorthand for <Layout orientation="horizontal">, which positions its Cells horizontally.

┌─┬─┬─┬─┐
│ │ │ │ │
└─┴─┴─┴─┘
import {Row} from '@enact/ui/Layout';
ArrayBooleanFunctionModuleNumberObjectString