A widget that displays its children in a vertical array.

To cause a child to expand to fill the available vertical space, wrap the child in an Expanded widget.

The Column widget does not scroll (and in general it is considered an error to have more children in a Column than will fit in the available room). If you have a line of widgets and want them to be able to scroll if there is insufficient room, consider using a Block.

For a horizontal variant, see Row.

If you only have one child, then consider using Align or Center to position the child.

Layout algorithm

Layout for a Column proceeds in six steps:

  1. Layout each child a null or zero flex factor (e.g., those that are not Expanded) with unbounded vertical constraints and the incoming horizontal constraints. If the crossAxisAlignment is CrossAxisAlignment.stretch, instead use tight horizontal constraints that match the incoming max width.
  2. Divide the remaining vertical space among the children with non-zero flex factors (e.g., those that are Expanded) according to their flex factor. For example, a child with a flex factor of 2.0 will receive twice the amount of vertical space as a child with a flex factor of 1.0.
  3. Layout each of the remaining children with the same horizontal constraints as in step 1, but instead of using unbounded vertical constraints, use vertical constraints based on the amount of space allocated in step 2. Children with Flexible.fit properties that are FlexFit.tight are given tight constraints (i.e., forced to fill the allocated space), and children with Flexible.fit properties that are FlexFit.loose are given loose constraints (i.e., not forced to fill the allocated space).
  4. The width of the Column is the maximum width of the children (which will always satisfy the incoming horizontal constraints).
  5. The height of the Column is determined by the mainAxisSize property. If the mainAxisSize property is MainAxisSize.max, then the height of the Column is the max height of the incoming constraints. If the mainAxisSize property is MainAxisSize.min, then the height of the Column is the sum of heights of the children (subject to the incoming constraints).
  6. Determine the position for each child according to the mainAxisAlignment and the crossAxisAlignment. For example, if the mainAxisAlignment is MainAxisAlignment.spaceBetween, any vertical space that has not been allocated to children is divided evenly and placed between the children.
Inheritance

Constructors

Column({Key key, MainAxisAlignment mainAxisAlignment: MainAxisAlignment.start, MainAxisSize mainAxisSize: MainAxisSize.max, CrossAxisAlignment crossAxisAlignment: CrossAxisAlignment.center, TextBaseline textBaseline, List<Widget> children: const [] })

Creates a vertical array of children.

Properties

children → List<Widget>

The widgets below this widget in the tree.

read-only, inherited
crossAxisAlignment → CrossAxisAlignment

How the children should be placed along the cross axis.

read-only, inherited
direction → Axis

The direction to use as the main axis.

read-only, inherited
hashCode → int

Get a hash code for this object.

read-only, inherited
key → Key

Controls how one widget replaces another widget in the tree.

read-only, inherited
mainAxisAlignment → MainAxisAlignment

How the children should be placed along the main axis.

read-only, inherited
mainAxisSize → MainAxisSize

How much space space should be occupied in the main axis.

read-only, inherited
runtimeType → Type

A representation of the runtime type of the object.

read-only, inherited
textBaseline → TextBaseline

If aligning items according to their baseline, which baseline to use.

read-only, inherited

Operators

operator ==(other) → bool

The equality operator.

inherited

Methods

createElement() → MultiChildRenderObjectElement

RenderObjectWidgets always inflate to a RenderObjectElement subclass.

inherited
createRenderObject(BuildContext context) → RenderFlex

Creates an instance of the RenderObject class that this RenderObjectWidget represents, using the configuration described by this RenderObjectWidget.

inherited
debugFillDescription(List<String> description) → void

Add additional information to the given description for use by toString.

inherited
didUnmountRenderObject(RenderObject renderObject) → void

A render object previously associated with this widget has been removed from the tree. The given RenderObject will be of the same type as returned by this object's createRenderObject.

inherited
noSuchMethod(Invocation invocation) → dynamic

Invoked when a non-existent method or property is accessed.

inherited
toString() → String

Returns a string representation of this object.

inherited
toStringShort() → String

A short, textual description of this widget.

inherited
updateRenderObject(BuildContext context, RenderFlex renderObject) → void

Copies the configuration described by this RenderObjectWidget to the given RenderObject, which will be of the same type as returned by this object's createRenderObject.

inherited