TwoPane class

A widget that positions two panes side by side on uninterrupted screens or on either side of a separating DisplayFeature on screens interrupted by a separating DisplayFeature.

A DisplayFeature separates the screen into sub-screens when both these conditions are met:

• it obstructs the screen, meaning the area it occupies is not 0. Display features of type DisplayFeatureType.fold can have height 0 or width 0 and not be obstructing the screen.
• it is at least as tall as the screen, producing a left and right sub-screen or it is at least as wide as the screen, producing a top and bottom sub-screen.

When positioning the two panes, direction, paneProportion and panePriority parameters are ignored and values are replaced in order to avoid the separating DisplayFeature:

• On screens with a separating DisplayFeature, the two panes are positioned on each side of the feature. If the DisplayFeature splits the screen left and right, direction is Axis.horizontal. Otherwise, direction is Axis.vertical. The paneProportion and panePriority parameters are also ignored and each pane occupies a sub-screen.
• On screens without a separating DisplayFeature, direction is used for deciding if the 2 panes are laid out horizontally or vertically and paneProportion is used for deciding how much space each pane takes.

This widget is similar to Flex and also takes textDirection and verticalDirection parameters, which are used for deciding in what order the panes are laid out (e.g TextDirection.ltr would position startPane on the left and endPane on the right).

The panePriority parameter can be used to display only one pane on screens without any separating DisplayFeature, by using TwoPanePriority.start or TwoPanePriority.end. When TwoPanePriority.both is used or when the screen has a separating DisplayFeature, both panes are visible.

Similarly to SafeArea and DisplayFeatureSubScreen, this widget assumes there is no distance between it and the first MediaQuery ancestor. If this is not true, the bounds of display features will not align with the separation between the two panes. The padding parameter can be used to align TwoPane with the real position of display features. The padding parameter is the padding between TwoPane and the edges of the screen.

Pane widgets are wrapped in modified MediaQuery parents, removing padding, insets and display features that no longer intersect with them.

If not provided, textDirection defaults to the ambient Directionality. If none are provided, then the widget asserts during build in debug mode. The resolved direction of TwoPane is Axis.horizontal when there are display features separating the screen into two horizontal sub-screens, in which case the provided direction is ignored.

See also

• DisplayFeature and MediaQueryData.displayFeatures, to further understand display features
• MediaQueryData.removeDisplayFeatures which is used to remove padding, insets and display features for each pane.

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatelessWidget
• TwoPane

Constructors

TwoPane({Key? key, required Widget startPane, required Widget endPane, double paneProportion = 0.5, TextDirection? textDirection, VerticalDirection verticalDirection = VerticalDirection.down, Axis direction = Axis.horizontal, TwoPanePriority panePriority = TwoPanePriority.both, EdgeInsets padding = EdgeInsets.zero, Set<TwoPaneAllowedOverrides> allowedOverrides = const {TwoPaneAllowedOverrides.paneProportion, TwoPaneAllowedOverrides.direction, TwoPaneAllowedOverrides.panePriority}})

Create a layout that shows two pane widgets side by side.

const

Properties

allowedOverrides → Set<TwoPaneAllowedOverrides>

The parameters that TwoPane is allowed to override when a separating display feature is found.

final

direction → Axis

Same as Flex.direction.

final

endPane → Widget

The second pane.

final

hashCode → int

The hash code for this object.

no setter, inherited

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

padding → EdgeInsets

The padding between TwoPane and the edges of the screen.

final

panePriority → TwoPanePriority

Whether to show only one pane and which one, or both.

final

paneProportion → double

Proportion of the available space occupied by the first pane. The second pane takes over the rest of the screen.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

startPane → Widget

The first pane.

final

textDirection → TextDirection?

Same as Flex.textDirection.

final

verticalDirection → VerticalDirection

Same as Flex.verticalDirection.

final

Methods

build(BuildContext context) → Widget

Describes the part of the user interface represented by this widget.

override

createElement() → StatelessElement

Creates a StatelessElement to manage this widget's location in the tree.

inherited

debugDescribeChildren() → List<DiagnosticsNode>

Returns a list of DiagnosticsNode objects describing this node's children.

inherited

debugFillProperties(DiagnosticPropertiesBuilder properties) → void

Add additional properties associated with the node.

inherited

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode

Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.

inherited

toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String

A string representation of this object.

inherited

toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String

Returns a string representation of this node and its descendants.

inherited

toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String

Returns a one-line detailed description of the object.

inherited

toStringShort() → String

A short, textual description of this widget.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited