ThreePaneScaffoldValue

public class ThreePaneScaffoldValue internal constructor(
    public val primary: PaneAdaptedValue,
    public val secondary: PaneAdaptedValue,
    public val tertiary: PaneAdaptedValue,
    internal val currentDestination: ThreePaneScaffoldRole?,
) : PaneScaffoldValue<ThreePaneScaffoldRole>, PaneExpansionStateKeyProvider

The adapted value of ThreePaneScaffold. It contains each pane's adapted value. ThreePaneScaffold will use the adapted values to decide which panes should be displayed and how they should be displayed. With other input parameters of ThreePaneScaffold fixed, each possible instance of this class should represent a unique state of ThreePaneScaffold and developers can compare two ThreePaneScaffoldValue to decide if there is a layout structure change.

For a Material-opinionated layout, it's suggested to use calculateThreePaneScaffoldValue to calculate the current scaffold value.

Parameters

Properties

paneExpansionStateKey

public override val paneExpansionStateKey: PaneExpansionStateKey by
        lazy(LazyThreadSafetyMode.SYNCHRONIZED) {
            if (expandedCount != 2) {
                PaneExpansionStateKey.Default
            } else {
                val expandedPanes = Array<ThreePaneScaffoldRole?>(2) { null }
                var count = 0
                forEach { role, value ->
                    if (value == PaneAdaptedValue.Expanded) {
                        expandedPanes[count++] = role
                    }
                }
                TwoPaneExpansionStateKeyImpl(expandedPanes[0]!!, expandedPanes[1]!!)
            }
        }