Expander

A collapsible bordered region with a header that toggles the visibility of its content.

ExpanderComponent · type key standard.expander · Layouts · property blocks: ISurfaceStyleComponent

new ExpanderComponent("expander")

Properties

Property	Type	Default	Binding	Description
Own
`Expanded` SetExpanded · BindExpanded	`bool?`	`true`	two-way	Whether the section is open; two-way, so clicking the summary syncs back.
`ShowChevron` SetShowChevron · BindShowChevron	`bool?`	`true`	one-way	Whether the trailing disclosure chevron is drawn.
`Surface` SetSurface · BindSurface	`UISurfaceStyle?`	`UISurfaceStyle.Background`	one-way	What the component is made of.
From BorderedRegionComponentBase
`BorderThickness` SetBorderThickness · BindBorderThickness	`UIThickness?`	`1`	one-way	The border thickness; a bordered region draws an edge by default.
`Background` SetBackground · BindBackground	`UIThemeColor?`	`null`	one-way	The surface's background colour; unset leaves whatever the theme paints underneath.
`Padding` SetPadding · BindPadding	`UIResponsive<UIThickness>?`	`null`	one-way	The inner spacing between this component's edges and its content, optionally overridden per breakpoint.
`BackgroundImage` SetBackgroundImage · BindBackgroundImage	`string`	`null`	one-way	The picture painted over the background colour, centred and never repeated: a URL or a data URI.
`BackgroundImageFit` SetBackgroundImageFit · BindBackgroundImageFit	`UIImageFit?`	`UIImageFit.Cover`	one-way	How the picture fills the surface.
`BorderColor` SetBorderColor · BindBorderColor	`UIThemeColor?`	`null`	one-way	The border's colour, written as CSS `border-color`; unset leaves the stylesheet's own.
`BorderRadius` SetBorderRadius · BindBorderRadius	`UICornerRadius?`	`null`	one-way	The corner rounding, written as CSS `border-radius`; unset leaves the stylesheet's own.
`Overflow` SetOverflow · BindOverflow	`UIOverflow?`	`UIOverflow.Hidden`	one-way	Whether content that overflows this component's bounds is clipped.

Events

OnExpand(string command): Registers a command to invoke when the expander is expanded.
OnExpand(string command, params KeyValuePair<string, UIActionArgument>[] arguments): Registers a command with bound arguments to invoke when the expander is expanded.
OnExpandLiteral(string command, params KeyValuePair<string, object>[] arguments): Registers a command with literal arguments to invoke when the expander is expanded.
OnCollapse(string command): Registers a command to invoke when the expander is collapsed.
OnCollapse(string command, params KeyValuePair<string, UIActionArgument>[] arguments): Registers a command with bound arguments to invoke when the expander is collapsed.
OnCollapseLiteral(string command, params KeyValuePair<string, object>[] arguments): Registers a command with literal arguments to invoke when the expander is collapsed.

Methods

ConfigureDefaultHeader(Action<ExpanderHeaderRegion> configure): Configures the built-in default header region, throwing if a different header has been set.
SetCollapsed(): Sets ExpanderComponent.Expanded to false.
SetContent(IVisualComponent content): Sets the content region.

Common properties (16) — layout, visibility, theme, and the rest every component shares

Property	Type	Default	Binding	Description
`Visibility` SetVisibility · BindVisibility	`UIResponsive<UIVisibility>?`	`Visible`	one-way	What the component does with the room it was given, optionally overridden per breakpoint (e.g. collapsed from a given width up).
`Enabled` SetEnabled · BindEnabled	`bool?`	`true`	one-way	Whether the component responds to input; false dims it and marks it, and its subtree, inert.
`Theme` SetTheme · BindTheme	`UIThemeMode?`	`null`	one-way	The theme mode forced on this component's subtree, or `null` to inherit the ambient theme.
`HorizontalAlignment` SetHorizontalAlignment · BindHorizontalAlignment	`UIAlignment?`	`UIAlignment.Stretch`	one-way	Where the component sits within its grid cell along the horizontal axis.
`VerticalAlignment` SetVerticalAlignment · BindVerticalAlignment	`UIAlignment?`	`UIAlignment.Stretch`	one-way	Where the component sits within its grid cell along the vertical axis.
`Width` SetWidth · BindWidth	`UIResponsive<UILayoutLength>?`	`null`	one-way	The component width, optionally overridden per breakpoint.
`MinWidth` SetMinWidth · BindMinWidth	`UIResponsive<UILayoutLength>?`	`null`	one-way	The component minimum width, optionally overridden per breakpoint.
`MaxWidth` SetMaxWidth · BindMaxWidth	`UIResponsive<UILayoutLength>?`	`null`	one-way	The component maximum width, optionally overridden per breakpoint.
`Height` SetHeight · BindHeight	`UIResponsive<UILayoutLength>?`	`null`	one-way	The component height, optionally overridden per breakpoint.
`MinHeight` SetMinHeight · BindMinHeight	`UIResponsive<UILayoutLength>?`	`null`	one-way	The component minimum height, optionally overridden per breakpoint.
`MaxHeight` SetMaxHeight · BindMaxHeight	`UIResponsive<UILayoutLength>?`	`null`	one-way	The component maximum height, optionally overridden per breakpoint.
`ZIndex` SetZIndex · BindZIndex	`int?`	`0`	one-way	The stacking order within the visual tree.
`Margin` SetMargin · BindMargin	`UIResponsive<UIThickness>?`	`null`	one-way	The outer spacing around the component, optionally overridden per breakpoint.
`Placement` SetPlacement · BindPlacement	`UIResponsive<UIGridPlacement>?`	`null`	one-way	The grid placement, optionally overridden per breakpoint.
`Loading` SetLoading · BindLoading	`bool?`	`false`	one-way	Whether the component is in loading state — a live state a controller turns on and off.
`ShowContextMenu` SetShowContextMenu · BindShowContextMenu	`bool?`	`true`	one-way	Whether a right-click opens the `IVisualComponent.ContextMenu`; on a host with rows, whether it opens any row's. Off, the menu stays in the tree and nothing opens it.