Struct CollapsingHeader 

pub struct CollapsingHeader { /* private fields */ }

A header which can be collapsed/expanded, revealing a contained Ui region.

egui::CollapsingHeader::new("Heading")
    .show(ui, |ui| {
        ui.label("Body");
    });

// Short version:
ui.collapsing("Heading", |ui| { ui.label("Body"); });

If you want to customize the header contents, see CollapsingState::show_header.

Implementations

impl CollapsingHeader

pub fn new(text: impl Into<WidgetText>) -> Self

The CollapsingHeader starts out collapsed unless you call default_open.

The label is used as an Id source. If the label is unique and static this is fine, but if it changes or there are several CollapsingHeader with the same title you need to provide a unique id source with Self::id_salt.

pub fn default_open(self, open: bool) -> Self

By default, the CollapsingHeader is collapsed. Call .default_open(true) to change this.

pub fn open(self, open: Option<bool>) -> Self

Calling .open(Some(true)) will make the collapsing header open this frame (or stay open).

Calling .open(Some(false)) will make the collapsing header close this frame (or stay closed).

Calling .open(None) has no effect (default).

pub fn id_salt(self, id_salt: impl AsIdSalt) -> Self

Explicitly set the source of the Id of this widget, instead of using title label. This is useful if the title label is dynamic or not unique.

pub fn enabled(self, enabled: bool) -> Self

If you set this to false, the CollapsingHeader will be grayed out and un-clickable.

This is a convenience for Ui::disable.

pub fn show_background(self, show_background: bool) -> Self

Should the CollapsingHeader show a background behind it? Default: false.

To show it behind all CollapsingHeader you can just use:

ui.visuals_mut().collapsing_header_frame = true;

pub fn icon( self, icon_fn: impl FnOnce(&mut Ui, f32, &Response) + 'static, ) -> Self

Use the provided function to render a different CollapsingHeader icon. Defaults to a triangle that animates as the CollapsingHeader opens and closes.

For example:

fn circle_icon(ui: &mut egui::Ui, openness: f32, response: &egui::Response) {
    let stroke = ui.style().interact(&response).fg_stroke;
    let radius = egui::lerp(2.0..=3.0, openness);
    ui.painter().circle_filled(response.rect.center(), radius, stroke.color);
}

egui::CollapsingHeader::new("Circles")
  .icon(circle_icon)
  .show(ui, |ui| { ui.label("Hi!"); });

impl CollapsingHeader

pub fn show<R>( self, ui: &mut Ui, add_body: impl FnOnce(&mut Ui) -> R, ) -> CollapsingResponse<R>

pub fn show_unindented<R>( self, ui: &mut Ui, add_body: impl FnOnce(&mut Ui) -> R, ) -> CollapsingResponse<R>