Trait Panel 

pub trait Panel:
    EventEmitter<PanelEvent>
    + Render
    + Focusable {
    // Required method
    fn panel_name(&self) -> &'static str;

    // Provided methods
    fn visible(&self, cx: &App) -> bool { ... }
    fn closable(&self, cx: &App) -> bool { ... }
    fn zoomable(&self, cx: &App) -> bool { ... }
    fn set_active(
        &mut self,
        active: bool,
        window: &mut Window,
        cx: &mut Context<'_, Self>,
    ) { ... }
    fn set_zoomed(
        &mut self,
        zoomed: bool,
        window: &mut Window,
        cx: &mut Context<'_, Self>,
    ) { ... }
    fn on_added_to(
        &mut self,
        group: WeakEntity<TabGroup>,
        window: &mut Window,
        cx: &mut Context<'_, Self>,
    ) { ... }
    fn on_removed(&mut self, window: &mut Window, cx: &mut Context<'_, Self>) { ... }
    fn dump(&self, cx: &App) -> PanelState { ... }
}

Behavior a dockable panel provides. Presentation lives in the layer above: gpui_component::dock::Panel extends this with titles, toolbars, and menus.

Required Methods

fn panel_name(&self) -> &'static str

Identifies the panel in persisted layouts. Once chosen, never change it.

Provided Methods

fn visible(&self, cx: &App) -> bool

Whether the panel is drawn at all. A hidden panel keeps its place in the layout tree and its tab, and reappears when this turns back on; a container whose panels are all hidden gives up its slot.

fn closable(&self, cx: &App) -> bool

Whether the panel may be closed. A container can still refuse — the last group of a dock does — so this is permission, not a guarantee.

fn zoomable(&self, cx: &App) -> bool

Whether the panel can zoom at all. Where the zoom control appears is a presentation decision and belongs to the layer above.

fn set_active( &mut self, active: bool, window: &mut Window, cx: &mut Context<'_, Self>, )

Called with the frame-end net state when this panel becomes, or stops being, the displayed tab of its group: exactly one notification per edge, delivered on the next tick after the change — never same-value repeats nor false-then-true flips within one frame.

A panel removed from its group is NOT told false; Panel::on_removed is the deactivation signal. A hidden panel occupying the active slot still receives true even though rendering falls back to the first visible panel.

fn set_zoomed( &mut self, zoomed: bool, window: &mut Window, cx: &mut Context<'_, Self>, )

Called when the group displaying this panel zooms in or out.

Only the panel that is currently displayed is told: a group has one zoom state, and it is the visible panel that fills the dock. Panels sharing the group’s other tabs hear nothing, and a panel that is not displayed when the zoom changes is never told about it retroactively.

fn on_added_to( &mut self, group: WeakEntity<TabGroup>, window: &mut Window, cx: &mut Context<'_, Self>, )

Called when the panel joins a tab group, with a weak handle on it.

Delivered before any set_active, so a panel can hold the handle and act on the first activation. A panel moved between groups is told again, with the new group; it is not told it was removed in between.

fn on_removed(&mut self, window: &mut Window, cx: &mut Context<'_, Self>)

Called when the panel leaves the dock for good — closed, or displaced by a wholesale set_center, set_dock, remove_dock or load.

This is also the deactivation signal: a panel that was displayed is not told set_active(false) on its way out. A panel dragged from one group to another never leaves the dock, so it never hears this.

fn dump(&self, cx: &App) -> PanelState

The panel’s own persisted state, written into the layout under its panel_name and handed back to the PanelRegistry builder on the next load.

The default records the name and nothing else, which is enough for a panel whose builder can reconstruct it from the name alone.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors