bootstack.CommandBar#

class bootstack.CommandBar(*, button_variant='ghost', density='default', surface=None, padding=None, show_border=False, show_window_controls=False, draggable=False, parent=None, **kwargs)#

Bases: PublicWidgetBase

A horizontal strip of buttons, labels, and other widgets.

The command bar holds an app’s commands — buttons, a search box, a theme toggle — as distinct from the menu bar, which holds menus. Items are added left-to-right via add_button(), add_label(), add_separator(), add_spacer(), and add_widget(). Call add_spacer() to push subsequent items to the right side.

A command bar appears automatically at the top of App, Window, and AppShell (via app.commandbar) — use this widget directly to build a standalone command bar or a custom titlebar.

Parameters:

  • button_variant (ButtonVariant) – Default variant applied to every button added via add_button(). Default 'ghost'.

  • density (WidgetDensity) – Size of command-bar items. Default 'default'.

  • surface (SurfaceToken | str | None) – Background surface token. Defaults to the theme’s 'chrome' surface.

  • padding (int | tuple[int, int] | None) – Inner padding in pixels — an int (all sides) or a (horizontal, vertical) tuple. Defaults to 3 for default density and (3, 1) for compact.

  • show_border (bool) – If True, draws a border around the command-bar frame. Default False.

  • show_window_controls (bool) – If True, adds minimize, maximize, and close buttons to the right side. Default False.

  • draggable (bool) – If True, clicking and dragging the command bar repositions the window. Automatically enabled when show_window_controls=True. Default False.

  • parent (Any) – Override the context-stack parent.

  • **kwargs (Any) – Layout placement options applied by the parent container — fill, expand, anchor, margin, row, column, sticky. See Layout & Spacing.

property button_variant: str#

Default variant applied to buttons added via add_button().

property density: WidgetDensity#

Current density setting for command-bar items.

property is_attached: bool#

Whether the widget is currently placed in its layout.

True while the widget occupies space in its parent; False after detach (or before it has ever been placed). A detached widget keeps its state and can be returned to the layout with attach.

property schedule: Schedule#

Scheduler tied to this widget’s lifetime.

All jobs are automatically cancelled when the widget is destroyed. First access creates the Schedule instance; subsequent accesses return the same instance.

Usage:

self.schedule.delay(500, callback)
self.schedule.every(1000, tick)
job = self.schedule.idle(refresh)
job.cancel()
add_button(label=None, *, icon=None, on_click=None, accent=None, variant=None, **kwargs)#

Add a button to the command bar.

When both label and icon are given, the button shows text and icon side by side. When only icon is given, the button is icon-only.

Parameters:

  • label (str | None) – Button label text.

  • icon (str | None) – Icon name. When provided without label, renders icon-only.

  • on_click (Callable[[], Any] | None) – Callback fired when the button is clicked.

  • accent (AccentToken | str | None) – Color intent override.

  • variant (ButtonVariant | None) – Variant override. When omitted, falls back to the command bar’s button_variant (default 'ghost').

add_label(text=None, *, icon=None, font=None, **kwargs)#

Add a non-interactive label to the command bar.

Parameters:

  • text (str | None) – Label text.

  • icon (str | None) – Icon name displayed alongside the text.

  • font (str | None) – Font token, e.g. 'heading-md' or 'caption'.

add_separator(length=16)#

Add a vertical separator.

Parameters:

length (int) – Separator height in pixels. Defaults to 16.

add_spacer()#

Add a flexible spacer that pushes subsequent items to the right.

add_widget(widget, **pack_kwargs)#

Add an arbitrary widget to the command bar.

The widget must have been created with the command bar as its parent, or pass a raw internal widget here.

Parameters:

  • widget (Any) – A public widget instance or raw internal widget.

  • **pack_kwargs (Any) – Pack options forwarded to the widget’s placement.

attach(**kwargs)#

Return a detached widget to its layout, optionally moving it.

With no arguments, restores the widget to exactly where detach took it from. Any layout kwargs accepted by the original placement (e.g. fill, expand, anchor, sticky, margin) override the stored options. For stacked widgets, index= sets the position among the currently attached siblings (or pass an explicit before=/after= sibling); without one, the snapshotted position is used.

Calling attach on a widget that is already attached moves it (the kwargs are re-applied). Fires on_attach.

Parameters:

**kwargs (Any) – Layout placement options to override for this placement.

Raises:

ParentResolutionError – If the widget was never placed in a layout.

destroy()#

Destroy the widget and release the resources it holds.

Removes the widget from its parent, destroys its children, and cancels any pending or repeating jobs on its schedule. After this the widget must not be used again. Destroying a container destroys everything inside it.

detach()#

Remove the widget from its layout without destroying it.

The widget stops occupying space but keeps its state, children, and event bindings, ready to be returned with attach. The current position is snapshotted so a plain attach() restores it exactly — for stacked siblings this is the index among the currently attached siblings, so detaching other siblings first shifts that index.

Calling detach on a widget that is already detached, or one that was never placed in a layout, does nothing. Fires on_detach.

emit(event, *, data=None)#

Fire a named event on this widget, as if it produced the event itself.

This is how a composite widget surfaces high-level activity to its listeners, and the generic counterpart to the on_*() shorthands for firing events that have no dedicated method.

Parameters:

  • event (str) – The event name, unprefixed — the same name you pass to on() or an on_<event>() shorthand (e.g. 'change', 'select').

  • data (Any) – The payload delivered to handlers. For a data-carrying event, pass the matching payload dataclass from bootstack.events — the same object an on_<event>() handler receives. Leave as None for native events (click, hover, focus, …), which carry no payload.

Example

widget.emit("change", data=bs.events.ChangeEvent(value=new_value))
get_clipboard()#

Return the current text contents of the system clipboard.

Returns:

The clipboard text, or an empty string when the clipboard is empty or holds non-text data.

Return type:

str

on(event, handler=None)#

Bind handler to event, or return a composable Stream.

With a handler — binds immediately and returns a Subscription:

sub = widget.on("change", handler)
sub.cancel()

Without a handler — returns a Stream for operator chaining. The Tk binding is created lazily when .listen() is called:

sub = widget.on("change").debounce(300).listen(handler)
sub.cancel()
Parameters:

  • event (str) – Event name (e.g. "change", "click").

  • handler (Callable[[Any], Any] | None) – Optional callback. If omitted, a Stream is returned.

Returns:

Subscription when a handler is provided; Stream otherwise.

Return type:

Stream | Subscription

on_attach(handler=None)#

Register a callback fired when the widget enters the layout.

Fires each time the widget becomes visible in its parent — on initial placement and on every attach. Pair it with on_detach to keep per-visibility resources (timers, observers) tied to the widget’s presence on screen. The handler receives a curated Event.

Parameters:

handler (Callable[[Event], Any] | None) – Called when the widget is attached. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_destroy(handler=None)#

Register a callback fired when the widget is destroyed.

Fires once, as the widget is torn down — the place to release resources the widget owns that aren’t cleaned up automatically (file handles, observers, external subscriptions). The handler receives a curated Event.

Parameters:

handler (Callable[[Event], Any] | None) – Called as the widget is destroyed. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_detach(handler=None)#

Register a callback fired when the widget leaves the layout.

Fires each time the widget stops occupying space in its parent — on detach and when an ancestor hides it. Pair it with on_attach to release per-visibility resources. The handler receives a curated Event.

Parameters:

handler (Callable[[Event], Any] | None) – Called when the widget is detached. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

set_clipboard(text)#

Replace the system clipboard contents with text.

Parameters:

text (str) – The text to place on the clipboard.