bootstack.VStack#

class bootstack.VStack(*, parent=None, gap=0, padding=None, fill_items=None, expand_items=None, anchor_items=None, surface=None, show_border=False, width=None, height=None, **kwargs)#

Bases: _StackBase

Vertical stack — lays out children top-to-bottom with optional gap and alignment.

A lightweight container that packs children one above the other using the pack geometry manager. Use gap= to space children evenly, fill_items='x' to stretch them to the full width, and expand=True to let the stack grow vertically in its parent.

Example:

with bs.VStack(gap=12, fill_items="x", padding=16):
    bs.Label("Title", font="heading-md")
    bs.TextField()
    bs.Button("Submit", accent="primary")
Parameters:

  • gap (int) – Spacing in pixels between child widgets. Defaults to 0.

  • padding (Padding | None) – Space in pixels between the stack border and its content. Defaults to None (no padding).

  • fill_items (Fill | str | None) – Default fill direction applied to every child. Individual children can override this with their own fill=.

  • expand_items (bool | None) – When True, each child expands to consume extra space along the column. Defaults to None.

  • anchor_items (Anchor | str | None) – Default alignment anchor for children that do not fill their slot.

  • surface (SurfaceToken | AccentToken | str | None) – Background token. Accepts a surface token, an accent token, or any token with modifiers (e.g. 'primary[subtle]'). Defaults to None (inherits from parent surface).

  • show_border (bool) – When True, draws a 1 px border around the stack frame. Defaults to False.

  • width (int | None) – Fixed width of the stack in pixels. Disables frame propagation so children cannot resize the container. Setting both width= and height= fully constrains the frame; when only width= is set, height collapses to zero — pass fill='y', expand=True to let the parent control it. Defaults to None (size from children).

  • height (int | None) – Fixed height of the stack in pixels. Disables frame propagation so children cannot resize the container. Setting both height= and width= fully constrains the frame; when only height= is set, width collapses to zero — pass fill='x', expand=True to let the parent control it. Defaults to None (size from children).

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

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

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()
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

guide_layout(child, **layout_kw)#

Place child._internal under this container.

Records a Placement snapshot on the child so it can later be detach-ed and attach-ed. When attached=False is passed, the snapshot is recorded but the widget is NOT mapped — it starts hidden, ready to be shown with attach.

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.