bootstack.PageStack#

class bootstack.PageStack(*, padding=None, width=None, height=None, parent=None, **kwargs)#

Bases: PublicWidgetBase

A browser-style navigation container showing one page at a time.

Add pages with .add() and place children inside each page using the returned context manager. Navigate between pages with navigate(), back(), and forward().

Usage:

ps = bs.PageStack(fill="both", expand=True)
with ps.add("home"):
    bs.Label("Home page")
with ps.add("settings"):
    bs.Label("Settings page")
ps.navigate("home")

Parameters:

padding (Padding | None) – Space around the page area.
width (int | None) – Requested width in pixels.
height (int | None) – Requested height in pixels.
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 can_back: bool#: True if backward navigation is possible.

property can_forward: bool#: True if forward navigation is possible.

property current: str | None#: Key of the currently displayed page, or None.

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(key, *, layout='vstack', padding=None, gap=0, fill_items=None, expand_items=None, anchor_items=None, columns=None, rows=None, sticky_items=None, auto_flow='row')#

Add a page and return a handle for placing its children and navigating to it.

Parameters:

key (str) – Unique identifier for this page.
layout (LayoutKind) – Internal layout. Defaults to 'vstack'.
padding (Padding | None) – Space inside the page frame. Defaults to None.
gap (int) – Space between children in pixels. Defaults to 0.
fill_items (Fill | str | None) – Default fill direction applied to each child.
expand_items (bool | None) – Whether children expand to fill available space.
anchor_items (Anchor | str | None) – Default anchor applied to each child.
columns (int | list[int | str] | None) – Column definitions for 'grid' layout. An integer sets the number of equal-weight columns; a list sets per-column weights or sizes (e.g. [1, 2, 'auto', '120px']).
rows (int | list[int | str] | None) – Row definitions for 'grid' layout, same format as columns.
sticky_items (Sticky | str | None) – Default sticky value for grid children.
auto_flow (AutoFlow) – Grid auto-flow direction. Defaults to 'row'.

Returns:

StackPage — use as a context manager to place children, and as a handle to navigate() to the page.

Return type:

StackPage

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.

back()#

Navigate to the previous page in history.

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))

forward()#

Navigate to the next page in history.

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

item(key)#

Return the page handle for key.

Parameters:: key (str) – Page key assigned in add().
Returns:: The StackPage for that key — read its key or navigate() to it.
Return type:: StackPage

items()#

Return all page handles in insertion order.

navigate(key, data=None)#

Navigate to the page identified by key.

Parameters:

key (str) – Page identifier to navigate to.
data (dict | None) – Optional data dict passed to the page’s mount event.

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

on_page_change() → Stream#

on_page_change(handler: Callable[[PageChangeEvent], Any]) → Subscription

Register a callback fired after every navigation.

Returns:: Subscription (with handler) or Stream (without handler).
Return type:: Stream | Subscription

on_page_mount() → Stream#

on_page_mount(handler: Callable[[PageChangeEvent], Any]) → Subscription

Register a callback fired when a page is mounted.

Returns:: Subscription (with handler) or Stream (without handler).
Return type:: Stream | Subscription

page_keys()#

All registered page keys in insertion order.

remove(key)#

Remove a page and destroy its widget.

set_clipboard(text)#

Replace the system clipboard contents with text.

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