bootstack.TextArea#

class bootstack.TextArea(value='', *, textsignal=None, label=None, message=None, required=False, placeholder=None, max_length=None, read_only=False, wrap=True, height=4, width=None, scrollbars='auto', font='body', accent='primary', show_border=True, parent=None, **kwargs)#

Bases: PublicWidgetBase

A multi-line text input with optional label, placeholder, and scrollbars.

Parameters:

  • value (str) – Initial text content.

  • textsignal (Signal[str] | None) – Reactive Signal[str] linked to the text content.

  • label (str | None) – Label displayed above the field.

  • message (str | None) – Hint text displayed below the field.

  • required (bool) – If True, field cannot be left empty.

  • placeholder (str | None) – Placeholder text shown when the field is empty.

  • max_length (int | None) – Maximum number of characters allowed.

  • read_only (bool) – If True, text is visible but not editable.

  • wrap (bool) – If True (default), long lines wrap at the widget boundary.

  • height (int) – Visible row count. Default 4.

  • width (int | None) – Width in character units. Omit to let the widget fill its container via layout.

  • scrollbars (Literal['auto', 'vertical', 'both', 'none']) – Scrollbar visibility. Default 'auto'. Horizontal scrolling requires wrap=False.

  • font (str) – Semantic font token. Default 'body'. See Typography.

  • accent (AccentToken | str) – Accent token applied to the focus border. Default 'primary'.

  • show_border (bool) – If True (default), wraps the text area in a themed border with a focus ring.

  • 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 Arranging Widgets.

property error: Signal[str]#

Reactive Signal[str] — current validation error message.

Empty string when the field is valid. Updates in lockstep with valid.

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 is_dirty: bool#

True if the content has changed since the last mark_saved() call.

property read_only: bool#

Whether the text area is visible but not editable.

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()
property signal: Signal[str] | None#

The reactive Signal bound to this field, or None if unbound.

property text: str#

The current display text. Same as value for a text area (no formatting layer). Read-only — assign to value to change it.

property valid: Signal[bool]#

Reactive Signal[bool] — True when all validation rules pass.

Starts True. Updates after every validation run (blur or manual validate() call). Subscribe a named handler to react immediately when validity changes (a lambda cannot assign, so define a function): def on_valid(ok): btn.disabled = not ok then area.valid.subscribe(on_valid).

property value: str#

The current text content.

add_validation_rule(rule_type, **kwargs)#

Attach a validation rule to this field.

Parameters:

  • rule_type (RuleType) – The kind of validation rule to apply.

  • **kwargs (Any) – Rule options such as message=, min=, max=, trigger=.

append(text)#

Append text to the end of the content.

Applies even when read_only=True, leaving the area read-only afterward.

Parameters:

text (str) – Text to add at the end of the content.

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.

capture(path, *, inset=0, settle=0.1)#

Save a picture of this widget to an image file.

Captures the area this widget occupies on screen — one widget, a whole window, or the entire application, depending on what you call it on. The file extension selects the format, so .png, .jpg, and .pdf all work.

The widget has to be visible. A capture reads pixels from the display, so the window is brought to the front first and a hidden or detached widget cannot be captured at all. Any always-on-top setting the window already had is left as it was found.

Pair it with a save dialog to let the user choose where it goes:

import bootstack as bs

def on_export():
    chosen = bs.ask_save_file(initial_file="dashboard.png")
    if chosen:
        app.capture(chosen)
Parameters:

  • path (str | Path) – Where to write the image. Missing parent folders are created, and the extension chooses the format.

  • inset (int) – Pixels to trim from every edge, zero or more. Use 2 on a whole window to drop the native border artifact.

  • settle (float) – Seconds to let the desktop finish repainting before the pixels are read. The default covers the common case of a dialog closing just beforehand. The interface pauses for this long, so a second click on the control that started the capture waits its turn rather than starting an overlapping one.

Returns:

The path that was written.

Raises:

BootstackError – If the widget is not visible on screen or has been scrolled out of view, if inset is negative, if no capture backend is available, or if the file cannot be written.

Return type:

Path

Added in version 0.3.0.

clear()#

Clear all text content.

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.

It is meant for the framework’s own events — 'change', 'select', 'input' and the rest of the data-carrying names. A handler registered through on() or an on_<event>() shorthand receives what is emitted.

Names that map onto a native event instead ('click', 'focus', 'blur', 'submit', …) are a different matter: emitting one asks the toolkit to deliver a real input event, which carries no payload and can reach handlers the widget installed for its own use. Emitting those is not a way to notify listeners, and a listener bound through on() may not see it. Drive the widget through its properties and methods instead.

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. Pass the matching payload dataclass from bootstack.events — the same object an on_<event>() handler receives.

Example

from bootstack.events import ChangeEvent

field.emit("change", data=ChangeEvent(value=new_value))
focus()#

Give keyboard focus to the text area.

insert(text)#

Insert text at the cursor.

Read-only blocks user edits, not programmatic ones: this applies even when read_only=True, leaving the area read-only afterward.

Parameters:

text (str) – Text to insert at the current cursor position.

mark_saved()#

Reset the dirty flag — call after saving content.

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_blur() → Stream#
on_blur(handler: Callable[[Event], Any]) → Subscription

Register a callback fired when the text area loses focus.

Parameters:

handler (Callable[[Event], Any] | None) – Called with an Event. Omit to get a composable Stream instead.

Returns:

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

Return type:

Stream | Subscription

on_change() → Stream#
on_change(handler: Callable[[ChangeEvent], Any]) → Subscription

Register a callback fired when the value is committed (on blur).

Parameters:

handler (Callable[[ChangeEvent], Any] | None) – Called with a ChangeEvent. Omit to get a composable Stream instead.

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_focus() → Stream#
on_focus(handler: Callable[[Event], Any]) → Subscription

Register a callback fired when the text area gains focus.

Parameters:

handler (Callable[[Event], Any] | None) – Called with an Event. Omit to get a composable Stream instead.

Returns:

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

Return type:

Stream | Subscription

on_input() → Stream#
on_input(handler: Callable[[InputEvent], Any]) → Subscription

Register a callback fired on every edit.

Parameters:

handler (Callable[[InputEvent], Any] | None) – Called with an InputEvent. Omit to get a composable Stream instead.

Returns:

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

Return type:

Stream | Subscription

on_invalid() → Stream#
on_invalid(handler: Callable[[ValidationEvent], Any]) → Subscription

Register a callback fired when validation fails.

Parameters:

handler (Callable[[ValidationEvent], Any] | None) – Called with a ValidationEvent. Omit to get a composable Stream instead.

Returns:

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

Return type:

Stream | Subscription

on_modified() → Stream#
on_modified(handler: Callable[[TextModifiedEvent], Any]) → Subscription

Register a callback fired when the dirty state changes.

Parameters:

handler (Callable[[TextModifiedEvent], Any] | None) – Called with a TextModifiedEvent. Omit to get a composable Stream instead.

Returns:

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

Return type:

Stream | Subscription

on_redo() → Stream#
on_redo(handler: Callable[[InputEvent], Any]) → Subscription

Register a callback fired after a redo operation.

Parameters:

handler (Callable[[InputEvent], Any] | None) – Called with an InputEvent. Omit to get a composable Stream instead.

Returns:

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

Return type:

Stream | Subscription

on_undo() → Stream#
on_undo(handler: Callable[[InputEvent], Any]) → Subscription

Register a callback fired after an undo operation.

Parameters:

handler (Callable[[InputEvent], Any] | None) – Called with an InputEvent. Omit to get a composable Stream instead.

Returns:

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

Return type:

Stream | Subscription

on_valid() → Stream#
on_valid(handler: Callable[[ValidationEvent], Any]) → Subscription

Register a callback fired when validation passes.

Parameters:

handler (Callable[[ValidationEvent], Any] | None) – Called with a ValidationEvent. Omit to get a composable Stream instead.

Returns:

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

Return type:

Stream | Subscription

on_validate() → Stream#
on_validate(handler: Callable[[ValidationEvent], Any]) → Subscription

Register a callback fired after any validation run.

Parameters:

handler (Callable[[ValidationEvent], Any] | None) – Called with a ValidationEvent. Omit to get a composable Stream instead.

Returns:

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

Return type:

Stream | Subscription

redo()#

Redo the last undone edit.

select_all()#

Select all text content.

undo()#

Undo the last edit.

validate()#

Run validation rules against the current value.

Returns:

True if all rules pass, False otherwise.

Return type:

bool