Struct TextFieldState 

pub struct TextFieldState {
    pub inner: Rc<RefCell<TextFieldStateInner>>,
    /* private fields */
}

Observable state holder for text field content.

This is the primary API for managing text field state. All edits go through the edit method which provides a mutable buffer.

Example

use cranpose_foundation::text::TextFieldState;

let state = TextFieldState::new("Hello");

// Edit the text
state.edit(|buffer| {
    buffer.place_cursor_at_end();
    buffer.insert(", World!");
});

assert_eq!(state.text(), "Hello, World!");

Thread Safety

TextFieldState uses Rc<RefCell<...>> internally and is not thread-safe. It should only be used from the main thread.

Fields

inner: Rc<RefCell<TextFieldStateInner>>

Internal state for editing machinery. Public for cross-crate pointer-based identity comparison (Hash).

Implementations

impl TextFieldState

pub fn new(initial_text: impl Into<String>) -> Self

Creates a new text field state with the given initial text.

pub fn with_selection( initial_text: impl Into<String>, selection: TextRange, ) -> Self

Creates a state with initial text and selection.

pub fn desired_column(&self) -> Option<usize>

Gets the desired column for up/down navigation.

pub fn set_desired_column(&self, col: Option<usize>)

Sets the desired column for up/down navigation.

pub fn text(&self) -> String

Returns the current text content. Creates composition dependency when read during composition.

pub fn selection(&self) -> TextRange

Returns the current selection range.

pub fn composition(&self) -> Option<TextRange>

Returns the current composition (IME) range, if any.

pub fn line_offsets(&self) -> Vec<usize>

Returns cached line start offsets for efficient multiline operations.

Each entry is the byte offset where a line starts. For example:

• “ab\ncd” -> [0, 3] (line 0 starts at 0, line 1 starts at 3)
• “” -> [0]

The cache is lazily computed on first access and invalidated on text change. This avoids O(n) string splitting on every frame during selection rendering.

pub fn copy_selection(&self) -> Option<String>

Copies the selected text without modifying the clipboard. Returns the selected text, or None if no selection.

pub fn value(&self) -> TextFieldValue

Returns the current value snapshot. Creates composition dependency when read during composition.

pub fn add_listener( &self, listener: impl Fn(&TextFieldValue) + 'static, ) -> usize

Adds a listener that is called when the value changes.

Returns the listener index for removal.

pub fn set_selection(&self, selection: TextRange)

Sets the selection directly without going through undo stack. Use this for transient selection changes like during drag selection.

pub fn can_undo(&self) -> bool

Returns true if undo is available.

pub fn can_redo(&self) -> bool

Returns true if redo is available.

pub fn undo(&self) -> bool

Undoes the last edit. Returns true if undo was performed.

pub fn redo(&self) -> bool

Redoes the last undone edit. Returns true if redo was performed.

pub fn edit<F>(&self, f: F)

where F: FnOnce(&mut TextFieldBuffer),

Edits the text field content.

The provided closure receives a mutable buffer that can be used to modify the text and selection. After the closure returns, the changes are committed and listeners are notified.

Undo Coalescing

Consecutive character insertions within the coalescing timeout are grouped into a single undo entry. The group breaks when:

• Timeout expires (1 second between edits)
• Whitespace or newline is typed
• Cursor position jumps (non-consecutive insert)
• A non-insert operation occurs (delete, paste multi-char, etc.)

Panics

Panics if called while already editing (no concurrent or nested edits).

pub fn flush_undo_group(&self)

Flushes any pending undo snapshot to the undo stack. Call this when a coalescing break is desired (e.g., focus lost).

pub fn set_text(&self, text: impl Into<String>)

Sets the text and places cursor at end.

pub fn set_text_and_select_all(&self, text: impl Into<String>)

Sets the text and selects all.

Trait Implementations

impl Clone for TextFieldState

fn clone(&self) -> TextFieldState

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TextFieldState

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for TextFieldState

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for TextFieldState

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.