Struct Selection 

pub struct Selection {
    pub anchor: usize,
    pub focus: usize,
}

A text selection defined by two byte offsets into the source string.

When anchor == focus the selection is a collapsed caret.

Fields

anchor: usize

Byte offset where the selection started (the fixed end).

focus: usize

Byte offset of the current cursor / the moving end.

Implementations

impl Selection

pub fn new(offset: usize) -> Self

Create a collapsed selection (caret) at offset.

pub fn extend_to(&mut self, focus: usize)

Extend the selection so that the focus moves to focus.

pub fn is_collapsed(&self) -> bool

Returns true when anchor and focus are at the same position.

pub fn normalized(&self) -> (usize, usize)

Returns (start, end) in ascending byte-offset order.

pub fn byte_to_grapheme(text: &str, byte_offset: usize) -> usize

Convert a UTF-8 byte offset to a grapheme cluster index.

A “grapheme cluster” here is defined as a sequence of bytes whose first byte has the form 0b0xxx_xxxx (ASCII) or 0b11xx_xxxx (leading multibyte byte). This is a simplified model; for full Unicode grapheme cluster segmentation use the unicode-segmentation crate (not a dependency here per the Pure Rust / no-extra-crate policy).

pub fn grapheme_to_byte(text: &str, grapheme_idx: usize) -> usize

Convert a grapheme cluster index to the byte offset of its first byte.

pub fn highlight_rects( &self, glyphs: &[Vec<GlyphPosition>], line_height: f32, ) -> Vec<(f32, f32, f32, f32)>

Compute highlight rectangles for the selected region.

Returns Vec<(x, y, w, h)> — one rect per line that is (even partially) covered by the selection.

pub fn extend_word_forward(text: &str, byte_offset: usize) -> usize

Return the byte offset just past the end of the word that starts at or after byte_offset.

pub fn extend_word_backward(text: &str, byte_offset: usize) -> usize

Return the byte offset of the start of the word at or before byte_offset.

pub fn extend_line_start( glyphs: &[Vec<GlyphPosition>], byte_offset: usize, ) -> usize

Return the byte offset of the first glyph on the line that contains byte_offset.

pub fn extend_line_end( glyphs: &[Vec<GlyphPosition>], byte_offset: usize, ) -> usize

Return the byte offset past the last glyph on the line that contains byte_offset.

Trait Implementations

impl Clone for Selection

fn clone(&self) -> Selection

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Selection

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

Formats the value using the given formatter.

impl PartialEq for Selection

fn eq(&self, other: &Selection) -> 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.

impl Eq for Selection

impl StructuralPartialEq for Selection