Enum CursorAffinity 

pub enum CursorAffinity {
    Downstream,
    Upstream,
}

Disambiguates the two visual placements a single character position can have at a soft-wrap boundary. A long paragraph that wraps across lines K and K+1 has one character position N that sits at both the END of line K and the START of line K+1; affinity picks which one the caret renders at and which line Home/End-style navigation considers “current”.

Affinity is a display concern: it makes no sense without a layout engine and a wrap width. It is never persisted with the text model (cf. Cocoa NSSelectionAffinity on NSTextView, not on NSTextStorage; Chromium PositionWithAffinity at the editing layer, not on Position; same in Qt and CodeMirror).

At positions that are NOT wrap boundaries — the interior of a line, the start of the first wrap-line, the end of the last wrap-line of a paragraph — affinity is a no-op and the rendering is identical.

Variants

Downstream

Place the caret at the END of the previous wrap line. This is the visual “trailing” placement and the default for any position not produced by an upstream-side interaction.

Upstream

Place the caret at the START of the next wrap line.

Trait Implementations

impl Clone for CursorAffinity

fn clone(&self) -> CursorAffinity

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CursorAffinity

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

Formats the value using the given formatter.

impl Default for CursorAffinity

fn default() -> CursorAffinity

Returns the “default value” for a type.

impl PartialEq for CursorAffinity

fn eq(&self, other: &CursorAffinity) -> 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 Copy for CursorAffinity

impl Eq for CursorAffinity

impl StructuralPartialEq for CursorAffinity