EnsureSelectionBoundaries

Forms, interaction, unicode

Description

Internal helper of TPDFlibFormSession that builds and caches the Unicode boundary tables for the current edit value

For fsuUnicodeCodePoint it scans the UTF-16 value and records one boundary per code point, treating a valid surrogate pair as a single supplementary code point and an unpaired surrogate as one standalone code point

For fsuGraphemeCluster it builds extended grapheme cluster boundaries so combining sequences and joined emoji remain indivisible

Each table starts with the boundary at zero and stores zero-based UTF-16 offsets, and a non-empty cached table is reused until InvalidateSelectionBoundaries clears it

The tables back every index conversion between UTF-16 code units, Unicode code points and grapheme clusters

Declaration

procedure EnsureSelectionBoundaries(
  IndexUnit: TPDFlibFormSelectionUnit);

Parameters

Example

Session.SetSelectionRange(1, 2, fsuUnicodeCodePoint);
Session.GetSelectionRange(fsuUTF16CodeUnit, Sel);

See also

InvalidateSelectionBoundaries, EnsureVisualCaretOrder, ClampTextLength, SetSelectionRange, GetSelectionRange, TPDFlibFormSelectionUnit, TPDFlibFormSession