SelectionUTF16ToUnit
Forms, interaction, unicode
Description
Converts a zero-based UTF-16 position within the active edit value into a count of complete selection units
With fsuUTF16CodeUnit the index is returned unchanged after clamping
With fsuUnicodeCodePoint or fsuGraphemeCluster the boundary table for that unit is built on demand and searched, so a position inside a surrogate pair maps to its containing code point and a position inside a cluster maps to the preceding cluster boundary
Boundary tables are cached for the current edit value and discarded whenever that value changes
Declaration
function SelectionUTF16ToUnit(Index: Integer;
IndexUnit: TPDFlibFormSelectionUnit): Integer;Parameters
| Index | Zero-based UTF-16 position, clamped into the range 0 through the current value length |
|---|---|
| IndexUnit | Selection unit the result is counted in |
Return value
Returns the number of complete code points or grapheme clusters that precede the UTF-16 position, or the clamped index itself for fsuUTF16CodeUnit
Example
// A surrogate pair counts as one code point unit
Session.SetEditValue('A' + WideChar($D83D) + WideChar($DE00) + 'B');
CaretUnits := Session.SelectionUTF16ToUnit(3, fsuUnicodeCodePoint);
// CaretUnits = 2See also
SelectionUnitToUTF16, GetSelectionRange, SetSelectionRange, TPDFlibFormSelectionUnit, TPDFlibFormSession