HPDFShapeHeadlessTextOrderedSpan Function

Shape a selected style span against a complete physical line using paragraph-derived embedding levels, scripts and visual positions

function HPDFShapeHeadlessTextOrderedSpan(const Context: UnicodeString;
  FirstUnit, UnitCount: Integer; const Order: THPDFHeadlessTextOrder;
  const FontBytes: SysUtils.TBytes; MaximumGlyphs: Integer;
  CancellationToken: THPDFCancellationToken;
  CharacterAdvance: Double = 0; WordAdvance: Double = 0): THPDFHeadlessShapedGlyphs;

Order must cover every UTF-16 unit of the complete physical-line Context; obtain it from HPDFResolveHeadlessTextLineOrder or HPDFReorderHeadlessTextLine

FirstUnit and UnitCount select complete scalars within the physical line; the real HarfBuzz buffer receives the surrounding line text whilst direction and script come from the resolved paragraph order

Returned glyph source offsets are relative to the selected style span; glyph IDs, advances and offsets use the real embedded font and a scale of 1000 units per em

The function validates matching arrays, unique scalar visual ranks, embedding levels, surrogate consistency, finite spacing, glyph limits and cancellation; malformed order does not silently fall back to isolated direction detection

Character spacing is applied once per shaped cluster apart from a cluster containing only Unicode directional controls; word spacing applies to a space cluster, and callers retain their original logical value and style text separately from the visual glyph order