THotPDF Font Fallback Methods

Configures ordered fallback faces and exposes coverage and vertical-metric diagnostics

Declarations

procedure SetFontFallbackChain(Script: THPDFFontScript;
  const FontNames: array of AnsiString);
procedure ClearFontFallbackChain(Script: THPDFFontScript);
procedure ClearAllFontFallbackChains;
function FontFallbackCount(Script: THPDFFontScript): Integer;
function FontFallbackName(Script: THPDFFontScript;
  Index: Integer): AnsiString;
function FontScriptForCodePoint(CodePoint: Cardinal): THPDFFontScript;
function ResolveFontForCodePoint(CodePoint: Cardinal;
  const PrimaryFontName: AnsiString;
  out ResolvedFontName: AnsiString): boolean; overload;
function ResolveFontForCodePoint(CodePoint: Cardinal;
  const PrimaryFontName: AnsiString; const FontStyle: TFontStyles;
  out ResolvedFontName: AnsiString): boolean; overload;
function AnalyzeUnresolvedGlyphs(const Text: WideString;
  const PrimaryFontName: AnsiString): THPDFUnresolvedGlyphInfoArray; overload;
function AnalyzeUnresolvedGlyphs(const Text: WideString;
  const PrimaryFontName: AnsiString; const FontStyle: TFontStyles):
  THPDFUnresolvedGlyphInfoArray; overload;
function GetUnresolvedGlyphs: THPDFUnresolvedGlyphInfoArray;
procedure ClearUnresolvedGlyphs;
function GetVerticalGlyphMetrics(CodePoint: Cardinal;
  out AdvanceY, OriginY: Integer): boolean;
procedure SetVerticalDefaultMetrics(AdvanceY, OriginY: Integer);

Types

THPDFFontScript = (hfsCommon, hfsLatin, hfsGreek, hfsCyrillic,
  hfsHebrew, hfsArabic, hfsIndic, hfsSoutheastAsian, hfsCJK,
  hfsKana, hfsHangul, hfsEmoji, hfsOther);

THPDFUnresolvedGlyphInfo = record
  CodePoint: Cardinal;
  FontName: AnsiString;
  Script: THPDFFontScript;
  SuggestedFonts: AnsiString;
end;

THPDFUnresolvedGlyphInfoArray = array of THPDFUnresolvedGlyphInfo;

Member topics

• SetFontFallbackChain
• ClearFontFallbackChain
• ClearAllFontFallbackChains
• FontFallbackCount
• FontFallbackName
• FontScriptForCodePoint
• ResolveFontForCodePoint
• AnalyzeUnresolvedGlyphs
• GetUnresolvedGlyphs
• ClearUnresolvedGlyphs
• GetVerticalGlyphMetrics
• SetVerticalDefaultMetrics
• VerticalDefaultAdvanceY
• VerticalDefaultOriginY

Behavior

• ResolveFontForCodePoint checks the primary face first, then the matching script chain, then hfsCommon
• The result is true only when an installed face resolves the scalar without GDI face substitution
• Repeated family, face-style, and scalar probes use a bounded 1024-entry cache that is invalidated after private font registration
• Explicit-style overloads inspect the selected bold and italic face; original overloads retain regular-face behavior
• AnalyzeUnresolvedGlyphs deduplicates repeated unresolved scalar and primary-face pairs
• GetVerticalGlyphMetrics returns registered OpenType vertical metrics when available and exposes the configured defaults otherwise
• SetVerticalDefaultMetrics requires a positive advance in 1000-unit glyph space

Related APIs

• Font Fallback and Vertical Text
• THPDFPage fallback and vertical text methods