THotPDF Shaping Subset and ToUnicode Mapping Methods

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THotPDF API reference

THotPDF Methods Auto Shaping GSUB

記錄讓 shaped GIDs 正確 render 與 extract 的 glyph-subset 與 ToUnicode plumbing

Delphi 語法

procedure EnableShapingFeatureForSubset(const FeatureTag: AnsiString); overload;

procedure EnableShapingFeatureForSubset(Feature: THPDFShapingFeature); overload;

procedure MarkUnicodeGlyphUsed(GID: Word);

procedure RegisterToUnicodeReverseMapping(SubstCodepoint: Cardinal; const SourceCodepoints: array of Cardinal);

procedure ClearToUnicodeReverseMappings;

function ToUnicodeReverseMappingCount: Integer;

function AssignSyntheticCodepointForGID(GID: Word; out SyntheticCP: Word): Boolean;

function GetSyntheticCodepointForGID(GID: Word): Word;

procedure MarkSyntheticCpRTL(Cp: Word);

function IsRTLSyntheticCp(Cp: Word): Boolean;

function IsRTLSyntheticGID(GID: Word): Boolean;

Covered APIs

API	使用注意事項
`EnableShapingFeatureForSubset`	Marks GSUB features whose output glyphs must be retained in the embedded subset
`MarkUnicodeGlyphUsed`	Adds a returned substitute GID to the embedded font subset closure
`RegisterToUnicodeReverseMapping`	Registers a substitute codepoint to source-codepoint mapping for extraction and accessibility
`ClearToUnicodeReverseMappings`	Clears all caller-registered reverse mappings for the current document
`ToUnicodeReverseMappingCount`	Returns the number of registered reverse mappings
`AssignSyntheticCodepointForGID`	Allocates a private-use synthetic codepoint that renders a glyph ID through CIDToGIDMap
`GetSyntheticCodepointForGID`	Returns the synthetic codepoint already assigned to a glyph ID
`MarkSyntheticCpRTL`	Marks a synthetic codepoint as right-to-left so emit ordering remains correct
`IsRTLSyntheticCp`	Reports whether a synthetic codepoint was marked for right-to-left emission
`IsRTLSyntheticGID`	Reports whether a glyph ID resolves to a synthetic codepoint marked for right-to-left emission

使用注意事項

當 shaping workflow 輸出的 glyph IDs 無法透過一般 Unicode cmap entry 到達時，請使用這些 APIs。Synthetic codepoints 會透過 CIDToGIDMap 路由 rendering，而 reverse mappings 則會為 text extraction 還原原始 source codepoints

請參閱： AssignSyntheticCodepointForGID GSUB lookup methods Indic shaping methods