THotPDF Shaping Subset and ToUnicode Mapping Methods

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THotPDF API 參考

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;

涵蓋的 API

API	使用注意事項
`EnableShapingFeatureForSubset`	標記必須把輸出 glyph 保留在內嵌子集中的 GSUB features
`MarkUnicodeGlyphUsed`	把回傳的 substitute GID 加入內嵌字型子集閉包
`RegisterToUnicodeReverseMapping`	註冊 substitute codepoint 對 source-codepoint 的對應，供文字擷取與無障礙使用
`ClearToUnicodeReverseMappings`	清除目前文件中所有由呼叫端註冊的反向對應
`ToUnicodeReverseMappingCount`	傳回已註冊反向對應的數量
`AssignSyntheticCodepointForGID`	配置一個 private-use synthetic codepoint，透過 CIDToGIDMap 轉譯指定的 glyph ID
`GetSyntheticCodepointForGID`	傳回已指派給某個 glyph ID 的 synthetic codepoint
`MarkSyntheticCpRTL`	把 synthetic codepoint 標記為右至左，讓發出順序保持正確
`IsRTLSyntheticCp`	回報某個 synthetic codepoint 是否已標記為右至左發出
`IsRTLSyntheticGID`	回報某個 glyph ID 是否會解析到已標記為右至左發出的 synthetic codepoint

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