Incremental save session

Komponent: TPdf · Enhed: PDFium

Tilføjer kun ændrede eller nye indirekte objekter, mens hver tidligere output-byte bevares

Syntax

procedure BeginIncrementalSave(AllowSignedDocument: Boolean = False);

function CommitIncrementalSave(Stream: TStream; out Info: TPdfIncrementalCommitInfo): Boolean;

function CommitIncrementalSave(const FileName: string; out Info: TPdfIncrementalCommitInfo): Boolean;

procedure EndIncrementalSave;

property IncrementalSaveActive: Boolean;

AllowSignedDocument	Explicitly permits a session on a signed document; the default rejects it
Stream	TStream that receives the complete accumulated PDF after this commit
FileName	Output path replaced only after a sibling temporary file succeeds
Info	Per-commit statistics returned after the destination write succeeds

Commit Information

ChangedObjectCount	Number of changed or new indirect objects appended by this commit
AppendedByteCount	Bytes appended after the exact previous-output prefix
OutputByteCount	Total bytes in the complete output returned by this commit
RevisionCount	Number of non-empty revisions committed in the current session

Description

BeginIncrementalSave fanger et stabilt PDFium-semantisk snapshot som både sammenligningsbaseline og det første komplette output

Hver commit fanger den aktuelle tilstand, opløser aktive classic-, hybrid-, xref-stream- og object-stream-objekter og sammenligner derefter objektgeneration og nøjagtige body-bytes

Kun ændrede eller nye indirekte objekter skrives efter det foregående output, efterfulgt af den mindste krævede xref- og trailer-revision

En classic-xref-kilde fortsætter med klassiske xref-tabeller, mens en xref-stream-kilde fortsætter med selvindekserede xref-streams

Hvis intet ændredes, returneres det foregående output byte for byte, ingen revision tilføjes, og RevisionCount rykker ikke frem

Fil-overloadet skriver en søskende midlertidig fil, erstatter destinationen atomisk og gendanner sessiontilstand, hvis skrivning eller erstatning fejler

Constraints

Encrypted documents are rejected because appended object bodies would require object-key-aware re-encryption
Signed documents are rejected unless AllowSignedDocument is True; explicit permission does not validate DocMDP or FieldMDP policy
Freeing an existing indirect object is not yet supported and raises EPdfError
The session snapshot path is independent of the Compressed property so object comparison remains stable
The current memory-backed object materializer rejects states of 2 GiB or larger
Unloading the document ends the active session automatically

Example

var
  Info: TPdfIncrementalCommitInfo;
begin
  Pdf.BeginIncrementalSave;
  try
    Pdf.PageNumber := 1;
    Pdf.PageRotation := ro90;
    Pdf.CommitIncrementalSave('revision-1.pdf', Info);
    Pdf.PageRotation := ro180;
    Pdf.CommitIncrementalSave('revision-2.pdf', Info);
  finally
    Pdf.EndIncrementalSave;
  end;
end;