HotPDF är ett nativt VCL PDF-bibliotek för Delphi- och C++Builder-program som behöver direkt PDF-skapande och redigering, formulär, annoteringar, kryptering, digitala signaturer, Unicode-teckensnitt, standardmedveten utdata och preflight-rapporter utan extern PDF-runtime.
Den här artikeln är skriven för engineers maintaining PDFs that may already contain signatures, revisions, compressed objects, or repair history. Den behandlar object streams and incremental updates som produktionsnära dokumentteknik, inte som ett isolerat komponentanrop.
Den praktiska risken är att rewriting a file as if it were newly generated can discard revision history, break signatures, or hide damaged cross-reference data. Därför behöver flödet ett skrivet kontrakt, observerbar diagnostik och realistiska regressionsfiler.
Arkitekturbeslut
Understand the existing revision chain. whether existing signatures or audit trails must remain valid / policy for object stream preservation, decompression, or recompression
- whether existing signatures or audit trails must remain valid
- policy for object stream preservation, decompression, or recompression
- repair handling when cross-reference data is inconsistent
- metadata and catalog updates that should be appended instead of rewritten
Implementeringsflöde
Choose full rewrite or incremental save deliberately. The order below keeps the workflow reviewable for Delphi and C++Builder teams.
- inspect the source for signatures, xref streams, object streams, and prior revisions
- select incremental update only when the business goal requires preservation
- write changed objects to a new revision and leave untouched objects stable
- verify signatures, object counts, and cross-reference consistency after saving
- record the reason if a full rewrite was required for repair or normalization
Valideringsbevis
Revision evidence to capture. Keep these fields with the output or support record.
- source revision count, signature presence, xref style, and object stream count
- save mode, changed object identifiers, and whether object streams were preserved
- validator output before and after the update
- signature status for every signed revision after the final file is written
Compressed objects change support diagnostics
Object streams, hybrid cross-reference tables, and incremental saves are normal in modern PDFs. The workflow should know whether it is preserving a revision, appending a new revision, or creating a clean output file.
Review questions before release
Before this reaches production, the team should be able to answer these questions without reading source code.
- Who owns whether existing signatures or audit trails must remain valid?
- What evidence proves source revision count, signature presence, xref style, and object stream count?
- What happens when a full rewrite can invalidate signatures even when visible content is unchanged?
- Which regression file covers record the reason if a full rewrite was required for repair or normalization?
Engineering review notes for object streams and incremental updates
Use these review notes to make sure the feature has moved beyond a demo and can be defended during release, support, and customer escalation.
- Decision: whether existing signatures or audit trails must remain valid. Implementation pressure point: select incremental update only when the business goal requires preservation. Acceptance evidence: validator output before and after the update. Regression trigger: object-stream compression can make diff-based support investigations misleading
- Decision: policy for object stream preservation, decompression, or recompression. Implementation pressure point: write changed objects to a new revision and leave untouched objects stable. Acceptance evidence: signature status for every signed revision after the final file is written. Regression trigger: a full rewrite can invalidate signatures even when visible content is unchanged
- Decision: repair handling when cross-reference data is inconsistent. Implementation pressure point: verify signatures, object counts, and cross-reference consistency after saving. Acceptance evidence: source revision count, signature presence, xref style, and object stream count. Regression trigger: repairing a damaged file may require a support note explaining lost revisions
- Decision: metadata and catalog updates that should be appended instead of rewritten. Implementation pressure point: record the reason if a full rewrite was required for repair or normalization. Acceptance evidence: save mode, changed object identifiers, and whether object streams were preserved. Regression trigger: linearization can be lost after incremental updates unless the workflow rebuilds it
- Decision: whether existing signatures or audit trails must remain valid. Implementation pressure point: inspect the source for signatures, xref streams, object streams, and prior revisions. Acceptance evidence: validator output before and after the update. Regression trigger: object-stream compression can make diff-based support investigations misleading
- Decision: policy for object stream preservation, decompression, or recompression. Implementation pressure point: select incremental update only when the business goal requires preservation. Acceptance evidence: signature status for every signed revision after the final file is written. Regression trigger: a full rewrite can invalidate signatures even when visible content is unchanged
- Decision: repair handling when cross-reference data is inconsistent. Implementation pressure point: write changed objects to a new revision and leave untouched objects stable. Acceptance evidence: source revision count, signature presence, xref style, and object stream count. Regression trigger: repairing a damaged file may require a support note explaining lost revisions
Gränsfall
- a full rewrite can invalidate signatures even when visible content is unchanged
- repairing a damaged file may require a support note explaining lost revisions
- linearization can be lost after incremental updates unless the workflow rebuilds it
- object-stream compression can make diff-based support investigations misleading
Delphi / C++Builder notes
HotPDF Component should sit behind a small service boundary that receives files, streams, profiles, and credentials, then returns output paths, warnings, metrics, and validation status. Important terms include object stream, incremental update, xref stream, revision, signature preservation, repair.
Delphi-kodexempel
Följande Delphi-skiss visar en praktisk servicegräns för detta ämne. Håll policykontroller, loggning och validering utanför det smala produktanropet så att arbetsflödet går att testa.
procedure SaveCompactIncrementalPdf(const OutputFile: string);
var
Pdf: THotPDF;
begin
Pdf := THotPDF.Create(nil);
try
Pdf.FileName := OutputFile;
Pdf.UseXRefStream := True;
Pdf.UseObjectStreams := True;
Pdf.BeginDoc;
AddRevisionContent(Pdf);
Pdf.EndDoc;
CompareObjectStreamProfile(OutputFile);
finally
Pdf.Free;
end;
end;Produktionschecklista
- Run the workflow on an empty file, a normal customer file, and a worst-case file
- Open the generated PDF with the target viewer, validator, printer, or downstream application
- Log product version, profile version, input hash, output path, elapsed time, and warning count
- Keep passwords, certificates, temporary files, and customer data under explicit retention rules
- Add regression documents when a customer file exposes a new edge case