Delphi ActiveX Requires Chilkat v11.7.0+

Remove a PDF's Old Revisions

See more PDF Optimization Examples

Demonstrates dropOldRevisions. A PDF that has been edited and saved several times carries every earlier revision: the superseded objects are still in the file, reachable through the older cross-reference sections. The audit reports them as "oldRevisions", and dropping them is often the single largest saving in a real document. Dropping them requires a full rewrite, which is why it invalidates existing digital signatures. Delphi ActiveX

var
success: Integer;
pdf: TChilkatPdf;
json: TChilkatJsonObject;
jsonOut: TChilkatJsonObject;
fac: TCkFileAccess;

begin
success := 0;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  The PDF used in this example is available at grand_canyon_hiking_guide.pdf

pdf := TChilkatPdf.Create(Self);
success := pdf.LoadFile('qa_data/pdf/grand_canyon_hiking_guide.pdf');
if (success = 0) then
  begin
    Memo1.Lines.Add(pdf.LastErrorText);
    Exit;
  end;

//  How much of this file is superseded revisions?
json := TChilkatJsonObject.Create(Self);
jsonOut := TChilkatJsonObject.Create(Self);
success := pdf.Optimize('audit',json.ControlInterface,jsonOut.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(pdf.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('fileSize:     ' + IntToStr(jsonOut.IntOf('fileSize')));
Memo1.Lines.Add('oldRevisions: ' + IntToStr(jsonOut.IntOf('usage.oldRevisions.bytes')));

//  Drop them, and nothing else, so that the saving is attributable.
json.UpdateBool('compressUncompressed',0);
json.UpdateBool('recompressFlate',0);
json.UpdateBool('replaceLegacyFilters',0);
json.UpdateBool('imagePredictors',0);
json.UpdateBool('dedupeStreams',0);
json.UpdateBool('dedupeObjects',0);
json.UpdateBool('removeUnreferenced',0);
json.UpdateBool('removeUnusedResources',0);
json.UpdateBool('removeUnusedLayers',0);
json.UpdateBool('coalesceContent',0);
json.UpdateBool('tidyContent',0);
json.UpdateBool('subsetFonts',0);
json.UpdateBool('dropOldRevisions',1);

success := pdf.Optimize('optimize',json.ControlInterface,jsonOut.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(pdf.LastErrorText);
    Exit;
  end;

success := pdf.WriteFile('qa_output/grand_canyon_one_revision.pdf');
if (success = 0) then
  begin
    Memo1.Lines.Add(pdf.LastErrorText);
    Exit;
  end;

//  The saving is an estimate: what the old revisions occupied is known exactly, but the writer
//  decides the final layout.  Measure the written file for the real number.
fac := TCkFileAccess.Create(Self);
Memo1.Lines.Add('bytesSaved (reported): ' + IntToStr(jsonOut.IntOf('bytesSaved')));
Memo1.Lines.Add('written file:          ' + IntToStr(fac.FileSize('qa_output/grand_canyon_one_revision.pdf')));