Delphi DLL Requires Chilkat v11.7.0+

Remove PDF Objects Nothing Refers To

See more PDF Optimization Examples

Demonstrates removeUnreferenced. When a page, an image or a whole section is replaced in an editor, the objects it used often stay in the file with nothing pointing at them any more. They are not old revisions -- they are in the current revision, simply unreachable -- so only a reachability walk from the document catalog finds them. In a publication assembled over several editing passes this is frequently the largest single saving. Delphi DLL

var
success: Boolean;
pdf: HCkPdf;
json: HCkJsonObject;
jsonOut: HCkJsonObject;

begin
success := False;

//  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 watersense_accomplishments.pdf

pdf := CkPdf_Create();
success := CkPdf_LoadFile(pdf,'qa_data/pdf/watersense_accomplishments.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

json := CkJsonObject_Create();
jsonOut := CkJsonObject_Create();
success := CkPdf_Optimize(pdf,'audit',json,jsonOut);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

Memo1.Lines.Add('fileSize: ' + IntToStr(CkJsonObject_IntOf(jsonOut,'fileSize')));
Memo1.Lines.Add('removeUnreferenced would save: ' + IntToStr(CkJsonObject_IntOf(jsonOut,'estimatedSavings.removeUnreferenced')));

//  Optimize with the defaults and see how many objects were actually dropped.
success := CkPdf_Optimize(pdf,'optimize',json,jsonOut);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

success := CkPdf_WriteFile(pdf,'qa_output/watersense_optimized.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

Memo1.Lines.Add('objects removed: ' + IntToStr(CkJsonObject_IntOf(jsonOut,'actions.removeUnreferenced.count')));
Memo1.Lines.Add('bytes saved:     ' + IntToStr(CkJsonObject_IntOf(jsonOut,'actions.removeUnreferenced.bytesSaved')));

//  Nothing a page needs is ever removed: the walk starts at the document catalog and follows every
//  reference, including the ones in annotations, the structure tree, named destinations and the
//  optional-content configuration.
Memo1.Lines.Add('pages after: ' + IntToStr(CkPdf_getNumPages(pdf)));

CkPdf_Dispose(pdf);
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);