Lazarus Pascal Requires Chilkat v11.7.0+

Get Every Occurrence of a Label in a PDF

See more PDF Text Extraction Examples

Demonstrates the "labelOccurrence" option. When the same label appears more than once (for example "Total:" on each of several receipts), "first" (the default) uses the first occurrence, "all" returns every occurrence with its page, and a number selects one occurrence. Lazarus Pascal

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Pdf,
  Chilkat.JsonObject;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  pdf: TPdf;
  json: TJsonObject;
  jsonOut: TJsonObject;
  i: Integer;
  count_i: Integer;

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 (three receipts, one per page) is available at three_receipts.pdf

  pdf := TPdf.Create;
  success := pdf.LoadFile('qa_data/pdf/three_receipts.pdf');
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  json := TJsonObject.Create;
  jsonOut := TJsonObject.Create;

  //  Each of the three pages is a receipt with a "Total:" line.
  json.UpdateString('label','Total');
  json.UpdateString('labelValue','right');

  //  By default only the first occurrence (in reading order) is used.
  success := pdf.ExtractText('text',json,jsonOut);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;
  WriteLn('First total: ' + jsonOut.StringOf('text'));

  //  labelOccurrence "all" returns every occurrence.  The "text" member holds the values joined
  //  by line breaks, and labelMatches has one entry per occurrence with its page.
  json.UpdateString('labelOccurrence','all');
  success := pdf.ExtractText('text',json,jsonOut);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  i := 0;
  count_i := jsonOut.SizeOfArray('labelMatches');
  while i < count_i do
    begin
      jsonOut.I := i;
      WriteLn('Page ' + jsonOut.IntOf('labelMatches[i].page') + ' total: ' + jsonOut.StringOf('labelMatches[i].text'));
      i := i + 1;
    end;

  //  A number selects one occurrence: 2 is the second.
  json.UpdateInt('labelOccurrence',2);
  success := pdf.ExtractText('text',json,jsonOut);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;
  WriteLn('Second total: ' + jsonOut.StringOf('text'));

  //  The occurrences are counted over the selected pages, so combining "pages" with the label
  //  is another way to pick one receipt:
  json.UpdateString('labelOccurrence','first');
  json.UpdateString('pages','3');
  json.UpdateString('label','Receipt No.');
  success := pdf.ExtractText('text',json,jsonOut);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;
  WriteLn('Receipt number on page 3: ' + jsonOut.StringOf('text'));

  //  Sample output:

  //  First total: $19.86
  //  Page 1 total: $19.86
  //  Page 2 total: $17.34
  //  Page 3 total: $23.62
  //  Second total: $17.34
  //  Receipt number on page 3: 1003


  pdf.Free;
  json.Free;
  jsonOut.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.