Lazarus Pascal Requires Chilkat v11.7.0+

QR Code with a Text Caption

See more QR Code Examples

Demonstrates printing a line of text under a QR code, such as the order number or the address the code holds, so that a person can read it too. render.text turns the caption on and gives its value, which is printable ASCII and is drawn in a built-in font that needs no font files. The caption can go above or below the symbol, be aligned left, center or right, and be scaled. 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.Formats,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  json: TJsonObject;
  fmt: TFormats;
  jsonOut: TJsonObject;

begin
  success := False;

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

  json := TJsonObject.Create;
  json.UpdateString('payload.text','https://www.chilkatsoft.com/order/12345');
  json.UpdateInt('render.moduleSize',6);

  //  The caption.  It need not be the same as the text in the QR code.
  json.UpdateBool('render.text.enabled',True);
  json.UpdateString('render.text.value','ORDER 12345');
  //  position is "below" (the default) or "above".  alignment is "center" (the default), "left" or "right".
  json.UpdateString('render.text.position','below');
  //  Each dot of the caption's font is drawn this many pixels wide.
  json.UpdateInt('render.text.scale',3);

  json.UpdateString('output.path','qa_output/qr_caption.png');
  json.UpdateBool('output.overwrite',True);
  json.UpdateString('output.return','none');

  fmt := TFormats.Create;
  jsonOut := TJsonObject.Create;
  success := fmt.QrCode('generate',json,jsonOut);
  if (success = False) then
    begin
      WriteLn(fmt.LastErrorText);
      Exit;
    end;

  WriteLn('caption: ' + jsonOut.StringOf('measurements[0].text'));
  WriteLn('caption scale: ' + jsonOut.IntOf('measurements[0].textScale'));
  WriteLn('height added for the caption: ' + jsonOut.IntOf('measurements[0].textBandPx') + ' pixels');
  WriteLn('image: ' + jsonOut.IntOf('measurements[0].canvasWidth') + ' x ' + jsonOut.IntOf('measurements[0].canvasHeight') + ' pixels');

  //  The image written to qa_output/qr_caption.png:

  //  

  //  Sample output:

  //  caption: ORDER 12345
  //  caption scale: 3
  //  height added for the caption: 21 pixels
  //  image: 222 x 243 pixels


  json.Free;
  fmt.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.