Lazarus Pascal Requires Chilkat v11.7.0+

QR Code Colors and Transparent Background

See more QR Code Examples

Demonstrates colored QR codes. render.foreground is the color of the dark modules and render.background the color behind them, each as #RRGGBB. Either can instead be an object with a color and an opacity from 0 to 1, and a background opacity of 0 gives a PNG with a transparent background to place over a page or a design. Readers need contrast: keep the modules clearly darker than whatever ends up behind them. 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;
  fmt: TFormats;
  jsonOut: TJsonObject;
  json: TJsonObject;
  json2: TJsonObject;

begin
  success := False;

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

  fmt := TFormats.Create;
  jsonOut := TJsonObject.Create;

  //  Dark blue modules on a pale yellow background.
  json := TJsonObject.Create;
  json.UpdateString('payload.text','https://www.chilkatsoft.com/');
  json.UpdateInt('render.moduleSize',6);
  json.UpdateString('render.foreground','#1B3A6B');
  json.UpdateString('render.background','#FFF8DC');
  json.UpdateString('output.path','qa_output/qr_blue.png');
  json.UpdateBool('output.overwrite',True);
  json.UpdateString('output.return','none');
  success := fmt.QrCode('generate',json,jsonOut);
  if (success = False) then
    begin
      WriteLn(fmt.LastErrorText);
      Exit;
    end;
  WriteLn('colored: ' + jsonOut.StringOf('outputs[0].path') + ', ' + jsonOut.IntOf('outputs[0].byteCount') + ' bytes');

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

  //  

  //  The same modules on a fully transparent background.
  json2 := TJsonObject.Create;
  json2.UpdateString('payload.text','https://www.chilkatsoft.com/');
  json2.UpdateInt('render.moduleSize',6);
  json2.UpdateString('render.foreground','#1B3A6B');
  json2.UpdateString('render.background.color','#FFFFFF');
  json2.UpdateNumber('render.background.opacity','0');
  json2.UpdateString('output.path','qa_output/qr_transparent.png');
  json2.UpdateBool('output.overwrite',True);
  json2.UpdateString('output.return','none');
  success := fmt.QrCode('generate',json2,jsonOut);
  if (success = False) then
    begin
      WriteLn(fmt.LastErrorText);
      Exit;
    end;
  WriteLn('transparent: ' + jsonOut.StringOf('outputs[0].path') + ', ' + jsonOut.IntOf('outputs[0].byteCount') + ' bytes');

  //  qa_output/qr_transparent.png, placed here over a checkerboard and over a colored page
  //  to show that whatever is behind the image shows through:

  //  

  //  Sample output:

  //  colored: qa_output/qr_blue.png, 1345 bytes
  //  transparent: qa_output/qr_transparent.png, 1377 bytes


  fmt.Free;
  jsonOut.Free;
  json.Free;
  json2.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.