Lazarus Pascal Requires Chilkat v11.7.0+

Fit a QR Code within a Maximum Size

See more QR Code Examples

Demonstrates limiting the size of the image. render.maxWidth and render.maxHeight are the largest image allowed. With render.sizing set to shrinkToFit, QrCode starts from the module size asked for and reduces it, a whole pixel at a time, until the image fits, but never below render.minModuleSize. If it cannot fit, the call fails with noFit rather than returning a code too small to scan. 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/barcode_overview.asp');

  //  Ask for 10-pixel modules, but accept anything down to 3 pixels to stay within 300 x 300.
  json.UpdateInt('render.moduleSize',10);
  json.UpdateString('render.sizing','shrinkToFit');
  json.UpdateInt('render.minModuleSize',3);
  json.UpdateInt('render.maxWidth',300);
  json.UpdateInt('render.maxHeight',300);

  json.UpdateString('output.path','qa_output/qr_fit_300.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('module asked for: ' + jsonOut.StringOf('measurements[0].requestedPitch') + ' pixels');
  WriteLn('module used: ' + jsonOut.IntOf('measurements[0].pitch') + ' pixels');
  WriteLn('image: ' + jsonOut.IntOf('measurements[0].canvasWidth') + ' x ' + jsonOut.IntOf('measurements[0].canvasHeight') + ' pixels');

  //  The image written to qa_output/qr_fit_300.png:

  //  

  //  The same code cannot fit in 100 x 100 with modules of at least 3 pixels.
  json.UpdateInt('render.maxWidth',100);
  json.UpdateInt('render.maxHeight',100);
  success := fmt.QrCode('generate',json,jsonOut);
  if (success = False) then
    begin
      WriteLn('100 x 100: ' + jsonOut.StringOf('errors[0].code') + ' (' + jsonOut.StringOf('errors[0].message') + ')');
    end;

  //  Sample output:

  //  module asked for: 10 pixels
  //  module used: 7 pixels
  //  image: 287 x 287 pixels
  //  100 x 100: noFit (the symbol does not fit the render constraints: minModuleSize)


  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.