Lazarus Pascal Requires Chilkat v11.7.0+

Get the Modules of a QR Code (Bit Matrix)

See more QR Code Examples

Demonstrates getting the QR code itself, as a grid of dark and light modules, to draw with something other than the built-in PNG and SVG output: on a canvas, in a PDF, on a display, or with a label printer language. With output.includeModuleData the response has symbols[0].moduleData, a bit matrix with one bit per module, each row starting on a new byte, most significant bit first, 1 for dark. The quiet zone is not part of the matrix. The example prints the symbol using two characters per module. 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.BinData,
  Chilkat.StringBuilder,
  Chilkat.Formats,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  json: TJsonObject;
  fmt: TFormats;
  jsonOut: TJsonObject;
  width: Integer;
  height: Integer;
  rowBytes: Integer;
  bd: TBinData;
  sbRow: TStringBuilder;
  row: Integer;
  col: Integer;
  b: Integer;
  mask: Integer;

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','CHILKAT');
  json.UpdateBool('output.includeModuleData',True);

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

  width := jsonOut.IntOf('symbols[0].moduleData.width');
  height := jsonOut.IntOf('symbols[0].moduleData.height');
  rowBytes := jsonOut.IntOf('symbols[0].moduleData.rowBytes');
  WriteLn('kind: ' + jsonOut.StringOf('symbols[0].moduleData.kind'));
  WriteLn('modules: ' + width + ' x ' + height + ', ' + rowBytes + ' bytes per row');

  //  The matrix is height rows of rowBytes bytes.
  bd := TBinData.Create;
  success := bd.AppendEncoded(jsonOut.StringOf('symbols[0].moduleData.bytesBase64'),'base64');
  if (success = False) then
    begin
      WriteLn(bd.LastErrorText);
      Exit;
    end;

  sbRow := TStringBuilder.Create;

  mask := 128;
  for row := 0 to height - 1 do
    begin
      sbRow.Clear();
      for col := 0 to width - 1 do
        begin
          //  The module at (col,row) is a bit of the byte at (row * rowBytes) + (col / 8).
          //  The leftmost module of each byte is its most significant bit.
          if ((col mod 8) = 0) then
            begin
              mask := 128;
            end;
          b := bd.GetByte((row * rowBytes) + (col / 8));
          if (((b / mask) mod 2) = 1) then
            begin
              sbRow.Append('##');
            end
          else
            begin
              sbRow.Append('  ');
            end;
          mask := mask / 2;
        end;

      WriteLn(sbRow.GetAsString());
    end;

  //  The same symbol as the PNG that the call also returned:

  //  

  //  Sample output:

  //  kind: bitMatrix
  //  modules: 21 x 21, 3 bytes per row
  //  ##############              ##############
  //  ##          ##      ####    ##          ##
  //  ##  ######  ##  ##  ####    ##  ######  ##
  //  ##  ######  ##  ##          ##  ######  ##
  //  ##  ######  ##  ##  ##  ##  ##  ######  ##
  //  ##          ##  ####  ##    ##          ##
  //  ##############  ##  ##  ##  ##############
  //                  ####
  //  ##  ##########      ####    ##########
  //      ####          ##  ########    ######
  //  ####  ########    ####  ##  ####      ####
  //        ##  ##      ############    ####  ##
  //    ######  ####  ######  ##    ##  ##
  //                  ##  ##  ##    ##  ##    ##
  //  ##############        ##  ##    ##      ##
  //  ##          ##  ##  ##        ######  ####
  //  ##  ######  ##  ####  ##  ##    ##
  //  ##  ######  ##  ##  ############    ##
  //  ##  ######  ##  ##      ##  ####  ##
  //  ##          ##    ##  ########          ##
  //  ##############  ##      ##      ######


  json.Free;
  fmt.Free;
  jsonOut.Free;
  bd.Free;
  sbRow.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.