//---------------------------------------------------------------------------
// Generowanie kodow kreskowych Interleaved Code 2 of 5
// www.algorytm.org
// (c)2007 Tomasz Lubinski

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Image1: TImage;
    Button1: TButton;
    Kod: TEdit;
    procedure Button1Click(Sender: TObject);
  private
    curentPos: Integer;
    procedure DrawBars(txt: String);
    procedure DrawSignBars(bars: array of Byte); overload;
    procedure DrawSignBars(bars: array of Char; spaces: array of Char); overload;
    function Check(txt: String): Boolean;
    function CheckLetter(ch: Char): Boolean;
    function GetLetterValue(ch: Char) : Integer;
    function CheckDigit(txt: String): Integer;
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

  codeI25sign: array[0..9] of char = (
      '0', '1', '2', '3', '4', '5', '6', '7', '8', '9');

  codeI25bars: array[0..9] of array[0..4] of char = (
     ('N', 'N', 'W', 'W', 'N'),
     ('W', 'N', 'N', 'N', 'W'),
     ('N', 'W', 'N', 'N', 'W'),
     ('W', 'W', 'N', 'N', 'N'),
     ('N', 'N', 'W', 'N', 'W'),
     ('W', 'N', 'W', 'N', 'N'),
     ('N', 'W', 'W', 'N', 'N'),
     ('N', 'N', 'N', 'W', 'W'),
     ('W', 'N', 'N', 'W', 'N'),
     ('N', 'W', 'N', 'W', 'N')
        );

   start: array[0..3] of byte = (
        1, 0, 1, 0
        );

   stop: array[0..3] of byte = (
        1, 1, 0, 1
        );

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin


        if Check(Kod.Text) = False then
            begin
                ShowMessage('Incorrect text');
                exit;
            end;

        DrawBars(Kod.Text);

end;

function TForm1.Check(txt: String): Boolean;
var
        i: Integer;
        res: Boolean;
begin
        res := True;

        if (Length(txt) mod 2) = 0 then
                res := False;

        for i:=1 to Length(txt) do
                if (CheckLetter(txt[i])) = False then
                        begin
                                res := False;
                                break;
                        end;

        Result := res;
end;

function TForm1.CheckLetter(ch: Char): Boolean;
var
        i: Integer;
        res: Boolean;
begin
        res := False;

        for i:=Low(codeI25sign) to High(codeI25sign) do
                if codeI25sign[i] = ch then
                        begin
                                res := True;
                                break;
                        end;

        Result := res;
end;

// returns letter value for check digit
function TForm1.GetLetterValue(ch: Char) : Integer;
var
        i: Integer;
begin
        Result := 0;

        for i:=Low(codeI25sign) to High(codeI25sign) do
                if (codeI25sign[i] = ch) then
                        begin
                                Result := i;
                                break;
                        end;
end;

// return check digit
function TForm1.CheckDigit(txt: String): Integer;
var
        i, sum, w1, w2 : Integer;
begin
        sum := 0;
        w1 := 0;
        w2 := 0;

        for i:=1 to length(txt) do
        begin
                if (i mod 2) = 0 then
                        w1 := w1 + getLetterValue(txt[i])
                else
                        w2 := w2 + getLetterValue(txt[i]);
        end;

        if (length(txt)) mod 2 = 0 then
                w1 := w1 * 3
        else
                w2 := w2 * 3;

        sum := w1 + w2;
        sum := sum mod 10;
        sum := 10 - sum;
        sum := sum mod 10;

        Result := sum;

end;

procedure TForm1.DrawBars(txt: String);
var
        i, odd, even : Integer;
begin
        curentPos := 0;
        Image1.Canvas.Brush.Color := clWhite;
        Image1.Canvas.Rectangle(0, 0, 441, 121);

        //print start character
        drawSignBars(start);

        //print characters
        for i:=1 to Length(txt) div 2 do
        begin
                odd := getLetterValue(txt[2*(i-1) + 1]);
                even := getLetterValue(txt[2*(i-1) + 2]);
                drawSignBars(codeI25bars[odd], codeI25bars[even]);
        end;

        //print the last digit and check digit
        odd := getLetterValue(txt[Length(txt)]);
        drawSignBars(codeI25bars[odd], codeI25bars[CheckDigit(txt)]);

        //print stop character
        drawSignBars(stop);

        //Draw text
        Image1.Canvas.Font.Size := 10;
        Image1.Canvas.Brush.Color := clWhite;
        Image1.Canvas.Font.Color := clBlack;
        Image1.Canvas.TextOut(curentPos div 2 + 20 - Length(txt)*3, 100, txt);
end;

procedure TForm1.DrawSignBars(bars: array of Byte);
var
        i : Integer;
begin
        Image1.Canvas.Brush.Color := clBlack;

        //print bars
        for i:=low(bars) to high(bars) do
                begin
                        if (bars[i] = 1) then
                                Image1.Canvas.Rectangle(curentPos + 20, 10, curentPos + 22, 100);

                        curentPos := curentPos + 2;
                end;
end;

procedure TForm1.DrawSignBars(bars: array of Char; spaces: array of Char);
var
        i : Integer;
begin
        Image1.Canvas.Brush.Color := clBlack;

        //print bars
        for i:=low(bars) to high(bars) do
                begin
                        if (bars[i] = 'W') then // wide bar
                                begin
                                        Image1.Canvas.Rectangle(curentPos + 20, 10, curentPos + 24, 100);
                                        curentPos := curentPos + 4;
                                end
                        else                   // narrow bar
                                begin
                                        Image1.Canvas.Rectangle(curentPos + 20, 10, curentPos + 22, 100);
                                        curentPos := curentPos + 2;
                                end;

                        if (spaces[i] = 'W') then // wide space
                                curentPos := curentPos + 4
                        else                      // narrow space
                                curentPos := curentPos + 2;

                end;
end;

end.