unit SpBrUnit;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, LResources, Forms, Controls, Graphics, Dialogs,
  StdCtrls, contexthelpunit;

type

  { TSpBrFrm }

  TSpBrFrm = class(TForm)
    HelpBtn: TButton;
    ResetBtn: TButton;
    CancelBtn: TButton;
    ComputeBtn: TButton;
    ReturnBtn: TButton;
    OldRelEdit: TEdit;
    MultKEdit: TEdit;
    NewRelEdit: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    procedure ComputeBtnClick(Sender: TObject);
    procedure FormShow(Sender: TObject);
    procedure HelpBtnClick(Sender: TObject);
    procedure ResetBtnClick(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end; 

var
  SpBrFrm: TSpBrFrm;

implementation

{ TSpBrFrm }

procedure TSpBrFrm.ResetBtnClick(Sender: TObject);
begin
     OldRelEdit.Text := '';
     NewRelEdit.Text := '';
     MultKEdit.Text := '';
end;

procedure TSpBrFrm.FormShow(Sender: TObject);
begin
     ResetBtnClick(self);
end;

procedure TSpBrFrm.HelpBtnClick(Sender: TObject);
begin
  ContextHelpForm.HelpMessage((Sender as TButton).tag);
end;

procedure TSpBrFrm.ComputeBtnClick(Sender: TObject);
var
   oldrel, newrel, Factor : double;
begin
     oldrel := StrToFloat(OldRelEdit.Text);
     Factor := StrToFloat(MultKEdit.Text);
     newrel := (Factor * oldrel) / (1.0 + (Factor - 1.0) * oldrel);
     NewRelEdit.Text := FloatToStr(newrel);
end;

initialization
  {$I spbrunit.lrs}

end.