Tips dan Trik Delphi

function  fibit(n: Integer): Integer;
var
  a, b, i, temp: Integer;
begin
  temp := 1;
  a := 1;
  b := 1;
  for i := 1 to n - 1 do
  begin
    temp := a + b;
    a := b;
    b := temp;
  end;
  Result := temp;
end;

function MinutesToDaysHoursMinutes(AMinutes: Integer): string;
const
  HOURSPERDAY = 8;    // wieviele Stunden hat der Tag? (Beispiel hier: 1 Arbeitstag)
var
  Days: Integer;
  Hours: Integer;
  Minutes: Integer;
begin
  if (AMinutes > 0) then
  begin
    Hours   := AMinutes div 60;
    Minutes := AMinutes mod 60;
    Days    := Hours div HOURSPERDAY;
    Hours   := Hours mod HOURSPERDAY;
  end
  else
  begin
    Hours   := 0;
    Minutes := 0;
    Days    := 0;
  end;

  Result := Format('%.2d:%.2d:%.2d', [Days, Hours, Minutes]);
end;

function Distance(const x1, y1, x2, y2: Double): Double;
var
  dx: Double;
  dy: Double;
begin
  dx     := x2 - x1;
  dy     := y2 - y1;
  Result := Sqrt(dx * dx + dy * dy);
end;

Function degress(nilai : Double) : Double;
begin
     result := (180 / 3.14159265358979) * nilai;
End;

function GetRegDataType(const strRegPath, strRegValue: string): string;
var
  s: string;
  objRegistry: TRegistry;
begin
  try
    // creates the registru manager object
    objRegistry := TRegistry.Create;
    objRegistry.RootKey := HKEY_LOCAL_MACHINE;

    // opens the specified key if exists
    if objRegistry.OpenKey(strRegPath, false) then begin
      case objRegistry.GetDataType(strRegValue) of
        rdUnknown: s := 'Unknown';
        rdString: s := 'String';
        rdExpandString: s := 'ExpandString';
        rdInteger: s := 'Integer';
        rdBinary: s := 'Binary';
      end;
    end else
      s := '(Can't get data type)';
  finally
    // destroys the registry manager object
    objRegistry.Free;
  end;

  // set the return
  result := s;
end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
procedure ReadFromRegistry;
var
R : TRegistry;
begin
R := TRegistry.Create;
try
    R.RootKey := HKEY_CURRENT_USER;
    if R.OpenKey('\Software\fdehell\srf', True) then
    begin
    Form1.left:=R.ReadInteger('left');
    Form1.top:=R.ReadInteger('top');
    Form1.height:=R.ReadInteger('height');
    Form1.width:=R.ReadInteger('width');
    end;
Finally
R.CloseKey;
R.Free;
end;
end;


procedure WriteToRegistry;
var
R : TRegistry;
begin
R := TRegistry.Create;
try
    R.RootKey := HKEY_CURRENT_USER;
    if R.OpenKey('\Software\fdehell\srf', True) then
    R.WriteInteger('left',Form1.Left);
    R.WriteInteger('top',Form1.Top);
    R.WriteInteger('height', Form1.Height);
    R.WriteInteger('width', Form1.Width);
Finally
R.CloseKey;
R.Free;
end;
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
var
R : TRegistry;
begin
R := TRegistry.Create;
try
    R.RootKey := HKEY_CURRENT_USER;
    if R.OpenKey('\Software\fdehell\srf', True) then
    R.WriteInteger('left',Form1.Left);
    R.WriteInteger('top',Form1.Top);
    R.WriteInteger('height', Form1.Height);
    R.WriteInteger('width', Form1.Width);
Finally
R.CloseKey;
R.Free;
end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
ReadFromRegistry;
end;

procedure TForm1.FormClick(Sender: TObject);
var
  AppName : PChar;
begin
  AppName := PChar( Application.ExeName );
  ShellExecute( Handle, 'open', AppName, nil, nil, SW_SHOWNORMAL );
  close;
end;


end.

uses WinSpool;
... 
procedure TForm1.Button1Click(Sender: TObject);
var
  NewDevMode: TDeviceModeA;
  MyDir: PChar;
  Int: Integer;
begin
  GetMem(MyDir, 500);
  GetPrinterDriverDirectory(nil, nil, 1, MyDir, 200, Int);
  Label1.Caption:=StrPas(MyDir);
  FreeMem(MyDir);
end;

                                        

uses
  Printers;

function GetPixelsPerInchX: Integer;
begin
  Result := GetDeviceCaps(Printer.Handle, LOGPIXELSX)
end;

function GetPixelsPerInchY: Integer;
begin
  Result := GetDeviceCaps(Printer.Handle, LOGPIXELSY)
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
  Caption := Format('x: %d y: %d DPI (dots per inch)',
                   [GetPixelsPerInchX, GetPixelsPerInchY]);
end;

var
  strIni: array[0..MAX_PATH] of Char;
  arrWindows: array[0..64] of Char;
begin
  GetWindowsDirectory(strIni, SizeOf(strIni));
  StrCat(strIni, '\win.ini');
  with TIniFile.Create(strIni) do
    try
      WriteString('windows', 'device', 'HP LaserJet 4 Plus,HPPCL5MS,LPT1:');
    finally
      Free;
    end;

  StrCopy(arrWindows, 'windows');
  SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0, LongInt(@arrWindows));
end;

                                        

uses
  Printers, Messages;

function GetDefaultPrinter: string;
var
  ResStr: array[0..255] of Char;
begin
  GetProfileString('Windows', 'device', '', ResStr, 255);
  Result := StrPas(ResStr);
end;

procedure SetDefaultPrinter1(NewDefPrinter: string);
var
  ResStr: array[0..255] of Char;
begin
  StrPCopy(ResStr, NewdefPrinter);
  WriteProfileString('windows', 'device', ResStr);
  StrCopy(ResStr, 'windows');
  SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0, Longint(@ResStr));
end;

procedure SetDefaultPrinter2(PrinterName: string);
var
  I: Integer;
  Device: PChar;
  Driver: PChar;
  Port: PChar;
  HdeviceMode: THandle;
  aPrinter: TPrinter;
begin
  Printer.PrinterIndex := -1;
  GetMem(Device, 255);
  GetMem(Driver, 255);
  GetMem(Port, 255);
  aPrinter := TPrinter.Create;
  try
    for I := 0 to Printer.Printers.Count - 1 do
    begin
      if Printer.Printers = PrinterName then
      begin
        aprinter.PrinterIndex := i;
        aPrinter.getprinter(device, driver, port, HdeviceMode);
        StrCat(Device, ',');
        StrCat(Device, Driver);
        StrCat(Device, Port);
        WriteProfileString('windows', 'device', Device);
        StrCopy(Device, 'windows');
        SendMessage(HWND_BROADCAST, WM_WININICHANGE,
          0, Longint(@Device));
      end;
    end;
  finally
    aPrinter.Free;
  end;
  FreeMem(Device, 255);
  FreeMem(Driver, 255);
  FreeMem(Port, 255);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  label1.Caption := GetDefaultPrinter2;
end;

//Fill the combobox with all available printers
procedure TForm1.FormCreate(Sender: TObject);
begin
  Combobox1.Items.Clear;
  Combobox1.Items.AddStrings(Printer.Printers);
end;

//Set the selected printer in the combobox as default printer
procedure TForm1.Button2Click(Sender: TObject);
begin
  SetDefaultPrinter(Combobox1.Text);
end;