How to remember a window's size, state and position

  1const

  2  CRegKey = 'Software\Demos\WdwStateDemo\1.0';

  3 

  4// Helper function to read registry values, and

  5// deal with cases where no values exist

  6function ReadIntFromReg(Reg: TRegistry;

  7  Name: string; Def: Integer): Integer;

  8  {Reads integer with given name from registry

  9  and returns it. If no such value exists, returns

 10  Def default value}

 11begin

 12 if Reg.ValueExists(Name) then

 13    Result := Reg.ReadInteger(Name)

 14  else

 15    Result := Def;

 16end;

 17 

 18procedure TForm1.FormDestroy(Sender: TObject);

 19var

 20  Reg: TRegistry;         // the registry

 21  State: Integer;         // state of window

 22  Pl : TWindowPlacement;  // used for API call

 23  R: TRect;               // used for window pos

 24begin

 25  {Calculate window's normal size and position

 26  using Windows API call - the form's Width, Height,

 27  Top and Left properties will give maximised window

 28  size if form is maximised, which is not what we

 29  want here}

 30  Pl.Length := SizeOf(TWindowPlacement);

 31  GetWindowPlacement(Self.Handle, @Pl);

 32  R := Pl.rcNormalPosition;

 33  Reg := TRegistry.Create;

 34  try

 35    // Open required key - create if doesn't exist

 36    Reg.RootKey := HKEY_CURRENT_USER;

 37    Reg.OpenKey(CRegKey, True);

 38    // Write window size and position

 39    Reg.WriteInteger('Width', R.Right-R.Left);

 40    Reg.WriteInteger('Height', R.Bottom-R.Top);

 41    Reg.WriteInteger('Left', R.Left);

 42    Reg.WriteInteger('Top', R.Top);

 43    // Write out state of window

 44    {Record window state (maximised, minimised or

 45    normal) - special case when minimised since form

 46    window is simply hidden when minimised, and

 47    application window is actually the one

 48    minimised - so we check to see if application

 49    window *is* minimised and act accordingly}

 50    if IsIconic(Application.Handle) then

 51      {minimised - write that state}

 52      State := Ord(wsMinimized)

 53    else

 54      {not minimised - we can rely on window state

 55      of form}

 56      State := Ord(Self.WindowState);

 57    Reg.WriteInteger('State', State);

 58  finally

 59    Reg.Free;

 60  end;

 61end;

 62 

 63procedure TForm1.FormCreate(Sender: TObject);

 64var

 65  Reg: TRegistry;   // the registry

 66  State: Integer;   // state of window

 67begin

 68  Reg := TRegistry.Create;

 69  try

 70    // Open required key - exit if it doesn't exist

 71    Reg.RootKey := HKEY_CURRENT_USER;

 72    if not Reg.OpenKey(CRegKey, False) then Exit;

 73    // Read the window size and position

 74    // - designed form sizes are defaults

 75    Self.Width := ReadIntFromReg(Reg, 'Width', Self.Width);

 76    Self.Height := ReadIntFromReg(Reg, 'Height', Self.Height);

 77    Self.Left := ReadIntFromReg(Reg, 'Left', Self.Left);

 78    Self.Top := ReadIntFromReg(Reg, 'Top', Self.Top);

 79    // Now get window state and restore

 80    State := ReadIntFromReg(Reg, 'State', Ord(wsNormal));

 81    {check if window was minimised - we have special

 82    processing for minimised state since Delphi

 83    doesn't minimise windows - it uses application

 84    window instead}

 85    if State = Ord(wsMinimized) then

 86    begin

 87      {we need to set visible true else form won't

 88      restore properly - but this causes a brief

 89      display of form.

 90      Any ideas on how to stop this?}

 91      Self.Visible := True;

 92      Application.Minimize;

 93    end

 94    else

 95      Self.WindowState := TWindowState(State);

 96  finally

 97    Reg.Free;

 98  end;

 99end;