Turn off NumLock

Problem/Question/Abstract:

Using Delphi 5, I'm trying to setup a routine that would automatically turn off the NUMLOCK key when loaded. Assume that I am writing a standalone utility that could be loaded in the startup folder to do this function.

Answer:

Solve 1:

procedure SwitchToggleKey(Key: byte; State: boolean);
var
  ks: TKeyboardState;
  ScanCode: integer;
begin
  if not key in [VK_CAPITAL, VK_NUMLOCK, VK_SCROLL, VK_INSERT] then
    exit;
  if (key = VK_NUMLOCK) and (Win32Platform = VER_PLATFORM_WIN32_WINDOWS) then
  begin
    GetKeyboardState(ks); {for Win95/98}
    if state then
      ks[key] := ks[key] or 1
    else
      ks[key] := ks[key] and 254;
    SetKeyboardState(ks);
  end
  else if odd(GetKeyState(key)) <> state then
  begin
    ScanCode := MapVirtualKey(key, 0);
    keybd_event(key, ScanCode, {KEYEVENTF_EXTENDEDKEY} 0, 0);
    {Simulate a key release}
    keybd_event(key, ScanCode, {KEYEVENTF_EXTENDEDKEY or } KEYEVENTF_KEYUP, 0);
  end;
end;

Note that not all controls "honor" the INSERT key, and others will only respond to the INSERT key while they have focus. I'm surprised that the Extended Key "attribute" works for the non-extended keys. Strangely enough, it works as well without KEYEVENTF_EXTENDEDKEY.


Solve 2:

procedure SimulateKeystroke(Key: byte; extra: DWORD);
begin
  keybd_event(Key, extra, 0, 0);
  keybd_event(Key, extra, KEYEVENTF_KEYUP, 0);
end;

function IsKeyToggled(key: byte): boolean;
var
  state: word;
begin
  state := windows.GetKeyState(key);
  result := (state mod 128) = 1;
end;

function CapsLockStatus: boolean;
begin
  result := IsKeyToggled(VK_CAPITAL);
end;

function NumLockStatus: boolean;
begin
  result := IsKeyToggled(VK_NUMLOCK);
end;

procedure ToggleCapsLock;
begin
  SimulateKeystroke(VK_CAPITAL, 0);
end;

procedure ToggleNumLock;
begin
  SimulateKeystroke(VK_NUMLOCK, 0);
end;

procedure TForm1.btnOnClick(Sender: TObject);
begin
  if not NumLockStatus then
    ToggleNumLock;
end;

procedure TForm1.btnOffClick(Sender: TObject);
begin
  if NumLockStatus then
    ToggleNumLock;
end;


Solve 3:

I want to determine the state of the Num lock key on the keyboard and set it to on when my application begins or opens a specific form.

Note that the keyboard LED may not reflect the keys state correctly on all Windows platforms if you set it this way in code.

procedure SetLockKey(vcode: Integer; down: Boolean);
begin
  if Odd(GetAsyncKeyState(vcode)) <> down then
  begin
    keybd_event(vcode, MapVirtualkey(vcode, 0), KEYEVENTF_EXTENDEDKEY, 0);
    keybd_event(vcode, MapVirtualkey(vcode, 0), KEYEVENTF_EXTENDEDKEY or
      KEYEVENTF_KEYUP, 0);
  end;
end;

SetLockKey(VK_NUMLOCK, True); {num lock down}