How to handle KeyBoard input messages on non-windowed objects?

Question

I read here about how to create a Window Handle into a non-windowed conrol. I did just the way I read, but nothing happens. So I come to you guys.

My class is this way right now:

interface  

type

    TMyObject = class
    private
        fMsgHandlerHWND : HWND;
        procedure WndMethod(var Msg: TMessage);
    public
        constructor Create;
        destructor Destroy; Override;
    end;

implementation

constructor TMyObject.Create;
begin
    inherited;
    fMsgHandlerHWND := AllocateHWnd(WndMethod);
end;

destructor TMyObject.Destroy;
begin
   deallocatehwnd(fMsgHandlerHWND);
  inherited;
end;

procedure TMyObject.WndMethod(var Msg: TMessage);
begin
    if Msg.Msg = WM_KEYUP then
        MessageBeep(0)
    else
        Msg.Result := DefWindowProc(fMsgHandlerHWND, Msg.Msg, Msg.wParam, Msg.lParam);
end;

I do use my FormCreate to execute var := TMyObject.Create.

Following the line where Windows sends broadcast messages when I press/release a key (correct me if I'm wrong); I'm not sure why it did not work. Somoeone can tell me what did I do wrong? There is another way to catch KeyBoard input with a non-windowed object? If so, how?

Answer 1

Keyboard events are delivered to the window with input focus. That's never going to be your hidden window.

if you want to catch input events the cleanest way is to use the OnMessage event of the global Application object. All queued messages pass through this event handler. Subscribe to it using a TApplicationEvents instance.