Delphi/Lazarus: Get Title of Active Window

Today, I would like to show you how to retrieve the title respectively caption of the window currently having the focus in Windows.

The following function is working with Delphi as well as Lazarus (the unit Windows has to be included).

function GetTitleOfActiveWindow: string;
var
  AHandle: THandle;
  ATitle: string;
  ALen: Integer;
begin
  Result := '';
  AHandle := GetForegroundWindow;

  if AHandle <> 0 then begin
    ALen := GetWindowTextLength(AHandle) + 1;
    SetLength(ATitle, ALen);
    GetWindowText(AHandle, PChar(ATitle), ALen);
    result := Trim(ATitle);
  end;
end;  

First of all, we determine the handle of the window that is in the foreground at the moment and thus has the focus. After that, we are reading out the title of this window returning it as the result of the function.