How to apply a keyboardhook on F1 within the application

Question

For our application we created a Online Help where customers can look up stuff about our application. They can reach this in the menus but I also wanted to make it available by pressing the F1 key where ever you are within our application(since this is mostly used for Help within other applications).

I tried using the RegisterHotKey function but as it turns out, this registers the hotkey system wide. I only want it to open our Online Help when you are within our application.

So i tried to setup a Keyboard hook but this also seems to apply it system wide. Is there a way to make sure that pressing the F1 key within the application will open it, but not when you don't have the application focused?

Code what I tried:

procedure WMHotKey(var Msg: TWMHotKey); message WM_HOTKEY;

procedure TZZ_Main_Form.WMHotKey(var Msg: TWMHotKey);
begin
  if Msg.HotKey = HotKeyIDF1 then btOnlineHelpClick(nil);
end;

Within the FormCreate and FormDestroy:

RegisterHotKey(Handle, HotKeyIDF1, 0, VK_F1);
UnRegisterHotKey(Handle, HotKeyIDF1);

Regarding the keyboard hook, what i tried:

  hkHook := SetWindowsHookEx(WH_KEYBOARD,@KeyboardProc,hInstance,GetCurrentThreadID());

function KeyboardProc(Code, wParam, lParam: Integer): Integer;
var
  url: String;
  ShellInfo: TShellExecuteInfo;
begin
  try
    case wParam of
      VK_F1:
      begin
        url := 'ourOnlineHelpLink'
        if url <> '' then
        begin
          FillChar( ShellInfo, SizeOf( TShellExecuteInfo ), 0 );
          ShellInfo.cbSize := SizeOf( TShellExecuteInfo );
          ShellInfo.fMask := SEE_MASK_NOCLOSEPROCESS or SEE_MASK_FLAG_NO_UI or
                         SEE_MASK_FLAG_DDEWAIT;
          ShellInfo.Wnd := HWnd_Desktop;
          ShellInfo.lpVerb := 'OPEN';
          ShellInfo.lpFile := PChar( url );
          ShellInfo.lpParameters := nil;
          ShellInfo.lpDirectory := nil;
          ShellInfo.nShow := sw_ShowNormal;

          ShellExecuteEx( @ShellInfo );
        end;
      end;
    end;
  finally
     Result := -1;
  end;
end;

Answer 1

You can intercept the F1 application-wide by using TApplicationEvents.OnHelp.

Drop the component on your main form, or in a datamodule that is created before your main form. Double-click the OnHelp event on its events tab, and add code similar to the following (the parameter types changed after Delphi 2007, so I've included support for both):

// Delphi 2007 and earlier
{$IFDEF VER185}
function TMainForm.ApplicationEvents1Help(Command: Word; Data: Integer;
  var CallHelp: Boolean): Boolean;
begin
  CallHelp := False;
  // Call your own procedure to implement help as you'd like
  Result := True;
end;
{$ELSE Greater than D2007}
function TMainForm.ApplicationEvents1Help(Command: Word; Data: NativeInt;
  var CallHelp: Boolean): Boolean;
begin
  CallHelp := False;
  // Call your own procedure to implement help as you'd like
  Result := True;
end;
{$ENDIF}