Hintergrundform abdunkeln, wenn andere Form Modal geöffnet wird?

[KodeZwerg]

Hier ein Auszug wie ich es mache:

Delphi-Quellcode:

  private
    fHiddenWnd: HWND;
    fHiddenClass: ATOM;

Delphi-Quellcode:

procedure TfrmMain.DestroyHidden;
begin
  if (fHiddenWnd <> 0) then
    DestroyWindow(fHiddenWnd);
  if (fHiddenClass <> 0) then
    Winapi.Windows.UnregisterClass(MakeIntResource(fHiddenClass), HInstance);
  fHiddenWnd := 0;
  fHiddenClass := 0;
  BringToFront;
  Application.ProcessMessages;
end;

procedure TfrmMain.CreateHidden(const Color: TColor = COLOR_WINDOW; const AlphaBlend: Boolean = True; const AlphaBlendValue: Integer = 127; const Transparent: Boolean = True; const ExcludeBorder: Boolean = True);
  function HiddenProc(fWnd: HWND; fMsg: UINT; fWParam: WPARAM; fLParam: LPARAM): LRESULT; stdcall;
  begin
    Result := DefWindowProc(fWnd, fMsg, fWParam, fLParam);
  end;
var
  WndClass: TWndClass;
  S: string;
  BorderWidth: Integer;
  hMenuHandle: HMENU;
  dwExStyle: DWORD;
begin
  if ((fHiddenClass <> 0) or (fHiddenWnd <> 0)) then
    DestroyHidden;
  BorderWidth := 0;
  if (ExcludeBorder) then
    BorderWidth := BorderWidth + GetSystemMetrics(SM_CYSIZEFRAME) + GetSystemMetrics(SM_CYEDGE) + GetSystemMetrics(SM_CYBORDER);
  FillChar(WndClass, SizeOf(WndClass), 0);
  WndClass.style := CS_NOCLOSE or CS_VREDRAW or CS_HREDRAW;
  WndClass.lpfnWndProc := @HiddenProc;
  WndClass.cbClsExtra := 0;
  WndClass.cbWndExtra := 0;
  WndClass.hInstance := HInstance;
  WndClass.hIcon := LoadIcon(0, IDI_APPLICATION);
  WndClass.hCursor := LoadCursor(0, IDC_APPSTARTING);
  if (Color < 31) then
    WndClass.hbrBackground := GetSysColorBrush(Color)
    else
    WndClass.hbrBackground := GetSysColorBrush(COLOR_WINDOW);
  WndClass.lpszMenuName := '';
  S := Format('%s@%x', [ExtractFileName(Application.ExeName), GetCurrentThreadId]);
  WndClass.lpszClassName := PChar(S);
  fHiddenClass := Winapi.Windows.RegisterClass(WndClass);
  Sleep(1);
  dwExStyle := WS_EX_TOOLWINDOW;
  if (Transparent) then
    dwExStyle := dwExStyle or WS_EX_TRANSPARENT;
  if (AlphaBlend) then
    dwExStyle := dwExStyle or WS_EX_LAYERED;
  if (fHiddenClass = 0) then
    Exit
  else
    fHiddenWnd := CreateWindowEx(dwExStyle,
                          MakeIntResource(fHiddenClass),
                          PChar(S),
                          WS_POPUP or WS_VISIBLE or WS_CLIPSIBLINGS or WS_CLIPCHILDREN,
                          Self.Left + BorderWidth, Self.Top {+ GetSystemMetrics(SM_CYCAPTION) + BorderWidth},
                          Self.Width - (BorderWidth * 2), Self.Height - BorderWidth {- BorderWidth - GetSystemMetrics(SM_CYCAPTION)},
                          Self.Handle, 0, HInstance, nil);
  if (fHiddenWnd <> 0) then
    begin
      if AlphaBlend then
        Winapi.Windows.SetLayeredWindowAttributes(fHiddenWnd, 0, AlphaBlendValue, LWA_ALPHA or ULW_ALPHA);
      EnableWindow(fHiddenWnd, LongBool(not Transparent));
      hMenuHandle := GetSystemMenu(fHiddenWnd, False);
      if (hMenuHandle <> 0) then
        begin
          DeleteMenu(hMenuHandle, SC_SIZE, MF_BYCOMMAND);
          DeleteMenu(hMenuHandle, SC_MAXIMIZE, MF_BYCOMMAND);
          DeleteMenu(hMenuHandle, SC_MINIMIZE, MF_BYCOMMAND);
          DeleteMenu(hMenuHandle, SC_RESTORE, MF_BYCOMMAND);
          DeleteMenu(hMenuHandle, SC_MOVE, MF_BYCOMMAND);
          DeleteMenu(hMenuHandle, SC_CLOSE, MF_BYCOMMAND);
          DeleteMenu(hMenuHandle, 0, MF_BYCOMMAND);
          CloseHandle(hMenuHandle);
        end;
    end;
  Application.ProcessMessages;
end;

Beispiel:

Delphi-Quellcode:

procedure TfrmMain.Click(Sender: TObject);
begin
  CreateHidden(Random(30));
  with TfrmOptions.Create(nil) do
    begin
      try
        Icon := Self.Icon;
        ShowModal;
      finally
        Release;
      end;
    end;
  DestroyHidden;
end;