Hintergrundform abdunkeln, wenn andere Form Modal geöffnet wird?

[DaCoda]

Ich habe mich aber entschieden den Code bzw. Aufruf von Uwe Raabe seinem Basiscode zu verwenden und das "Faden" nicht zu nutzen.
Damit ist der Aufruf aus meiner Sicht schöner/einfacher.

Aufrufbeispiele:

Code:

  ShowModalDimmed(Form, nil);

  ShowModalDimmed(Form, ParentForm);

  ShowModalDimmed(Form, ParentForm, Alphablend, BackColor, Centered);

Function:

Code:

function ShowModalDimmed(aForm: TForm; aParentForm: TForm; AlphaBlendValue: Integer = 100; BackColor: TColor = clGray; Centered: Boolean = True): TModalResult;
var
  Back: TForm;

  Dummy_Rect: TRect;

  targetAlpha: Integer;
  Dummy_Alpha_inc: Integer;
  alphaDiff: Integer;
begin
  Back := TForm.Create(nil);
  try
    Back.AlphaBlend := True;

    targetAlpha := AlphaBlendValue;
    if targetAlpha > 255 then
      targetAlpha := 255;
    if targetAlpha < 1 then
      targetAlpha := 1;

    Back.AlphaBlendValue := targetAlpha;
    Back.Color := BackColor;
    Back.DoubleBuffered := True;
    Back.BorderStyle := bsNone;

    if aParentForm <> nil then begin
      Back.Position := aParentForm.Position;
      Back.RoundedCorners := aParentForm.RoundedCorners;
      Dummy_Rect := GetFormShadow(aParentForm);
      Back.SetBounds(aParentForm.Left + Dummy_Rect.Left, aParentForm.Top + Dummy_Rect.Top, aParentForm.Width - Dummy_Rect.Right, aParentForm.Height - Dummy_Rect.Bottom);
    end else begin
      Back.SetBounds(0, 0, Screen.Width, Screen.Height);
    end;
    Back.Show;

    if Centered then begin
      aForm.Position := poMainFormCenter;
    end;

    Result := aForm.ShowModal;
    Back.Hide;
  finally
    Back.Free;
  end;
end;

Und die Function von Mathias (NoGAD):

Code:

function GetFormShadow(aForm: TForm): TRect;
var
  R1, R2: TRect;
begin
  (* Breite eines Schattens einer TForm *)
  Result := default (TRect);
  if (Win32MajorVersion >= 6) and DwmCompositionEnabled then
  begin
    if DwmGetWindowAttribute(aForm.Handle, DWMWA_EXTENDED_FRAME_BOUNDS, @R1, SizeOf(R1)) = S_OK then
    begin
      R2 := aForm.BoundsRect;
      Result.Left := R2.Left - R1.Left; // Linke Breite des Schattens
      if Result.Left < 0 then
        Result.Left := Result.Left * -1;
      Result.Right := (R2.Right - R1.Right) + Result.Left; // Rechte Breite des Schattens
      if Result.Right < 0 then
        Result.Right := Result.Right * -1;
      Result.Top := R2.Top - R1.Top; // Obere Höhe des Schattens
      if Result.Top < 0 then
        Result.Top := Result.Top * -1;
      Result.Bottom := (R2.Bottom - R1.Bottom) + Result.Top; // Untere Höhe des Schattens
      if Result.Bottom < 0 then
        Result.Bottom := Result.Bottom * -1;
    end;
  end;