Bitmap soll gelegentlich unsichtbar sein

[Sir Rufo]

Wieso, die Klasse erfüllt genau das, was du gefordert hast, auch in dem von dir beschriebenen Kontext

Delphi-Quellcode:

type
  TKlasseB = class
  private
    FBitmap: TLayerBitmap;
  protected
    function GetBitmap: TBitmap;
    procedure SetBitmap( const Value : TBitmap );
    function GetBitmapEnabled : Boolean;
    procedure SetBitmapEnabled( const Value : Boolean );
  public
    constructor Create;
    destructor Destroy; override;
    property Bitmap: TBitmap read GetBitmap write SetBitmap;
    property BitmapEnabled: Boolean read GetBitmapEnabled write SetBitmapEnabled;
  end;

constructor TKlasseB.Create;
begin
  inherited;
  FBitmap := TLayerBitmap.Create;
end;

destructor TKlasseB.Destroy;
begin
  FBitmap.Free;
  inherited;
end;

function TKlasseB.GetBitmap: TBitmap;
begin
  Result := FBitmap;
end;

procedure TKlasseB.SetBitmap( const Value : TBitmap );
begin
  FBitmap.Assign( Value );
end;

function TKlasseB.GetBitmapEnabled : Boolean;
begin
  Result := FBitmap.CanDraw;
end;

procedure TKlasseB.SetBitmapEnabled( const Value : Boolean );
begin
  FBitmap.CanDraw := Value;
end;