compositeContext = composite.createContext(getColorModel(), getDestinationColorModel(), renderingHints);
  public void setComposite(Composite comp)  {    composite = comp;    compositeContext = composite.createContext(getColorModel(),                                               getDestinationColorModel(),                                               renderingHints);    if (! (comp.equals(AlphaComposite.SrcOver)))      isOptimized = false;    else      updateOptimization();  }