ScaleRectToFit
fBitmapRect= ScaleRectToFit(fBitmap->Bounds(), r.InsetByCopy(borderwidth, borderwidth));
BRect r = ScaleRectToFit(fBitmap->Bounds(), BRect(0, 0, fMaxWidth - 1, fMaxHeight - 1));
BRect ScaleRectToFit(const BRect &from, const BRect &to);
BRect r = ScaleRectToFit(fImage->Bounds(), BRect(0, 0, 200, 200));
imgsize = ScaleRectToFit(fImage->Bounds(), BRect(0, 0, 200, 200));