BBitmapField
class BBitmapField : public BField
BBitmapField(BBitmap* bitmap);
BBitmapField::BBitmapField(BBitmap* bitmap)
BBitmapField::Bitmap()
BBitmapField::SetBitmap(BBitmap* bitmap)
BBitmapField* bitmapField = static_cast<BBitmapField*>(field);
return static_cast<bool>(dynamic_cast<const BBitmapField*>(field));