the widget contains a #GdkPixbufAnimation
there is no image displayed by the widget
the widget contains a #GIcon. This image type was added in GTK+ 2.14
the widget contains a named icon. This image type was added in GTK+ 2.6
the widget contains a #GtkIconSet
the widget contains a #GdkPixbuf
the widget contains a [stock item name][gtkstock]
the widget contains a #cairo_surface_t. This image type was added in GTK+ 3.10
Describes the image data representation used by a #GtkImage. If you want to get the image from the widget, you can only get the currently-stored representation. e.g. if the gtk_image_get_storage_type() returns #GTK_IMAGE_PIXBUF, then you can call gtk_image_get_pixbuf() but not gtk_image_get_stock(). For empty images, you can request any storage type (call any of the "get" functions), but they will all return %NULL values.