globalmapper.SetChildLayerOpCallback
====================================

.. currentmodule:: globalmapper
.. py:function:: SetChildLayerOpCallback ((function aCallbackFunc, object aUserData)) -> None

    Sets the function to call to report the load or close of a child layer. This happens during draw or export of a map
    catalog or online layer. The layer handle provided via the callback can then be used in other function calls that
    take a layer handle so you can do things like customize vector styles. You can get the parent layer handle by
    calling GetLayerInfo. Notice that the *aCallBackFunc* and *aUserData* are actually part of a tuple, which is passed
    into the function as a single parameter.

    :param function aCallbackFunc: The callback function; see below
    :param object aUserData: User data that will be passed back to callback function. May be any Python object
    :returns: Nothing
    :rtype: None

    The callback function should be a function which has the following parameters:

    :param GM_LayerHandle_t32 aChildLayer: Handle to new loaded layer
    :param GM_ChildLayerOp_t8 aChildLayerOp: The operation (i.e. load or close) that just happened
    :param GM_LayerHandle_t32 aParentLayer: Handle to new loaded layer's parent
    :param object aUserData: User data original provided in call to set this callback
    :param int aReserved: Reserved for future use; must be 0.