TBaseVirtualTree.OnGetNodeDataSize Event

Data management event.

property OnGetNodeDataSize: TVTGetNodeDataSizeEvent;

Triggered when access to a node's data happens the first time but the actual data size is not yet set. Usually you would specify the size of the data you want to have added to each node by NodeDataSize, e.g. SizeOf(TMyRecord) is quite usual there (where TMyRecord is the structure you want to have stored in the node). Sometimes, however it is not possible to determine the node size in advance, so you can leave NodeDataSize being -1 (the default value) and the OnGetNodeDataSize event is triggered as soon as the first regular node is created (the hidden root node does not have user data but internal data which is determined by other means).

NodeDataSize, Data handling

TBaseVirtualTree Class