TCustomTreeView.OnHasChildren property
Event handler signalled to determine if a given node in the tree view has child nodes.
Declaration
property OnHasChildren: TTVHasChildrenEvent read FOnHasChildren write FOnHasChildren;Description
OnHasChildren is a
TTVHasChildrenEvent property with the
event handler signalled to determine whether a specified node has child nodes.
It is signalled (when assigned) from the NodeHasChildren method, and allows
the control to determine whether child nodes for a given node can be displayed
on the control. It occurs when a TTreeNode instance gets the value for its
HasChildren property and updates the States for the node.
Arguments to the event handler include:
- Sender
- The TCustomTreeView instance for the event.
- ANode
- The TTreeNode instance examine for child nodes in the handler routine.
The handler routine returns a Boolean value which indicates whether the specified node has child nodes which can be displayed on the control. The return value can be set to False - even when the tree node actually has child nodes. This allows properties in child nodes, like Data or Level, to be used to determine their effective visibility.
See also
An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.