A Tree list is a control used as a support for TREE_COLUMN objects.
This object manages a list of lines using Adelia language's list handling instructions, and presents the list as a tree. Where two or more consecutive lines have identical values in their first columns, nodes are created from the first column containing different values, rather than beginning the arborescence from the root of the tree.
Two or more consecutive lines in which all the column values match form a single branch in the tree.
This object can also be used to merge two or more consecutive columns. In this case, the values of the merged columns are combined into a single text containing separators, but nodes are not created for each column.
This object also lets you perform drag and drop operations. It already supported this feature internally via certain events and properties of the TREE_COLUMN list object (which have been retained for compatibility reasons).
A number of new events, properties and methods have been added to allow drag and drop between two tree lists, in either the same program or different programs, or between a tree list and another Visual Adelia object that supports drag and drop.
We recommend using now the new version of the drag and drop feature.
Important: If events relating to both drag and drop versions are used with the same object, only the new version's events will be processed.
As in the old version, the ability to initiate a drag and drop operation is determined by the value of the TREE_COLUMN object's DRAG_DROP property for a particular line.
When you merge two columns of which only one allows drag and drop, you can start a drag and drop operation by clicking in the part of the text corresponding to the column in which drag and drop was enabled.
The tree list can act as the data source for a drag and drop operation if the DD_BeginDrag event is supported by the Visual Adelia program.
The tree list can be the destination of such an operation if the DD_DROP_ALLOWED property is set to *TRUE.
Click below for further information about:
the properties,
the events,
the methods,