Using the <i class="emphasis">TreeView</i> Class

Using the TreeView Class

As discussed in the In Depth section of this chapter+, tree view controls are designed to display a hierarchy of nodes, much like the left pane in the Windows Explorer. Here is the class hierarchy of the TreeView class:

Object
   MarshalByRefObject
      Component
         Control
            TreeView

You can find the notable public properties of TreeView objects in Table 10.3, the notable public methods in Table 10.4, and the notable public events in Table 10.5. Note that I'm omitting those properties, methods, and events TreeView objects inherit from the Control class—you'll find all that in Chapter 5, Tables 5.1, 5.2, and 5.3.

Table 10.3: Noteworthy public properties of *TreeView* objects.
Property	Means
BorderStyle	Gets/sets the tree view's border style.
CheckBoxes	Gets/sets whether checkboxes should be displayed next to tree nodes.
FullRowSelect	Gets/sets whether a selection should select the whole width of the tree view.
HideSelection	Gets/sets whether the selected tree node stays highlighted when the tree view loses the focus.
HotTracking	Gets/sets whether a tree node label should change its appearance when the mouse pointer moves over it.
ImageIndex	Gets/sets the image list index of the current image.
ImageList	Gets/sets the image list used with this tree view.
Indent	Gets/sets the distance that each level should be indented.
ItemHeight	Gets/sets the height of tree nodes.
LabelEdit	Gets/sets whether tree node text can be edited.
Nodes	Gets the collection of tree nodes.
PathSeparator	Gets/sets the string the tree node uses as a path delimiter.
Scrollable	Gets/sets whether the tree view should display scroll bars as needed.
SelectedImageIndex	Gets/sets the image index for the image to display when a node is selected.
SelectedNode	Gets/sets the node that is selected.
ShowLines	Gets/sets whether lines are drawn between tree nodes.
ShowPlusMinus	Gets/sets whether plus-sign (+) and minus-sign (-) buttons are shown next to tree nodes with child tree nodes.
ShowRootLines	Gets/sets whether lines should be drawn between the tree nodes and the root node.
Sorted	Gets/sets if the tree nodes should be sorted.
TopNode	Gets the first visible tree node.
VisibleCount	Gets the number of nodes that can be seen currently.

Table 10.4: Noteworthy public methods of *TreeView* objects.
Method	Means
BeginUpdate	Disables redrawing of the tree view.
CollapseAll	Collapses all nodes.
EndUpdate	Enables redrawing of the tree view.
ExpandAll	Expands all the nodes.
GetNodeAt	Gets the node that is at the given location.
GetNodeCount	Gets the number of nodes.

Table 10.5: Noteworthy public events of *TreeView* objects.
Event	Means
AfterCheck	Occurs when a node checkbox is checked.
AfterCollapse	Occurs when a tree node is collapsed.
AfterExpand	Occurs when a tree node is expanded.
AfterLabelEdit	Occurs when a tree node label text is edited.
AfterSelect	Occurs when a tree node is selected.
BeforeCheck	Occurs before a node checkbox is checked.
BeforeCollapse	Occurs before a node is collapsed.
BeforeExpand	Occurs before a node is expanded.
BeforeLabelEdit	Occurs before a node label text is edited.
BeforeSelect	Occurs before a node is selected.
ItemDrag	Occurs when an item is dragged into the tree view.