TreeView | .NET Windows Forms in a Nutshell

TreeView

marshal by reference, disposable

System. Windows .Forms (system. windows .forms.dll)

class

This Control represents a hierarchical set of nodes in a tree view (similar to the Windows Explorer Folder View). You can add TreeNode objects to the Nodes collection. These are root nodes. To add further elements to the hierarchy you add additional TreeNode objects to the root TreeNode.Nodes collections. GetNodeCount() will return you the count of all nodes in the tree.

You can add CheckBoxes for each node, enable HotTracking (link-like) behavior, ShowLines and ShowRootLines (drawn from node to node), and ShowPlusMinus glyphs (little plus-shaped expansion boxes next to nodes with children). You can also set the distance by which to Indent each level of child nodes.

When you select an item, normally you are only permitted to click on imagery representing the label text. This can sometimes be awkward , so you can enable FullRowSelect to give users a larger target. HideSelection determines whether the selection highlight is displayed even when the control loses the focus. You can get or set the selected node with the SelectedNode property.

The nodes can be Sorted , and you can ExpandAll( ) and CollapseAll() nodes. To find the node under a particular point, you can use the GetNodeAt() method.

The tree raises events both Before and After select, check, collapse, and expand operations. If the control allows LabelEdit , you will also get BeforeLabelEdit and AfterLabelEdit events. The BeforeXXX events use the TreeViewCancelEventArgs class and can therefore be aborted.

 public class  TreeView  : Control {  // Public Constructors  public  TreeView  ();  // Public Instance Properties  public override Color  BackColor  {set; get; }  // overrides Control  public override Image  BackgroundImage  {set; get; }  // overrides Control  public BorderStyle  BorderStyle  {set; get; }    public bool  CheckBoxes  {set; get; }    public override Color  ForeColor  {set; get; }  // overrides Control  public bool  FullRowSelect  {set; get; }    public bool  HideSelection  {set; get; }    public bool  HotTracking  {set; get; }    public int  ImageIndex  {set; get; }    public ImageList  ImageList  {set; get; }    public int  Indent  {set; get; }    public int  ItemHeight  {set; get; }    public bool  LabelEdit  {set; get; }    public TreeNodeCollection  Nodes  {get; }    public string  PathSeparator  {set; get; }    public bool  Scrollable  {set; get; }    public int  SelectedImageIndex  {set; get; }    public TreeNode  SelectedNode  {set; get; }    public bool  ShowLines  {set; get; }    public bool  ShowPlusMinus  {set; get; }    public bool  ShowRootLines  {set; get; }    public bool  Sorted  {set; get; }    public override string  Text  {set; get; }  // overrides Control  public TreeNode  TopNode  {get; }    public int  VisibleCount  {get; }  // Protected Instance Properties  protected override CreateParams  CreateParams  {get; }  // overrides Control  protected override Size  DefaultSize  {get; }  // overrides Control   // Public Instance Methods  public void  BeginUpdate  ();    public void  CollapseAll  ();    public void  EndUpdate  ();    public void  ExpandAll  ();    public TreeNode  GetNodeAt  (int  x  , int  y  );    public TreeNode  GetNodeAt  (System.Drawing.Point  pt  );    public int  GetNodeCount  (bool  includeSubTrees  );    public override string  ToString  ();  // overrides System.ComponentModel.Component   // Protected Instance Methods  protected override void  CreateHandle  ();  // overrides Control  protected override void  Dispose  (bool  disposing  );  // overrides Control  protected OwnerDrawPropertyBag  GetItemRenderStyles  (TreeNode  node  , int  state  );    protected override bool  IsInputKey  (Keys  keyData  );  // overrides Control  protected virtual void  OnAfterCheck  (TreeViewEventArgs  e  );    protected virtual void  OnAfterCollapse  (TreeViewEventArgs  e  );    protected virtual void  OnAfterExpand  (TreeViewEventArgs  e  );    protected virtual void  OnAfterLabelEdit  (NodeLabelEditEventArgs  e  );    protected virtual void  OnAfterSelect  (TreeViewEventArgs  e  );    protected virtual void  OnBeforeCheck  (TreeViewCancelEventArgs  e  );    protected virtual void  OnBeforeCollapse  (TreeViewCancelEventArgs  e  );    protected virtual void  OnBeforeExpand  (TreeViewCancelEventArgs  e  );    protected virtual void  OnBeforeLabelEdit  (NodeLabelEditEventArgs  e  );    protected virtual void  OnBeforeSelect  (TreeViewCancelEventArgs  e  );    protected override void  OnHandleCreated  (EventArgs  e  );  // overrides Control  protected override void  OnHandleDestroyed  (EventArgs  e  );  // overrides Control  protected virtual void  OnItemDrag  (ItemDragEventArgs  e  );    protected override void  OnKeyDown  (KeyEventArgs  e  );  // overrides Control  protected override void  OnKeyPress  (KeyPressEventArgs  e  );  // overrides Control  protected override void  OnKeyUp  (KeyEventArgs  e  );  // overrides Control  protected override void  WndProc  (ref Message  m  );  // overrides Control   // Events  public event TreeViewEventHandler  AfterCheck  ;    public event TreeViewEventHandler  AfterCollapse  ;    public event TreeViewEventHandler  AfterExpand  ;    public event NodeLabelEditEventHandler  AfterLabelEdit  ;    public event TreeViewEventHandler  AfterSelect  ;    public event TreeViewCancelEventHandler  BeforeCheck  ;    public event TreeViewCancelEventHandler  BeforeCollapse  ;    public event TreeViewCancelEventHandler  BeforeExpand  ;    public event NodeLabelEditEventHandler  BeforeLabelEdit  ;    public event TreeViewCancelEventHandler  BeforeSelect  ;    public event ItemDragEventHandler  ItemDrag  ;    public event PaintEventHandler  Paint  ;  // overrides Control  }

Hierarchy

System.Object System.MarshalByRefObject System.ComponentModel.Component(System.ComponentModel.IComponen, System.IDisposable) Control(IOleContro, IOleObject , IOleInPlaceObject , IOleInPlaceActiveObject , IOleWindow , IViewObject , IViewObject2 , IPersist , IPersistStreamInit , IPersistPropertyBag , IPersistStorage , IQuickActivate , System.ComponentModel.ISynchronizeInvoke , IWin32Window) TreeView

Returned By

TreeNode.TreeView

Passed To

TreeNode.FromHandle()