Infragistics2.Win.UltraWinTree.v8.1
EventManager Property
See Also  Example
Infragistics.Win.UltraWinTree Namespace > UltraTree Class : EventManager Property

The EventManager controls whether events are fired. It provides an easy way to disable the firing of events.

Syntax

Visual Basic (Declaration) 
Public ReadOnly Property EventManager As TreeEventManager
C# 
public TreeEventManager EventManager {get;}

Remarks

Using the EventManager, the firing of events can be enabled or disabled.

Disabling an event will not have any effect on the internal processing of the control. It will only stop the Event handler from being called.

Example

The following sample code illustrates how the event manager can be used to temporarily enable/disable events.

Visual BasicCopy Code
    Imports Infragistics.Win.UltraWinTree

    Private Sub button20_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles button20.Click

        If Me.ultraTree1.ActiveNode Is Nothing Then Return

        Dim eventManager As TreeEventManager

        ' Get the tree's event manager.
        ' The event manager is used to temporarily disable events
        ' to prevent them from being raised. This can be very
        ' convenient in a situation where one or more properties
        ' are being set in code and the events they would normally
        ' raise would cause unnecessary or counter-productive
        ' code to be executed.
        '
        ' Note: All events are enabled by default.
        eventManager = Me.ultraTree1.EventManager

        ' Disable the Before/AfterSelect events
        eventManager.SetEnabled(TreeEventIds.BeforeSelect, False)
        eventManager.SetEnabled(TreeEventIds.AfterSelect, False)

        ' Toggle the selection state of the active node.
        ' Note: This would normally cause the Before/AfterSelect
        ' events to be raised. However, since the above code
        ' disabled the events they won't be.
        Me.ultraTree1.ActiveNode.Selected = Not Me.ultraTree1.ActiveNode.Selected()

        ' Re-enable the Before/AfterSelect events
        eventManager.SetEnabled(TreeEventIds.BeforeSelect, True)
        eventManager.SetEnabled(TreeEventIds.AfterSelect, True)

        ' The 'AllEventsEnabled' property lets you enable/disable
        ' all events will a single line of code. If any event is
        ' disabled the 'AllEventsEnabled' property returns false.
        If Not eventManager.AllEventsEnabled Then
            eventManager.AllEventsEnabled = True
        End If

        ' The event manager also exposes an 'IsEnabled' method
        ' to see if an event is enabled or disbled.
        If Not eventManager.IsEnabled(TreeEventIds.BeforeSelect) Then
            eventManager.SetEnabled(TreeEventIds.BeforeSelect, True)
        End If

        ' The tree event manager also exposes overloaded
        ' 'IsEnabled' and 'SetEnabled' methods that take an
        ' event group so that, for example all 'Before' or all
        ' 'After' events can be enabled/disabled. If any event
        ' in the group is disabled the 'IsEnabled' method returns
        ' false.
        If Not eventManager.IsEnabled(EventGroups.BeforeEvents) Then
            eventManager.SetEnabled(EventGroups.BeforeEvents, True)
        End If

        ' The 'InProgress' method will return true if the
        ' specified event is currently being raised. This
        ' is often helpful in methods that can be called
        ' from various points in an application to determine
        ' what is triggering the call.
        If eventManager.InProgress(TreeEventIds.BeforeSelect) Then
            ' ...
        End If

        eventManager.SetEnabled(EventGroups.AfterEvents, True)

    End Sub

C#Copy Code
       using Infragistics.Win.UltraWinTree;

       private void button20_Click(object sender, System.EventArgs e)
       {

           if ( this.ultraTree1.ActiveNode == null )
               return;

           // Get the tree's event manager.
           // The event manager is used to temporarily disable events
           // to prevent them from being raised. This can be very
           // convenient in a situation where one or more properties
           // are being set in code and the events they would normally
           // raise would cause unnecessary or counter-productive
           // code to be executed.
           //
           // Note: All events are enabled by default.
           TreeEventManager eventManager = this.ultraTree1.EventManager;

           // Disable the Before/AfterSelect events
           eventManager.SetEnabled( TreeEventIds.BeforeSelect, false );
           eventManager.SetEnabled( TreeEventIds.AfterSelect, false );

           // Toggle the selection state of the active node.
           // Note: This would normally cause the Before/AfterSelect
           // events to be raised. However, since the above code
           // disabled the events they won't be.
           this.ultraTree1.ActiveNode.Selected =
               !this.ultraTree1.ActiveNode.Selected;

           // Re-enable the Before/AfterSelect events
           eventManager.SetEnabled( TreeEventIds.BeforeSelect, true );
           eventManager.SetEnabled( TreeEventIds.AfterSelect, true );

           // The 'AllEventsEnabled' property lets you enable/disable
           // all events will a single line of code. If any event is
           // disabled the 'AllEventsEnabled' property returns false.
           if ( !eventManager.AllEventsEnabled )
               eventManager.AllEventsEnabled = true;

           // The event manager also exposes an 'IsEnabled' method
           // to see if an event is enabled or disbled.
           if ( !eventManager.IsEnabled(TreeEventIds.BeforeSelect ) )
               eventManager.SetEnabled(TreeEventIds.BeforeSelect, true );

           // The tree event manager also exposes overloaded
           // 'IsEnabled' and 'SetEnabled' methods that take an  
           // event group so that, for example all 'Before' or all
           // 'After' events can be enabled/disabled. If any event
           // in the group is disabled the 'IsEnabled' method returns
           // false.
           if ( !eventManager.IsEnabled(EventGroups.BeforeEvents ) )
               eventManager.SetEnabled(EventGroups.BeforeEvents, true );

           eventManager.SetEnabled(EventGroups.AfterEvents, true );

           // The 'InProgress' method will return true if the
           // specified event is currently being raised. This
           // is often helpful in methods that can be called
           // from various points in an application to determine
           // what is triggering the call.
           if ( eventManager.InProgress( TreeEventIds.BeforeSelect ) )
           {
               // ...
           }
       
       }

See Also