Shape.OnRegionChanged Method

Raises the RegionChanged event.

Namespace:  Microsoft.VisualBasic.PowerPacks
Assembly:  Microsoft.VisualBasic.PowerPacks.Vs (in Microsoft.VisualBasic.PowerPacks.Vs.dll)

Syntax

'宣言
Protected Overridable Sub OnRegionChanged ( _
    e As EventArgs _
)

protected virtual void OnRegionChanged(
    EventArgs e
)

protected:
virtual void OnRegionChanged(
    EventArgs^ e
)

abstract OnRegionChanged : 
        e:EventArgs -> unit 
override OnRegionChanged : 
        e:EventArgs -> unit 

protected function OnRegionChanged(
    e : EventArgs
)

Parameters

• e
  Type: System.EventArgs
  An EventArgs that contains the event data.

Remarks

Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.

The OnRegionChanged method also enables derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors

When you override OnRegionChanged in a derived class, be sure to call the OnRegionChanged method of the base class so that registered delegates receive the event.

Examples

The following example is an event-raising method that is executed when the Enabled property value changes. The Shape class has several methods with the name pattern OnPropertyNameChanged that raise the corresponding PropertyNameChanged event when the PropertyName value changes (PropertyName represents the name of the corresponding property.)

The following example changes the color of a line when the Enabled property of a class derived from LineShape is changed to false.

Public Class DisabledLine
    Inherits LineShape
    Protected Overrides Sub OnEnabledChanged(ByVal e As EventArgs)
        ' Change the color of the line when selected.
        If Me.BorderColor = SystemColors.InactiveBorder Then
            Me.BorderColor = Color.Black
        Else
            Me.BorderColor = SystemColors.InactiveBorder
        End If
        MyBase.OnEnabledChanged(e)
    End Sub
End Class

public class DisabledLine :
    LineShape
{
    protected override void OnEnabledChanged(EventArgs e)
    {
        // Change the color of the line when selected.
        if (this.BorderColor == SystemColors.InactiveBorder)
        {
            this.BorderColor = Color.Black;
        }
        else
        {
            this.BorderColor = SystemColors.InactiveBorder;
        }
        base.OnEnabledChanged(e);
    }
}

.NET Framework Security

• Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.

See Also

Reference

Shape Class

Microsoft.VisualBasic.PowerPacks Namespace

Other Resources

How to: Draw Lines with the LineShape Control (Visual Studio)

How to: Draw Shapes with the OvalShape and RectangleShape Controls (Visual Studio)

Introduction to the Line and Shape Controls (Visual Studio)