CODEWITHSUNDEEP
vb.neteventscallbackaddressof
tmighty
tmighty

Reputation: 11399

VB.NET Event addressof

I would like to set up a callback that would be raised in my class by a different class:

Public Class CameraWindow
        Inherits System.Windows.Forms.Control
        Private m_camera As Camera = Nothing

        ' Camera property
        <Browsable(False)> _
        Public Property Camera() As Camera
            Get
                Return m_camera
            End Get
            Set(value As Camera)
                ' lock
                Monitor.Enter(Me)

                ' detach event
                If m_camera IsNot Nothing Then
                    m_camera.NewFrame -= New EventHandler(AddressOf camera_NewFrame)
                    timer.[Stop]()
                End If

                m_camera = value
                needSizeUpdate = True
                firstFrame = True
                flash = 0

                ' atach event
                If m_camera IsNot Nothing Then
                    m_camera.NewFrame += New EventHandler(AddressOf camera_NewFrame)
                    timer.Start()
                End If

                ' unlock
                Monitor.[Exit](Me)
            End Set
        End Property

        ' On new frame ready
        Private Sub camera_NewFrame(sender As Object, e As System.EventArgs)
            Invalidate()
        End Sub

The event is defined in 

  Public Class Camera

        Public Event NewFrame As EventHandler

But VB.NET does not like the way I attach and detach the events. Can somebody tell me how to do it correctly?

Thank you very much for the help!

Upvotes: 1

Views: 1263

Answers (1)

Tim Schmelter
Tim Schmelter

Reputation: 460148

That looks as if you're normally using C#. In VB.NET you use the AddHandler statement:

AddHandler m_camera.NewFrame, AddressOf camera_NewFrame

To remove the handler use RemoveHandler

RemoveHandler m_camera.NewFrame, AddressOf camera_NewFrame

However, if the event handler is in a different class it need to be public:

Public Sub camera_NewFrame(sender As Object, e As System.EventArgs)
    Invalidate()
End Sub

and you need an instance:

AddHandler Camera.NewFrame, AddressOf m_camera.camera_NewFrame

Upvotes: 4

Related Questions