Question

I am trying to bind structure members to Labels in Windows Forms. However, I’m unable to do this because this structure is a member of a class, and I need to bind a couple of members to Labels.

Let’s say that this structure is a System.Drawing.Point, and I want to bind X and Y property to a Label.

Imports System.ComponentModel
Public Class Form1
    Implements INotifyPropertyChanged

    Private _pt As Point
    Public Property Pt As Point
        Get
            Return _pt
        End Get
        Set(value As Point)
            _pt = value
            RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("Pt"))
        End Set
    End Property


    Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        Label1.DataBindings.Add("Text", Me, "Pt")
        Label2.DataBindings.Add("Text", Me.Pt, "X")
        Label3.DataBindings.Add("Text", Me, "Pt.Y")
    End Sub

    Public Event PropertyChanged(sender As Object, e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged

End Class

If I set the bindingsource to Me and datamember to structure then Label1 will show the result of ToString() method, Label2 value of X property and Label3 will not change.

But if I assign a new Point to Pt property, then only Label1 will update its value. Label2 will not because datasource is no longer the same. Also, Label3.DataBindings.Add("Text", Me, "Pt.Y") does not work, because it’s not possible that datamember is “submember”.

I have also tried to make a new Structure that implements INotifyPropertyChanged in all its properties, but no luck.

Is there a way to make binding for Label2 or Label3 possible, even if I assign new Structure to it?

My goal is to assign new Point to Me.Pt property and observe values of Pt.X and Pt.Y on Label2 and Label3 via databinding.

Answer 1

You almost got it right. Label1 and Label3 will work AS IS. Change

Label2.DataBindings.Add("Text", Me.Pt, "X")

to

Label2.DataBindings.Add("Text", Me, "Pt.X")

And Label2 will also start working.

Just make sure you assign a new value through a property, and not through your _pt field.