Oh…spent lot of time trying to pass values between Parent and Child forms. It is much needed for my SoftPhone application to keep track of call states across windows. Finally, I was able to achieve it using delegates and events (interesting concepts, though)
To pass value from Parent (Form1) to Child Form (Form2)
Step 1: Create delegate for function
Public Delegate Sub PassData(ByVal Message As String)
Step 2: Create Object for deleage
Public frm2PassData As PassData
Step 3: Create public procedure in child form with same signature as delegate
Public Sub GetData(ByVal Message As String)
TextBox1.Text = Message
End Sub
Step 4: Link Delegate with frm2 function
frm = New Form2
frm2PassData = New PassData(AddressOf frm.GetData)
frm.show
Step 5: To pass data from Parent Form to child form, just call delegate object as below
if frm2passdata isnot nothing then
frm2passdata(“Hello”)
end if
To pass value from Child Form to Parent Form (use Events)
Step 1: Declare Public event in Child Form
Public Event Notification(ByVal Message As String)
Step 2: RaiseEvent in Child form, as applicable
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
RaiseEvent Notification(TextBox1.Text)
End Sub
Step 3: Create procedure in Parent form with same signature as Event
Public Sub Getdata(ByVal Message As String)
Me.Text = Message
End Sub
Step 4: Add event handler for child form
AddHandler frm.Notification, AddressOf Getdata
Done..easy isn’t it?
