Events for Custom Associated Control

Question

Hello Friends,
I am here with another problem

I have created a custom textbox which is inheritated from textbox
i declared a new property called AssociatedLabel
In gotfocus Event I change the color (BackColor and Forecolor) of the associatedLabel
as well as in the lostfocus

e.g. TextBox1 is associated with label1
TextBox2 is associated with label2
Textbox3 is also associated with Label2

Now I want to write some code in some Events for the associatedLabel

How can I access those events

Any help will be appreciated.

Answer 1

First of all what does trigger the event?

---

Success
Cor

Answer 2

Hi

Thanks for reply

If AssociatedLabel is clicked then textbox(with which the label is associated) should be focused

Answer 3

Hello Vishal,

                  Here you have to catch label event and then operate to textbox.

So flow is from lable ---> Textbox  and not from Textbox--> lable.

So better handle events of the lable and at that time change focus from your associated label to textbox.

  By the way why are u passing whole control as associated control do u have some more functionality in it (in textbox ) for that control ?

---

Want to add MVP with my name.

Answer 4

So better handle events of the lable and at that time change focus from your associated label to textbox.

  By the way why are u passing whole control as associated control do u have some more functionality in it (in textbox ) for that control ?

---

Want to add MVP with my name.

Ya I want to handle the events for associatedLabel in the TextBox class that i have created But How?

And Yes I have many other functionalities in it

Answer 5

 By the way why are u passing whole control as associated control

---

If I cant do it with label then its OK as it is not so Important

But I have another property AssociatedListBox also and I have to Handle the events of listbox

Answer 6

In the Set method of the AssociatedLabel property, use AddHandler to attach event handlers to the label's events, e.g.

      AddHandler value.click, addressof OnLabelClick

---

Armin

Answer 7

In the Set method of the AssociatedLabel property, use AddHandler to attach event handlers to the label's events, e.g.

      AddHandler value.click, addressof OnLabelClick

---

Armin

I tried this on a listbox

tis is what I have tried

AddHandler value.KeyPress, AddressOf Key_Press

Private Sub Key_Press(ByVal sender As TextBox, ByVal e As System.Windows.Forms.KeyPressEventArgs)
        Dim x As TextBox = DirectCast(sender, TextBox)
        Call lstBox_KeyPress(x, Associated_LstBox, e)
End Sub

I get the following runtime error

Unable to cast object of type 'System.Windows.Forms.ListBox' to type 'System.Windows.Forms.TextBox'.

I have also tried it without directCast but same result

Answer 8

If AssociatedLabel is clicked then textbox(with which the label is associated) should be focused

That would need the label to have an associated textbox.

You could do that by setting the textbox as the Tag value of the label, and then adding code in the label click event to acces the Tag property and set the focus accordingly.

The Property Set for the AssociatedLabel property of the custom text box could include code to se thte Tag property of the label to the text box where the property is being set. But you still need to add code to the label click event - I don't know of a way that the custom text box can control the event processing of the label.

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        MyTextBox1.AssociatedLabel = Label1
    End Sub

    Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click
        Dim T As TextBox = CType(sender.tag, TextBox)
        T.Focus()
    End Sub
End Class

Public Class myTextBox
    Inherits TextBox
    Private myLabel As Label

    Public Property AssociatedLabel() As Label

        Get
            Return myLabel
        End Get
        Set(ByVal value As Label)
            myLabel = value
            If Not myLabel Is Nothing Then
                myLabel.Tag = Me
            End If
        End Set
    End Property

End Class

Answer 9

That would need the label to have an associated textbox.

I have tried that before few days, At first sight it looks OK

But then I got Problems as there are more textboxes associated with a single label in some forms

Thanks for the kind reply

Answer 10

In the Set method of the AssociatedLabel property, use AddHandler to attach event handlers to the label's events, e.g.

      AddHandler value.click, addressof OnLabelClick

---

Armin

I tried this on a listbox

tis is what I have tried

AddHandler value.KeyPress, AddressOf Key_Press

Private Sub Key_Press(ByVal sender As TextBox, ByVal e As System.Windows.Forms.KeyPressEventArgs)
        Dim x As TextBox = DirectCast(sender, TextBox)
        Call lstBox_KeyPress(x, Associated_LstBox, e)
End Sub

I get the following runtime error

Unable to cast object of type 'System.Windows.Forms.ListBox' to type 'System.Windows.Forms.TextBox'.

I have also tried it without directCast but same result

Why do you cast to Textbox as the associated control is a Label? The property is named AssociatedLabel, not AssociatedTextbox. The textbox is the class in which you have the code.

In addition, why do you handle the KeyPress event as a label can not have the focus and consequently does not receive key events?

And how is it possible to assign a Listbox to the AssociatedLabel property as the type of the AssociatedLabel property is Label?

The code how I expect it to be...:

Class MyTextBox
   Inherits TextBox

   Private _AssociatedLabel As Label

   Public Property AssociatedLabel() As Label
      Get
         Return _AssociatedLabel
      End Get
      Set(ByVal value As Label)

         _AssociatedLabel = value

         AddHandler _AssociatedLabel.Click, AddressOf OnLabelClick

      End Set
   End Property
   Private Sub OnLabelClick(ByVal sender As Object, ByVal e As EventArgs)

      Focus()

   End Sub
End Class

(reduced example without checks)

---

Armin

Answer 11

The code how I expect it to be...:

Class MyTextBox
   Inherits TextBox

   Private _AssociatedLabel As Label

   Public Property AssociatedLabel() As Label
      Get
         Return _AssociatedLabel
      End Get
      Set(ByVal value As Label)

         _AssociatedLabel = value

         AddHandler _AssociatedLabel.Click, AddressOf OnLabelClick

      End Set
   End Property
   Private Sub OnLabelClick(ByVal sender As Object, ByVal e As EventArgs)

      Focus()

   End Sub
End Class

(reduced example without checks)

---

Armin

I have done exactly that and got this runtime error

I have not tried it with label but I tried with ListBox

Unable to cast object of type 'System.Windows.Forms.ListBox' to type 'System.Windows.Forms.TextBox'.

This error is on the Form1.Designer.VB

On the first line (Public Class Form1)

Answer 12

I have done exactly that and got this runtime error

I have not tried it with label but I tried with ListBox

Unable to cast object of type 'System.Windows.Forms.ListBox' to type 'System.Windows.Forms.TextBox'.

This error is on the Form1.Designer.VB

On the first line (Public Class Form1)

If it is a runtime error, look at the exception details, mainly the stacktrace. Look at the top stack frame to see the location of the exception. Do the same for the InnerException property.

Without knowing the failing line it's impossible to help.

---

Armin

Answer 13

I just tried with the label and it works fine

I dont know why it gives me this error

Anyway Here I paste the details of the stackTrace because I dont understand what is it trying to tell

   at AdvancedTextBox.MyTxtBox._Lambda$__1(Object a0, KeyPressEventArgs a1) in E:\Collections\VB.NET\Custom Controls\AdvancedTextBox\AdvancedTextBox\MyTxtBox.vb:line 216    at System.Windows.Forms.Control.OnKeyPress(KeyPressEventArgs e)    at System.Windows.Forms.Control.ProcessKeyEventArgs(Message& m)    at System.Windows.Forms.Control.ProcessKeyMessage(Message& m)    at System.Windows.Forms.Control.WmKeyChar(Message& m)    at System.Windows.Forms.Control.WndProc(Message& m)    at System.Windows.Forms.ListBox.WndProc(Message& m)    at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)    at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)    at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)    at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)    at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)    at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)    at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)    at System.Windows.Forms.Application.Run(ApplicationContext context)    at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()    at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()    at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)    at WindowsApplication1.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81    at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)    at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)    at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()    at System.Threading.ThreadHelper.ThreadStart_Context(Object state)    at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)    at System.Threading.ThreadHelper.ThreadStart()

Answer 14

Please post line 216 of file MyTxtBox.vb

Also post your code of the AssociatedLabel property.

---

Armin

Answer 15

Ya, I got it

I passed wrong arguments in the sub

I passed sender as Textbox instead of sender as object

Thank you for helping

Answer 16

But then I got Problems as there are more textboxes associated with a single label in some forms

That would work only only if the code executing in the label click did not need to refer to any particular textbox.  But you have indicated that "If AssociatedLabel is clicked then textbox(with which the label is associated) should be focused".  That cannot work if you have more than one textbox associated with a single label.

Answer 17

Ya, I got it

I passed wrong arguments in the sub

I passed sender as Textbox instead of sender as object

Thank you for helping

I have no clue what you are doing. You don't have to call an event handler manually. Changing to type object even increases the possibility of passing a wrong type.

Nice it works for you, but I'm really interested in which code you have now.

---

Armin