How to change the colour of an object by pressing a button in a different form?

Question

Right now I am trying to program system in a game I am making where the player is able to change the colour of the game's paddle from a different form. The way it works is this: there will be a form (ColourChoose) containing multiple buttons of different colours. When one of these buttons is pressed, the program should change the colour of the paddle, which is located in the GameBoard window. The issue is that, when I press on one of the buttons and the GameBoard loads up, the paddle doesn't appear. Physically, it is still there (because you can see the ball bouncing off of it), but it is not visible on the GameBoard. I have not made any changes whatsoever to the visibility of the paddle, all I have done is simply tried to change the paddle's colour.

I have 2 pieces of code for this (due to being in two different forms). This is the first piece of code from the ColourChoose window:

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Colour = Color.Red
End Sub

And this is the 2nd piece of code from the GameBoard window, which is supposed to be linked to the code from ColourChoose:

   Private Sub GameBoard_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim Colour As Color = ColourChoose.Colour
        Paddle.BackColor = Colour
End Sub

How do I make it so that the button on one form will change the colour of another object located in a different form WITHOUT the paddle hiding itself for some reason?

UPDATE: For some reason, my code in the GameBoard window is in the section that handles the LOADING of the board. For some reason my paddle doesn't have a dedicated section of code, as the code for the paddle's movement is kinda all over the place, so the paddle itself has no dedicated code.

Answer 1

Hi @GG01Coding-3690 ,
I make some changes based on your code.
Here is my result.

Here is the code.

GameBoard

    Public paddlecolor As Color = Color.Orange  
    Private Sub GameBoard_Activated(sender As Object, e As EventArgs) Handles MyBase.Activated  
        Paddle.BackColor = paddlecolor  
    End Sub  

ColorChoose

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click  
        GameBoard.paddlecolor = Color.Blue  
    End Sub  
  
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click  
        GameBoard.paddlecolor = Color.Red  
    End Sub  

Hope the code could be helpful.
Best Regards.
Jiachen Li

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Answer 2

Usually this simple solution works:

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    GameBoard.Paddle.Colour = Color.Red
End Sub

Also change the Modifiers properties of Paddle control (in Form Designer) to "Public".

Answer 3

Hi,
you can use Binding and NotifyPropertyChanged like in following demo:

Imports System.ComponentModel  
Imports System.Runtime.CompilerServices  
  
Public Class Form26  
  
  Private lbl As New Label With {.Location = New Point(10, 50), .Size = New Drawing.Size(100, 100)}  
  Private vm As New ViewModel  
  Private mnu As New MainMenu()  
  Private WithEvents mnuItem As New MenuItem With {.Text = "Choose Color"}  
  
  Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load  
    Me.Menu = mnu  
    mnu.MenuItems.Add(mnuItem)  
    Me.Controls.Add(lbl)  
    lbl.DataBindings.Add("BackColor", vm, "LabelColor")  
  End Sub  
  
  Private Sub btn_Click(sender As Object, e As EventArgs) Handles mnuItem.Click  
    Dim dialog As New ColourChoose(vm) With {.Text = "ColourChoose", .Height = 100, .Width = 250}  
    dialog.ShowDialog()  
  End Sub  
  
  Public Class ViewModel  
    Implements INotifyPropertyChanged  
  
    Private _labelColor As Color = Color.Yellow  
    Public Property LabelColor As Color  
      Get  
        Return Me._labelColor  
      End Get  
      Set(value As Color)  
        Me._labelColor = value  
        OnPropertyChanged()  
      End Set  
    End Property  
  
    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged  
    Friend Sub OnPropertyChanged(<CallerMemberName> Optional propName As String = "")  
      RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propName))  
    End Sub  
  End Class  
  
  Public Class ColourChoose  
    Inherits Form  
  
    Public Sub New(vm As ViewModel)  
      Me.vm = vm  
    End Sub  
  
    Private vm As ViewModel  
  
    Private WithEvents btn1 As New Button With {.Text = "Red", .Top = 10, .Left = 10, .Tag = Color.Red}  
    Private WithEvents btn2 As New Button With {.Text = "Green", .Top = 10, .Left = 150, .Tag = Color.Green}  
    Private Sub ColourChoose_Load(sender As Object, e As EventArgs) Handles MyBase.Load  
      Me.Controls.AddRange(New Control() {btn1, btn2})  
    End Sub  
    Private Sub btn1_Click(sender As Object, e As EventArgs) Handles btn1.Click, btn2.Click  
      vm.LabelColor = CType(CType(sender, Control).Tag, Color)  
    End Sub  
  End Class  
  
End Class  

Result: