How to disable the directional arrow keys from selecting focus (VB 2010)

Question

_{Thursday, October 30, 2014 4:42 AM}

I have a space invaders game, and I use arrows to control the space ship to go left and right, however, I also have a 'Pause' button, which stops the timer that acts as a movement component. However, with the button in place, the arrow keys will no longer move the spaceship sideways, and instead cause the button to gain focus. Is there any way to disable that, so that I can still control my spaceship with the arrow keys, without changing them to something else, and to still have the button there?

Thanks in advance!

All replies (2)

_{Thursday, October 30, 2014 7:25 AM ✅Answered | 1 vote}

This will detect arrow keys, or any keys I suppose, no matter what control has focus. If the app is running and is the active app on the desktop this function for the Form it is in will detect keystrokes for that Form.

Protected Overrides Function ProcessCmdKey(ByRef msg As Message, ByVal keyData As Keys) As Boolean
        If keyData = Keys.Left Then
            Me.Text = "Left"
        ElseIf keyData = Keys.Right Then
            Me.Text = "Right"
        End If
        Return Nothing
End Function

La vida loca

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_{Thursday, October 30, 2014 11:15 AM ✅Answered | 1 vote}

Here is an example of being able to use arrows keys as well as have arrow key sensitive controls like buttons, scrollbars, etc on a form. With this concept you also have the ability to use the forms key related events like KeyUp, KeyDown contol events (not to be confused with arrow key up or arrow key down).

Add a button to a new form with this code: -

Public Class Form2
    Const Increment As Integer = 5
    Dim bmp As Bitmap
    Dim rct As Rectangle
    Dim F(4) As Boolean

    Private Sub Form2_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        rct = New Rectangle(30, 30, 100, 100)
        bmp = SystemIcons.Error.ToBitmap
        Me.KeyPreview = True
        Timer1.Interval = 20
        Me.DoubleBuffered = True
        Me.ClientSize = New Size(500, 500)
    End Sub

    Private Sub Form2_Paint(sender As Object, e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
        e.Graphics.DrawImage(bmp, rct)
    End Sub

    Protected Overrides Function ProcessCmdKey(ByRef msg As Message, keyData As Keys) As Boolean
        If F(4) Then Return False
        If keyData = Keys.Left Then F(0) = True
        If keyData = Keys.Right Then F(1) = True
        If keyData = Keys.Up Then F(2) = True
        If keyData = Keys.Down Then F(3) = True
        If F(0) Or F(1) Or F(2) Or F(3) Then
            Button1.Enabled = False
            'disable all other relevant controls here also
            F(4) = True : Timer1.Start()
            Return True
        End If
        Return MyBase.ProcessCmdKey(msg, keyData)
    End Function

    Private Sub Form2_KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown
        If e.KeyCode = Keys.Left Then F(0) = True
        If e.KeyCode = Keys.Right Then F(1) = True
        If e.KeyCode = Keys.Up Then F(2) = True
        If e.KeyCode = Keys.Down Then F(3) = True
    End Sub

    Private Sub Form2_KeyUp(sender As Object, e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyUp
        If e.KeyCode = Keys.Left Then F(0) = False
        If e.KeyCode = Keys.Right Then F(1) = False
        If e.KeyCode = Keys.Up Then F(2) = False
        If e.KeyCode = Keys.Down Then F(3) = False
    End Sub

    Private Sub Button1_Click(sender As Object, e As System.EventArgs) Handles Button1.Click
        ' do something

    End Sub

    Private Sub Timer1_Tick(sender As Object, e As System.EventArgs) Handles Timer1.Tick
        If Not F(0) And Not F(1) And Not F(2) And Not F(3) Then
            F(4) = False
            Button1.Enabled = True
            're-enable all other relevant controls too
            Timer1.Stop()
            Exit Sub
        End If
        If F(0) Then rct.X -= Increment
        If F(1) Then rct.X += Increment
        If F(2) Then rct.Y -= Increment
        If F(3) Then rct.Y += Increment
        Me.Invalidate()
    End Sub
End Class

If you try this example you will see that the controls are temporarily disabled when you use the Arrow keys to move a sprite on the form. Diagonal movement is possible by pressing more than one arrow key.

Leon Stanley - ♪Don't pay the ferryman - till he gets you over to the other side♪ . um . I apply this to corporations - not to God.