Question

The code given below works fine. The only problem is mouse wheel/keyup cannot be used after the TOP image is displayed, it fills the keyboard buffer. Then I have to wait awhile to use wheel/keydown. Also the images after wheel/keydown goes beyond last image. It should stop at the last image like it stops at the first image. Code courtesy of Geek On Demand.

Private Sub Images_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
PictureBox1.Image = ImageList1.Images.Item(increaseCount(count))
End Sub

Private Sub Images_MouseWheel(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseWheel
    Try
        If e.Delta > 0 Then
            PictureBox1.Image = ImageList1.Images.Item(decreaseCount(count))
        ElseIf e.Delta < 0 Then
            PictureBox1.Image = ImageList1.Images.Item(increaseCount(count))
        End If
    Catch ex As Exception
    End Try
End Sub

Private Sub Images_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyDown
    Try
        If e.KeyCode = Keys.Down Then
            PictureBox1.Image = ImageList1.Images.Item(increaseCount(count))
        End If
    Catch ex As Exception
    End Try
End Sub

Private Sub Images_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyUp
    Try
        If e.KeyCode = Keys.Up Then
            PictureBox1.Image = ImageList1.Images.Item(decreaseCount(count))
        End If
    Catch ex As Exception
    End Try
End Sub

Private Function increaseCount(ByRef count As Integer) As Integer
    count += 1
    If count + 1 > ImageList1.Images.Count Then
        count = 0
    End If
    Return count
End Function

Private Function decreaseCount(ByRef count As Integer) As Integer
    count -= 1
    If count - 1 > ImageList1.Images.Count Then
        count = 0
    End If
    Return count
End Function

Answer 1

You can modify the decrease count function as :

Private Function decreaseCount(ByRef count As Integer) As Integer
 count -= 1
  If count - 1 > ImageList1.Images.Count Or count<0 Then
    count = 0
  End If
 Return count
End Function