Wyo VB Lecture Notes

Objective #1: Be able to use the KeyDown & KeyPress methods.

• A form's KeyDown method allows your program to respond to presses of keys on the keyboard including the arrow keys.
  
  Private Sub Form1_KeyDown(...)

     If (e.KeyCode = Keys.Right Or e.KeyCode = Keys.D or e.KeyCode = Keys.NumPad6) Then
        picPlayer.Left = picPlayer.Left + 5
     ElseIf (e.KeyCode = Keys.Left Or e.KeyCode = Keys.A or e.KeyCode = Keys.NumPad4) Then
        picPlayer.Left = picPlayer.Left - 5
     ElseIf (e.KeyCode = Keys.Up Or e.KeyCode = Keys.W or e.KeyCode = Keys.NumPad8) Then
        picPlayer.Top = picPlayer.Top - 5
     ElseIf (e.KeyCode = Keys.Down Or e.KeyCode = Keys.S or e.KeyCode = Keys.NumPad2) Then
        picPlayer.Top = picPlayer.Top + 5
     End If

  End Sub

• A form's KeyPress method also allows your program to respond to presses of various letter keys on the keyboard but not the arrow keys.
  
  Private Sub Form1_KeyPress(...)

     If (e.KeyChar = "d") Then
        picPlayer.Left = picPlayer.Left + 1
     ElseIf (e.KeyChar = "a") Then
        picPlayer.Left = picPlayer.Left - 1
     ElseIf (e.KeyChar = "w") Then
        picPlayer.Top = picPlayer.Top - 1
     ElseIf (e.KeyChar = "s") Then
        picPlayer.Top = picPlayer.Top + 1
     End If

  End Sub
  
  The following technique will not be covered on any tests or quizzes but it may be helpful in projects.
  
  If you have placed a button, Windows Media Player or other object on your form, you may need to set the form's KeyPreview property to True in order for the KeyPress method to work correctly. Or, you may need to use the ProcessCmdKey Function rather than the KeyDown or KeyPress methods as demonstrated below.
  
  Protected Overrides Function ProcessCmdKey(ByRef msg As Message, ByVal keyData As Keys) As Boolean
     ' collision detection in the Maze2 assignment can be placed here
  
     If (keyData = Keys.Right Or keyData = Keys.D or keyData = Keys.NumPad6) Then
        picPlayer.Left = picPlayer.Left + 5
        Return True
     ElseIf (keyData = Keys.Left Or keyData = Keys.A or keyData = Keys.NumPad4) Then
        picPlayer.Left = picPlayer.Left - 5
        Return True
     ElseIf (keyData = Keys.Up Or keyData = Keys.W or keyData = Keys.NumPad8) Then
        picPlayer.Top = picPlayer.Top - 5
        Return True
     ElseIf (keyData = Keys.Down Or keyData = Keys.S or keyData = Keys.NumPad2) Then
        picPlayer.Top = picPlayer.Top + 5
        Return True
     End If
  
     Return MyBase.ProcessCmdKey(msg, keyData)
  End Function