DoEvents not working

J

JoshK

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Apr 12, 2006
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Akron, OH
ok I have a time that ticks every 10ms to update one lable with the current mouse position, and also set a panel to the color unser the mouse

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Dim point As Point
point.X = Windows.Forms.Cursor.Position.X
point.Y = Windows.Forms.Cursor.Position.Y
lblMouse.Text = point.X & "," & point.Y
Dim color As Color
color = GetPixelColor(point.X, point.Y)
lblColor.Text = ColorTranslator.ToWin32(Drawing.Color.FromArgb(color.A, color.R, color.G, color.B)).ToString
pnlColor.BackColor = color
System.Windows.Forms.Application.DoEvents()

End Sub

while thats happening I want to be able to save the current mouse position and the color to a listbox when the user hits the 'w' key

Private Sub Form1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress
If e.Equals(Keys.W) Then lstCommands.Items.Add(lblmouse.tostring & " :: " & lblcolor.tostring)
End Sub

As you can see I put DoEvents() but when I hit the w key nothing happens, I also tried removing the IF in form1_keypress and the keypress just doesnt activate.


Please help
 
By default the KeyPress event only fires for the control that has focus, which will never be the form if the form has child controls.

You should set the form's KeyPreview property to True. This causes the form to intercept all keyboard input and process it before it is sent to child controls, which should be all you need to do to make your program work.
 
Great thanks, I'll give it a try. Then, for future reference, what if I have a textbox for some kind of information, what if the user hit one of the keys that I have in KeyPress event. Is there a way to turn KeyPreview on and off in code?
 
One possiblility would be to examine the ActiveControl property and act based on that...
Visual Basic: 
Private Sub Form1_KeyDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyDown
    If ActiveControl Is TextBox1 Then
        'You probably want to do nothing here
    Else
        If e.KeyCode = Keys.W Then
            'Do things here
        End If
    End If
End Sub
You could also set the KeyPreview property when a TextBox gets or loses focus...
Visual Basic: 
Private Sub TextBox1_Enter(ByVal sender As System.Object, ByVal e As em.EventArgs) Handles TextBox1.Enter
    KeyPreview = False
End Sub
 
Private Sub TextBox1_Leave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.Leave
    KeyPreview = True
End Sub
 
Just so nobody gets confused its not strictly neccessary to alter behaviour for a textbox unless you don't want the form to perform the action when it is focused. Text typed will still appear in the textbox it was just also call the forms keypress. As such if the forms key press only handles shortcut keys and such, you will not need to code special cases for your textboxes.
 
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