Visual Basic

1-Sep-12 11:30

Having trouble getting exactly the answer I need in google, MSDN.

Desired: A user can select a PictureBox on the form which becomes the activeBrick. Whenever there is an activeBrick selected, arrow keys should move this one pixel at a time around the form within a Panel control called pnlTableau.

I have done this:

Me.KeyPreview = true

My attempted solution was this:

Private Sub BrickMove(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyUp

    If activeBrick IsNot Nothing Then
        Select Case e.KeyCode
            Case Keys.Up
                If activeBrick.Top > 0 Then activeBrick.Top -= 1
            Case Keys.Down
                If activeBrick.Bottom < pnlTableau.Height Then activeBrick.Top += 1
                e.Handled = True
            Case Keys.Left
                If activeBrick.Left > 0 Then activeBrick.Left -= 1
                e.Handled = True
            Case Keys.Right
                If activeBrick.Right < pnlTableau.Width Then activeBrick.Left += 1
                e.Handled = True
        End Select
    End If
    Me.Refresh()
End Sub

The Me.Refresh line at the end is because my active PictureBox has a dotted red rectangle around it, which will "drag" if the form is not repainted.

The problem: I have a few radio buttons on the form also. The arrow keys DO move the PictureBox, but the arrow keys also shift the selected radio button, which is not behavior I want. I thought e.Handled = True would suppress this, but it doesn't.

If I move this code to the KeyDown event, the PictureBox does not move at all but the radio buttons are still selected.

Thanks in advance.

ChandraRam2-Sep-12 23:57

ChandraRam

2-Sep-12 23:57

Is the position of the radio button linked to that of the PictureBox(es) in the form design?

Steven St. John3-Sep-12 3:35

3-Sep-12 3:35

No. The form has several radio buttons to the left of a Panel control. These set options for the PictureBoxes which are dynamically added to the Panel control's control array at runtime.

I presume it is normal behavior for Windows to process arrow keys in this way, just as Tab moves the focus from one control to another. I want the arrow keys to be handled programmatically and to not affect which radio button is selected.

ChandraRam3-Sep-12 4:00

ChandraRam

3-Sep-12 4:00

OK, I misunderstood your question... sorry.

The only thing I could find, if the code was pasted from the actual project, is the e.Handled is missing for the up arrow. Don't know if that helps?

Steven St. John3-Sep-12 7:25

3-Sep-12 7:25

Thank you but no, the problem occurs with any of the 4 arrow presses.

Alan N3-Sep-12 6:00

Alan N

3-Sep-12 6:00

The MSDN documentation for the KeyPreview property isn't exactly clear http://msdn.microsoft.com/en-us/library/system.windows.forms.form.keypreview.aspx[^]. It starts off with the statement that the form will receive all KeyXXXX events from the focussed control, but then adds a note that some controls may cancel a keystroke and disable the preview.

There is short thread on stackoverflow[^] which I think you will find interesting. In one of the answers, Hans Passant describes overriding the form's ProcessCmdKey method as a better solution, e.g.

Protected Overrides Function ProcessCmdKey(ByRef msg As Message, keyData As Keys) As Boolean
  If activeBrick IsNot Nothing Then
    If keyData = Keys.Down OrElse keyData = Keys.Up Then
      MoveBrick(keyData)
      Return True
    End If
  End If
  Return MyBase.ProcessCmdKey(msg, keyData)
End Function

A quick test suggests that this is much more useful technique than KeyPreview and it does not rely on the uncertain cooperation of the focussed control.

Alan.

Steven St. John3-Sep-12 7:32

3-Sep-12 7:32

Indeed, this does work perfectly! In my case I had to add 2 OrElses to cover the Left and Right arrows as well, but it was very nice of you to not only find a solution but modify the code I posted directly.

Many thanks.

(Also thank you for the link to stackOverflow. You are right, I did find that interesting.)

Sonhospa3-Sep-12 7:14

3-Sep-12 7:14

Alan's recommendation works just perfect and leaves the RadioButtons untouched! You can make the 'MoveBrick' function a little bit easier than what you had before.

Private Function MoveBrick(ByVal keyData As Keys) As Boolean
    Dim oldLocation As Drawing.Point = activeBrick.Location
    Dim newLocation As Drawing.Point = oldLocation

    Select Case keyData
        Case Is = Keys.Up
            newLocation.Y = oldLocation.Y - 1
        Case Is = Keys.Down
            newLocation.Y = oldLocation.Y + 1
        Case Is = Keys.Left
            newLocation.X = oldLocation.X - 1
        Case Is = Keys.Right
            newLocation.X = oldLocation.X + 1
    End Select

    activeBrick.Location = newLocation
    Return True

End Function

Steven St. John3-Sep-12 7:35

3-Sep-12 7:35

Thank you for this suggested code. I agree this is readable and efficient, and it tests perfectly in my project.

Kind regards.

Sonhospa3-Sep-12 21:30

DataContext Not Updating Its Database

3-Sep-12 21:30

You're welcome. Thumbs Up | :thumbsup:

Sonhospa31-Aug-12 23:16

Re: DataContext Not Updating Its Database

31-Aug-12 23:16

Hello everybody,

I'm trying to add records to the 'Customer' and the 'Item' classes of my DataContext. The Sub is part of the (partial) DataContext class. Adding new records seems to be a simple thing when I believe all the sources I read, but I'm obviously still wrong with something: 'SubmitChanges' doesn't update the underlying database... Confused | :confused:

This despite the fact that all the DB records (old & new) are printed to the screen before, i.e. seem to be part of the 'Inserts' list. BTW, there are no exceptions thrown.

Can someone please tell me what's wrong with that code?

Public Sub InsertTest()

     Dim cust As New Customer                            ' add new customer
     With cust
         .First_Name = "Paul"
         .Last_Name = "Miller"
     End With
     Customer.InsertOnSubmit(cust)

     Dim item1 As New Item                               ' add new product item
     With item1
         .Item_Name = "DVD"
         .Item_Price = 19.75
     End With
     Item.InsertOnSubmit(item1)

     Dim item2 As New Item                               ' add new product item
     With item2
         .Item_Name = "BlueRay"
         .Item_Price = 29.75
     End With
     Item.InsertOnSubmit(item2)

     ' ONLY FOR DEBUGGING
     ' print changed objects
     Dim mySet As System.Data.Linq.ChangeSet = Me.GetChangeSet()
     Dim liste As Object = mySet.Inserts

     For Each entry As Object In liste                '<----- prints existing & added entries
         Select Case True
             Case TypeOf (entry) Is Item
                 Console.WriteLine(entry.Item_Name)
             Case TypeOf (entry) Is Customer
                 Console.WriteLine(entry.last_name)
             Case Else
                 Console.WriteLine("Objekt vom Typ '{0}'", entry.GetType.Name)
         End Select

     Next

     SubmitChanges()                                    '<---- isn't writing changes to database
     Console.ReadLine()

 End Sub

modified 3-Sep-12 17:46pm.

Sonhospa3-Sep-12 7:21