It took me awhile to figure this one out. I needed a textbox that would scroll the text off the left side of the textbox. It also needed to be able to have more than one string to display. It would cycle through the strings, changing from the current string to the next string when the current string has scrolled off the screen.
I was able to find a lot of examples on the Net, but none of them worked quite right. One didn’t work at all, one caused the program to crash while debugging (which kicked VS out of debug mode like I had clicked stop debug!), and the last one worked, but did not meet my requirements. The one that worked scrolled the text to the right. And it had some interesting code to it. That example was found here .
What I came up with was a UserControl as follows:
Private mStartPos As Integer
Private mText As Collection
Private mTextNum As Integer = 1
Private mScrollSpeed As Integer = 1
Public Sub New()
' This call is required by the Windows Form Designer.
InitializeComponent()
mText = New Collection()
mStartPos = 0
Timer1.Enabled = True
End Sub
This sets up the form. I added a Timer to the designer that is used to update the scrolling. There are also some public accessor subs/properties:
Public Sub AddMarqueeText(ByVal str As String)
If str <> "" Then
mText.Add(str, str)
End If
End Sub
Public Sub RemoveMarqueeText(ByVal str As String)
If str <> "" Then
mText.Remove(str)
End If
End Sub
Public Property ScrollSpeed() As Integer
Get
Return mScrollSpeed
End Get
Set(ByVal value As Integer)
If value < 1 Then
mScrollSpeed = 1
ElseIf value > 10 Then
mScrollSpeed = 10
Else
mScrollSpeed = value
End If
Timer1.Interval = mScrollSpeed * 10
End Set
End Property
These should be pretty self explanatory. Now the code for the Timer Tick event and Paint event:
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
If mStartPos >= CStr(mText(mTextNum)).Length Then
'Change to the next text
If mTextNum = mText.Count Then
mTextNum = 1
Else
mTextNum += 1
End If
mStartPos = 1
Else
mStartPos += 1
End If
Invalidate()
End Sub
Private Sub ScrollingTextBox_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
Dim str As String = CStr(mText.Item(mTextNum))
Dim g As Graphics = e.Graphics
Dim tmpStr As String = str.Substring(mStartPos)
g.DrawString(tmpStr, Me.Font, New SolidBrush(Me.ForeColor), 0, 0)
End Sub
And there you have it. A simple CompactFramework UserControl that holds a collection of strings, scrolls the text as needed, and changes the text that it is displaying. Right now I am using VS2008 and v3.5 of the CF.Net, but I don’t think there is anything in here that is version specific.
Micro Software Development 