Flickering

Don P

New member
Joined
Nov 29, 2004
Messages
3
Programming Experience
Beginner
I need to get rid of a flickering that happens everytime my scrolling text appears. If anyone can help me it will be great. Here's the code of the form:

Public Class ticker
Inherits System.Windows.Forms.Form

Dim S As New setup
Dim widthX As Single
Dim heightY As Single = 3
Dim g As Graphics
Dim xmlst As String 'string from the xml file
Dim fo As Font
Dim str As String
Dim strwidth As SizeF 'gets the xml string's width and height
Dim douX As Double 'stores the xmlstring's width

Private Sub ticker_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

g = Me.CreateGraphics() 'get the graphics object of the form
widthX = Me.Width ' x co- ordinate or width
' Debug.Write(String.Format("The width is {0}", ‘CStr(Me.Width)))
Me.loadthenews()
Me.SetStyle(ControlStyles.DoubleBuffer, True)
Me.UpdateStyles()
Dim gr As Graphics
Timer1.Interval = 75
Timer1.Start()
fo = New Font("Arial Narrow", 18, FontStyle.Italic, GraphicsUnit.Point)
strwidth = g.MeasureString(str, fo)
douX = strwidth.Width
Me.SetStyle(ControlStyles.DoubleBuffer, True)
Me.UpdateStyles()
End Sub

Private Sub loadthenews()
Dim readXML As New XmlTextReader("http://www.betstreetsmart.com/sports.xml")

While readXML.Read()
If readXML.NodeType = XmlNodeType.Text Then
str += " " & readXML.Value
End If
End While
End Sub

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick

'Debug.Write(vbCr & strwidth.Width & vbCr)
'Debug.Write(String.Format("widthX = {0}", CStr(widthX) & vbCr))

g.Clear(Me.BackColor)
g.DrawString(str, fo, Brushes.White, widthX, heightY)
' Debug.Write(String.Format("the string width is {0}", ‘
' CStr(strwidth.Width)))

If widthX <= (0 - douX) Then 'check whether all text ‘have been scrolled
widthX = Me.Width
Else
widthX -= 5
End If
End Sub

Private Sub NewsTicker_hover(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.MouseHover
Timer1.Stop()
Debug.Write(String.Format("The string width is {0}", CStr(douX)))
End Sub

Private Sub NewsTicker_leave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.MouseLeave
Timer1.Start()
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Me.Close()

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

Me.WindowState = FormWindowState.Minimized

End Sub

Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click

System.Diagnostics.Process.Start("www.sportscallcenter.com")

End Sub

Private Sub ticker_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Click

System.Diagnostics.Process.Start("www.betandclick.com/form.htm")

End Sub

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

Static CustomColors() As Integer = {RGB(255, 0, 0), RGB(0, 255, 0), RGB(0, 0, 255)}
'initializing CustomColors with an array of integers and putting Red, Green,
'and Blue in the custom colors section
Try
With ColorDialog1
.Color = BackColor
'initializing the selected color to match the color currently used
'by the richtextbox's foreground color
.CustomColors = CustomColors
'filling custom colors on the dialog box with the array declared above
If .ShowDialog() = DialogResult.OK Then
BackColor = .Color
CustomColors = .CustomColors
'Storing the custom colors to use again
End If
ColorDialog1.Reset()
'resetting all colors in the dialog box
End With
Catch es As Exception
MessageBox.Show(es.Message)
End Try

End Sub

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click

Me.Timer1.Interval = Me.Timer1.Interval - 10
If (Me.Timer1.Interval <= 10) Then
Me.Timer1.Interval = 100
End If

End Sub


End Class
 

Sautin

New member
Joined
Jan 10, 2005
Messages
4
Programming Experience
3-5
first add an image object to your form and make sure to scale it to be your drawing surface. I.E. form resize - resize your image

then in the routine where you create your graphics do this.

Dim bit As Bitmap = New Bitmap(MyBase.Width, MyBase.Height)

Dim myGraphics As Graphics = Graphics.FromImage(bit)

''Drawing routines here

picImage.Image = bit

picImage.Refresh()

Note' picImage = the image added to your form/control

Hope this helps. I do animation in my Controls using pure GDI+ and I get zero flicker even with refresh rates at 100 on a timer object and without DoubleBuffering

 

Paszt

Staff member
Joined
Jun 3, 2004
Messages
1,500
Location
Raleigh, NC - USA
Programming Experience
Beginner
I think the reason you get flickering is because you're drawing such a long string.
I created a ticker using a label. Set the text of the label and simply move the label, checking to see if it has scrolled all the way across the screen.
 
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