[RESOLVED] Stop Scrolling label Flicker

[seanwpb]

i have the attached project with a scrolling label and the label flickers badly. i have tried LockWindowUpdate and that may have been worse. its a label inside a picture box and the label doesnt have a hWnd so i user LockWindowUpdate(Picture1.hWnd) and it didnt work. i also tried not having the label in the picture box any ideas how i can make it stop flicking?

[Witis]

one way, is to use 2 picture boxes and BitBlt.
steps:
In the timer subroutine:
1. the first picture box has the label in it and in the timer the label is moved to the left like you already have.
2. now use the print statement to print the text directly onto the picture box (using the position of the label as the coordinates for printing the text onto the picture box)
3. use BitBlt to copy the picture box onto which you just printed text to the other picture box, and this will stop the flicker.
4. Hide the picture box with the label in it (it will flicker) so that you only see smooth scrolling text in the BitBlted picture box.

Here are the declarations and an example of using BitBlt to copy from one picture box to the other.

Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal X As Long, ByVal Y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Private Const SRCCOPY = &HCC0020

BitBlt Picture1.hDC, 0, 0, Picture1.ScaleWidth, Picture1.ScaleHeight, Picture2.hDC, 0, 0, SRCCOPY

[seanwpb]

Witis,

thanks for the response. i tried what i think your saying and it didn't work so im not understanding this

here is my timer1 code

lblTime.Caption = Time
    lblDate.Caption = Date
    
    
    
    Picture1.Print "This is an example of Marquee Scrolling Text Using A Label And A Picture Box. this is a big example to see what is going to happen when this thing is really big"
    
   BitBlt Picture1.hDC, 0, 0, Picture1.ScaleWidth, Picture1.ScaleHeight, Picture5.hDC, 0, 0, SRCCOPY
    
      Label1.Move Label1.Left - 25
      
      If Label1.Left < -Label1.Width Then Label1.Left = Picture1.Width

picture5 is the new picture box. i made the declaration too. no error just an empty picture5 with no scrolling. i have never done bitblt before. i have attached it again

[Witis]

Hi seanwpb, see the code below and the attached form which should make it clearer.

Set timer to 10ms

Option Explicit
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal X As Long, ByVal Y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Private Const SRCCOPY = &HCC0020

Private Sub Timer1_Timer()
    Label1.Move Label1.Left - 20 ' move the label to the left for scrolling effect
    If Label1.Left < -Label1.Width Then Label1.Left = Picture1.Width
    Me.Picture1.CurrentY = Me.Label1.Top ' use the label coordinates to set printing position
    Me.Picture1.CurrentX = Me.Label1.Left ' use the label coordinates to set the printing position
    Me.Picture1.Print Me.Label1 ' print the label text on to the picture box
    Picture2.Cls ' clear the destination picbox
    BitBlt Picture2.hDC, 0, 0, Picture1.ScaleWidth, Picture1.ScaleHeight, Picture1.hDC, 0, 0, SRCCOPY ' bitblt picture1 to picture2 to remove flicker
End Sub

[seanwpb]

Witis,

thanks for the code. i see how it works now. The only issue is when you change the font size and or bold label1 in picture1 its all messed up. there appears to be two lines of text on top of each other in both picture boxes. any idea how to fix that?

[seanwpb]

ok i got it to work great. i modified your timer code by commenting out two lines and i can now change the font to a much bigger one and it looks perfect

Witis, thanks for all your help

Private Sub Timer1_Timer()
    Label1.Move Label1.Left - 10 ' move the label to the left for scrolling effect
    If Label1.Left < -Label1.Width Then Label1.Left = Picture1.Width
    Me.Picture1.CurrentY = Me.Label1.Top ' use the label coordinates to set printing position
    Me.Picture1.CurrentX = Me.Label1.Left ' use the label coordinates to set the printing position
    'Me.Picture1.Print Me.Label1 ' print the label text on to the picture box
    'Picture2.Cls ' clear the destination picbox
    BitBlt Picture2.hDC, 0, 0, Picture1.ScaleWidth, Picture1.ScaleHeight, Picture1.hDC, 0, 0, SRCCOPY ' bitblt picture1 to picture2 to remove flicker
End Sub

if anyone is interested in an easy demo see attached