Progressbar To Quick... VB6 - Xtreme Visual Basic Talk

05-03-2007, 09:51 AM

LittleDevil LittleDevil is offline

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Progressbar To Quick... VB6

Hi Guys

I have a listView control that fills from a recordset and sets a fields name in the listView....this is in a loop untill all names are listed and the user can then click on a name and see a record...

This all works fine.

But on 1 database there are 1000's of names and takes a few seconds to load and I have added a progressbar control onto the form to show the user the % done as a visual aid for large lists.

I put the progress bar code into my recordsets loop and incrimented till the recordset hits EOF and then its done...

This is also working.

But when I load up the large list of names the progressbar shows done well before the list finishes showing all the names and appears off putting a little and wondered what I can do to solve this? Can I slow the progress bar down somehow if there are over a certain amount of records?

Thanks in advance for any help.
L

05-03-2007, 09:58 AM

JPB

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Posts: 629

I think you just need to change the Max property of your progress bar to the RecordCount of the recordset (if I understood your problem correctly).

05-03-2007, 05:21 PM

LittleDevil LittleDevil is offline

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Posts: 247

Hi,
Sorry for not being clearer, I will post a snip of my code to show you what Ive done and as far as I see I have set the RecordCount as you mention ..

This is running as I say but the progress bar is done way before the list fills and finally shows all records..

Code:

a = rs.RecordCount
b = 0
ProgressBar1.Max = 100

Do Until rs.EOF
' fill the list in here along with the small list icons

 b = b + 1
    ProgressBar1.Value = CInt((b / a) * 100)
    rs.MoveNext
    
Loop

rs.Close
Set rs = Nothing
Exit Sub

Thats about all I have ...
Any thoughts or suggestions are welcome.
Thanks

05-03-2007, 06:30 PM

JPB

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Join Date: Oct 2004

Posts: 629

Hmmm, code looks alright to me. Only 2 things that I can think of:

1) Try putting a DoEvents after the rs.MoveNext line. Maybe the ProgressBar is updating itself, but the list is waiting for an opportune moment.
2) What is the value of rs.RecordCount? (try Debug.Print rs.RecordCount). Is it accurate? Depending on the CursorLocation, DB Engine, etc... the RecordCount property can sometimes = -1 or just be an estimation (IIRC). You could try rs.CursorLocation = adUseClient (if you are using ADO for data access, and if it doesn't have a negative impact your requirements) and see if that helps.

05-03-2007, 06:39 PM

LittleDevil LittleDevil is offline

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Join Date: Apr 2003

Posts: 247

Thank you,

That was it...
I had a wrong Recordcount getting returned and fixed that and all is well.
Thank you for your help.
L

05-04-2007, 09:01 AM

PianoMan

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Join Date: Oct 2003

Location: NC, USA

Posts: 470

Quote:

Originally Posted by LittleDevil

Code:

a = rs.RecordCount
b = 0
ProgressBar1.Max = 100

Do Until rs.EOF
' fill the list in here along with the small list icons

 b = b + 1
    ProgressBar1.Value = CInt((b / a) * 100)
    rs.MoveNext
    
Loop

rs.Close
Set rs = Nothing
Exit Sub

Thats about all I have ...
Any thoughts or suggestions are welcome.

A sugestion. If you're looping through the entire recordset, why not just increment the progressbar each time you move to the next record.

Code:

a = rs.RecordCount
b = 0
ProgressBar1.Max = a -1 'set the max to the .RecordCount property

Do Until rs.EOF
' fill the list in here along with the small list icons

 b = b + 1
 rs.MoveNext
 ProgressBar1.Value = ProgressBar1.Value + 1 'increment by 1 each time you loop through
DoEvents
Loop

rs.Close
Set rs = Nothing
Exit Sub

This way you're ensured that the ProgressBar progress matches what you are doing in the recordset.

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05-04-2007, 10:32 AM

loquin

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Now, if you have thousands of records, updating the progress bar and issuing a DoEvents for every record is REALLY going to slow down your app. A LOT.

However, if you need to see the bar update, and you have a lot of records, here's a handy workaround: Only update the bar when the change would result in a VISIBLE change in the progress bar. (a change that results in at LEAST one pixel change on the progress bar (that uses smooth scrolling)) Suppose that you have 10000 records, and your progress bar is 200 pixels wide. This means that you only need to update the progress bar every 50 records! (10000 Records/200 pixels = 50 records/pixel ) Note that if you are using a progress bar with standard scrolling, each "step" is about 15 pixels wide...

You're already keeping track of your current record number. before you begin your loop, calculate the number of pixels in your progress bar, then calculate the records per pixel. Then, inside the loop, only update the bar when needed.

Code:

Const TwipsPerInch as Integer = 1440 ' useful for scalemodes other than twips/pixels
Const intStdScrollScale as Integer = 15
Dim lngCurrentRecord as long
Dim lngRecPerPixel as Long
Dim lngNumRecs as Long

  lngNumRecs = rs.Recordcount ' (Or, issue a select count SQL statement first)

  ' calculate the number of records per pixel
  Select Case me.Scalemode
    Case 1 'twips
      lngRecPerPixel = rs.RecordCount\(me.ProgressBar1.Width/Screen.TwipsPerPixelX)
    Case 3 ' Pixels
      lngRecPerPixel = rs.RecordCount\me.ProgressBar1.Width
    Case Else
      lngRecPerPixel = 1 
      ' You'll need to work out any other scale modes 
      ' yourself, remembering that there are 1440 twips per inch.
  End Select

  ' account for progress bar scroll mode
  If me.ProgressBar1.Scrolling = ccScrollingStandard then 
    lngRecPerPixel = lngRecPerPixel * intStdScrollScale 
  End If

  ' Since the number of records COULD exceed 32767, always use percentage,
  ' rather than actual record number
  Me.ProgressBar1.Max = 100 ' percent

  Do Until rs.EOF
    ' fill the list in here along with the small list icons
    lngCurrentRecord = lngCurrentRecord + 1 
    rs.MoveNext
    
    ' ONLY if we need to, calculate percentage & update...
    If lngCurrentRecord Mod lngRecPerPixel = 0 Then
      ProgressBar1.Value =  cSng(lngCurrentRecord / lngNumRecs * 100)
      DoEvents 
    End If
  Loop

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Last edited by loquin; 05-04-2007 at 10:48 AM.

05-05-2007, 07:04 PM

LittleDevil LittleDevil is offline

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Thats very clever, Thank you.....

The DoEvents did indeed slow it down dramatically so I took it out right away...

Thanks again
L

05-07-2007, 09:18 AM

loquin

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However, without the DoEvents, you won't see any changes in the progress bar until the loop is done. Which, really defeats the purpose of a progress bar, doesn't it???

As I posted earlier, just update the progress bar and issue a DoEvents ONLY when a change in the progress bar .Value would result in a visible change in the progress bar.