.NET (Core and Framework)

Re: Retrieve node texts from treenode

20-Jul-09 11:39

It sounds like you want to "walk the tree", in which case you'll really need a recursive method to do that (one that calls itself). In you case the method will return the text of the current node and then call itself passing each child node as a parameter.

I just love Koalas - they go great with Bacon.

vidhyaravichandar20-Jul-09 15:53

vidhyaravichandar

20-Jul-09 15:53

Hi,

thanks for ur reply...

I cud hav recursive function. But i dont know how to loop through it. I mean, How to use nextnode method and loop through all the nodes in the treenode which has child nodes....

How to include xml

ksss_maheshece19-Jul-09 21:15

ksss_maheshece

19-Jul-09 21:15

Hello friends,
I have a xmal file which contains all the javascript validation, section group ect fro my wep based application.I wanna use that file globally over my application.How can i include and access that file?

Async Sockets

Lee Humphries19-Jul-09 20:38

19-Jul-09 20:38

I've just recently ported a sockets client from .Net 2.0 to .Net 3.5 ...
and now it runs into reoccurring problems, of which I'm a little suspicious may be related to subtle differences between the frameworks that I'm not allowing for.

Specifically the Receive Callback function is being invoked, but the socket itself is no longer connected (and probably disposed). This is in spite of the fact that data is expected to be received.

private void ReceiveCallback(IAsyncResult ar)
{
  SocketError sErr = SocketError.Success;
  int bytesRead = 0;
  lock (this)
  {
    try
    {
      // Retrieve the client socket from the asynchronous state object.
      Socket socket = (Socket)ar.AsyncState;

      sErr = new SocketError();

      // Read data from the remote device.
      // however this line frequently throws an exception
      bytesRead = socket.EndReceive(ar, out sErr);
      ...

And the essentials of the exception are:

ReceiveCallback threw an error. System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'System.Net.Sockets.Socket'.
   at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult, SocketError& errorCode)

The associated socket error code is 10038 - which when you read its description isn't very helpful either.

Just to add to this the previous version of this client is still running and still connecting to the same server without issue.

My request is if anyone can point me in the right direction as to what I'm missing or doing wrong. You can reasonably assume that I've googled every permutation of the above in my quest.

Here's some possibilities:
* There's some subtle distinction in how v2.0 and v3.5 sockets connect (e.g. defaults for various socket options) that the server I'm connecting doesn't like / understand.
* It's a speed issue. The v2.0 code has got a whole heap of throttling tricks, that the v3.5 based version does not - I don't think this one's likely (already been playing around in this area).
* It's a threading and/or locks problem on the socket itself.
* I'm missing something important in using sockets - not likely, but this excuse is here for completeness, just in case you have some "traps for young players" type of insight.
* Or something else.

I just love Koalas - they go great with Bacon.

Re: Async Sockets

Nicholas Butler19-Jul-09 22:13

Nicholas Butler

19-Jul-09 22:13

It sounds like your Socket object is being disposed! I would expect that putting a reference to it in your AsyncState would stop the GC collecting it, so are you disposing of it somewhere else?

I don't have a simple answer, but you could try this: Derive from Socket and override Dispose. Put a breakpoint in there to find out when it is being disposed and by whom.

Also, the code you posted has a couple of no-no's:

1) Locking on this is considered bad practice - use a private object to lock on.

2) You don't need to initialise sErr as it is passed as an out parameter.

Nick

----------------------------------
Be excellent to each other Smile | :)

Re: Async Sockets

Lee Humphries20-Jul-09 11:34

Re: Async Sockets - the answer

20-Jul-09 11:34

Thanks for those suggestions Nick.

As to the bad practices, they actually originally came from sample code that I was trying as a part of resolving this problem. I left them in there in case it triggered someone's memory (and they had better suggestions).

I've already looked at the actual .Net sockets code so I understand some of the mechanisms involved. In particular it relates to the m_IntCleanedUp member and the code related to its handling. But it hasn't really told me what I need to know to resolve the above.

I just love Koalas - they go great with Bacon.

Lee Humphries20-Jul-09 19:11

Combobox - DrawItem and dragging scroll bar problem

20-Jul-09 19:11

Thanks to Nick's suggestion

Nick Butler wrote:
Derive from Socket and override Dispose.

.
I managed to find the fault when I overrode Disconnect and had it dump a stack trace.

The previous version of this service used WSE, the new version of this service uses WCF. In the previous version I had put a call to disconnect in the destructor to ensure that the socket got cleaned up properly. Under WCF the destructor was being invoked at an inopportune time resulting in the socket being disconnected (but not actually disposed).

Various aspects to the solution, but the two main ones were:
1. Remove the 'cleanup' call to disconnect from the destructor. i.e. If you're using my service then you call the disconnect yourself.
2. Supply the decoration [OperationBehavior(TransactionScopeRequired = true)] to each method exposed by the WCF service.

I just love Koalas - they go great with Bacon.

test

chandni patel18-Jul-09 23:35

chandni patel

18-Jul-09 23:35

sfsgfgjhklj
gjgjgkk
k

jhjhfddserty
gdfgguijkk Rose | [Rose]

Re: test

Abhijit Jana19-Jul-09 0:14

Abhijit Jana

19-Jul-09 0:14

chandni patel wrote:
sfsgfgjhklj
gjgjgkk
k

jhjhfddserty
gdfgguijkkRose

What kind of Testing are you doing over here? OMG | :OMG:

Please DONT SPAM. If you have some problem, then asked over here, everybody will try to help you. But don't SPAM in this healthy site.

cheers,
Abhijit
CodeProject MVP
Web Site:abhijitjana.net
My Latest Article : IIS Remote Debugging

Result

leckey19-Jul-09 18:42

leckey

19-Jul-09 18:42

Yep, you are an idiot.

Back in the blog beatch!
http://CraptasticNation.blogspot.com/[^]

Re: test

0x3c019-Jul-09 20:45

0x3c0

19-Jul-09 20:45

Please refrain from spamming. You have a message forum on your profile for that

Between the idea
And the reality
Between the motion
And the act
Falls the Shadow

David Hovey18-Jul-09 19:18

Re: Combobox - DrawItem and dragging scroll bar problem

18-Jul-09 19:18

Hi there. I need some help with drawing items for a ComboBox Control.

For the most part the ComboBox draws just fine. I can scroll up and down and everything is good. The problem is when I drag the scrollbar "thumb" or box to get through the list faster. The items do not display correctly.

The ComboBox is set to DropDownList and OwnerDrawVariable.

I understand the code below is not very meaningful as I could use the windows implementation to draw the items. The program I'm working on displays certain items in bold, so the code below just illustrates the problem I have.

Thanks for your help!!

Public Class Form1

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

        Dim i As Integer

        For i = 1 To 200
            ComboBox1.Items.Add(i)
        Next

    End Sub

    Private Sub ComboBox1_DrawItem(ByVal sender As Object, ByVal e As System.Windows.Forms.DrawItemEventArgs) Handles ComboBox1.DrawItem

        If e.Index = -1 Then
            Exit Sub
        End If

        e.DrawBackground()

        e.Graphics.DrawString(ComboBox1.Items(e.Index).ToString(), e.Font, New SolidBrush(Color.Black), e.Bounds.X, e.Bounds.Y)

    End Sub

End Class

Luc Pattyn19-Jul-09 2:43

Re: Combobox - DrawItem and dragging scroll bar problem

19-Jul-09 2:43

Hi,

not sure this will fix it, however it might as your current code is too expensive: for every item drawn you:
- create a new SolidBrush
- and you don't call Dispose on it, which you should as the class offers such method.

It would be better to create a brush once, and keep it handy in a class member so you can reuse it for all items. And actually, you don't even need this as there is a class offering standard brushes, so all you need is Brushes.Black

Smile | :)

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David Hovey19-Jul-09 6:50

Re: Combobox - DrawItem and dragging scroll bar problem

19-Jul-09 6:50

Thanks for the comment. You remind me to think about that more.
New code is below, but issue still exists.

I was thinking that perhaps I needed a custom class, that overrides the OnPaint method. This doesn't seem correct as the method would draw the part of the control that doesn't drop down.

I searched for quite a while and it doesn't seem anyone else has had this problem.

Public Class Form1

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

        Dim i As Integer

        For i = 1 To 200
            ComboBox1.Items.Add(i)
        Next

    End Sub

    Private Sub ComboBox1_DrawItem(ByVal sender As Object, ByVal e As System.Windows.Forms.DrawItemEventArgs) Handles ComboBox1.DrawItem

        If e.Index = -1 Then
            Exit Sub
        End If

        e.DrawBackground()

        e.Graphics.DrawString(ComboBox1.Items(e.Index).ToString(), e.Font, Brushes.Black, e.Bounds.X, e.Bounds.Y)

    End Sub

End Class

Luc Pattyn19-Jul-09 8:26

Re: Combobox - DrawItem and dragging scroll bar problem [modified]

19-Jul-09 8:26

Hi,

I haven't done any ComboBox.DrawItem myself, however I use ListBopx.DrawItem a lot, and they are documented very similarly. Never had any problems. Is your CB double-buffered? is your Form? Mine normally are.

You haven't told in any detail what is wrong with the result.

here are some suggestions:
- if the comboBox.Items are strings, no need to call ToString()
- use the entire e.Bounds in DrawString, not just X and Y
- if the visual result does not provide a clue, I would add logging code to figure for which items DrawItem gets called/doesn't get called assuming some of the items are not repainted, hence show previous content.

BTW: the MSDN example on CB.DrawItem creates and doesn't dispose of its SolidBrush and Font!

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

David Hovey19-Jul-09 11:51

Re: Combobox - DrawItem and dragging scroll bar problem

19-Jul-09 11:51

Ok. Well here is the info I have.
I changed the code quite a bit. Created a custom combobox at runtime. Form and combobox are doublebuffered.
It also creates a log file showing index, bounds, and time of DrawItem method being executed.

To describe the problem. It would appear that the Background is not being drawn correctly (but this only describes the appearance-I don't think this is the cause). When I quickly scroll the entire list, to the end, the majority of the items appear as a "blob" of black as if all of the items were drawn over top of eachother. The odd thing is this is intermittent. Out of the 20 items shown in the drop down maybe 3 or 4 will be displayed correctly.

The log file shows that when quickly dragging through a list, the items are only being drawn on either the last or second to the last visible item bounds. When dragging up the items are only drawn on either the top or second visible item bounds. Since this is the case, internally, either Windows or the .NET framework, would have to be storing the item graphics and then be moving the previous item graphics up or down.
But if you click on the scroll bar to get the next or previous "page" all the items will be redrawn from top to bottom...

I uploaded the log file to my website http://www.hoveytech.com/drawitemlog.txt

Not sure where to go from here.

Thanks for your quick answers and continued help!

Public Class Form1
    Private m_fBold As Font
    Private WithEvents m_cboCustom1 As CustomCombo

    Private Sub m_cboCustom1_DrawItem(ByVal sender As Object, ByVal e As System.Windows.Forms.DrawItemEventArgs) Handles m_cboCustom1.DrawItem

        If e.Index = -1 Then
            Exit Sub
        End If

        e.DrawBackground()

        If e.Index Mod 4 = 0 Then
            e.Graphics.DrawString(m_cboCustom1.Items(e.Index).ToString(), m_fBold, Brushes.Black, e.Bounds)
        Else
            e.Graphics.DrawString(m_cboCustom1.Items(e.Index).ToString(), e.Font, Brushes.Black, e.Bounds)
        End If

        LogDrawItem(e.Index, e.State, e.Bounds)

    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load


        Me.DoubleBuffered = True

        m_cboCustom1 = New CustomCombo
        m_cboCustom1.Location = New Point(30, 30)
        m_cboCustom1.DropDownStyle = ComboBoxStyle.DropDownList
        m_cboCustom1.DrawMode = DrawMode.OwnerDrawVariable
        m_cboCustom1.MaxDropDownItems = 20
        Me.Controls.Add(m_cboCustom1)

        m_fBold = New Font(m_cboCustom1.Font, FontStyle.Bold)

        Dim i As Integer

        For i = 1 To 200
            m_cboCustom1.Items.Add(i)
        Next

    End Sub

    Private Sub LogDrawItem(ByVal iIndexDrawn As Integer, ByVal iState As System.Windows.Forms.DrawItemState, ByVal rect1 As Rectangle)

        Dim sw As System.IO.StreamWriter = New System.IO.StreamWriter(Application.StartupPath & "\drawitemlog.txt", True)

        sw.WriteLine("DrawItem method ran for index: " & iIndexDrawn.ToString() & vbTab & "bounds: " & rect1.ToString() & vbTab & "at " & Now().ToLongDateString & " " & Now().ToLongTimeString())

        sw.Close()

    End Sub
End Class

Public Class CustomCombo
    Inherits System.Windows.Forms.ComboBox

    Public Sub New()

        Me.DoubleBuffered = True

    End Sub
End Class

modified on Sunday, July 19, 2009 5:58 PM

Luc Pattyn19-Jul-09 12:17

Re: Combobox - DrawItem and dragging scroll bar problem

19-Jul-09 12:17

Hi David,

I noticed you have chosen OwnerDrawVariable, which means each item has its own height, and before DrawItem fires a MeasureItem event gets fired, asking you for the height of the item.

Suggestion:
- try OwnerDrawFixed;
- or provide a MeasureItem handler.

With this fixed it works fine for me (also remove the logging in DrawItem for good responsiveness).

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

David Hovey19-Jul-09 12:33

19-Jul-09 12:33

Thanks for your help!
It works now!!

loading text [modified]

deadcell_618-Jul-09 8:50

deadcell_6

18-Jul-09 8:50

im wanting to click on a item in a listbox and load the txt file into a richtextbox from the folder my main program resides in

can anyone show me how to do this in c#?

modified on Saturday, July 18, 2009 3:01 PM

Re: loading text

Luc Pattyn18-Jul-09 9:07