VS 2010 - BackgroundWorker And ListView (Improvement)
Jan 7, 2011
Here's my code :
VB
'Clearing the selected items of the listview
ListView1.SelectedItems.Clear()
'Random selection of farms from the listview
Dim random As New Random()
Dim rand As Integer = random.[Next](0, ListView1.Items.Count)
[Code] .....
I'm running it under a BGW and it works fine but is there anyone who can comment on it and make my code a bit better. I've a background worker and I am running it again and again on the RunWorkerCompleted like this
VB
Private Sub BGW_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BGW.RunWorkerComplete
BGW.RunWorkerAsync()
End Sub
Is it bad coding or is there any alternative to run it?
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Sep 8, 2010
I'm using a vb.net backgroundworker thread for processing and I need to periodically add items to a listview (with multiple columns) during the thread processing.I can easily use the following code for delegating the task to add an item to a listview, but I can't figure out how to additional info to other columns on the same row.he thread, I'd execute the following to trigger the invoke to add to listview:AddListItem(ListView1, filepath)Here is the delegate code, if someone can show me how to add the t
Delegate Sub AddListItem_Delegate(ByVal [Label] As ListView, ByVal [text] As String)
Private Sub AddListItem(ByVal [ListView] As ListView, ByVal [text] As String, Optional ByVal [text2] As String = "")
[code].....
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Jan 25, 2012
I'm working on a mathematical model written in VB6. The amount of CPU time this model is consuming is becoming a concern to some of our customers and the notion has been floated that porting it to VB.NET will improve its performance.The model is performing a lot of single-precision arithmetic (a finite-difference scheme over a large grid) with small bursts of database access every five seconds or so (not enough to be important). Only basic arithmetic functions with occasional use of the ^ 4 operator are involved.
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Jul 8, 2009
I have a WPF ListView that I am trying to filter within a BackgroundWorker. My code is shown below:
Dim Worker As New BackgroundWorker
AddHandler Worker.DoWork, AddressOf Me.FilterAsync
Me.TextBoxText = Me.TextBox.Text
Worker.RunWorkerAsync(Me.TextBox)
[code]....
This code runs through the filtering however it fails with an error "The calling thread cannot access this object because a different thread owns it." on the following line:
ListView.Filter = New Predicate(Of Object)(AddressOf Me.FindItemsAsync)
What would be the problem here? I can't seem to find any samples with filtering through the BackgroundWorker.
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Feb 6, 2012
I have 2 Form, form1 and form2, there are listview in form1 and there are backgroundworker in form2, I trying to add Items to listview in form1 with backgroundworker in form2, but when I run the backgroundworker, nothing happen with listview, but its work when I am not using Backgroundworker in form 2_load
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Nov 30, 2009
I'm trying to add information to a ListView from a BackgroundWorker thread. I thought I could do this in this manner:
vb.net
Private Delegate Sub _ListView(ByVal lvi As ListViewItem)
Public Sub test(ByVal lvi As ListViewItem)
[Code].....
When I attempt to run the "test" sub the BackgroundWorker, I get an error:
Argument not specified for parameter 'lvi' of 'Public Syb test(lvi as System.Windows.Forms.ListViewItem)'.
Is there something I need to specify when declaring the sub, or in the sub itself?
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Sep 20, 2009
I'm using the following to check the state of checkboxes and then activate some public subs based on the checked state of the checkboxes:
vb.net
Public Sub TestSub() If Me.CheckBox1.InvokeRequired Then Me. CheckBox1.Invoke(New MethodInvoker(AddressOf TestSub)) Else Begin() End If End Sub
Within the Begin sub, I have code that performs specific actions and then updates a ListView with that information.As far as I can tell, the actions are being performed, but the ListView isn't being updated with the info.I'm calling the Test sub from a seperate form, within the BackGroundWorker's DoWork event.Would I have to check the InvokeRequired property of the ListView as well?I'm looking more into the documentation of the BackGroundWorker.
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May 9, 2011
Can someone point me out a way to add items to listview cotrol from a backround worker, I've searched the web for a way to do this but with no success
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Dec 14, 2009
in my button click event i ececure
If BackgroundWorker4.IsBusy Then
BackgroundWorker1.CancelAsync()
End If[code]....
after proceess completed if press the button again.i got the following error msg
This BackgroundWorker is currently busy and cannot run multiple tasks concurrently.
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Sep 5, 2010
I have some issues with background worker progress reporting functionality. I'm implementing a progress indicator and even if I marked the backgroundworker as report progress (true), it won't report progress until it finish the job.
The code is like this:
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
action_1()
[code]....
The result is as expected (label1 with 100 value) but only when worker finished all the steps. If I'm triggering a messagebox in ProgressChange I see two message windows at the end of DoWork handle.
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Feb 16, 2010
I'd like to have a backgroundworker process data that will eventually populate a gridview in my windows form. I need to use a backgroundworker because the process takes a little while, normally causing the program to slow/freeze until it's opening and streaming connections.. So, I'm using a background worker to perform these methods.How can I take the data from the background worker (on a separate thread than the UI) and use it to populate controls in the UI?
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Sep 24, 2009
I have the download progress bar working in my program but I can't find any working code to determine the amount uploaded. here is my upload code
[code]...
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Feb 16, 2010
I cannot figure this one out.. I have a background worker that will perform a task streaming data from some webpages. this data is then passed back and displayed in a gridview. It has been working fine.
I've recently implemented a listbox, which its values will be passed into the function that the background worker will perform as parameters, originally i had taken a single value from a textbox.
Now, I thought maybe it had something to do with the listbox, so I used a static value, just a simple String, as the parameter, and again, I get the TargetInvocationException was unhandled.. There's no difference in how I perform the task I'm trying to have the backgroundworker complete, the only difference is where it exists in my if condition statement:
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles ScrapeSites.DoWork
Dim results As ArrayList
Dim worker As System.ComponentModel.BackgroundWorker = DirectCast(sender, System.ComponentModel.BackgroundWorker)
[Code]...
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Apr 27, 2010
i have a standard login form that allows the user to enter username and password and click OK or cancel. I have a progress bar called pbLaunch with the visible property set to false and the animation set to marquee. when the user clicks OK i would like to run a separate thread called bgwProgress that makes the progress bar visible and fires up the marquee just to show that something is happening while form1 loads up.....so far i'm stuckn the ok click event i have the following:
Try
Dim bgwProgress As New System.ComponentModel.BackgroundWorker
bgwProgress.WorkerSupportsCancellation = True
[code].....
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Mar 3, 2011
I just want to to change a label name from the backgroundworker, the code is plain simple:
label1.text = WebBrowser1.DocumentTitle and the error returned would be "Specified cast is not valid".
Now running the code from a button would do the job, but from the bgworker not, and I can't seem to get around it.
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Oct 14, 2009
I have a class that downloads a specific file from the net.This class uses a BackgroundWorker. I tried to implement kleinma's Download Files From Web With Progressbar [URL]../showthread.php?t=396260), but I'm having difficulties making it work. I'm including a test project, so if someone is willing to take a look at it, it would be great .
The part I'm having trouble with is updating the progressbar and progress label. The errormessage I receive is in Norwegian, but it has something to do with threads. I suppose I should use Invoke or something, but I don't know where to start..
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Apr 18, 2012
I'm struggling with a thing or two...and i've read some stuff about the backgroundworker but im stuck Basically what i have is a : PUBLIC FUNCTION TEST (path as string) : which at the end of work , adds an item to the form1.listbox. That works quite nice but freezes the app. I've tried using the backgroundworker, the function in the background worker seems to work nicely, the bad thing is that i dont get any results in the form1.listbox.
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Jan 19, 2012
I've wrote this code to accomplish what the image below looks like. This works fine for anything that is around 40x40 but if I try to do 100x100 it takes forever and sometimes errors out with a window handle error. Once it gets around the 40th column the labels start adding slower and slower. Is there anything I can do to make this more efficient? I added the backgroundworker routine in there to see if it would speed things up at all but it doesn't.
vb.net
Private Sub CreateGrid(ByVal rows As Integer, ByVal ranges As Integer)
If Me.InvokeRequired Then
[code]....
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Oct 8, 2010
I am trying to create a tool which executes some oracle procedures and telnet commands. Besides this Job my tool also needs to update a counter in some table in oracle db at regular intervals(10 secs as per current settings). So I used backgroundworker class in VB.NET to implement this back ground job of updating the counter. My problem is I have put logs at every possible exit of the backgroundworker_dowork functions but still this logic stops working after some time --7-8 hours. I am not able to understand when/where/why/how is it stopping? I am saying logic has stopped because it stops incrementing the counter. And am saying it is exiting abruptly because in _RunWorkerCompleted, I have written a log and closed the application but nothing comes in the log and application is not exiting.
Private Sub backlogicthread_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles backlogicthread.DoWork
WriteLog("Background worker", "entered")
dbbackcontrol = New OracleConnection(odbcBill)
Dim dr As OracleDataReader
[Code] .....
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Jul 5, 2011
I have a backgroundworker that is downloading data from different webpages and process them to a datagridview.I get the Cross-thread operation not valid error on the first For loop.
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
dim i as integer
tot = (numPostnrTo.Value - numPostnrFrom.Value) / 10
[code]....
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Apr 19, 2012
I want to populate a listview and leave selected records that are true
I have a DB record which is ID int, desc varchar, selected boolean.
I have tried the code below
LVProducts is a Listview and DS is a dataset
CODE:
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May 22, 2011
I want to execute a few external apps, where in between a RichTextBox gets updated.. Say when program1 has been startet the RichTextBox is updated.. And when program2 has been startet the RichTextBox is beeing updated again.So what i've done so far is this:
Public Class Form1
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
[code]....
But when doing the above i get the following error:
Quote:
Cross-thread operation not valid: Control 'RichTextBox1' accessed from a thread other than the thread it was created on.
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Nov 15, 2011
I have a VB.NET 2010 app that uses a backgroundworker to process MS Word docs. All of the code does what it is supposed to do, except when my code calls ReportProgress(). The UI cannot process the ProgressChanged event fast enough before the values in the class that are passed are changed. I know this because I inserted a System.Threading.Thread.Sleep(100) line after each ReportProgress() call which allows time for the UI to make the updates properly. I guess I am looking for a better solution thanThread.Sleep(100) since this adds to the amount of time it takes to process all of the files. Here are some snippets of code that I am using:
[Code]...
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Apr 2, 2012
i'm in the need to start a backgroundworker inside another one.Now...The first one BGW starts a for cycle, and inside this one there is the second BGW that has to upload an image to a server.The trouble is that, the progress event and the complete event of the internal BGW are never called.
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Apr 28, 2012
I'm filling a FlowLayoutPanel with PictureBoxes at runtime, each picturebox has an image from the List(of Image). Depending on the selected folder, loading the images "freezes" the program, so I want to use a BackgroundWorker. I'm having problems with "Cross-thread operation not valid". I want to fill the FlowLayoutPanel with the images from selected folder and a ComboBox with the names of the files.
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Sep 8, 2011
I want is to generate an ID to my listview per row it is possible? For example I have 10 records in listview and I want to add an ID per row in randomly. Here's my sample picture... but it's wrong...coz' at the column 3 it's a repeating ID...
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Sep 23, 2009
I have wrote a code that should write some text in a xml file and add a item for every file in the fileadddialog to the listview. But i can't make it to work, the writing works, both with multi-select and single files. But it only add the Movie to the listview if the file don't exists (read the code to understand).
Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
fileaddDialog.ShowDialog()
If DialogResult.OK Then
[code]....
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Oct 24, 2011
The only way I know how to put an item in a list view is to make a new item, which is the first column, then add a sub item for the columns after that and the item is placed in the row.For this Project I am wondering if there is a way to easily add items to individual cells, based on the column and group, not add items in a row at a time.
Something like the following image is what I need to do with code. To get this I manually added the items in the designer. But the logic bases where to put the class on the other classes in that time block (Mon at 8-1030am is one block). However if we have to add them a row at a time it throws off our logic and thought process.
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Mar 23, 2012
How can I get items in listview? I know how to get the current item if selected but Im trying to put it in a loop where i need to get my three row items there.
I have 3 columns and I want to get there items and insert it in entry string.
This code is wrong
Dim a As Integer = 0
For a = 0 To ListView1.Items.Count
columname.Text = ListView1.FocusedItem.Text(a)
[Code].....
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Apr 24, 2010
I know this is going to be an easy question but I cannot figure it out by reading everything I find on google.I want to populate a listview and leave selected records that are true
I have a DB record which is
ID int,
desc varchar,
[code].....
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