I know the reason of getting this error" Cross-thread operation not valid: Control 'ListBox1' accessed from a thread other than the thread it was created on"
Is there any solution other than raising .ReportProgress event to update the form?
My code is calling a COM component to retrieve data from a contact management product. That code works fine when called directly from my VB code. However, if I add a Progress dialog and run the SAME code via the BackgroundWorker, the COM component does not run. It generates an error: Object does not match target type. when attempting to access items from the COM component.
Also, if I run my application via a batch file that simply calls the application, the COM component does not run. In this case, it generates an exception as soon as the COM component is accessed in the code. I have posted questions to the COM component vendor but after several days have not gotten any responses. Someone told me I could not access COM objects on a thead, but the same BackgroundWorker code works when communicating with Outlook or Lotus Notes (which I believe are both COM).
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I am writing an application that calls data collectors (via ip or modem), collects data from them and reformats it. I had this much written when I was asked to make it multi-threaded so that I can collect from multiple sites at one time. I have that written using backgroundworkers and it appears to be working well. On my UI I have a text box that needs to update with status details like, dialing, collecting, reformatting, etc. I planned to simply write the status updates to the text box from an UpdateStatus routine. Found that had all sorts of nasty threading issues, so I added a delegate to call the status update routine. Problems seem to be fixed except that the updates to the UI are coming in chunks instead of one by one as they really occur. Can anybody tell me how to force the status update in the text box to update more asynchronously?
View 4 RepliesI am trying to learn Background worker and have written up a very simple app to understand this process. My form has a
textbox and a label. When the user clicks on the button, it updates the label with the value that they have entered into the textbox(I know this can be done elsewhere in the code besides the dowork event, I am just
testing and learning). Please help..I am not sure what I am missing. The label does not update.
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I have a backgroundworker doing everything I want it to but I cannot seem to figure out how to get a listbox in the Windows Form to update from the worker. I have tried an number of things and have looked high and low, but I seem to be missing something. Is there a simple way to do this? here is a bit of my code:
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When it comes to Backgroundworker's, I just make a total mess, even after reading over and over again the Backgroundworker component info on the msdn site... I have a code I would like to run on the form but if I do it with a simple "Public Sub" it will make the form lag, freeze, until the operation is done. So I try to paste the same code into a backgroundworker, and use Runworkerasync, but I get errors stating that the backgroundworker can't access controls on the form.
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I have seen others with a similar issue but not quite what I was looking for. In the backgrounderworker class dowork event I create an instance of a new class and call one of it's function. Previously, I had this code in a windows.form.timer tick event and would pass a delegate in as one of the parameters which would allow the function and other functions it calls within the class to call a method on the form to update a datagrid on the GUI. Is there a way to do this within the dowork event? I need this because the function I call from dowork calls other functions and I want each of those functions to log information in the GUI datagrid.
View 3 Repliestion (even if it falls outside my form).I found some code to get the color.I would like to constantly update the backcolor of a panel to reflect the current color beneath the cursor until it is clicked.Here's an example of what I have tried (bwColor is the name of my backgroundworker):
VB.NET
Private Shared GetColor As Color
Private Sub bwColor_DoWork(ByVal sender As Object, ByVal e As
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I have created what amounts to a progressbar which is launched using a backgroundworker. So all is well the main UI/process is doing its thing and the progressbar is ticking away. What I would like to do is update some text that is in the progressbar. So when the main UI/process finishes one of its tasks I want to update a message in the progressbar. NOT have the progressbar update the main UI/process but rather have the main UI update the progressbar.
View 7 RepliesI place some code below to simplify the process.
1) I am trying to use background worker to download a large file and update a progress bar to reflect the changes as the large 5GB file is being downloaded, and also update percentage completed to the label.text(lblInfo).
2) As I was goggling I came across some info that a web client is needed to calculate the maximum size of the file and divide by 100 and you can stream it down with the web client. Reading it is one thing, implementing it is another as I spent week trying to get it to work.
UCPocoAPoco
Imports System
Imports System.IO
Imports System.Diagnostics
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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
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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.
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:
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I have build a VB.Net windows application which does uploads data into database and basically updates two controls:
1. A textbox which is constantly updated with one line per database record upload.
2. A label which keeps track of the count of database record uploaded.
I have used BackgroundWorker thread concept, where the thread's bgwWorker_DoWork() method contains the business logic for upload and bgwWorker_ ProgressChanged() updates the 2 UI controls based on uploads.But the issue I am facing is that I do not get complete updates on both the UI controls. Sometimes the thread bypasses update of textbox and sometimes of label. I could resolve this issue by adding System.Threading.Thread.Sleep(25) before each UI control update code.[code]
I tried to update the button text on a form from a backgroundworker.do_work event, and it failed, with the usual cross-thread exception message.However, by pure chance, I also tried to update text in a system.windows.form.toolstripstatuslabel also from this backgroundworker.do_work event, and it DOES work. Question: why is this? Is it perhaps because theres some kind of implicit shared behaviour with system.windows.form.toolstripstatuslabel?
View 4 Repliesin 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.
I think (?) this is about object design, and perhaps about structural and/or creational patterns. But a bit hard to say when I only know a couple of patterns yet.[code]But... what if we INSTEAD want each Product instance only to (in some way) refer to one instance of a specific list of Components. So we wan't to save the products list to one file, and the components list to another file. Then would I build the objects the same way, or different? So let's then say we have now Class B as below. [code]
1. Will not need to update each component variable of the products list when the components list changes.
2. If the Product object shall be shown in a DataGridView, for editing properties, it seems easier to implement the selection of the component property.
Is this wrong approach? Is it suitable in some cases, and if so, when? Are there other solutions I perhaps am not aware of that would be appropriate? Is this about structural design patterns? and if so, can the alternatives above be catagorized to some pattern type? I don't really know exactly what I'm looking for.. But I think probably I'm looking to understand whether the object design will be determined by the way the objects are saved.. And if i shall save the objects by serializing to file, vs saving to a database, would I create the business objects differently?
I am converting an old Vb6 solution to .net 2.0 in vs2010. I've been working in C# for about 3 years now and .net for 5. I don't recall having this problem in C#, but if I want initialize a readonly collection of DerivedControlFoo Is there a clean way to do it besides creating a sub to do it all off somewhere else? I'd love to be able to do it at the class level at the declaration for readability and simplicity.
View 1 RepliesCreate a DLL component for database operation and use created component in another project. Required methods, events and properties
a. Connect
b. Add
c. Delete
d. Save
e. Record navigation (first, next, previous, last)
f. Properties for all database fields
g. Events for validation of database fields.
I've created a component whose name I'd like to be able to change while editing in the component tray. I've added a Designer action for a name property, but now I'm stuck.
Looking at the property grid, I can see that the name property is parenthesised, indicating that it's not a regular property.
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.
View 11 RepliesI have a gridview in which when I click edit, update, and cancel button comes. I have a variable named status. If status=false then update should change to insert and if status=true then update should be update itself.
<asp:TemplateField >
<ItemTemplate>
<asp:LinkButton ID="lnkEdit" runat="server" CommandName="Edit" Text="Edit">
</asp:LinkButton>
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We have two update panels on our webpage. Now first update panel is having button cancel. While second update panel is having a file upload control.Now if the user uploads a file that is going to upload in about 2 mins, and in between, say after 30 seconds the user clicks the cancel button, the upload taking place in update panel 2 should stop.
View 2 Repliesgood example on backgroundworker control in vb.net for doing some process in background for ex a reading a doc file in textbox by using backgroundworker in vb.net?
View 2 RepliesIs it possible to set a backgroundworker as STA
View 1 Replieswhat is this BackgroundWorker and how to use it? Can it be used as a replacement to System.Threading.Thread??
View 2 RepliesI've got a bit of a problem, I'm using a backgroundworker to do a lot of processing and it adds items to a listview with: AddListItem(ListView1, listItem)
Here is the delegate code to send the command to the listview outside of the thread:
Delegate Sub AddListItem_Delegate(ByVal [ListView] As ListView, ByVal [text] As Object)
Private Sub AddListItem(ByVal [ListView] As ListView, ByVal [text] As ListViewItem)
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The problem is, as you might imagine, flickering of the listview. Can anyone help me out with a solution to execute a LockWindowUpdate(Me.Handle) command in the backgroundworker? I've tried creating a new delegate but it's not working (errors, I don't understand vb.net enough).
I am programming using VB.NET 2005. I am using a BackgroundWorker to load a large list or text file and process it.
Is it possible to use the same background worker to process something else, i.e. to process the text file that was loaded? somthing like
Dim bwkMain as New BackgroundWorker()
If its possible, how do I implement it in the same form as I have already implemented for the first one?
EDIT The question is: is it possible to use the same BackgroundWorker for another task, after it finishes one task?
I have limited experience in VB.net and have become stuck. I have tried to search for answers on other threads without success.I have an application that displays real time data.Queries are made to a MySQL database on another PC over the internet every 10 seconds to gather the most recent data.I have done the query within a BackgroundWorker so that the GUI is still responsive while the query is answered.What I've done works great for several hours or maybe for a couple of days but then the DoWork task appears to hang.
The code I'm using is to run the background worker is:
vb
If Not(backgroundWorker1.IsBusy) Then Me.backgroundWorker1.RunWorkerAsync() End If
The backgroundWorker runs just once and there's very little code in the DoWork routine:
vb
Private Sub backgroundWorker1_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles backgroundWorker1.DoWork rs = New
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Is there anyway I can set up a timeout on the maximum allowed time that the DoWork task can be active for? And if so how would I then go on to stop the backgroundWorker?I understand that CancelAsync isn't going to help as my DoWork task is not repeating as it runs once only, then stops and 10 secs later I run it again.
I'm trying to add a backgroundWorker to my application, but I can't find it.I tried looking in the toolbox, but didn't find it. I looked in the Choose items dialog box and it is checked. Tried unchecking and checking it again, no difference.
I tried using Dim worker As System.ComponentModel.BackgroundWorker but get an error:
Type 'System.ComponentModel.BackgroundWorker' is not defined.Is there any way to add it to my program?
I used sample from jmcilhinney at Link to create background proces and it works like a charm. But. In my menu i have two (2) different toolstrip buttons which i need to run the same BackgroundWorker1_DoWork method, but different ackgroundWorker1_RunWorkerCompleted methods. Is that doable?
1. In BackgroundWorker1_DoWork method i use some time-consuming operation which at end sets two global variables.
2. In BackgroundWorker1_RunWorkerCompleted method I use some Select case statment based on that two global variables that are not the same for ToolstripButton1 and ToolstripButton2.
Vb.net
Private Sub FirstButtonToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles FirstButtonToolStripMenuItem.Click
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