I don't really understand background workers much but would like to be able to use them in my programs, could someone give me an example with some good notes to help me understand how I might use the background worker with around 10 threads just to handle something simple like a math problem.
View 4 RepliesI create two background workers in my program;
' set up the background workers
Dim Bgw1 As New System.ComponentModel.BackgroundWorker
Dim Bgw2 As New System.ComponentModel.BackgroundWorker
Bgw1.WorkerReportsProgress = True
[Code]...
Note, I've tried googleing, I've came across a article sateting that if you have to handle more then one task in the background, you should use System.Threading [URL]../showthread.php?t=101283) But I don't know what team mean with it?, or how you should use System.Threading to back your own 'background worker'.
I am a bit of a noobie with vb.net and I made this application that does a lot of http requests and stream reading. But when it does this it always freezes my application.So I did a little research and found that I could use background workers to solve this. But I have no idea where to start. So if you could look at my code and tell me where and how I can add background workers to prevent the freezing that would be awesome.[code]
View 2 RepliesFor my project I connect to a large number of variables in multiple Beckhoff PLC's. I connect to the PLC in the Form load event.But the first time connect to all plc's taking too long.The data from the plc's. be sent to my program can not cope with the private sub OnNotification. This is because the program is busy with making connections with various other plc's.If the program is fully launched it works ok, but I also want to start working properly.I solve it just with a timer and a counter. Each program cycle I make a connection, the next cycle the next etc.until all connections are made. This should be better.I would like background workers use to make the connections to the PLC's. bgworkers provide the connection.The main program is not blocked, and the incoming data from the PLC's can be handled properly In the form Load event I start the bgWorkers containing the code for connect and AddHandler. Unfortunately it will not work this way?
Imports TwinCAT.Ads
Imports System.IO
Public Class Form1
Inherits System.Windows.Forms.Form
[code]....
Okay so I've dug around all day and found that using multiple "background workers" would do what I would need for my application.How can I create 4 background workers and then feed the urls to the webrequest from a listbox? [code]
View 7 RepliesHow to use the background workers in my case. while my web cam is trying to start i want to show a progress bar.
Private Sub strcam_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles strcam.Click
mycam.startCam(PictureBox1.Handle.ToInt32)
End Sub
I tried many methods to achieve that without any luck. I tried also application.doevents().
I have a gif image that shows a circle go round like the one on vista. However when i use the application.doevents() the circle is shown BUT it start go round only when the web cam starts....I don`t know what to do.....I need somehow to perform two tasks at the same time. Can bagroundworkers used in this case or i need to do something else?
I have been pulling my hair out trying to get this to work. If I step through the code in debugger it all works great. My problem is if I just run it, only the last task responds. I'm guessing I am overwriting the background working or something. I am sure I am doing a few things wrong but my code is now messy as I tried many way while searching. I know of the threadpool and .Net 4.0 tasks but having a hard time getting to do what I need.
Basicly I am writing a program (trying more likely) that takes a list of computers and pings then, then checks their uptime and reports back.This works fine in the UI thread (Obviously that locks up my screen). I can have the background worker just do this, but then it does each computer 1 by one, and while the screen is responsive it still takes a long time.
So my answer was to have a for loop for each server launching a new background worker thread. My solution does not work.I have seen other threads that I could do it, but I need to use with events to call code to update to UI when each is done.
What is the most simple way to do this?
Here is my code. Most is just copy paste + modify till I get it working right.
So In the main class I have the testworker.
(I tried using Testworker() but it said I could not do that WithEvents)
When I click the button the list loads.
Private WithEvents TestWorker As System.ComponentModel.BackgroundWorker
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles Button1.Click
[Code]...
I am dynamically creating an unlimited number of background workers and would like to handle errors from them.
In a try statement I am using the following:
Catch ex As Exception
'Me.BeginInvoke(New UpdateTextCallback(AddressOf Error_Text), New Object() {Message, Account})
Exit Sub
End Try
I have commented out the BeginInvoke command because I can not get it to work. I get an error the the handle has not been created. This subroutine is in a module and I can not figure out how to get the invoke to work.
Basically after I queue all works, I want to wait until all I queued has been done. How do I do so?[code]I notice there is no way to know how many threads are still running in the threadpool.
View 2 Repliesis it possible to call another program in the background? I'n doing a project that uses .net to control a camera. the camera is nikon, which has a sdk. unfortunately, the sdk is an unmanaged dll, from the research I did, people complained that it is difficult to use it in .net. actually, no1 has example. but the sdk has sample in vc++. so, I'm thinking maybe can build the control program by vc++, then use vb.net or c# to it and run it in the background. so, I do not have to mess the dll to .net.
is this a good choice? or, not really? how to do it? if I use a console program, how to avoid popping up the cmd window?
I want to use a background worker control in my application, and have it report progress to a Progress Bar It will download data and stuff, and I want to be able to change the text on a label.
View 2 Replieshow can I make my Form background color transparent?just the form those object/text are not included.
I watched this in yout*** like a month ago, i keep on searching but i cannot find.if you want to be happy, find something you love to do and do it for free, then find someone to pay you for it.
I'm looking to create a program which will run in the background, but will capture any data input by a barcode scanner. Since barcode scanners work more or less as keyboards (I'm not familiar with the specifics of the implementation, but my reading and their behaviour suggests this) my plan was to simply capture all keypresses and look for a distinctive pattern (sequence of numbers entered in improbably fast succession).
I'm a little concerned, however, about the fact that this will require holding up keypresses until I confirm a match. The holdup will probably be barely noticable, but it's still not ideal. My quesetion is: is there any better means of implementation than simple key and pattern detection, for example detecting that the keypresses originate from a barcode scanner?
Is it possible to start an application not being visible? This application is a batch application and my application would look way better if I could hide this batch.
View 2 RepliesI would like to have my application basically appear as if it was part of the desktop background, I've removed the form border etc and made the background colour of the form the same as our standard company background so it all blends in nicely. I have also made it so the app does not appear in the toolbar and it is set to launch on startup so it appears as soon as the user logs in - so all works fine and looks fine because any new apps that the user opens will open on top of my app. The only problem is that if they press the Show Desktop button (or use Windows Key + D) to minimize all apps, mine gets minimized as well and disappears. Its easy enough to get the user to make it appear again as it has a system tray icon that they can interact with, but it would be better if it just didn't vanish when they did this.Now I know the best thing for this on Windows 7 would be a Gadget but the problem is that Gadget's annoyingly have to be HTML/javascript and a) I'm not great with web coding and b) I don't think it is even possible to do what my app does from a HTML/javascript page... oh and c) I can't find any way to deploy gadgets in a business network (there is no way we are installing it manually on all 300 of our PCs), so the gadget idea is not looking very promising.I'm wondering if there is some window message I can capture and ignore in the WndProc event handler
View 12 RepliesHow would I get the file path of my form's background image? I tried me.backgroundimage.tostring but it always came back as something like system.forms.bitmap or something.
View 2 RepliesI made a lot of letters, and I set all of thiers background color to Transpert. I STILL don't see any transperancy, because when I put "one letter on the other one", i can see thier background.
View 4 RepliesI have the API to play WAV files and it works, but how do I keep the music going even after a button is pressed on the form? When I press the button it plays a sound effect, and then the musi is stopped.
View 7 RepliesIs it possible for visual basic to have commands sent to it when it is minimised. ie i am using internet explorer and i say "Click submit" and the submit button will be pressed even though the window isnt focused.
View 1 RepliesI have a form, and the background color of the form is set to the transparency key, making the background of the form transparent. The problem I'm having, is that the form cannot recognize the MouseClick event (when I click on the transparent background of the form). I figured out that the transparent background is triggering this problem. When I shut off the transparency, everything works fine.My question is.. Is there any work around? I still need to use the form to be able to access certain objects that are rendering there, so I don't think I could use something like a "Panel" for example, because the objects will render underneath and possibly make them inaccessible.
View 5 RepliesSo I have this in my coding:
vb
file = My.Computer.FileSystem.OpenTextFileWriter("c:command.bat", False)
file.WriteLine("@echo off")
file.WriteLine("cd " & TextBox2.Text)
file.WriteLine("adb shell dumpsys meminfo " & TextBox1.Text & " > C:Sample.txt")
file.Close()
Shell("C:command.bat")
What I want it to do is to run the batch file without it opening if that makes sense. Right now this runs on a loop for 10 minutes and on every 2 second tick it opens and then closes the .bat. Which is really annoying to see a .bat open and close every two seconds. Is there anyway to get this process to run silently in the background so the user doesnt even know that it is running?
i want background worker to use file copy, how?
View 1 RepliesI have some code that gets the documenttext of the current page in the browser, the trouble is that im trying to use it in a backgroundworker so the ui remains responsive. Everything works fine as is If I run from a button click event, but in the background worker I get errors when trying to use the webbrowser.
'if urltocheck is blank use hidden webbrowser to get page text
If urltocheck = vbNullString Then
'make sure browser isnt already loading
[Code]...
Thats the code how do I make these calls the the browser from the backgroundworker? Or how I can I run an enormous for loop from the ui thread, and still keep the ui responsive?
is it possible to cycle through background images from my resources for a button by pressing it the button, what's the simplest code to do this?
View 8 RepliesIt's always been my understanding that ByVal means is that you are passing a copy of a variable to your Subroutine. You can make changes to the copy and the original will not be altered.So if that's true I have two questions- How is my DataGridView updating without me passing the arguments back to it- The backgroundworker works fine as long as I don't reorgnize the columns in the datagrid.
'I pass the rows of my datagridview to the background worker
bgwGetHostStatus.RunWorkerAsync(dgvMonitoredSites.Rows.Cast(Of DataGridViewRow).ToArray)
'It grabs a website name from the IP column and reports if it's down or not in the status column. Now if
[code].....
On my main form I have a 9 button grid that I need to fill with a gradient colour so that it represents a "heat map" going from Green (lower left) to Red (upper right). The "heat map" needs to be generated dynamically as - if I use an pregenerated image I have noticed colour variances when working on different screens / projectors as in the app there are other dynamically generated graphics & the two sets of colours need to match.So to achieve this - on my main form I have a PictureBox that I fill with the gradient colour.On top of the PictureBox I place my grid of 9 buttons.I then hide each button & take a screenshot of what is behind it & that then becomes the background image for the button. The button is then made visible.All works fine when I am testing in on a simple form The issue is that this arrangement needs to be placed on a tab control & I'm having difficulty replicating what I could do successfully on the simple form.....
Code for the colour gradient :-
Dim A As Integer
Dim B As Integer
Dim C As Integer
Dim D As Integer
[code]...
I know that this has been asked alot on the internet and i've searched for it, but can't find any good thread/page about it.What i wanna do is:I have a listview where the user can add items to. But i want the user to able to choose backgroundcolor.The only option i can find is ForeColor, and it does nearly what i want, it colors all text on the row the user add. But as I said I want it to color the background of the row, not the text.
View 3 RepliesI have a application which processes 1000's datas.. for each processing it needs to update gui and db and many variables in my application. So what i have planned is to use 50~90 background worker with my own algorithm of thread pool, synchronization and thread close.So here is it efficient in terms of memory and performance. just confused what to use.. backgroundworker componenet or standard thread.
View 11 RepliesI know how to embed WAV files; I need to find the code to embed MP3 files onto the background. I don't want to use a pathname, can it be in resources?
View 1 Replieshow to put image in right lower corner of form as a background?
View 7 Replies