Multiple Controls On Winform Mutliple Threads?
Jul 3, 2010
I've created a news ticker control, which reads from RSS feeds and scrolls the text Horizontally. The plan is to have 3 of these on my Windows form, which will each display their own information.
The control is created as a label, which is populated with the text, and then scrolls right to left using a timer, once the label gets to the end of the text, and disappears of the left side, the rss is re-read, and then the cycle resumes. The problem is that with multiple copies of this controls on my form, once one gets to the end of it's run, all three freeze while the rss is reread, rather than just the control that needs to do it.
Is there a way to run each of these controls independently (threading?)? Or is there a glitch in my code causing this? (below - some elements not included, but it should be fairly obvious what is happening!)
[Code]...
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Jul 29, 2010
I have a lot of forms set up, probably about 10-15 so far (more to come). Some forms 'lay' on top of other forms, and each form contains multiple controls. I am discovering that my approach is not very likely to succeed in what I am thinking of doing.
Here is one example: LeftControlPanel form contains 5 controls, but 5 other forms 'lay' on top of it and use transparencies to load up bitmaps. Since I cannot parent the forms that 'lay' on top of the form, I cannot figure out a good way to move them.Is it logical that when I move LeftControlPanel to a different x location, I would just move all the forms that 'lay' on top of them as well?Seems like a clunky approach of moving one form since parenting the transparency forms will remove all the transparencies that are set up...
Is there a bit better logic I might be missing, or bite the bullet and start moving multiple forms at once?
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Oct 19, 2011
I just had a new, last-minute idea on to take on a task, so I am running to StackExchange for quick help.
What I want to do is execute a series of methods right in a row, each in their own threads. I want the application to wait until all of these threads are completed, after which the program will resume. It also has to use managed threading (thread pool).
What quick examples could you provide to help me along the way? If it's too complex, what things should I know about so that I can Google it on my own?
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Sep 15, 2011
I have a loop that creates several threads as such[code]...
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Apr 18, 2012
CompatibleTextRendering support for winform controls. label, check box etc have a property UseCompatibleTextRendering when this property set to true your app support East Asian languuages without having installing there languages on windows. But there is no UseCompatibleTextRendering for textbox, listbox, contextmenustrip etc i can Inherits ContextMenuStrip for this support using this code.
Public Class MyMenu
Inherits ContextMenuStrip
Public Sub New()
Renderer = New MyRenderer()
[code]...
if we can add this support to other controls like listbox combobox etc.
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Sep 11, 2010
I'm trying to update the UI from a background thread, but the method I'm using at the moment isn't working. From what I've been reading, the method I'm using should work, but it isn't.[code]...
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Jun 8, 2010
I've just recently figured out threading, and how to use it. I was even able to figure how to make a background thread modify the text property of any form control that has a text property.
I figured if you could specify the name of the control whose Text property you want to modify, it could be done easily, and I was right[code]...
Is there a way that you could do this, but eliminate the need to specify the control type as a parameter and maybe have the application determine what control you're trying to use by it's name?
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May 21, 2010
Where can I find alternative button controls for vb.net Winform?
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Apr 18, 2012
I'm trying to create a list of labels and textboxes. No errors but they aren't rendering on the form. I have confirmed my loop have values[code]...
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Oct 27, 2010
With threads and parallel processes you can process raw data but notcontrolsUielements) because they belong to another thread,
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Sep 8, 2010
In main thread I create panel(s) (based on some configuration), and then in the next step based on the file type (like video, ppt, image...) I create appropriate controls (dynamically) to show on the forms.
The creation of the control will be done in separate threads (for each file). After creating the control, it throws an error when I try to add that control to the panel (which was created in the main thread), something like cross thread violation, control was accessed from one thread other that it was created.
Can some one please help me in this regard? In this scenario, everything - creating the panels and controls - will be dynamic. Nothing will be static.I tried some of the articles found here on StackOverflow (like, control.BeginInvoke() .. etc), but wasn't able to solve my problem.
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Mar 18, 2011
I have a form with a datarepeater that contains various controls (i.e. datetimepickers, text boxes, combobox) that are populated via a binding source. I also have other controls on the form that are not part of the data repeater. I would like to force validating all controls after the data is populated. I have successfully forced validating the non-datarepeater controls using Me.ValidateChildren() at the end of my load event. However, it does not fire the validating events for the controls within the data repeater. I have unsuccessfully tried many different attempts to set and move focus within the datarepeater controls trying to get the validating events kicked off. I am not sure where would be the best place (e.g. in drawItem? in ItemCloned?) to place the code and what it should be exactly.
Here was my latest attempt:
Private Sub DataRepeater1_DrawItem(ByVal sender As Object, ByVal e As Microsoft.VisualBasic.PowerPacks.DataRepeaterItemEventArgs) _
Handles DataRepeater1.DrawItem
For i = 0 To e.DataRepeaterItem.Controls.Count - 1
e.DataRepeaterItem.Controls.Item(i).Focus()
e.DataRepeaterItem.Controls.Item(0).Focus()
Next
I successfully handled the validating events in the data repeater caused by user input errors. However, I have the unusual situation that the data coming into my form is already bad for some of the controls. The purpose of the form is to validate the data coming in to it and from user-input. I am newbie with vb.net.
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Sep 14, 2010
I drew a Group Box around a bunch of controls cause I wanted to the Box, meanwhile all the controls are glued to the Group Box. How can I remove the Group Box without removing the Controls?
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Jun 6, 2011
I have following code for 3 DataGridView Controls in my VB.NET winform application. How can I simplify this code?
With DataGridView1
.Columns.Add("Column 0", "TaskName")
.AutoResizeColumns()[code]........
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Apr 18, 2010
it would be best if I just copy and pasted the code (it's very trivial).
Private Sub Main() Handles MyBase.Shown
timer.Interval = 10
timer.Enabled = True
End Sub
[code]....
An exception, "The object is currently in use elsewhere", is raised during the tick event.
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Aug 5, 2010
I need to get all controls on a form that are of type x, I'm pretty sure I saw that code once in the past that used something like this:
dim ctrls() as Control
ctrls = Me.Controls(GetType(TextBox))
I know I can iterate over all controls getting children using a recursive function, but wondering if there is something more easier or straightforward, maybe:
Dim Ctrls = From ctrl In Me.Controls Where ctrl.GetType Is Textbox
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Aug 8, 2011
I have a winform with a main panel that is anchored top, left; dock: fill, and set to a specific size to contain another panel of content that we want to scroll through. The other panel along with a few other controls are on the main panel. Now, for some reason, after running the application the controls will be shifted down (never horizontally) some random amount. Now, the "random amount" may in fact be the last position of the scroll bar or something, but either way, it is unintended functionality. I have resorted to automatically resetting the locations of these controls on the main form in the constructor?
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Jan 13, 2010
I am writing a project in Visual Basic where I need to run several instances of the same method in parallel. I can do this using BackgrooundWorker by having several (4) copies of my code module (modules 1, 2, 3 and 4) with a call to background worker in each. I then have a Main form which invoke the 4 modules which setup 4 simultaneous background threads. Seeing as the code is the same I want to simply invoke the same module 4 times.
However when I do this I get an error from Backgroounworker that it is already busy. As I understand it this means that it is being shared. However, I have specifically instantiated it as "private" (private with events worker as new backgroundworker). I have tried running the same code in a Class instead of a Module but unless I make it public I have no way of invoking it from Main. I need to be able to pass each thread data from main for it to work on and if the class is private I cant invoke it.
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Nov 6, 2010
This code will show you how I started multiple threads:
For i As Integer = 0 To 10
Dim MyThread As New System.Threading.Thread(New System.Threading.ThreadStart(AddressOf MySub))
MyThread.Start()
Next
Now I'm trying to stop the threads before closing my application but I don't know how to do that?
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Jan 25, 2012
how to convert videos files using vb.net and ffmpeg. But as far as i know we cannot use multiple threads to run same exe file to convert files. Do you know how i can convert multiple videos using one external exe file (ffmpeg)?
I have not tried because my computer time was over. So iam just asking a general doubt whether if we attach it to one process then wouldn't the process get locked? Then can we multi-thread this application or not ?
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Jul 28, 2010
I'm testing here something, but i don't know what's the best way to do this.I have a var that tells the application the number of threads that will be started, inside the thread/function that i call i need to return/get two values i have two sub functions, each one returns an integer.Then in the end i need to sum the values.
Example:
Thread1/Function
SF1 - Returns 2
SF2 - Returns 3
Thread2/Function
SF1 - Returns 1
SF2 - Returns 5
After all threads are over, i get the
SF1Total = 2 + 1 and
SF2Total = 3 + 5.
I'm thinking in using shared vars, and inside the function/subfunctions update the values. It's this a correct way to do it? Other question, the threads are assync, but i need to know when the last one finishes. How do i control this? The order they finish doesn't need to be the order they were called....
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May 31, 2012
I have this class and I have a loop that launches multiple threads from the same class. This is all done from the main form.Now I want to update the richtextbox on the main from these classes.I have tried those begininvokes etc etc and nothing worked, no error but no output as well.Here the code for launching the threads :
Private PingObjects(100000) As Account 'Account is the class and login is the sub in it...
PingObjects(I) = New Account
Threads(I) = New Threading.Thread(AddressOf PingObjects(I).login)
[code]....
And to update the rtb, im using MainForm.log.text = "....." Nothing happens, no error.I have tried using the begin invoker method as well.
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Sep 28, 2010
To get pass the cross referencing error when running a thread, I use this code
[Code]...
But the AddressOf doesn't accept parameters... So how do I get pass that? Or is there another way to use delegate?
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Aug 10, 2011
I've read a lot of different questions on SO about multithreaded applications and how to split work up between them, but none really seem to fit what I need for this. Here's how my program currently basically works:
Module Module1
'string X declared out here
Sub Main()
[Code]....
This is only a rough outline of what actually happens in my code by the way.
My problem being that if multiple threads start running Main2(), they're dealing with the same X value as in the other threads. The loop inside of main2 executes multiple times per millisecond, so I can't just stagger the loops. There is often duplication of work done.
How can I properly divide up the work so that the two threads running simultaneously never have the same work to run?
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May 12, 2010
I need help to implement multiple threads in application.Assume ds.table(0) has 5 and sometime 6 rows rows for i=0 to ds.tables(0).rows.count-1.I have to apply multiple threads, means all five/six rows should start at once using thead and "Process 1" .."Process 4" should also handled by threads.This is hierarchy that I have to apply with threads, how can I do it. It is requested to put piece of code so I can understand better.
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Jul 7, 2011
I know a little about threading and delegates, as well as socket programming. I'm working with a VB.NET-compatible SDK called TrueVision3D to create a small online game for me and my friends. The problem is that I cannot for the life of me figure out how to pass data from one thread to another. I've created 2 seperate threads on seperate forms.
The first thread is created on a form titled FrmLogin, and it contains all the socket code. I need to be able to update variables in the second thread, which mainly consists of a render loop. The second thread is created on a form titled FrmMain. I'm not quite sure if it matters what forms the threads are created on, I'm just trying to give as much information about the issue as I can. I've tried using delegates and events to pass information from the thread back to the form it was created on, which works fine, but how do I pass data to the second thread from the first?
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Aug 4, 2010
I have an application that needs to perform a series of different actions at specific points in time.To do this I have a timer with various actions that occur in its tick event.One possible action is to send out a few messages via a serial port and then wait (between 1- 300 mins typically) for the next timer tick.Another possible action is to continuously toggle one of the control lines on the serial port until the next tick (again 1-300 mins).
In most instances, i'm happy for everything to run on the main thread, but in the case of toggling the line endlessly, I thought it better to give it its own thread.My problem is that for the new thread to use the Serial Port, it must open the port. Likewise, it must close it before the main thread can have it back.
Here are 2 code snippets
Private Sub activityTimer_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles activityTimer.Tick
Dim some variables here
activityTimer.Stop()
If speedThread.ThreadState = ThreadState.Running Then
[code]....
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Jan 27, 2012
I have a map image with data associated with the map indicated by RGB index. The data has been populated into an MS Access database. I imported the information in the database into my program as an array and sorted them to go in the order I want the program to run.
I want the program to find the nearest pixel that has a different color from the incumbent pixel being compared. (Colors are stored as string attributes of object Pixel)
First question: Should I use integers to represent my colors instead of string? Would this make the comparison function run significantly faster?
In order to find the nearest pixel of different color, the program begins with all 8 adjacent pixels around the incumbent. If a nonMatch is not found, it then continues onto the next "degree", and in this fashion, it spirals out from the incumbent pixel until it hits a nonMatch. When found, the color of the nonMatch is saved as an attribute of incumbent. After I find the nonMatch for each of the Pixels, the data is re-inserted into the database
The program accomplishes what I want in the manner I've written it, but it is very very slow. After 24 hours, I am only about 3% through with execution.
Question Two: Does my program behavior sound about right? Is this algorithm you would use if you had to accomplish this task?
Question Three: Would it be appropriate for me to use threads in order to finish execution of the program faster? How exactly does that work?
Question Four: Would it be more "intelligent" for my program to find the nonMatch for each pixel and insert it into the database immediately after finding it? (I'm making a guess that this would be good in multi-threading, because while one record is accessing the database (to insert), another record is accessing the array of pixels (shared global variable in program).
Question Five: If threading is a good idea, I'm guessing I would split the records up into more manageable chunks (i.e. quarters), and have each thread run the same functions for their specified number of records? Am I close at all?
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Jul 29, 2010
In the same line of this thread Now i have a problem with the control of the ending threads. This is my
vb.net threadsEnded = 0 For j As Integer = 0 To numThreads - 1
[Code]...
Some times the application doesn't finish and if i pause the application i see that the threadEnded var doesn't have the correct value, seems like some thread doesn't update the value of the var.
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Sep 4, 2010
I have a created a class, which contains a sub routine.This sub routine, should ideally be accessable by objects which are not members of the class, so I would like to make the sub, a 'shared sub' (call it Sub1).
Question: I am using many threads and there will be possibly 100s of 1000s of threads all wanting to use Sub1 (which is at present, is not shared).At present Sub1 , is not a shared sub, so every time a thread wishes to use Sub1 , I am creating a (dummy) instance of the class and then applying Sub1, to that instance.
My program works flawlessly using the above technique.Question: If I were to turn Sub1 (which is not currently shared) into a shared sub, and directly had various threads calling Sub1, would there be any issues with locking, ie. would it possible for 2 threads to enter that thread and start overwriting variables, which another thread has written to?
NOTE: there are no shared variables/properties in Sub1 and all variables used in Sub1 are declared within the sub itself.
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