I'm not sure exactly how to describe this. In VB6, there was a Timer command. I could create a variable of type Timer and loop until the current value for Timer exceeded the initial plus a given amount of time. This allowed me to update form variables while the timing loop was executing. How can I do something similar in .NET?
Here is a sample of the VB6 code:
Code:
Dim StartTimer As Double
StartTimer = Timer
Do
[code]....
I have a VB.NET 2010 app I am writing that does a lot of work on a RS485 bus in 2 seperate threads. These threads are started as soon as the app is opened and run as long the app is open. I would like to have the threads update labels on the main (and only) form every so often based on what's happening on the serial bus. I know it involves invokes and delegates but I haven't found a straight forward answer on how to implement it.
View 5 RepliesI've seen a good bit written on avoiding updating a form from a thread.However,I was wondering if that was a problem if the thread exists in an object that programatically builds the form?Thus the form and associated logic exist within the same "thread space." Seems on the face of it like it would work since everything in the form should be in a single dispatch queue.
View 8 RepliesI'm not sure exactly how to describe this. In VB6, there was a Timer command. I could create a variable of type Timer and loop until the current value for Timer exceeded the initial plus a given amount of time. This allowed me to update form variables while the timing loop was executing. How can I do something similar in .NET?[code]...
View 5 RepliesI'm having some problems with updating a form from a background thread, started in the MyApplication_Startup sub.As far as I know updating forms or controls on forms have to be done threadsafely.
When the application starts up, some threads are being created which create an object in which a download for a zipfile will be started. The object has some delegates to let the GUI know what the status of the download is, for example 'started' or 'finished'. Also the mainform will be shown on which a datagrid has been placed to show the user which files will be downloaded and in which phase the download is.
All this works amazingly fine but when I want to update the datagrid's cells p�r thread the datagrid aint updated. I know the problem is that the thread in which the Form is created isn't the same as the thread which wants to update the grid?
I'm running some tasks on a BackgroundWorker thread and needed to display the current tasks in a label.Before adding the label, the tasks were completing just fine and the UI was responsive.Once I added the labels, the UI has become unresponsive. The issue, I believe, is the Invoke property.I've declared all my tasks, including the updating, in a sub and am getting the Invoke property of the label each time, in order to set the information.The following is an example of what I'm doing:
VB.NET
Private Sub Test()If lblTask.InvokeRequired = True Then Dim mi As New MethodInvoker(AddressOf Test) lblTask.Invoke(mi)
[code]....
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.
I have a Public Sub I am using to enumerate running processes and then display them in a ListView.I want to be able to update the list automatically each second. I've thought of doing this in two different ways, but the method that I want to use is checking if the process has exited or not.
When reading up on the Process Properties, I ran into .HasExited and .Refresh.I thought that I could use a timer and have it tick at 1 second intervals. I would then check, each second, if the Process has exited. If it has, remove it from the list.The problem with this, is that I don't want to put the sub in the timer because it would just constantly flicker the control. I need to figure out a way to access the variables inside of the Sub while inside of the Timer's .Tick event.The other issue is being able to add processes that aren't there. Which I can within another sub. I was thinking I could create a sub that grabbed the Processes by ID, compare them to the list, and them add them if they aren't there. If I did this, I could also remove Processes by ID that aren't in the list.
I have a small problem that I am sure is due mostly to my inexperience with threading. I have used simple entirely self-contained threads before, but not to a great extent. I understand the basic laws that surround them, such as how a thread cannot access another thread's member directly, and must use delegates.
[Code]...
We have an issue with an application where we are making a call to an asynchronous process on LostFocus of a TextBox, the asyncronous process then needs to be able to update the main form UI (or display a dialog from the main form UI) while running asynchronously.We have thought about call backs and having it truely asynchronous but we need everything to execute in the correct order and this is for a data entry system where speed and accuracy of data entry is important.Example code shows what we are trying to do and if you switch to Begin Invoke the order of processing is not correct.[code]Does anyone know how we can invoke something else on the main form thread while is is still busy processing the LostFocus event?
View 2 RepliesThe program i am writing has 5 features, all of which i want to run in their own threads. On the main for I have a listView which contains all the accounts (user password etc). The thread is defined as:
Public fbaThread As New Thread(New ThreadStart(AddressOf fba_Start))
In cmdAdderStart i begin the new thread by:
fbaRun = True
fbaThread.Start()
[Code]....
I have managed to write the UpdateDebug() to update my txtDebug on the main form. But now I am having trouble being able to pull the values from lvAccounts.items().subitems I can accomplish this with global variables but i'm sure this is not the best way to do this.
I am writing a basic application to provide remote support to multiple computers over a TCP Stream. For example, if my brother/dad has an issue with their computer, rather than going over to help them I can just use remote support (Yes, I know Windows has Remove Desktop, and their is TeamViewer, ect. But where is the fun in using those =P)Anyway, it basically works by taking a PrintScreen of their computer, sending it to mine and displaying it in a PictureBox, then when I click the image, it records the coordinates of my mouse, sends it to theirs (Little Maths for resolutions and positions ofc) and clicks, then sends a new image.
My problem is, I want a ListView displaying the PC Info, like:
PCName - RAM - Free HDD Space - 32/64Bit - Processor Speed
Now, my problem is, I have a Class which does the TCP Server, and in that class when it Receives a Message, it calls the Sub "RunCommand(ByVal Command As String)", which then splits the String and works with it.So, for example, their PC would send the String "Info|DadPC|2GB|235GB|32Bit|2.2GhZ|" And mine would split it, and add that data accordingly.However, what happens is, nothing. If I put in "MsgBox()" anywhere in the Code, it shows it is all Split, and received correctly and everything is fine, but no matter what happens, it wont add to the ListView (Or anywhere else on the form, for example "GUI.Text = Info(1)" Wont work either)?
I have been trying to update a textbox on the main form of my program using a different thread, however the changes are not relected in the textbox.I am using MS Dev studio 2010 beta 2.0 .NET 4.0. Here's my code....
The main form
Code:
Public Class frmMain
Private Engine As New clsEngine
Private txtMessage As String
[Code]...
I've got a bunch of labels that I update regularly in the program, resulting in lagg, which is bad, so how can I update the labels in a thread?
When I try
Thread = New System.Threading.Thread(AddressOf ShowInfo)
Thread.Start()
[Code]......
This is slightly different to just updating a UI from a worker thread. The object which calls the thread, calls another object, and it is this object which is is trying to update the UI. It doesn't however work.
Imports System.Threading
Public Class Form1
Public Delegate Sub GetText(ByVal sText As String)
Public GetSomeText As GetText
Public Sub New()
' This call is required by the Windows Form Designer.
[Code] .....
with the code:
T02FldDct01("DPF01") = "ABC"
T02FldDct01("DPF02") = "DEF"
T02Database01.Open()[code].....
I am getting the following error at the ExecuteNonQuery() line: "Parameterized query 'Update Table01 Set T02=@DPV01,T03=@DPV02 Where T01=@T02Ctr'
expects a parameter value which was not supplied. Parameter name: @DPV01"
T02 is a nvarchar field.The Dictionary was defined and populated as follows:
Dim T02FldDct01 As New Dictionary(Of String, String)
T0201 = "01"
T0202 = "02"[code]....
why the update routine will not recognize this Dictionary variable?
I have created a structure with some variables that I'm trying to update during the course of a sub routine but they are not updating, when I cycle though them at the end all the variables are still set to 0.
Imports System.Data
Imports System.Collections
Structure Team
[code]....
I am trying to populate some fields in Word document using DocVariable:[code]The proplem that I am facing is when I open the document after running the program the fields won't be updated, so I have to go each field and highlight it then > right click > update field to get the new value!I need a way to update them or my work will be meaningless.I forgot to say that the DocVariables are inside textboxes.
View 1 RepliesVBasic / VS2008 / .NET 3.5 / Meas Studio 8.5 I've searched and seen a number of convoluted ways of doing this but.... What I am trying to do should be simple and in my mind (and from previous experience) it should work. It doesn't At least not after 10 hours of tweaking, editing, researching....
Straightforward project, 3 components - MainModule, MainForm, CNCNoForm. I declare public var NCPgmNo in the module. I open the CNCNoForm from the MainForm. This form has 2 controls - Numeric Up/Down Box & Close Button. I enter a number in the Num box (read only property is set to false), then assign the value to the var. NCPgmNo in the value-changed event sub. I close the form, returning to the MainForm. The variable does not pass even though it is public and declared in the module. I tried removing it from the Numupdown event and assigned the var before 'me.close'. Still N/G.
If I put a breakpoint right after the line that assigns the var, it is correct. It just does not pass to the MainForm. I started with a textbox, then changed to a Meas. Studio Numeric control, finally Numeric up/down. Same results with all 3. I though the CNCNoForm was broken so I removed it from the project and rebuilt it with a new name (yes name references in the MainForm and MainModule are correct). One other thing. If I call the CNCNoForm repeatedly, it reads the previous value. I am ready to give up computers and take up farming or hiking.
[Code]....
I have a class in vb.net defined as public class A
class A is created on Load and gets called once per program loop
The constructor for class A includes the argument (byref Value as long)
I have a global variable called varB that is passed to class A on creation.
now why when varB is altered during the program loop, the change is not reflected within the class?
My "form1" is just a simple page with buttons that launch different forms which do all the work, the "form1" code for the first four buttons is below. What I want is for each form to run in a separate thread.
Public Class Main
Private Sub btnDownLoadStockPrices_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDownLoadStockPrices.Click
LoadStocksFromDownloadSite.Visible = True
End Sub
[Code]...
I've found plenty of code examples to have different buttons on a single form run a subroutine in a separate thread, but for some reason I can't seem to apply it to an entire form.I think it's something simple, like I need to tie each new thread as a handle to each forms "load" routine, but I just can't get it to work. I don't care about "synchronizing" threads at all, as each form is really a completely different functional program.
I have a few classes. One of the classes handles everything to do with updating controls (Such as adding items to a listview, etc.) and another is handling loops. I'm trying to add something to a richtextbox from another thread.[code]..
View 3 RepliesI have got this module which copies a specific folder and all files inside it.[code]...
View 8 RepliesI have some controls in a .net 4.0 form - a listbox and a listview item.I also have another thread in the same class which is checking a host for output.It uses delegates to display all incoming data to a richtextbox - this works fine.If the data has a particular signature it sends it to a parser sub in another module.This module tries to update the listbox and listview items with that data after it has manipulated it.The problem is; no data is displayed and no errors are thrown.If I add a msgbox("Test") after the code, it shows the messagebox.If I add a test messagebox inside the delegate function, it shows the messagebox. If I put the same MainForm.ListBox1.Items.Add("Howdy") in a ButtonTest.Click event it adds it correctly.
View 14 Repliesi have lurked on these forums before and finally signed up..i have a situation that, after days of searching the web, i have not been able to come up with a solution for.i have to fire off a function that takes a large amount of time (writes to database, creates files, etc etc)this function is a non-shared function of a class. if need be i could make it Shared.[code]the code works great, but what i need to be able to do is update a form with a progress bar as the job is processing.all of the examples i have seen that do this are being called from within a Windows Form and they access the form directly - i cant do that in this case. my form needs to be 1 form for 1 job being executed - can process multiple jobs at one time and thus i need multiple forms.i have tried making the form part of my delegate class but since it runs in the same thread the effect is it "freezes" until the job is complete.i have just started looking into using a background worker but again, all examples i have seen use the component as part of a form - that wont work for me.
View 3 RepliesI've been programming in vb.NET for a whileAnd to be honest, its turning out to be a real pain.Here is the
Form1.vb: Imports System.Threading
Public Class Form1
Dim trd As Thread[code].....
So, I have a form (form1) with a label on, this label simply reports the status of the thread.The thread begins the Class1.Main() sub, and I have a delegate setup to change the text propoerty of the label.Now,I know the label is created on the UI thread,so I assumed the delegate would work. However,it seems that it updates the .text property, but doesnt redraw the control when .Update() is called .What am I doing wrong?I have found lots of examples of delegates, but all run from within the same class. I want to use threads too, not a backgroundworker! This code is a "simplified" version of a project I am on, which is encountering the same problems
I am trying to pass some status from a IP call in a shared sub to a label on my form. This is the current code that i am using:
[Code]....
I have a datagridview where i add rows using array like this:
Dim srow() As String = {getIDprodus(cmbprodus.Text), cmbprodus.Text, getprodusforma(cmbprodus.Text), txtcantitate.Text}
griddetalii.Rows.Add(srow)
Next, i need to let user to modify the added row. So when user selects a row and press EDIT, a new form is popped out using this code:
Dim i = griddetalii.CurrentRow.Index
frmdetaliiiesire.cmbprodus.Text = griddetalii.Item(0, i).Value
frmdetaliiiesire.txtcantitate.Text = griddetalii.Item(1, i).Value
[Code]....
In textbox1 i have put the index of the current row selected in grid The problem is when i push OK, the applications crashes and i receive an error: INDEX WAS OUT OF RANGE
If the users changes the values from the same form, it's works. But changing them from another form crashes the applications
I have a "housekeeping Form" set up that...when triggerd by the main form, updates records, sends email, clears and refills an access table all of which runs from a Form.Load Event my problem is the form "PLEASE WAIT WHILE SYSTEM IS UPDATING" will not fully load while all these things are happning I have tried ME.Show and ME. Activate
View 7 RepliesI update a Form's Title from within the form, but it doesn't update. Any idea how to "Refresh" it so that the update displays?
View 2 Replies