VS 2005 Update UI In Event Raised From Thread?
Jul 3, 2011
I want to raise an event from a non-UI thread where the event will be handled by the UI. Currently, I have to use .Invoke in my methods (which updates UI) called from the event.
How can I raise the event, similar to Background Worker's progress update event, where I don't have to specifically do an .Invoke for UI updates?
Do I wrap the event with a delegate or something? Sample code will be fine though, if the explanation was tedious.
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May 2, 2009
I'm new to VB and relatively fresh in programming in general. I'm trying to write code to make a label flash red. The method involves using a timer. Problem is, it flashes, but I can't figure out how to make it stop. xD Here's my
Private Sub SeleneExplainsToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SeleneExplainsToolStripMenuItem.Click
lblNumbers.ForeColor = Color.Red
Timer1.Enabled = True
AddHandler Timer1.Tick, AddressOf OnTimerEvent
End Sub
[Code]...
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Jun 2, 2010
I want to know what the Event has raised in a multi handler.
[Code]...
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May 17, 2012
I am making a function of an application that when a function is called the application will close all processes that are owned by the user and were started after a specific point. My thoughts on this would be to trigger an event in my application every time a process is started and ended, and only if the processes is owned by the user, the event should get information (e.g. the process ID, name, etc) about that process and add or remove that information to/from an array depending on if the process starts or ends. Then when a function is called end all the processes in that array.
[Code]...
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Mar 22, 2010
A winforms dialog is using BackgroundWorker to perform some asynchronous operations with significant success. On occasion, the async process being run by the background worker will need to raise events to the winforms app for user response (a message that asks the user if they wish to cancel), the response of which captured in an CancelEventArgs type of the event.
Being an implementation of threading, I would have expected the RaiseEvent of the worker to fire, and then the worker would continue, hence requiring me to pause the worker until the response is received. Instead however, the worker is held to wait for the code executed by the raise event to complete.
It seems like method I am calling via the event call is actually on the worker thread used by the background worker, and I am surprised, since I expected to see it on the Main Thread which is where the mainform is running. Also surprisingly, there are no cross thread exceptions thrown.
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Apr 20, 2009
how can I raise an event after a thread has just ended?
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Sep 7, 2010
This is the abstracted code for simplicity.
Public Class Form1
Dim WithEvents bt As New Button
Private Sub Bt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bt.Click
MsgBox("Click")
[code]...
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Mar 9, 2010
I have an ASP.Net web user control which represents a single entry in a list. To allow users to reorder the items, each item has buttons to move the item up or down the list. Clicking on one of these raises an event to the parent page, which then shuffles the items in the placeholder control.Code fragments from the list entry:
Public Event UpClicked As System.EventHandler
Protected Sub btnUp_Click(ByVal sender As Object, ByVal e As System.EventArgs)
Handles btnUp.Click
[code]....
It originally looked in testing like every other time the value for sender (verified by its properties) that reaches UpClicked is of an adjacent ListItem, not the one I've just clicked on - the first click is always wrong, then the second for the correct control.At present,testing appears to show that the button's click event is just being ignored every other time through.Breakpoints on the click events within the control simply aren't being hit, though the events are definitely being established.
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Aug 23, 2011
[code]But even here it seems the handler isn't registered until after New has completed.However, in real life the event is raised within code that's semantically part of the object initialisation, and I'd really rather not have to create some Initialize function.
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Apr 29, 2009
I'm working on a Windows Service that watches a few folders for changes, creations, and deletions. It all works well with the exception of one watcher that watches a single file (XML File with Configuration Settings) for minor changes.
I tried taking the Windows Service code and putting it into a simple windows application with start/stop buttons for the filesystem watchers and stepped through it. It never detects the file change of the XML config file. The changes are indeed occurring and the "Date Modified" of the file is updating.
XmlEventReferences = New System.IO.FileSystemWatcher()
XmlEventReferences.Path = "C:XmlReferences"
XmlEventReferences.Filter = "*.xml"
[Code].....
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Jul 27, 2010
I want to write an event that will simply display something when it is raised. I have never really worked with event driven programming before and am just trying to get a simple example working. It is not yielding any errors, but when I switch to debug mode I can see that the event it not raising correctly.
[Code]...
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Jan 11, 2012
I have a user control named "LettersDropControl". It has a dropdown list. I am using this control in a aspx page. When I change the selected item it is not calling the ddlLetters_SelectedIndexChanged event handler? What change I need to make in order to execute the code in ddlLetters_SelectedIndexChanged event handler?
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="LettersDropControl.ascx.cs" Inherits="MSAJAX1.LettersDropControl" %>
public partial class LettersDropControl : System.Web.UI.UserControl {
private string selectedLetter;
public string SelectedLetter {
[Code] .....
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Mar 2, 2011
I must be missing something really basic, but I just can't figure this out. I have a module (declared as a Module, i.e. a VB "static class") and I have an event declared in it, and places to raise the event. But I can't figure out how to handle the event.
Let's call the module MyModule with an even MyEvent. Like so:
Module MyModule
Public Event CallHelp()
Sub ExamineStuff( ByVal input As String)
[code]....
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Nov 14, 2011
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?
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Apr 18, 2011
The event handlers in my parent class are never called though the events are raised in the child class.
The Code:
Public Class childForm
Public Event checkboxchangedEvent(ByVal checkbox1 As Boolean, ByVal checkbox2 As Boolean)
Private Sub checkboxchanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged, CheckBox2.CheckedChanged
[code]....
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Aug 5, 2011
I have an MDI application that can either run in TABBED or WINDOWED mode. When a user selects something from the menu a form is shown. All menuItem clicks pretty much look the same:
Dim frm As New <SomeForm>
frm.MdiParent = MDIParentForm
frm.Show()
[code].....
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May 12, 2011
I have a test class with an implementation similar to this:
public class MyObject Public Event testEvent(ByVal duh As Boolean)
Public Sub New()
'some code here
End Sub
[Code]...
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Oct 26, 2009
I discovered that an event raised (directly on indirectly) in the constructor cannot be handled outside the very class. To prove if that was the actual problem, I wrote a simple exemplary app.
Class with the event:
Namespace Utils
Public Class A
Public Event Test()
Public Sub New()
CallTest()
[Code] .....
The reason of such behavior became quite obvious after writing those pieces, but maybe there is a way to omit it?
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Jun 30, 2010
In a list of timers, how do I determine the index of the item that elapsed without having to iterate the collection as shown below (e.g. can I pass a paramater to OnTimedEvent, or can the collection raise an event to say which item fired???). It's the individual timer index that I need as I'm using it to refer to something else.
(I wont know how many items I'll have in the list in advance so I can't create an individual event handler for each timer - I don't think I should even if I did).
Public Class Form1
Private _timers As New List(Of System.Timers.Timer)
Private Sub Form3_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
[code]....
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Feb 28, 2010
I have a central page loading child controls into a container in a Silverlight Project.Problem is events like button click events are fired twice after processing the child forms.Suspect it might have something to do with a double initializecomponent??
Private Sub btVolgende_Click(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles btVolgende.Click
Select Case Stadium
[code].....
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Nov 4, 2010
I have a User Control that has been added to the page dynamically. When I click a button on that user control[cod]e...
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Aug 2, 2011
I'm trying to capture the initial value of a listbox immediately after it's clicked on, and before the SelectedIndex is changed. The following was taken from: MouseDown in WinForm ListBox Kills SelectedIndexChanged, converted to VB. The ListBoxComponent Class is in a Component that shows at the top of the Toolbox.
Public Class ListBoxComponent
Inherits ListBox
Public Const WM_LBUTTONDOWN As Integer = &H201
Public Event PreSelect As EventHandler
[code]....
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Nov 18, 2009
I have a program that runs for some time and I would like to update the user on its progress. The rest of the GUI is updated using Delegates and Invokes and such (Java is Soooo much cleaner in this regard - everything is thread safe!!), but there is no invoke method for the progress bar. How can I use a delegate to update the progress bar when there is no invoke to invoke!!
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Sep 24, 2009
could someone tell me how to fire an event in main thread from another thread as well as fire and forget without use a new thread?
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Apr 14, 2009
I have a "partial" class in VB.NET. Half of it is auto generated by a code generation tool. That half implements INotifyPropertyChanged, so any properties in that part of the partial class raise the PropertyChanged event.In my "custom" part of the class, I declare another property that depends on one of the properties in the auto-generated side. Therefore, when that auto-generated property changes, I also want to raise a PropertyChanged event on my custom property that depends on it.
If I go into the generated part of the class and raise the event there, that will get overwritten if I ever re-generate that part, so I don't want to do that. I would rather add an event handler in my side of the partial class that checks if the generated property changed, and if so, raise another event for my custom property.
[Code]...
I'm assuming it's because normally you'd use the WithEvents keyword to tell the compiler that you're subscribing to events from that object. I don't have a clue how to do this inside of the class that's actually raising the event, or if that's even possible.
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Jun 15, 2010
Im working on a program ( vb 2005 CE framework ). I have mainly two threads, the main one and another one I use it for a different thing.When I tried to update the UI this exception was thrown : Control.Invoke must be used to interact with controls created on a separate thread.well !I have tried to use the INVOKE, but it wouldn't work. this is where I get the error :
Public Sub PaintKeys()
Dim tempLevel As clsLevel
Dim tempKey As ClsKey
[code]....
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Apr 22, 2011
Objective to clear the datagrid view after updating. This should happen when the user clicks the OK button when the update is confirmed. Below is what i have.I currently have
Private Sub SaveToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SaveToolStripMenuItem.Click
'This updates datsource
Try
[code]....
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Jun 22, 2012
The usual VB way to handle a computationally heavy task is to put it in a background worker thread, while the main thread keeps handling the UI.Say for whatever reason I needed to do this the other way around: the main thread doing the grunt work and the background one updating the UI.Here's what I have so far. The only problem is, while the UI window (Form1) does get redrawn, you can't interact with it, not even move or resize it (the mouse cursor turns to hourglass and won't click).
Public Class ProgressDisplay
Private trd As Thread
Public Sub New()
trd = New Thread(AddressOf threadtask)
[code]....
The client will call it like this (actually in unmanaged c++ over COM but you get the picture):
Dim prog = new ProgressDisplay()
DoLotsOfWork(addressof prog.update) ' DoLotsOfWork method takes a callback argument to keep client informed of progress
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Dec 7, 2010
below is a small part of my asynchronous TCP connection code. When I connect I'm passing a ListViewItem as Object parameter. I'd like to update the ListViewItem once the connection has been established or an error occurs. ServerConnect runs on a separate thread, because it's an asynchronous connection, so I can't update the ListViewItem directly.
Does anybody know how to update the ListViewItem?
I looked at jmcilhinney's asynchronous TCP example in the Codebank forum, but it confused me. I don't know which parts I need and which parts I don't need.
::edit::
One more thing. I also need to update the ListViewItem in the Read sub, but I'm passing "buffer" as Object, so how would I update the ListViewItem there?
vb.net
Imports System.Net.Sockets
Public Class TCP
Private Socket As TcpClient
[Code].....
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Apr 22, 2012
I am trying to write an app that in the thread will do some tasks, the form lokks like this:and what it should is something like this:
- retrieve data, populate a row in the listview, increase the first progress bar
- retrieve data, populate a row in the listview, increase the first progress bar
- retrieve data, populate a row in the listview, increase the first progress bar
[code]....
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