I am getting this error: Unable to cast object of type 'SGA.AppContext' to type System.ComponentModel.ISynchronizeInvoke'.I am not using a start up for my project but a sub main() and a threaded class AppContext
View 14 Repliesthis is sumit from Larsen & Toubro Mumbai-India,I am writing a code for some sort of software in which execution of some code is required as soon as my software receive a barcode from barcode scanner (serial input). Now through datareceived event handler i am able to read the barcode but after that i am not able to send this barcode to any textbox or even i am not able to start any other event like performclick to any button or anything. I am getting an exception as cross linking of threads not possible. please refer to the image and give me the solution asap.
View 2 RepliesMy application need to communicate with my self made device through serial port. I have to change the selected index of Tabs when I press a button on my device. I have Form1, Form2, Module1 Form1 Contains the Serial Port Control. Form2 contains the Tab which needs to be changed. When I press a button on device them, the button pressed is stored in an integer form in a global variable.The Interrupt for the Serial Port directs the control to the module1 where I decide using Select Case that what index of which TabControl I have to select.Depending on that, I change the Index of the required Tab.
PROBLEM:cross thread exception is fired as soon as the control reaches the statement where I Modify the SelectIndex property from the select case at Module1.While, on my other PC, the SelectIndex property is changed, but the next tab is not shown.
BUT, if I put all this code in a button control, and try to activate from there, then it works perfectly. However, I have to navigate through the tab controls using my self made device.I searched a lot on net and came across a solution which describes that we have to use delegate function and invokeRequired methods to ensure that the procedures run on the same thread.I am not able to decide that where exactly shoud the code for delegates and all be written, in form1, or form2, or module1.Also, in the hit and try that I did, I always got the value of InvoleRequired as False.
Here is the part of Code that I wrote for Delegates
Code:
'Form 1 is BLINDHELPER_SIGNIN
'form 2 is BLINDHELPER_USER
' I have defined these at Module1
Public Delegate Sub DeleToManageTabs(ByVal tb As TabControl)
Public Sub manage_Tabs(ByVal tab As TabControl)
MsgBox(tab.Name)
[code]....
After using this code also, there is no change in working of my application.
Frankly, NONE of this makes sense to me..[URL]..They just jump right into code without baby steps that explain the situation.Every other aspect of VBnet has been well spelled out to me and I get it -- but this business of using the serial port and going nowhere because of a cross thread error has me 100% baffled.
If anyone can point me to a tutorial that really explains it simply and well (without jumping into friggin' code).Even in the above link, they show 3 different techniques of addressing the same problem ! (Like I CARE
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This was the code and this is the thread HERE Ok its working and everything but when i want to perform something when click is noticed it says i cant cross-threads
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?
I have a main thread which is designed to be a batch processor - it spawns a series of 'child' threads from a loop (which can vary in terms of the no of items) - see below
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However, each of the 'child' threads could take anywhere from milliseconds to about a minute to process - depending on the complexity of each calculation. There may also be a large number of child threads - e.g 100s. Creating large numbers of child threads is not efficient. I therefore want some way to effectively queue each child thread (and cancel if the process is taking too long to complete). Autoevents seems like one way of doing this, but the only examples I can find seem to assume there are two different processes on seperate threads, not one process being repeated.
i guess the title pretty much states the question but i will give the senario to be more clear. i have a mousemove() event which i add in my program programmatically and i need a way for raising that event (again) programmatically too. raiseEvent control_mousemove() doesn't work as it says that "'control_MouseDown' is not an event of 'main'."
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How to raise event in vb asp.net 2.0 ?
View 2 RepliesIs it possible to run a sub routine on my form after all other sub routines have finished? I am having a problem using a filewatcher that watches a certain path and runs an SQL job if a certain file is pasted. For some reason my procedure leaves a file behind sometimes and others it does not. I was wondering can I use a form event to run a different procedure after all other sub routines on the form are completed that would check this directory for remaining files again?
View 1 RepliesI am comfortable with Vb.Net events and handlers.how to create event handlers in c#, and raise events.
View 4 RepliesNormally I raise an event like this:
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
I want to act with a service (kill the procces) whenever a process (executable file) comes up.Obviusly it is an Event but I don't know what event is.
View 1 RepliesI'm trying to raise an event from a class. It looks ok but it did not raise the event as expected...?
Steps
1 - Load the form2
2 - Boutton1 call the form1 and load the class animation
3 - Class animation raise the event for the form1
Here is the code !
Public Class Form1
Private WithEvents AnimationTextChange As Animation
Public Sub mdiMainEvent_StatusTextChange(ByVal _text As String) Handles
[Code]....
how to raise an event in vb2003
this my
Public Class Form1
Public Event TimerStart()
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
[Code].....
I have a class with a property, and I want to raise an event when the property value changes, but I have no idea how to declare events, or call them?
View 6 RepliesI have a button that I need to use twice, the first time I click it, it validates that a string inside a textbox is a certain length. That part works. What I want to do is press the same button again but when I press it the second time it is suppose to popup a hidden label. But when I try to use a raiseevent command it gives me an error saying "the button is not an event in my program" tell me how to use the OnClick?
View 9 RepliesHow do I format,
EventzBindingSource_AddingNew(EventzBindingSource,
???)
to raise this event:
[code].....
I have an MDI parent form and 2 child forms. Each child form has data bound controls bound to the same sql table; one from is for displaying data and the other is for editing data. After the editing form closes, I need to update the data in the display form (if it is displayed). I can think of a few ways to do this, but I would like the display form to simply respond to an event raised by the database. Is it possible to create (and raise) an event in the database proper? If not what is the best/acceptable way to update data on a data bound form?
View 1 RepliesI have 2 classes one main class called Mygrid and another class inside it called TLBoxEditingControl which inherits a textbox into grid cell.Also I have added one Listbox called LstBox to the usercontrol MyGrid.
1) Initially its visible is false. How can i make visible true in TLBoxEditingControl class.
2) I have an Event called MyList() in Main Class, how can I raise this event in TLBoxEditingControl class.
Here is the code i use, This is not working please expalin
Public Class MyGrid
Inherits DataGridView
Public Event MyList()
[code]....
I have added this control to a form and added this code
Private Sub MyGrid1_MyList() Handles MyGrid1.MyList
MsgBox("ggg")
End Sub
Here the event is not raising.
Is there is an event that get raised when oject of a custom/user control is set to nothing?
View 5 RepliesI want to get an event when a list item is added.
Private WithEvents newMessages As New List(Of NewMessageList)
Private Sub VariableChanged(ByVal NewValue As Integer) Handles newMessages.listChanged
MessageBox.Show(CStr(newMessages.Count))
[code]....
This part is the issue: newMessages.listChanged because the even can not be found. What am I missing?
I converted some code from c# to vb, I have the following error:-
m_axCalendar.DoRetrieveDayEvents += New AxXtremeCalendarControl._DCalendarControlEvents_DoRetrieveDayEventsEventHandler(m_axCalendar_DoRetrieveDayEvents)
Red Error = Error1'Public Event DoRetrieveDayEvents(sender As Object, e As AxXtremeCalendarControl._DCalendarControlEvents_DoRetrieveDayEventsEvent)' is an event, and cannot be called directly. Use a
[code]....
I can get rid of Blue error by changing it to : AddressOf m_axCalendar_DoRetrieveDayEvents Not sure how to fix red error?
How to raise combobox_SelectedIndexChanged(object sender, EventArgs e) programmatically? Lets say i have method called ClearFields(). I want to call the event before i hit the end of Clearfields() method.
View 4 RepliesI need to transform the following in VB.NET from C# (.NET 4)
class XXX:
public event EventHandler ContentScaleChanged;
if (otherXXX.ContentScaleChanged != null)
{
otherXXX.ContentScaleChanged(c, EventArgs.Empty);
}
I cant' do RaiseEvent ContentScaleChanged(c, EventArgs.Empty), because I need to raise that event on the otherXXX instance...
i've an owned form that never raise the paint event, and so i can't make it rounded...
View 6 RepliesI'm trying to raise an event in a mocked interface. I can get this in C#, but for some pain-in-the-butt reason can't get it working in VB.Net. Hopefully I haven't missed the boat conceptually and all I'm missing is some syntax. This is similar to the code I'm working with:
Public Interface ISendable
Event SendMessage(message As String)
End Interface
''**********
Public Interface IPrintable
Sub PrintAnnouncement(announcement As String)
[Code] .....
How to complete or correct the line in my test class that begins "sendable.Raise..."? Maybe there is more setup I need to do, but the Moq site didn't seem to indicate this is the case.
I have form 1 which will raise an event for form2 after doing some calculations. I know how to raise an event in form2 and then write the sub in form1 but i cannot do the reverse... how can I do this in reverse??? I cannot raise the event sub in form2 is not responding.
Example:
Form1:
Code:
Public Class Form1
Event test()
RaiseEvent test()
[Code] .....
I have a WinForms class that presents a TreeView of some network nodes. I have a separate module that interfaces with the network and detects when nodes are added or removed. I would like the module to trigger the TreeView when the network changes.Example
Public Class Main
Friend Sub TV_Main_Network_Click ( ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
[code].....
I have a Windows Service project designed to monitor an email account and make entries into a SQL Server database when certain emails arrive. This is a rewrite of a similar winforms program that works just fine, except that it requires that the computer be logged into an account and the program started manually, which I can avoid by using it as a service.In the service I maintain a list of logged messages - basically just a string and a timestamp indicating that something has happened. (That list is shared out over a WCF service but I think that's immaterial, at least at the moment.) In my custom class I declare a public event, and elsewhere I raise that event. For some reason, though, the RaiseEvent isn't being run in the service. For example:
[code]...
The problem in this case is that _pc_HandleEvent isn't ever being called. If I duplicate this setup in a regular winform program, everything works like it should. What am I doing wrong? How do I get a service to handle events raised from other classes?