Form Is Not Handling The Event Of A Custom Class?
Jul 24, 2010
I have a custom class which basically manages the program settings.
In it's New() event, I'm performing a check to see whether a value stored in My.Settings is the same as the default value (I made sure the value wasn't!), if not then it will perform a RaiseEvent ValueChanged().
On my form, I have an instance of the class declared "Private Withevents ProgramSettings as New clsProgramSettings", I also have a handler "Private Sub DoSomething() Handles ProgramSettings.ValueChanged" declared.
When I run the program the form gets loaded, the instance is created, the RaiseEvent is called, but the handler is not receiving the event?
I tried "Private Withevents ProgramSettings as clsProgramSettings", then creating the instance in the Form.Load(), but still no success!?
Is there something I'm doing wrong, or is there a problem with the IDE? I'm using VS 2010.
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Aug 12, 2009
My application's binary serialization was working well up to today (this is not a released app yet - still in development). I have a "Project" class that is the top-level class of a hierarchy of other classes related to its function. And before you think it, yes, all of those classes are marked as serializable. Infact, they all were being serialized before today.
I have one event on the Project class that assists in informing when the project's save status has changed (i.e. new, modified, saved). This event was added today along with some events on the other classes that filter up to the Project class (the project needs to be told when its objects have been modified). I unfortunately added all of this at the same time so I can't provide any incremental details as to when it stopped working, but when I try to save the project through my binary formatter it tells me that my main form is not marked as serializable. Well, yeah... of course it isn't! it shouldn't need to be because there is no member of my classes that even mentions the form. But for some reason handling the Project's event on the form triggers this error.
Serializing the form is not a solution. Neither is not being able to handle my Project events. If I comment out the handler it works fine -- and I don't even have to remove the WithEvents keyword on my form's Project variable. Now that I write that I'm speculating that it may have to do with the event being raised as a result of the serialization (occurs when the save button is clicked).
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Sep 24, 2010
I'm having an issue where my main form isn't updating even though I see the event fire off. Let me explain the situation and share some of my code which I'm sure will be horrible since I'm an amateur. I created a class to take in the settings for running a process in the background. I add some custom events in that class so I could use that in my form instead of a timer.
[Code]...
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Dec 1, 2011
I have an event defined and firing in class B
Public myEvent()
In class A:
Private WithEvents _b as B
Private Sub hander() Handles _b.myEvent
but, this handler does not get called.
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Jul 6, 2010
Basically, I have a custom child form class which has events that will be passed to the parent. In the custom child form, I have a declaration of a "MustInherit" class that inherits the DevExpress User Control Class.
The reason for this, is I have many user controls that derive from this base class, and the child form can have an instance of any one of these controls, and doesnt care which. The only requirement is that the child form can handle the same events from each type of control the same way.
Some watered down code snippets(still pretty long unfortunately):
'''Inherited Class
Public Class ChildControlInheritedClass
[Code].....
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Jan 11, 2010
I'm struggling to get a label or any item updated during an event handler I've tried Form.refresh/update, application.doevent, trowing laptop out of window, etc...
If i check for TextChange event on the label and return the value in a msgbox it is set however nothing is shown on the form I'm calling COM's in a backgroundWorker so the form stays responsive as the COMS take quite a bit of time to handle certain parts and I dont want the form to look as if it hangs.
Private Sub cmsCon_Change(ByVal iState As ACSCN.LoginState) Handles cmsCon.NotifyProgress is where the update occurs in the handler by calling the UpdateStatus() Method
Here is the
Imports System.ComponentModel
Public Class Avaya
'declaration
[Code].....
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Nov 14, 2011
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?
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Nov 17, 2009
I have a userControl11 (either in winform or wpf) which has a ValueChanged custom event. If I put it in client form and in form_load set its value to 100, it will trigger the ValueChanged event. But if I set this value inside the constructor of UserControl1 the custom event won't trigger. How can I force it to do so ?whatever the technical reason, functionally it does make sense. If the object is initializing its value from some sources unknown to the client form and the client form has a textbox bound to this usercontrol value, it is sure convenient that it could refresh its textbox at any time including when the form loads just using one single event handler. Without this the client form has to create another initializer for this bound textbox at form load.
Below the source code of my trials in winform:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
[code]....
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Nov 16, 2011
I have a BackgroundWorker in a vb.net program that is doing a lengthy data import routine. I want to modify its RunWorkerAsync method so that it fires a custom event on completion of the method. (So that a method in an automated process can respond to the event and resume its work). In a sense I want to 'extend' the RunWorkerAsync method to add an extra line of code--but I can't 'see' the code in the method (to just add the line raising the event) because BackgroundWorker is an MSDN class from Microsoft.The only solution that I can think of is to 'wrap' the background worker class in a wrapper that calls the .RunWorkerAsync method and then raises the event.
Public sub wrapperMethod()
myBackgroundWorker.RunWorkerAsync()
raise customEvent
end sub
Is there a design pattern that I might use? An easy way to address this with the .net language?
PS: Unfortunately, I'm automating some clanking legacy software and backgroundworker is used in many locations, so wrapping the backgroundworker will be a bit of work and may open bugs.
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Jun 22, 2010
I never did custom events and would like to make a sub procedure execute via a custom event from another form that does not have the custom event defined. For example I would like to raise the event from my ok button in one form and have the event in the other form execute. How to set this up using code examples?
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Jan 31, 2011
I want to create a custom class that has inside an array of another custom class (see my code below) but when the programm runs is crashes. Why? What is the right expression???? Plz help I'm a newbie in VB.net.....
Public Class ctrarray
Public nameclass As String
Public ctrlindex(glvar_spaces) As ctrlindexclass
End Class
[code]....
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Feb 15, 2011
I have alot of experience in working in VBA for excel, but not so much experience in creating my own structures so it's all still a bit foggy. I'm trying to capture the event for when the F1 key is pressed, not just when the form is active, but anytime the program is running. The code below expressing the handling is automatically generated for me in VB Express... But I'd like to change the situation to encompass anytime the program is open. I guess I have to reference events that happen in windows in general, but i don't know how to do it. I think i have to create the even in a class module?
[Code]...
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Jan 16, 2009
i declared a global variable button:
Dim button1 As New Button()
Now, i dont know how to add a click event in this button since it is a variable.
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Mar 8, 2010
When debugging a program, instead of doing this on EVERY piece of code:
Try
MyFunction()
Catch ex as Exception
MsgBox(ex.Message)
End Try
Is there a way to apply that to everything error I encounter without writing it on every function/sub/etc?
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Oct 25, 2010
I want to develop a program using VS 2010 Pro, VB and .NET 4.0 to run on a Windows standalone computer.The program will be loaded by another program that checks for a text file in a directory.When that file exists, the program I want to develop will be started and it will process the text file.The new program will not have any buttons or dialog boxes, it will simply display the progress of the processing of the text file and then it will simply terminate and exit.
I know I can start the processing by putting code in the LOAD event for the form, but i want to make a new class for all the processing to start from and have the new class perform all of the steps necessary to complete the processing of the text file.Of course this new class will use other classes to do all of the different processing steps.How do I execute that new class from the Form LOAD event?
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Jun 2, 2009
All of us use the try catch blocks. But what is the best way of handling errors within custom functions?Display a messagebox to the user when the exception is thrown (if possible within the function), or return a value indicating that an error was found within the function?
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Nov 3, 2011
I have a custom control I'm creating. When I click on it, it draws a dotted border and puts some nubs on it for resizing. This all works perfectly. Now I want it so when I click off of it, it deselects. I already have a variable to set up if it's selected or not and subs to draw/clear it. I just have to be able to detect when something else is selected or it gets clicked off of.
What I've Tried
My first and best solution to this was to use the LostFocus event, but, by custom control apparently won't let it fire. After some research, as far as I know, custom controls don't have Focus events because they are custom and could be changed (basically, you have to implement the focus events yourself).
My Question
Does anybody have a solution to either implement the focus events or a way to handle off clicking for custom controls?
Sources
Here is my controls current source:
Imports System.Drawing.Drawing2D
Public Class wDOMElement
Inherits Control
[Code]....
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Jun 18, 2010
I have created a class which generates a form in code. I have hooked up the buttons and a text box so that they work. Now, I am trying to hook up the Resize event (and probably will need other events) for this form. How do I do that? If I can understand how to do it for the Resize event, I should be able to apply that to whatever other events I might want to use. I can't just put "Handles frmMyForm.Resize" or "Handles Me.Resize". I get the message "Handles clause requires a WithEvents variable defined in the containing type or one of its base types." This all has been a learning experience.
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Mar 30, 2011
Problem that you may have when dealing with two objects that are raising some events. Here, to make it obvious, I am closing the form, but the problem can be experienced with any other 2 classes event. First, what is the problem !
Let suppose that by pressing a button, you want to raise a custom event, then execute a method and then close the form
In that case, you may use a code similar to this
Event BeepIt()
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
RaiseEvent BeepIt()
[CODE]...
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Oct 21, 2009
So I've made this control that inherits from the treeview control and basically loads objects from active directory into a treeview (url...).All working fine, but as this is the first custom control I have made that I have intended for other people to use, I'm not quite sure how I should approach error handling.I mean, obviously I shouldnt do something like show any exceptions in a messagebox because that might not be what the person that is using the control wants to happen. So do I just write out exception messages to the debug window? Do I swallow exceptions (guessing not)? Do I just totally ignore them so that they are thrown in the user's project?
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Sep 21, 2011
I'm completely confused about the event handling. I read some articles about it but after it I just get confused to write and use them in my classes.This is my class i. e.:
[Code]..
I dont have any argument passing. But I want to know how should I do it too. And I wanted to know if each instance of the Test class, run this event separately I mean each instance by themselves, This event AnEvent() will occur? Cuz I have lots of instances from my class.
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Aug 31, 2010
I am developing a COM dll library, and I have a little vb.net (vs 2005) application just to test it.I had my object declared in the application as
Private m_VarName As MyLib.CMyComClass
So far, so good.But now, I need an event to inform the application of some things, so I implemented such event in the COM dll, and changed the declaration to
Private WithEvents m_VarName As MyLib.CMyComClass
So far, so good, again. But if I add a Sub to handle my event:
Private Sub m_VarName_OnCaptureStop() Handles m_VarName.MyEvent
..
End Sub
The first time I create the object, nothing bad happens, but if I reinstantiate it
If (Not m_VarName Is Nothing) Then ReleaseComObject(m_VarName)
m_VarName= New MyLib.CMyComClass
then I get a cryptic TargetInvocationException, seemingly related to reflection (which, AFAIK, I am not using).If I remove the "Handles m_VarName.MyEvent" part, everything seems to work. In case it matters, I am not firing any event, for now.
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Nov 18, 2010
NET gurus... How would you convert this very chunk into VB?
[Code]...
When I use an online converter (Telerik), the middle line converts like this: Me.timer.Elapsed += New System.Timers.ElapsedEventHandler(ManageThreads) with 2 errors:
1- "Public eventElapsed is an event and cannot be called directly. Use raiseEvent
2- Delegate requires an Adess Of expression. Do I simply add "Address Of" ?
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Dec 15, 2011
I've been trying to figure out how to get this control to work for over a week. It can be found here: A Professional Calendar/Agenda View That You Will Use - CodeProject. It's a calendar/scheduler control that was designed using c# and I'm trying to use it in my vb.net app. I've sucessfully created a dll and have referenced that dll in my project and am able to see the controls in the toolbox as well as put them on my form. My problem is that I can't get ANY of the code that I wrote in the form to fire. No event handlers will work, not even the form_load which handles the mybase.load event. Nada. f a reason that this might be? How do I sucessfully add a handler to the events? I've used <code> addhandler monthView1.SelectionChanged, addressof (and nothing I put here ever works) </code>
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Jun 15, 2009
I have come accross many scenarios of handling datagridviewcombobox events, however none seem to fit my scenario, or I may be missing something.1. I need to capture the column index that the combobox is resident in. This is because I have a complete row of comboboxes that should set the header text to the selected value.here is the code I have so far:' I also use a list of string as datasource publicly declared
Public cs As New List(Of String)
'to insert the combo's into the grid
Dim row As New DataGridViewRow
cs.add("Book")
cd.Add("Author")
[code]....
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May 27, 2011
how to write below in vb.net??
Me.connection = New RAPI
connection.ActiveSync.Active += new ActiveHandler(ActiveSyncActive);
Private Sub ActiveSyncActive()
..................
End Sub
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May 7, 2009
I can come up with, if I understood the solution better, I could probably phrase a better subject line.[code]...
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Jan 8, 2009
I haven't done any programming in a while, and I have pretty much 0 experience with databases, so I'm hoping I can get some guidance with what I'm trying to achieve.I have a class (or want to have) which represents a person, for each person there's multiple dates, and for each date there's multiple events which have properties like time, place, duty, etc. I want to be able to save and load this from a database using a form. I want it to be able to function where I can type in the person's name and it will load all the data into the form, which has a combo box for the different dates and events, and when I select a different date and/or event I want the data to change correspondingly.
If someone could just give me a push in the right direction as to where I should be looking for help in achieving that I would really appreciate it. I don't have the class made to do any of that, just an idea of how it will function. I haven't worked much with classes, so I'm not sure how to approach it. Meaning I need guidance with classes and databases alike.
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Dec 27, 2010
Is it possible to raise event in one class and handle the event in another class? If so, how?
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Apr 18, 2010
Is it possible to handle a mouseDown event in VB.Net (2008) regardless of the control firing the mouseDown event? Basically, I just want to catch a mouseDown event at the "form level" and don't want to program mouseDown event handlers in every control. Is there a way to do this?
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