I have used delegates multiple times over the years but for some reason this very simple code isn't working:Form has one button and on textbox. Simply trying to update the textbox from another thread and although it looks fine it's not working.[code] the parameter is being passed to the DoSomething, the UpdateTextboxText is being run and gets the correct string. But the textbox itself remains blank and I'm stumped.
View 1 RepliesHow would you create and use a delegate to update the text of the main form from the DoWork event of a backgoundWorker?
View 4 RepliesI've run in to a very annoying situation. At the moment I have a program with 4 forms. 3 of these forms work fine, but the fourth seems to be a dud. After clicking any one of the buttons or controls on this form it works. But if I try to click anything again, it doesn't work. I can't use my back buttons, I can't even use the minimize, maximize and exit buttons in the top right corner which are automatically built in to the program. I fear I have accidentally changed a setting, or accidentally deleted some very crucial code for this
View 8 RepliesI want to show in my form, something to show the user that the program is working just wrote a Label, but Visual Basic Freeze during the process and the label it can not seen and there is not signal to know that the application is working.
View 1 RepliesThis is my problem. If I write this -
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But I'm just out of my wit why this code, written to do the same thing is not working -
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I am having a generic ListOf-collection holding the self-created User-object, I can filter for users by using lambda-expression like this:
Dim reviewers As List(Of User) = users.Where(Function(u) u.DvRoleID = 2).ToList
Instead of using the lambda expression I can also write the function and call it as argument like this:
Public Function GetReviewer1(ByVal u As User) As Boolean
If u.DvRoleID = 2 Then
Return True
[Code] .....
Now the question: why can't I create a delegate having the same signature as the GetReviewer1 function and use the delegate as argument inside the where-clause like this:
Delegate Function Criteria(ByVal u As User) As Boolean
Public Function GetReviewer1(ByVal u As User) As Boolean
If u.DvRoleID = 2 Then
[Code] .....
The compiler does not accept the crit delegate as argument.
I have a form and controls on from I work with background worker on my form and I want when I work with background worker in (for next) changed a data table example (mydt.clear()) or change a datagrideview..how to update controls on a form when we work with background worker? [code]
View 4 RepliesI've been fooling around with this for two hours and getting nowhere. I want to update a list box on a form with some text. Unfortunately the event that calls for the update is a timer which gives me a cross thread error.The listbox relies on a combo box which tells it the number of items to display. Here's my sub that performs the update.
Public Sub EventUpdate(ByVal EventMsg As String)
Dim DateTimeStamp As String = Format(DateAndTime.Now, "MM/dd hh:mm:ss")
With lbxEvents
[code].....
from the documentation we have this: Multicast Delegate: Represents a multicast delegate; that is, a delegate that can have more than one element in its invocation list.
so am i right to say that Multicast delegate is no different from a normal delegate other than the fact that it has arguments. so System.Action is a 'normal' delegate whereas System.Action(T)(Byval obj as T) is a multicast delegate?
I've got a couple of these NumericUpDown controls I put on a form. Without describing too much about the form I basically want to update some variables each time one of these NumUD controls changes value. So for each NumUD I have a call to a Recalculate subroutine within their "changedValue" event.
There are actually two problems. First, if I initialize the "Value" property to something other than zero in VB2010 at DESIGN TIME it won't even open the form when I hit RUN. It gives me a "No Source Available. No symbols loaded for any call stack frame" error. The error box says "InvalidOperationException" was not handled. So if I try to set the initial value of the Value property to anything but zero of either I get this error.
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I've created a Delegate that I intend to call Async.
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Code:
Public Class SendPings
Shared Sub New()
AddHandler Post.Saved, AddressOf Post_Saved[code].....
I get a error" Method 'Private Shared Sub Ping(item As BlogEngine.Core.IPublishable, itemUrl As System.Uri)' does not have a signature compatible with delegate 'Delegate Sub WaitCallback(state As Object)'.
I have a class that is in an assembly due to being required for other projects that I'm currently working on. One class lets call it Class Factory, creates a group of controls which require click event handlers to be attached, I have algorithms which determine polymorphic behavior based on certain features but that is relatively irrelevant.
Due to the event handler having to open up a specific form that isn't part of my assembly, and that form requiring this "Factory" class. Without creating circular reference is there any way I can essentially "delegate" the handler event for the form to define? As a simple work around I have had to maintain two separate classes, one in the project with the form and one in the assembly.
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Me.Width = 1500
Dim panel As New Panel
panel.Location = New Point(0, 0)
panel.Size = New Size(1000, 200)
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I have an app that basically monitors states, then when a state has changed, a notify form is triggered to show for the user.Timers are used on the form to showing a fading in/out of the form (somewhat like MS Outlook new email notification windows).I'm using a delegate from the main form to show the form, but when the first timer in the form is set to start, the timer's tick event is never ran. Everything up to that point in code works perfectly though.Is there something I need to do in order for the tick event to fire, like it would without the use of a delegate to show the form?[code]
View 2 RepliesI have a listbox of items that need to be processed, and I would like to process them asynchronously on a separate thread. (Never done this before).So I created a Delegate, a Callback, called the method that does the work on the listbox items.
I am getting an exception "System.InvalidOperationException": Cross-thread operation not valid: Control 'ListBoxBlah' accessed from a thread other than the thread it was created on.
Doing the asynchronous operation for individual items doesn't make sense to me because I am only doing it to perhaps perform a large number of operations (the listbox may have 20000 items) in the background while allowing the user to do other stuff.
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In my project i have moving picturebox array & if they intersect treeview will disable.& when i rightclick on the picturebox it will delete.After deleting picturebox its effects still there.When other picturebox moving on that deleted area still treeview is disabled.i used this code.
Me.Controls.Remove(a)
where a= new picturebox
I often see code snippets for handling each control of a certain type on a form or panel, etc.They always start with For Each ctrl and the do a test for control type.Many .NET users are not aware, as I was not until I tried it recently, that we can LINQ on the controls collection.Below is a simple sub I created for resetting every checkbox on a panel I use as a validator.
Private Sub ResetCheckBoxes(ByRef pnl As Panel)
Dim ctrls as System.Collections.Generic.IEnumerable(Of Object)
ctrls = From c In pnl.Controls Where TypeOf (c) Is CheckBox
[code]....
I want to use the following snippit.
For Each x As Control In Me.Controls
If TypeOf x Is CustomControl Then
SomeAction( x.CustomEventofCustomControl)
End If
Next
The problem here is that not all controls have event CustomEventofCustomControl, so the complier shrieks. How do I get around this.
I am working on a notepad like program and I am adding tabs I've been able to successfully make buttons to add and close tabs but now all my other codes are messed up (as I was using a richtextbox before).
View 21 RepliesI am trying to learn how to create Windows Forms custom controls in VB.Net by creating a .Net version of an old control I created in VB6. On this control, I have a UserControl with a Label (lblCaption), and several of the properties I add to the control should be passed to the label.This is the code I tried for the ForeColor property:
Code:
Protected mcolForeColor As Color = Color.FromKnownColor(KnownColor.ButtonHighlight)
Public Overrides Property ForeColor() As Color
Get
[code]....
When I change the ForeColor on the control in my test project, lblCaption does change to the color I selected; however, when I run the application, the label changes back to the default (button highlight) color, and the value of the property is also reverted back when I return to the form designer.What would be the proper way to implement the ForeColor property on a custom control?
With the following SQL " Dim Query As String = "UPDATE JobName_tbl SET [JobDate]=@NewDATE, JobAddress=@Newaddress Where JobID=@ID"
nothing happens nothing gets updated nor do I get an error.But as soon as I remove the [JobDate]=@NewDATE, it works fine.
Here is my code:
Public Sub UpdateAddress(ByVal JobID As Integer, ByVal JobUpdate As String, ByVal NewDate As Date)
Try
Dim Query As String = "UPDATE JobName_tbl SET [JobDate]=@NewDATE, JobAddress=@Newaddress Where JobID=@ID"
Dim DBcon As New DBConnection.Connection
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I'm running Microsoft Visual Studio 2010 SP1 and SQL Server 2008 R2 and I'm using vb.net coding. Any other information that you need to know, just ask.I've got a form in a master/ details setup that has one table in details view in the top half of a split container, and another table in a dgv in the bottom half of the container. Everything is working well except for one value. My dueDate value always reverts back to the date set when the record was made, which is the default value put in when a new record is made. It doesn't give me any errors to work off of, and I've even went and coded the update by hand with this code:
Dim Num, Contract, ID, Receive, Due, Notes, Inspect, SO, PO, Entry As String
Num = Order_NumToolStripTextBox.Text
Contract = Order_ContractTextBox.Text
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All that happens when I hit save is my due date will revert back to the old due date. I have no clue what would/could cause this. I've went through to see if anything that would store the original dueDate (from a check I set up in my coding) is coded somewhere it shouldn't be, but all it does is make the check that something had changed while on the form. it takes an array of all my text boxes and checks it with an array made before leaving the form. Nowhere else is the original dueDate saved.
i'm trying to work with master pages and referencing local and master contentplaceholders. I have a master file that has this:
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I am using Visual Basic Express 2010.
I have programmatically set up a Datagrid and binding navigator etc., but I cannot get the movenext, movelast buttons to actually hook up to the Data on the Datagrid.
I have tried to set up an addhandler for the BindingNavigatorMoveLastcontrol, and although I can get the BindingNavigatorMoveLastcontrol to display my messagebox
WHICH IT DISPLAYS TWICE FOR SOME REASON I cannot get it to actually move around the Dataset, or any of the other navigation properties for that matter.
Wednesday61
Imports System.Data.SqlClient
Imports System.Windows.Forms
Imports System.Drawing
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I'm trying to make a program which uses drag & drop functionality, however, it only works when I drop something onto the form, not the controls. If I do try on the controls, I just get the 'Unavailable' cursor.
The AllowDrop property is set in the properties bar, and I also set it when the form loads.
Current code:
Public Class Main
Private Sub Main_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles Me.DragDrop
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At work we have a pretty large web application that works by having a few pages, with lots of user controls which are nested in these pages. This is working fine most of the time but we have a problem at the moment where one of the user controls isnt working. Originally it was referenced from another project in the solution but when this wasnt working I decided to copy the file into the project and try to register it locally. It works on our development system, its only when we move it to deployment that it stops working, and I'm thinking it's something that I'm missing in the build. When you go to the page on Live the control is just missing, and no errors are generated.
View 2 RepliesI am using VB 2005 and the following code returns an error: No value given for one or more parameters. I swear I've done this before without any problems but I can't find my original code.[code]I tested the value of oldid which is set earlier and it does have a value.
View 2 RepliesI'm developing a system and the system contains an update function to update the DB. I have performed all the coding but have some minor problem in my SQL Statement and I'm unable to detect the SQL Statement Error. Hope someone could rectify the problem.
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Dim sqlupdate As String
sqlupdate = "UPDATE sysdep SET sysaccount= @sysaccount, syspw= @syspw WHERE id= @id"
Dim cmd1 As New OleDbCommand(sqlupdate, con1)
[Code]....
This is my code for update, but not working,UPDATE STATEMENT WRONG?
I'm trying to update my wallpaper with VB.NET and it's not working. Weird thing is, this same code works fine on my other machines (same OSes, Win XP Pro SP3). My code grabs a random picture then passes it to the SetWallpaper function:
<System.Runtime.InteropServices.DllImportAttribute("user32.dll", EntryPoint:="SystemParametersInfoW")> _
Public Shared Function SystemParametersInfo(ByVal uiAction As UInteger, ByVal uiParam As UInteger, ByVal pvParam As System.IntPtr, ByVal fWinIni As UInteger) As <System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.Bool)> Boolean
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