Working With The Controls Collection?
Feb 17, 2010
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]....
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Mar 25, 2011
I have an ASP.NET app with lots of textboxes all over the page that need updating at various points through program execution. These textboxes actually belong to a certain class, so for easy updating I thought I could create a Dictionary(Of string, object) and add the control.ID and the control to it and then for updating do something like this:
[Code]...
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Dec 13, 2011
I'm a bit confused here. I'm copying all the controls from one form to a panel on the main form and for some reason only about half of them copy.
Private Sub switchComponent()
Dim selection As String = TreeView1.SelectedNode.Text
Panel1.Controls.Clear()[code]....
When stepping through the code, serverDic(selection).Controls has 12 elements, but only 6 of them get copied. Next time this gets called, only 3 get copied. Does Panel1.Controls.clear() somehow kill the references?
EDIT: Just to show that there are infact 12 elements in the collection:
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Feb 24, 2010
Im trying to loop through a collection of controls see code:
Private Sub addZeros()
For Each ctrl As Control In Me.Controls
If TypeOf ctrl Is GroupBox Then
[Code]....
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Sep 22, 2009
I am trying to create radiobuttons, and then create code for them after they are created. I have the code to create the radiobuttons. What I want to do is create a sub for the event of changing the check value for the radiobutton. Or to have the check value recognized by a button click. For example, you click the button and if the first radiobutton has the circle filled then a msgbox comes up and says hurray. My code so far is this:
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Aug 27, 2010
Does anyone know how I can access the FontDialog's controls collection? I would like to disable the Font Style ListBox, set the Font Style's TextBox to readonly and disable the UnderLine and StrikeOut CheckBoxes.
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Apr 15, 2011
Maybe if I knew the right termanology, I could find the answer myself.. I am going to run a fairly long list of "If"s that will determine if certain controls appear on the form or not. In it's simplest form would be:
[Code]...
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Mar 6, 2012
How to get the last instance of label control in List (of Control) using linq?
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Jan 6, 2010
I am writing a simple control translation function that reads an XML file containing control names and their localized text. Within the application, each time a form is loaded, it iterates through every control and tests to see if that control is defined in the XML file. If it is, it then sets the control text to whatever localized text is defined in the XML file.
There are some tests and additional requirements (i.e. nested loops) for TabControl and MenuStrip etc., but the control that is giving me the most trouble is the ContextMenuStrip.[code]...
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Dec 29, 2009
I am trying to add controls to a collection runtime(toolstripmenus to a menustrip) However, when I try to loop through the collection, it says something like: "Collection has been edited. Listing function cannot be done" (it's a free translation since i have a finnish VB)
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Mar 12, 2009
I am trying to dynamically add some css and js elements into an ASP.Net page at runtime, but because this code is used in mutliple controls I need to ensure that the relevant links are only injected once.
Currently I have the folowing code in the OnPreRender event.
Dim head As HtmlControls.HtmlHead = Me.Parent.Page.Header
If Not _useCustomStyles Then
Dim litCustomCss As New LiteralControl("<link rel=" & Chr(34) & "stylesheet" &
[Code]....
Does .Contains look for this instance of an object (which I assume is why this is failing)?
Is there a way to check the controls collection for a specific id? Or am I going to have to write a sub to loop through the existing controls in the collection checking for the id.
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Oct 9, 2009
I have a small piece of code that iterates through the controls collection on a panel (below) Everything works fine until I want to focus on a control that doesn't support the selectall method i.e. a datetimepicker. Is there any way of determining the type of control and not call the selectall method when the type is datetimepicker. All my other controls support it so that's the only one I need to exclude.
[code]...
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Mar 31, 2011
I need a function to be performed on the page load, which uses a stored session variable. I have added the following to my <body> tag.
<body onload="doSomething(event,'<%= Session("StartTime") %>')>
This does work. However, it is causing a problem elsewhere, when I try to add a control to my controls collection:
[Code]....
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Aug 27, 2010
Does anyone know how I can access the FontDialog's controls collection? I would like to disable the Font Style ListBox, set the Font Style's TextBox to readonly and disable the UnderLine and StrikeOut CheckBoxes.
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Jun 2, 2011
I'm trying to make a collection class for buttons to address them as a whole, only I want to design the buttons at design time, and not add/set their properties programatically at runtime. Each button has its own image, so it doesn't seem right to add a bunch of lines of code which assign the properties when they're always going to be the same thing.Is it possible to create the controls at design time and then add them to an array at runtime? I did this, iterating through the buttons on the form and adding each of them to the class below.The problem is that once they're added they seem to be a different instance because changing their positions has no effect on the design-buttons on the form. Essentially i wanted the collection to be a reference to the items belonging to the form.Is that possible or should I be doing this a different way?[code]
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Apr 12, 2009
How can I find a List or Collection of User Controls available within the development enviroment and dynamically add them to a combox by their Name Property. I am looking for something along the lines of:
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Mar 2, 2010
I am trying to make a collection of controls that I can loop through. So I have this code in my form... Dim WizardFrameCollection As New Control.ControlCollection(Nothing)
I then try to add controls to the collection by I get a error "Object reference not set to an instance of an object." WizardFrameCollection.Add(Me.GroupBox1) I am not sure why I am getting this error. Groupbox1 is a groupbox that is on the form.
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Oct 22, 2009
This is really a continuation from my earlier post. I've never worked with this datatype/collection (system.collection.generic.Ienumerable) before so I'm struggling to declare the query globally so I can reference the results within other sub routines/functions. I also am struggling to convert it to other types.how I can convert the collection of xml elements/system.collection.generic.Ienumerable into an xmltextreader (I know I will have to change the query below as it select the value of the node and not the node itself) I imagine by converting the query result to system.IO.stream My first port of call was MSDN but I find the material very difficult to understand for this particular subject.
[Code]...
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Mar 9, 2009
at some points, I need to call the same method on those controls (ex. user presses the clear button on the big control, I want to call the clear f(x) on each of the controls)I thought to toss the controls in a collection, and then be able to handle them something like this:
nextturns out, and I should have realized, methods and properties of controls are not exposed when treated this way. The only thing that can be seen is the stuff that the base class (control, I guess) has.
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Jun 22, 2012
I 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.
[Code]...
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Jun 26, 2012
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
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Apr 18, 2011
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.
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May 10, 2012
I'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
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Jan 3, 2010
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).
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Feb 1, 2011
I 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?
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Jul 4, 2009
i'm trying to work with master pages and referencing local and master contentplaceholders. I have a master file that has this:
[Code]...
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Mar 23, 2011
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
[Code].....
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Sep 25, 2009
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.
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May 16, 2012
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
[Code]....
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Nov 10, 2009
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.
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