I am trying to create a UserControl in VB.net, under VS2010. I have the code for the UserControl and I would like to add it to a form. My problem is that, according to every book and forum I have seen, after I build the UserControl, it should show up in the Toolbox. It doesn't. I even downloaded code from a book, the code executes perfectly, but their TrafficLight control doesn't go in the Toolbox (even though the book says it should - and that the only way to set its properties and to add it to the form is through the Control properties). I have tried to add the control to the form manually, by declaring it
Dim myObj As New SomeClass.SomeControl
and in the Designer.vb, identical with the buttons on the form:
Friend WithEvents myObj As SomeClass.SomeControl
With both, I get an error saying
'myObj' is already declared as 'Friend WithEvents myObj As SomeControl' in this class.
And either way, I get an error when I try to look at the design:
Could not find type 'SomeClass.SomeControl'. Please make sure that the assembly that contains this type is referenced. If this type is part of your development project, make sure the project has been successfully built using settings for your current platform or AnyCPU.
The control by itself builds and shows up in design view (not in the Toolbox though, even though it Imports System.ComponentModel and Inherits System.Windows.Forms.UserControl and... what else ? I tried to build it in a separate project, to see if I creating a separate dll will make a difference, though I really want it in the same project.
Please help ! (BTW I have reinstalled VS2010 and it did no good)
Thank you.
Look in Tools / Options / Windows Forms Designer and set "AutoToolboxPopulate" to True (but note that this can take a noticeable amount of time if you haver many (i.e. dozens) of user controls.
Related
I have an ascx.vb file with a function that starts off like this:
Sub buildlist()
repcaldatelist.Visible = True
...
End Sub
I'm just trying to figure out what repcaldatelist is. When I use VS's "Go To Definition", it gives me a popup saying "The definition of the object is hidden." Using "Go To Implementation" does nothing.
I see the corresponding .ascx file with this line:
<asp:repeater ID="repcaldatelist" runat="server">
and I see how repcaldatelist is databound to it, so that page can display its data.
But what I'm trying to understand is, where does repcaldatelist come from? I want to see where it's initialized and what its type is.
I know this is probably really basic but I'm new to VB / Web User Controls and haven't had any luck searching for this online thus far. Please enlighten me.
ID="repcaldatelist" means that's the ID of the Repeater control. So in your .vb file, repcaldatelist is an object of type Repeater - the ID in the ascx/html translates into a variable name in the VB. If you hover over the variable in the .vb file in Visual Studio it should tell you the type as well.
Go To Definition / Implementation don't work because the Repeater class is part of the .NET framework, and it's closed-source - just a DLL on your machine. Therefore there's no source code or definition you can view. You just have access to its public API as defined by the docs (and should be available in intellisense as well).
I have the following classes in my vb.net application:
Form1
Usercontrol1
LnkLabel
Usercontrol1 is a user control , and doesnt contain any extra code. LnkLabel is a class that inherits Forms.Label. Its code is goven below:
Public class LnkLabel
Inherits Label
Sub clk handles me.click
Process.start(text)
End sub
End class
When I add an Instance of LnkLabel to usercontrol1, i get an error "type LnkLabel is not defined"
There are three instances of the error in uc1.designer.vb.How can I solve these Errors?
Note:
Visual Studio 2010
.Net FW 3.5
Edit:
The usercontrol1 donot contain any code that might be causing the error. It is just a new usercontrol added to the project.
LnkLabel is added to UC1 by the designer, not by using code at runtime.
The class name is LnkLabel, and not "LinkLabel".
I find that the easiest way to resolve this type of issue is to open the Designer.vb file directly.
To do this, choose Show All Files from the Project menu, then expand UserControl2. Double-click on the UserControl2.Designer.vb file.
You should also be able to get there by double-clicking on the error in the compile errors list.
Once there, search for the definition of UserControl1 or uc1, whatever it may be called (ensure you are in the type definition area, not the property assignment area).
Looking at the definition may give you an instant clue as to the problem (is it in the wrong namespace; did the name of the user control change after you created it, but the change was not propagated to this form; etc).
If it is not obvious what the issue is, use VS intellisense to help you get the right class. I usually clear the previous type definition and start typing the name I know it should be (i.e. UserControl), then select the appropriate value from Intellisense.
Selecting a different class (or correcting the class selection) will require a change to the control instatiation code and may also require a change to some of the properties (I usually just remove the properties I am unsure of and update the control directly in the designer).
Before you switch back to the designer, ensure that you save your changes and, if possible, compile the app.
I'm using vb.net (vs2010). I'm moving some winforms to a dll. I have a form that inherits from the one which has some subs and functions (like a test app).
My original form is: (.designer)
Partial Class Form1(Of T)
Inherits System.Windows.Forms.Form
....
End Class
Form itself contains code and a toolbar.
My test form is: (.designer)
Partial Class TestForm
Inherits Form1(Of Class1)
I get "Cannot create an instance of Form1`1[T] because Type.ContainsGenericParameters is true" when VS try to load the designer. App is usable. I can build and run the project without errors, but I need to add controls and some code to each new form.
I tried many ways:
Visual Studio 2008 Winform designer fails to load Form which inherits from generic class
How can I get Visual Studio 2008 Windows Forms designer to render a Form that implements an abstract base class?
http://www.codeproject.com/Questions/419770/Csharp-reflection-GetValue-from-a-field-in-generic
http://madprops.org/blog/Designing-Generic-Forms/
All examples are for C#, and I don't know if I'm missing something...
Is this a bad design ? I know this is a VS bug but still it seems everyone fixed it by these links.
EDIT:
I'm building a DLL. Form1 is on this DLL and TestForm is in a new project. Those links works if I'm in the same project (a.k.a. the dll).
Thanks!
Is this a bad design ? I know this is a VS bug
Bad design, not a VS bug. What you are trying to do is fundamentally incompatible with the way the Winforms designer works. It has strong WYSIWYG support, the designer creates an instance of the form's base class and allows code in that base class to run at design time. Which is why, for example, you can set the BackgroundImage property and it is immediately visible in the designer. The Form.OnPaintBackground() method paints it. The designer is not involved at all, it just sets the property.
To make that work, it must be able to create the base class object. It can't in your code, it doesn't know what kind of T to use. Not an issue when you design Form1, the T isn't needed yet since it derives from Form and creating an instance of Form is not a problem. Big issue when you design TestForm.
You'd probably argue that it should use Class1 as the T. It doesn't, the odds that it can use Reflection to discover the generic type argument from TestForm are exceedingly low. That requires the type to be compiled first. That's a chicken-and-egg problem at design time, the TestForm class gets compiled after you design it, not before or while you design.
It's not like you completely cannot use your approach. It builds and runs just fine. You just have to live without design time support for TestForm. That's usually a deal breaker, you have to re-consider your design.
I do apologize if this post is a duplicate, but I haven't found anything similar when I searched.
I'm fairly new to VB.NET and I'm currently playing around with user controls, figuring out good programming practices. As far as I understand, to create and use a UserControl, I need to create a project with the UserControl in it, then build the project and use that DLL (add it to Toolbox or otherwise).
My question is this: Is there a way a have a project (a Form with a bunch of things on it) that contains a UserControl written in a *.vb file inside that same Project? If you do that, the DLL (in my case) never gets produced, possibly because the UserControl is never used and building it is simply omitted. Is it perhaps a bad practice to do that altogether? It simply makes sense to me to keep a UserControl as a part of the Project that uniquely uses it. Is there a reason not to do that?
Thanks in advance! = )
SOLUTION:
Visual Studio does not automatically include your own controls to the toolbox by default! In order to change that, go to Tools>Options>Windows Form Designer>General and set AutoToolboxPopulate to True. When you build your project next time, your new Control will appear in your Toolbox.
It's a perfectly valid design decision to include a UserControl in a WinForm or WPF project that uses it. If you do this then VS will not create a DLL for the UserControl; instead the UserControl will be built into the assembly your project is producing.
If you did want to reuse a UserControl in multiple projects then you would want to create separate project that generates a DLL that can be reused.
How do you create your own custom component for vb.net 2008? I want it to simply output to a .dll, not a whole winforms app.
So, here is what I have done so far:
Made a class library project
Added a custom control object
Confused myself badly
Googled it, to no avail
How can I control the component? For example, I want my component to not have a visible design view, I want it to stay below like the stopwatch component and the notifyicon component and such, it is not something to be designed. Then, how do I edit the possible properties a user can control, and make them effect the end result? What do I place the code which powers the component on? The class library file, or something else?
Thanks for your help! I have a whole set of components I am going to create, this will get me going much faster than trial and error.
I think you may want to check some walkthrough on how to create components. Such as this one: Walkthrough: Authoring a Component with Visual Basic. Once you are done with that one, there are more walkthroughs on various related topics, such as how to use design-time support, implementing designers and so on.
OK... This is a really abbreviated example. You should start by basing yous off of an existing .net component.
Public Class MyControl
Inherits DataGridView
'...add your properties/functionality...'
End Class
Then compile the DLL, and add it as a reference to whatever project you are working on. Once added, you can add the controls in the DLL into your toolbox.
This has more instructions on how to modify a UserControl (slightly different from the one above, but it explains well. This is a general explanation.
#comments -
Yes, there, are things that will do what you want. Start with a class that inherits Form instead of DataGridView in the example I gave you, and the changes described in the links provided.
"Your properties and functionality" is whatever you want to do that the base control does not do.