I need to create a custom User Control with generics because I have a BindingSource with a data source of type T
public partial class ABMControl<T> : UserControl
{
public ABMControl()
{
InitializeComponent();
this.bindingSource.Datasource = typeof(T);
}
}
In the form designer the custom user control does not appear in toolbox because is generic.
What is the solution?
It's expected behavior for toolbox.
When dropping a control from toolbox onto your form, you are commanding the designer to create an instance of that control. You cannot create an instance of GenericControl<T> without determining T. Instead you need an instance of GenericControl<SomeClass>.
So it completely makes sense the generic control doesn't appear in toolbox because it has no usage in designer and designer doesn't know what type should it use for generic parameter when creating instance.
Also about designer, considering this post: Generic Base Class for UserControl starting from VS2015.1, Windows Forms Designer shows classes which have generic base classes without any problem. The following class will be shown in designer without any problem:
public class SomeClassControl:GenericControl<SomeClass>
{
}
For older versions of Visual Studio, use the workaround which is described in the linked post:
public class SomeClassControl:SomeClassControlBase
{
}
public class SomeClassControlBase:GenericControl<SomeClass>{}
Related
I have 2 forms that inherit a control from the class below:
public class AInbox: Form
{
public FlowLayoutPanel InboxItems;
}
The forms inherits as such:
public partial class Inbox : AInbox
{
...
}
In the Designer.cs file i commented out the original "InboxItems" control declaration and everything compiles and runs fine... except the GUI designer. When i open the Designer I get the error "The variable 'InboxItems' is either undeclared or was never assigned."
Is there any way to use this inheritance and still have the designer work?
I'd recommend against inheriting a form with generated code (like you're doing with Inbox).
If you want the child class (Inbox) to add additional controls, I wouldn't use the designer directly on the child class, because I don't think the visual studio form designer will play nicely when half of the form was designed in the parent class. If you need to reuse certain parts of your form in a different form, you might want to consider moving that part of the form to a separate user control. You can use the designer on this user control and later put the user control in the forms.
If you just need to have the same form, keep an instance of the form in your other class. Move your logic away from your form (view) and in your other class (controller).
I have an issue, and I don't know if I can do that, or if there is another way to do that. I have an abstract class called "BasePage", it is my .NET Standard library, so I can't access to System.Windows namespace. Its declaration is:
public abstract class BasePage<VR> where VR : new()
EDIT: The class above has a public property to access to VR
So now, for each platform (WPF, Xamarin, etc) I have to create its own implementation of the class begin VR the content control of each platform (UserControl for WPF, for example). I already did it and this is:
public class WindowsBasePage : BasePage<UserControl>
Now, every time I want to create a page to add content to a window, I have to create something like this:
public partial class UserPassPage : WindowsBasePage
{
public UserPassPage()
{
InitializeComponent();
}
}
The problem becomes when I have to set it in the XAML file (the View). I can create it and it builds:
<local:WindowsBasePage x:Class="Bitture.AppManager.Manager.UserPassPage"
[...]
xmlns:local="clr-namespace:Bitture.AppManager.Manager"
mc:Ignorable="d" >
</local:WindowsBasePage>
but I can't add components (like buttons, text, grids, stackpanels, etc). I want to know If I can do it with my current code or there is something I have to change. Because I have to access to the generic type WindowsBasePage that inherits from
class WindowsBasePage : BasePage<UserControl>
I am not sure what you are trying to do here but you can't add UIElements to a custom class of yours that doesn't inherit from any of the common WPF base classes such as for example Panel or ContentControl, and expect it to be rendered as a UserControl or some other WPF control.
This won't work. WPF knows about how to render WPF controls but it doesn't know how to render a custom BasePage<UserControl>.
I am building some applications that use OPC to control some industrial automation. I have decided it might be a good idea to create some custom controls for standard things I will use such as buttons and text boxes. One of my main reasons was that I felt in an ideal pattern the end object i.e. the button is the one who holds information about the OPC item it refers to otherwise in a typical application my Form class gets polluted by tons of variables that are in my mind scoped more global then they should. I started then by using the Tag property of the button but this requires some overhead code that is the same for each instance. I felt like the right thing to do is subclass controls that I would like to use and provide properties to configure each one.
With that context in mind my real question is this. To make it as portable as possible I decided there should a property to define the OPC Group. I declared a property like this
public class OPCButton : Button
{
[Category("OPC")]
public OPCConnectedGroup
{
get { return _OPCGroup; }
set { _OPCGroup = value; }
}
}
This shows up int the property list when I add the control but I am unable to bind this property even though my Form1 contains
public OPCConnectedGroup Connection1 = new OPCConnectedGroup();
I have resolved that the way to solve this is to probably create an additional control like OPCGrp that can be added to a Form then the Controls can reference this. To test I added a property of type Button and sure enough when I added it and browsed to the property it gave me options for all the buttons on the Form. I have no huge problems with this approach I just want to make sure that Im following a prototypical pattern because I will be responsible for maintaining the control library but not always implementing and Im trying to get it down to a 1-2 step process to implement a control.
Thanks
Matt
When defining OPCConnectedGroup you can inherit Component class.
This way if you have a property of type OPCConnectedGroup in your OPCButton, then at design time, you can put instances of OPCConnectedGroup on the form, and then if you choose your OPCButton at designer, that property of type OPCConnectedGroup will show as a drop down list that you can select one of instances that you put on the form for it.
Example:
If I have such MyButton and MyClass:
public class MyButton : Button
{
public MyClass MyClassInstance { get; set; }
}
public class MyClass : Component
{
public string SomeProperty {get;set;}
}
Then you can put some (or one) instance of MyClass on the component tray of the form:
And then if you select MyButton on your form, you can choose one of MyClass instances from in property grid:
I've got a usercontrol that inherits from an abstract class. Basically looks like this.
class SimpleSlideView : View
{
}
public abstract class View : UserControl
{
}
The project compiles and runs fine. I can take the usercontrol (from the toolbox) and drag it into a form and it is displayed in the designer correctly. However, if I try and open the SimpleSlideView control itself in the designer I receive the following error:
The designer must create an instance
of type 'Animation.View' but it cannot
because the type is declared as
abstract.
What have I missed?
You can find possible solution here: How can I get Visual Studio 2008 Windows Forms designer to render a Form that implements an abstract base class?
An application I'm working will have a number of forms with a lot of shared functionality. For instance, each form will have a DataGridView, many of the same buttons, much of the same UI code and so on.
I'd like to implement this by creating a base version of this common form, subclass it for all these very-similar-but-not-quite-the-same child forms, and tack on whatever additional controls and features I need for each of them.
I've already figured out that it helps to make the base form's controls protected because this allows things like anchoring to work propertly. However, I have yet to find a way to automatically make the derived forms the same size as the base form.
Experience tells me there should be a simple way to do this. While it's not much of a problem to just type in the required size by hand for every derived form right after creating it, I'd prefer to make everything as clean, simple, and automatic as possible.
I find it interesting that your derived forms do not automatically inherit the size from their base form, because this should work without you having to do anything about it.
Suspected cause of your problem:
I suspect your problem results from the fact that you're using Visual Studio's Forms Designer to edit the forms. Whenever you've edited a form, Windows Forms Designer generates the required code in the InitializeComponent method of your forms. Among all the generated code are assignments that set a form's size, even if it is identical to the base form's size. Therefore you might have to manually comment out those assignments if you want your derived form to have the same size as the base form, even when you change the base form's size after creating the derived forms. (However, I don't know if that might lead to further problems with the controls' positioning & layouting.)
// Code to be commented out in your derived form's InitializeComponent method:
this.AutoScaleDimensions = new System.Drawing.SizeF(...);
this.ClientSize = new System.Drawing.Size(...);
Once these lines are commented out, the size as set in your base form's InitializeComponent will be used for the derived form.
A workaround solution:
You can do the following so that you don't have to manually comment-out designer-generated code every time you've edited a form:
Create an form derived from your base form; let's call it FrozenBaseForm. You will derive all other forms from this class instead of directly from the base form. Now, in this "intermediate" class, you define a new property ClientSize:
public class FrozenBaseForm : BaseForm
{
new public SizeF ClientSize
{
get { return base.ClientSize; }
set { }
}
}
This will cause all assignments to ClientSize to have no effect at all and therefore preserve the size from the base form. This feels like a hack to tell the truth, but it seems to work. You might have to hide the Size property in the same way btw.
As said, derive your forms from FrozenBaseForm instead of from BaseForm directly:
public class DerivedForm1 : FrozenBaseForm { ... }
public class DerivedForm2 : FrozenBaseForm { ... }
...
Another option (last resort if all else fails):
As a last resort, you could simply forget about the Forms Designer and just define the derived forms manually in the code editor (though I personally would not want to do this):
public class DerivedForm : BaseForm
{
public DerivedForm()
{
// make all necessary changes to the base form:
...
}
}
public partial class derivedForm : baseForm
{
public derivedForm()
{
InitializeComponent();
this.Width = base.Width;
this.Height = base.Height;
}
}
Why not make the BaseForm set the size of itself?
public partial class BaseForm : Form
{
public BaseForm()
{
InitializeComponent();
// you could hardcode these or retrieve these values from a
// config file or something
this.Width = 640;
this.Height = 468;
}
}
Wouldn't this do what you want?