I am new to WPF and have created a WPF User Control Library
I added a Base class that looks like this
public class TControl : UserControl
{
}
and want all of my controls to inherit from it.
I have a Control called Notification which looks like
public partial class Notification : TControl
{
public Notification()
{
InitializeComponent();
}
Works fine except when ever i recompile the hidden partial class where InitializeComponent() is defined gets regenerated and inherits from System.Windows.Controls.UserControl
this gives me an
Partial declarations of 'Twac.RealBoss.UserControls.Notification' must not specify different base classes
error,
is there anyway to force the generated class to inherit from my base class?
Your XAML file probably has:
<UserControl x:Class="YourNamespace.Notification" .... >
Try changing this to:
<Whatever:TControl x:Class="YourNamespace.Notification" xmlns:Whatever="clr-namespace:YourNamespace" />
The error you are getting is because the use of UserControl in the XAML tells the compiler to produce a partial class inheriting from UserControl, instead of inheriting from your class.
You can completely remove the ": TControl":
public partial class Notification : TControl
{
}
and write:
public partial class Notification
{
}
instead, since the base class is defined in the XAML part, as Paul wrote.
Related
I changed my UserControl to be a ReactiveUserControl and now I can't view the Design View. Is there anything I can do to get the designer to work with ReactiveUserControl?
The Visual Studio designer has issues when your control or window directly inherits from a generic class. This was a pretty common issue with WinForms as well. You can work around this issue by defining another non-generic class that sits between the generic ReactiveUserControl and your control:
public partial class MyUserControl : MyUserControlBase
{
public MyUserControl()
{
InitializeComponent();
}
}
public abstract class MyUserControlBase: ReactiveUserControl<MyUserControlViewModel>
{
}
In the XAML, our root object element is defined as the base element (MyUserControlBase) and its class declaration is connected to the partial class defined above (MyUserControl):
<myNameSpace:MyUserControlBase
x:Class="MyNameSpace.MyUserControl"
xmlns:myNameSpace="clr-namespace:MyNameSpace"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
I have four UserControls in my WPF Application - e.g.
VisualA, VisualB, VisualC, VisualD
I want each of them need to inherit a generic "Player" Class which contains a heap of shared code -. e.g. methods, timers etc
So far this is what I have tried in my Control's XAML
<UserControl x:Class="VisualA"
And here is what I have in a separate Class file.
Partial Public Class VisualA
Inherits Player
End Class
Public Class Player
Inherits UserControl
End Class
In my Window, I'm referencing the UserControl as normal:
<local:VisualA></local:VisualA>
But, I'm getting the following error:
Base class 'System.Windows.Controls.UserControl' specified for class
'VisualA' cannot be different from the base class 'Player' of one of
its other partial types
What am I doing wrong?
I was also under the impression any code (i.e. methods) inside the inherited class (Player) would be able to access the Controls in the UserControl by referencing by name - is that correct?
The base class in the XAML is still set to UserControl. Change it to Player. Also note that the namespace for the Player type will have to be defined. i.e:
<BaseClasses:Player x:Class="VisualA"
xmlns:BaseClasses="clr-namespace:MyProject.BaseClasses"
... all your other namespaces used
I'm trying to use a C# class derived from UserControl as the base class for some xaml pages' layout root, so I can share some common functionality. I.e. the backing class is like:
public class BaseView : UserControl
{
// Some virtual functions I want in common ...
}
public class MyView : BaseView
{
// Overidden functions ...
}
The xaml file then references the class like:
<jt:BaseView x:Class="ns.MyView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:jt="clr-namespace:ns"
...>
</jt:BaseView>
This seems to work when running, but in the xaml editor, the code is all underlined with blue squiggly lines, with a fly-over message of something like "Cannot create instance of BaseView".
If I don't do this, and use UserControl in the xmal, I get errors because the partial class generated from the xaml then has the UserControl base class and not my custom base class.
How do I get the editor to know about my custom base class (i.e. get rid of the blue underlines)?
The most common cause for a design time "Cannot create instance..." sort of error is that the constructor of the element is doing something that doesn't make sense or is unavailable at design time.
I want to set a user control property to the value of a property in a parent control. For example, let's say my main window control has some initial configuration data. Currently I use the following in XAML:
<Window x:Class="MyProject.MainWindow"
x:Name="TopWindow" ... >
...
<local:MyUserControl Config="{Binding ElementName=TopWindow,
Path=MyUserControlConfig, Mode=OneTime}" />
</Window>
But this appears to require two dependency properties, one in the MainWindow (MyUserControlConfig):
namespace MyProject
{
public partial class MainWindow: Window
{
public static readonly DependencyProperty MyUserControlConfigProperty=
DependencyProperty.Register("MyUserControlConfig",
typeof(UserControlConfig), typeof(MainWindow));
public UserControlConfig MyUserControlConfig
{
get { return (UserControlConfig)
GetValue(MyUserControlConfigProperty); }
set { SetValue(MyUserControlConfigProperty, value); }
}
}
}
and one in MyUserControl (Config):
namespace MyProject
{
public partial class MyUserControl: UserControl
{
public static readonly DependencyProperty ConfigProperty=
DependencyProperty.Register("Config",
typeof(UserControlConfig), typeof(MainWindow));
public UserControlConfig Config
{
get { return (UserControlConfig) GetValue(ConfigProperty); }
set { SetValue(ConfigProperty, value); }
}
}
}
I really don't need to observe any changes, just to pass data into my user control at the time of creation. Is this possible to do using simple properties for at least one of the two or must I use two dependency properties to perform this (one time) initialization?
Update: Jay's solution leaves us with just a CLR property in the MainWindow class:
namespace MyProject
{
public partial class MainWindow: Window
{
public UserControlConfig MyUserControlConfig {get; private set;}
...
}
}
Now if it was just possible to remove the dependency property from the MyUserControl class and replace it with a simple property that still gets initialized via XAML binding (or some other XAML mechanism, so I can pass in the data source via XAML).
I could be mistaken, but if you can bind to CLR properties on other classes, I'd expect you could bind to a CLR proprety on your MainWindow class.
Have you tried that?
I have problem with base classes in WPF. I try to make a base class with some base elements, so that other windows can inherit these components. But all that i have, when I inherit base class is only empty window, without these elements. For better understanding i put my code here:
using XSoftArt.WPFengine;
namespace XSoftArt
{
public class WindowBase : Window
{
public WindowBase()
{
}
}
Code of the Windows, whitch inherits WindowBase:
namespace XSoftArt.WPFengine
{
public partial class NewAbility : WindowBase
{
public NewAbility()
{
base.ChildForm = this; InitializeComponent();
}
}
}
Or maybe someone can put an working example or link with implemented base classes in wpf?
Thanks
I don't think you really need to do what you are doing, but it is feasible. I think you are just forgetting to call the base class constructor.
using XSoftArt.WPFengine;
namespace XSoftArt
{
public class WindowBase : Window
{
//call base ctor
public WindowBase() : base()
{
}
}
}
You'll need to do this from your inherited classes as well:
namespace XSoftArt.WPFengine
{
public partial class NewAbility : WindowBase
{
public NewAbility() : base()
{
base.ChildForm = this; InitializeComponent();
}
}
}
And if you also have a XAML-defined view, you'll need to make sure your view is a WindowBase. To do this, change this:
<Window x:Class="MyApp.MyView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
...
>
<Grid>
</Grid>
</Window>
To this:
<local:WindowBase x:Class="MyApp.MyView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:XSoftArt;"
...
>
<Grid>
</Grid>
</local:WindowBase>
If you look at this class in Reflector you will see that the constructor calls the Window class's own "Initialize()" method, which sets a lot of things in motion. Specifically it appears to hook itself up to the Dispatcher, which is the work queue for all UI events.
In particular, you want to ensure that the InitializeComponent() method of the base class is called - this is the function that creates the controls that you defined in XAML.
Making a derived class is great if you want to inherit both controls and behaviour, but consider using Templates for a more flexible way of managing a common set of controls.
I don't think I'd ever use inheritance in WPF the way you're trying to use it.
I'll try and take a stab at answering your question. If I'm understanding you correctly, you're trying something like this:
You're creating a window that has both a XAML file and a code-behind.
You're adding "base elements" to the XAML for your window... I'm not sure what you mean by "base element", but I'm going to assume you mean you're adding UI elements to your window.
You're creating another window that "derives" from your first window in the code-behind, and the problem is that you're not seeing the UI elements on it from your "base" window.
If that is what you want to accomplish with WPF, I'd personally recommend against it, just because I'm personally not a fan of inheritance and have seen firsthand the dangers of letting inheritance get out of hand.
What you could try instead is organize your "base" UI elements into WPF UserControls. This tutorial might be able to guide you in the right direction. Good luck!