Using Base classes in WPF

Question

Hello. 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

Answer 1

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:

1. You're creating a window that has both a XAML file and a code-behind.
2. 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.
3. 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!

Answer 2

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.

Answer 3

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.