Question

I’m sure this is easy, but new to me for WPF using C#. I know about inheriting from classes and have done so many times such as in C# WinForms projects…

public class MyClass : DerivedFromClass
{}

However, stumped in WPF and here’s the issue. I want to build my own set of controls to be used as a baseline for a new learning project… preset my own styles, colors, backgrounds, and other functionality. No problem. Start first with a WPF Window and create “MyWindow”.

Now, I want to take this baseline “MyWindow” and subclass THAT for yet another class of MySubClassedWindow. So, I create a new Window class, and by default, VS2010 builds the both designer and code portions of the form. I do view code on the MySubClassedWindow and find

partial class MySubclassedWindow : Window
{}

In C# using WinForms, I would just change to (and I’ve included the class library reference that includes the “MyWindow” declaration.

partial class MySubclassedWindow : MyWindow
{}

When I do, I get a compilation error of

Partial declarations of 'MyNameSpace.MySubclassedWindow' must not specify different base classes

Answer 1

Your base class should just be a class file (not a Window).

So create WindowBase.cs

public class WindowBase : Window
{
    // ...
}

In MainWindow (for example) change the xaml.cs file to inherit from WindowBase instead

public partial class MainWindow : WindowBase
{
    public MainWindow()
    {
        InitializeComponent();
    }
    // ...
}

In MainWindow.xaml, include the namespace for WindowBase and change Window to base:WindowBase like this

<base:WindowBase x:Class="SubclassWindow.MainWindow"
                  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                  xmlns:base="clr-namespace:NamespaceForWindowBase"
                  Title="MainWindow" Height="350" Width="525">
    <!--...-->
</base:WindowBase>