User Control events when "splitting" a XAML file - wpf

Question

Several people have asked how to split up large XAML files into smaller more manageable or readable chunks. In my case I have a XAML file with 10 tabs and each tab has a lot of complex controls. So the XAML file for this is huge and hard to read.
The "standard" answer for this seems to be User Controls.
I'm sure this is a real noob question, but if all you're trying to do is split up the XAML file, how do you do it without splitting up the C#, too? When you create a WPF user control Visual Studio creates a new XAML file plus new code-behind file to go with it and handle the events.
What I really wanted was the equivalent of a "C# partial" directive for XAML so I could just split it up among multiple files but have the events handled in one place. How close can I get to that?
Thanks in advance!

Answer 1

There is no way to do as you describe (to allow multiple xaml files to share the same c# code). Also from what you describe there isn't an easy way to quickly abstract that code without having to make some changes. Since wpf events are typically driven by commands, the best solution would probably be to change your events to fire commands rather than putting the logic within the actual event handler itself, then calling it from the user control would be trivial.
But before you go changing all your code, you may be able to abstract out a lot of the long stuff using styles, which are way easier to abstract out and shouldn't mess with your events. So if you notice repeating how things are setup across lots of controls, just declare all of it as a style and you can move it into a resource dictionary elsewhere to remove some clutter.
To elaborate a bit you can use styles not just to stop repetition, but also to abstract out how you define your controls (much like you are trying to use user controls for, you can also define events there). For example...
<Style TargetType="TabItem" x:Key="Tab1Style">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate>
<StackPanel>
<!--Note even if this style is defined in a resource file the
events will still be tied to the class of the control
using the style-->
<Button Click="Button_Click"/>
<Button Click="Button_Click_1" />
<Button Click="Button_Click_2" />
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Then simplify one of your tabitems to simply...
<TabControl>
<TabItem Style="{StaticResource Tab1Style}" />
</TabControl>
If you really have your heart set on user controls you could also just route all the events out. Something like this...
<UserControl ...>
<Button Click="OnClick"/>
</UserControl>
public partial class UserControl1 : UserControl
{
public static readonly RoutedEvent ButtonClick = EventManager.RegisterRoutedEvent(
"ButtonClick", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(UserControl1));
public event RoutedEventHandler ButtonClickHandler
{
add { AddHandler(ButtonClick, value); }
remove { RemoveHandler(ButtonClick, value); }
}
private void OnClick(object sender, RoutedEventArgs e)
{
RoutedEventArgs newEventArgs = new RoutedEventArgs(UserControl1.ButtonClick);
RaiseEvent(newEventArgs);
}
public UserControl1()
{
InitializeComponent();
}
}
<Window>
<local:UserControl1 ButtonClickHandler="Button_Click" />
</Window>
private void Button_Click(object sender, RoutedEventArgs e)
{
MessageBox.Show("Click");
}
(like I said lots of plumbing code)