Split one big XAML in number of Sub-XAML files

Question

In my WPF4 Desktop-based application there is a big block with sidebar menu that repeats in each window and takes about 70 lines of XAML. In order to improve code reuse, I would like to split XAML file in two files:

1. XAML-file that contains code for sidebar menu (≈70 lines)
2. Base XAML file that contains «include/reference» to XAML-file with sidebar menu code

As I understood, there are two ways to implement my problem:

1. Use ResourceDictionary
2. Use UserControl/CustomControl

My questions are:

1. What is the difference between ResourceDictionary and UserControl? Could you give me examples where I have to use UserControl and where ResourceDictionary?

2. Could you give a full code example how to include/import content of one XAML-file to other?

P.S. Here is an example of code that I want to export to separate XAML-file:

<Border Style = "{StaticResource Body_SideBarMenu_Border_Settings}">
    <StackPanel Style = "{StaticResource Body_SideBarMenu}">
        <TextBlock Style = "{StaticResource Body_SideBarMenu_Title}"
                   Text = "{x:Static res:Resources.WinApp_SideBarMenu_Title}" />
        <TextBlock x:Name = "SideBar_WinReports"
                   Style = "{StaticResource Body_SideBarMenu_Item}"
                   Text = "{x:Static res:Resources.DashListMarker}">
            <Hyperlink KeyboardNavigation.TabIndex = "12"
                       Style = "{StaticResource Body_SideBarMenu_Item_Hyperlink}"
                       Click = "Call_WinReports_Click">
                <TextBlock Text = "{x:Static res:Resources.WinApp_ModuleName_Reports}" />
            </Hyperlink>
        </TextBlock>
    </StackPanel>
</Border>

Answer 1

ResourceDictionary is just a container for your styles/templates etc. So you really have a choice between using a style (and referencing it through a ResourceDictionary) or a UserControl.

In order to differentiate between the two, ask yourself a question: are you implementing just another look for some existing control, or you are implementing something really new, which is more than just a ListView (or a Border, or a ComboBox etc.)? In the former case, use a style; in the latter, create a new UserControl.

Specifically for your case, I would go for a UserControl.

---

Code example (although not full)

(Please note that a template for the following code can be inserted with VS's "add new UserControl")

Xaml:

<UserControl x:Class="SomeNamespace.SidebarMenu"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <UserControl.Resources> <!-- you can define local styles here -->
        <Style x:Key="SidebarMenuTextblock" TargetType=TextBlock>
            ...
        </Style>
    </UserControl.Resources>

    <Border Background=...>
        <StackPanel>

            <TextBlock
                x:Name="Put_a_name_if_you_want_to_reference_this_item_in_code_behind"
                Style="{StaticResource SidebarMenuTextblock}"
                Text="{x:Static res:Resources.WinApp_SideBarMenu_Title}" />

            ...

        </StackPanel>
    </Border>

</UserControl>

.cs:

using System;
using System.Windows;
using System.Windows.Controls;

namespace SomeNamespace
{
    public partial class SidebarMenu : UserControl
    {
        public NumericUpDown()
        {
            InitializeComponent();
        }
        ...
        // define here your properties etc,
    }
}

Now, you can use the control like that:

<Window
    x:Class="SomeOtherNamespace.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:controls="clr-namespace:SomeNamespace">

    <Grid>
        <controls:SidebarMenu PropertyIfYouDefinedOne="SomeValue"/>
        ...
    </Grid>

</Window>