Creating a Custom ScrollViewer using WPF UserControl

Question

I'm trying to create a ScrollViewer with some customizations. Like this:

UserControl1.xaml:

<UserControl x:Class="MyApp.Control.UserControl1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             d:DesignHeight="100" d:DesignWidth="300">
    <UserControl.Template>
        <ControlTemplate>
            <Grid>
                <Grid.RowDefinitions>
                    <RowDefinition Height="*" />
                    <RowDefinition Height="20" />
                </Grid.RowDefinitions>
                <ContentPresenter Grid.Row="0" Content="{Binding ElementName=uc, Path=DynamicUserControl}" />
                <Rectangle Grid.Row="1" Fill="#88ff0000" />
            </Grid>
        </ControlTemplate>
    </UserControl.Template>
</UserControl>

UserControl1.xaml.cs:

public partial class UserControl1 : UserControl
{
    public UserControl1()
    {
        InitializeComponent();
    }

    public static readonly DependencyProperty DynamicUserControlProperty = DependencyProperty.Register("DynamicUserControl", typeof(object), typeof(UserControl1), new PropertyMetadata(null));

    public object DynamicUserControl
    {
        get { return GetValue(DynamicUserControlProperty); }
        set { SetValue(DynamicUserControlProperty, value); }
    }
}

TestForm.xaml (Using the UserControl1):

<Window x:Class="MyApp.TestForm"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:MyApp.Control"
        mc:Ignorable="d"
        Title="TestForm" Height="200" Width="500">
    <Grid Background="{StaticResource AimDarkGradBg01}">
        <local:UserControl1>
            <local:UserControl1.DynamicUserControl>
                <Button>Click me</Button>
            </local:UserControl1.DynamicUserControl>
        </local:UserControl1>
    </Grid>
</Window>

But the problem is no matter what content I put in the local:UserControl1.DynamicUserControl, nothing is rendered.

Anyone can help me?

Answer 1

The problem is actually you binding expression. The correct binding should be like:

UserControl1.xaml:

<UserControl x:Class="MyControls.UserControl1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:MyControls"
             mc:Ignorable="d"
             x:Name="uc">
    <Grid>
        <ScrollViewer>
            <WrapPanel>
                <!-- Dynamic Content -->
                <ContentPresenter Content="{Binding RelativeSource={RelativeSource AncestorType={x:Type control:UserControl1}}, Path=DynamicUserControl}"/>
            </WrapPanel>
        </ScrollViewer>
        <Canvas>
            <!-- Some Code -->
        </Canvas>
    </Grid>
</UserControl>

If you noticed I removed your definition of the template, in which case you don't need it. You can simply just put your code inside the user control.

The other files are correct. Fix what I told you above and you're good to go.