依赖性属性不适用于WPF UserControl

Question

I created my own user control with dependency properties and added it to my main window, where I now want to be able set the dependency properties. The properties are not taking the value I set in the XAML of the main window and I am not sure what I am missing. In the code I set the default value for the FillBrush property to Yellow. In the XAML I set it to Red. When I click the Test button, it shows the property to be Yellow. Here is the code:

Window XAML

<Window x:Class="Test.Window2"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:test="clr-namespace:Test"
    Title="Window2" Height="200" Width="600">

    <StackPanel>
        <test:TestUserControl x:Name="myControl"
            FillBrush="Red" VerticalAlignment="Center" Margin="20"/>
        <Button Height="24" Width="300" Content="Test" Click="Button_Click" />
        <TextBox x:Name="debugTextBox" Margin="20"/>
    </StackPanel>
</Window>

Window Code Behind

public partial class Window2 : Window
{
    public static readonly DependencyProperty FillBrushProperty =
        DependencyProperty.Register("FillBrush", typeof(Brush), typeof(Window2),
        new UIPropertyMetadata(Brushes.Yellow));

    public Brush FillBrush
    {
        get { return (Brush)GetValue(FillBrushProperty); }
        set { SetValue(FillBrushProperty, value); }
    }

    public Window2() { InitializeComponent(); }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        this.debugTextBox.Text = 
            "Red: " + Brushes.Red +
            "  Yellow: " + Brushes.Yellow +
            "  Actual: " + this.FillBrush;
    }
}

User Control XAML

<UserControl x:Class="Test.TestUserControl"
             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="300" d:DesignWidth="300">
    <TextBlock Text="User Control"/>
</UserControl>

User Control Code Behind

public partial class TestUserControl : UserControl
{
    public static readonly DependencyProperty FillBrushProperty =
        DependencyProperty.Register("FillBrush", typeof(Brush), typeof(TestUserControl),
        new UIPropertyMetadata(Brushes.Cyan));

    public Brush FillBrush
    {
        get { return (Brush)GetValue(FillBrushProperty); }
        set { SetValue(FillBrushProperty, value); }
    }

    public TestUserControl()
    {
        InitializeComponent();
    }
}

What am I missing?

Answer 1

In the XAML you are setting the Fillbrush value on TestUserControl to Red, but when the button is clicked it shows the Fillbrush value for Window2 , not TestUserControl . And since the Fillbrush value for Window2 is not set in XAML it still has the default value of Yellow.