Default value for property of UserControl

Question

UserControl contains BorderBrush property derived from Control. How can I setup it's default value, for example, to Brushes.Black and make it available to be set by developer who will use my control?

I tried to assign initial value in <UserControl> tag in control's xaml file and in constructor of it, but when I do any of this, value assigned for the control externally is ignored.

Would [CSharper's answer](https://stackoverflow.com/a/845033/3993154) in [Bind to a value defined in Settings](https://stackoverflow.com/q/845030/3993154) work? — Sometowngeek, May 24 '17 at 01:50
@Sometowngeek dunno, can't check for now cos changed to aspnet developer a year ago — FLCL, May 24 '17 at 09:35

score 7 · Accepted Answer · answered Jul 23 '15 at 11:35

You would usually do this by overriding metadata for the BorderBrush property in your UserControl derived class:

public partial class MyUserControl : UserControl
{
    static MyUserControl()
    {
        BorderBrushProperty.OverrideMetadata(
            typeof(MyUserControl),
            new FrameworkPropertyMetadata(Brushes.Black));
    }

    public MyUserControl()
    {
        InitializeComponent();
    }
}

score 2 · Answer 2 · answered Jul 23 '15 at 11:36

Perhaps styles would be best. You could create a new UserControl, let's call it BorderedControl. I've created a new folder called Controls to hold it.

<UserControl x:Class="BorderTest.Controls.BorderedControl"
         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">
<Grid>

</Grid>
</UserControl>

Next, create a Resource Dictionary, UserControlResources. Be sure to include the namespace of the control:

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:ctrls="clr-namespace:BorderTest.Controls">
    <Style TargetType="{x:Type ctrls:BorderedControl}">
        <Setter Property="BorderBrush" Value="Lime"/>
        <Setter Property="BorderThickness" Value="3"/>
    </Style>
</ResourceDictionary>

Here you can set what ever properties you'd like to have default.

Then, include the resource dictionary in the user control resources:

<UserControl x:Class="BorderTest.Controls.BorderedControl"
         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">
<UserControl.Resources>
    <ResourceDictionary Source="/BorderTest;component/Resources/UserControlResources.xaml"/>
</UserControl.Resources>
<Grid>

</Grid>
</UserControl>

Finally, add the control to your main window:

<Window x:Class="BorderTest.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:ctrls="clr-namespace:BorderTest.Controls"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <ctrls:BorderedControl Width="100"
                           Height="100"/>
</Grid>
</Window>

Here is my solution:

Here is the application when you run it:

You can simply change the border of your user control with this:

<ctrls:BorderedControl Width="100"
                       Height="100"
                       BorderBrush="Orange"/>

Default value for property of UserControl

2 Answers2