是否可以像在XAML中使用其基类（在这种情况下为StackPanel）一样使用自定义WPF控件？

Question

I'd like to create a custom control based on StackPanel since I need to add some code to the derived class.

I created the custom control in Visual Studio.

When I want to use the custom control in an XAML I get various errors.

I'm new to WPF.

Is it (not) possible to use a customized WPF control just like its base class in XAML (StackPanel in this case) ?

c# code is

namespace MyNameSpace
{
    public class AbstractForm : StackPanel
    {
        static AbstractForm()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(AbstractForm), new FrameworkPropertyMetadata(typeof(AbstractForm)));
        }
        protected override Size MeasureOverride(Size constraint)
        {
            return base.MeasureOverride(constraint);
        }
        protected override Size ArrangeOverride(Size arrangeBounds)
        {
            return base.ArrangeOverride(arrangeBounds);
        }
        // more code
    }
}

Generic.xaml content is (most parts generated when creating the custom control):

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:MyNameSpace">

    <Style TargetType="{x:Type local:AbstractForm}"
        BasedOn = "{StaticResource {x:Type StackPanel}}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:AbstractForm}">
                    <Border Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}">
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

I then try to use "AbstractForm" like a StackPanel in MainWindow.xaml:

<Window x:Name="MyApp" x:Class="MyNameSpace.MainWindow"
        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:control="clr-namespace:MyNameSpace"
        mc:Ignorable="d"
        Title="MyApp" BorderBrush="{DynamicResource {x:Static SystemColors.ActiveCaptionTextBrushKey}}">
    <StackPanel x:Name="MyAppUI" Orientation = "vertical" HorizontalAlignment="Left" Margin="0,0,0,0" VerticalAlignment="Top">
        <control:AbstractForm x:Name="HeaderArea" Orientation = "horizontal" HorizontalAlignment="Left" Margin="0,0,0,0" VerticalAlignment="Top">
            <Image x:Name="appImage" HorizontalAlignment="Left" VerticalAlignment="Top" Source = "AppImage.gif"/>
            <StackPanel Orientation = "vertical" HorizontalAlignment="Left" Margin="0,0,0,0" VerticalAlignment="Top">
                <!-- more content -->
            </StackPanel>
        </control:AbstractForm>
        <!-- more content -->
    </StackPanel>
</Window>

When running my application I see the following errors (trying to re-translate from german):

• The 'Orientation' property was not found in 'AbstractForm'
• Element 'Orientation' not recognized or not accessable
• Property "Orientation" not contained in XML-Namespace "clr-namespace:MyNameSpace". Row ... column ...
• No content can be added to object of type "AbstractForm" (ie the <Image and another <StackPanel )

Answer 1

A StackPanel is not derived from Control and has therefore no Template property. Hence the ResourceDictionary does not compile.

Remove the Setter from the default Style, then rebuild your project.

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:MyNameSpace">

    <Style TargetType="{x:Type local:AbstractForm}"
           BasedOn="{StaticResource {x:Type StackPanel}}">
    </Style>
</ResourceDictionary>

---

It is also questionable if you need a default Style for your AbstractForm class at all.

If not, just delete the entire Generic.xaml file and the static constructor that overrides the default value of the DefaultStyleKey property. In other words, simply create a class derived from StackPanel.