Create a control in Resources and reuse it in XAML WPF

Question

I just try to create a simple Symbol/Geometry/Control and change and reuse it in several places in the same window.

Example: a black square with a circle in the midd

Answer 1

When you define a arbitrary Control in Resources, you can use it in the future in Control which have property Content and derived from Control class. These are the followings: ContentControl, Label, ContentPresenter, etc.

Also you must set x:Shared="False" for resource if you want to use this resource in many Controls, because x:Shared="True" by default then one Resource is common to all - in this case, the system swears on the duplicate Content. When x:Shared="False" when is created Resource for each element whenever it its request. Quote from MSDN:

When set to false, modifies WPF resource-retrieval behavior so that requests for the attributed resource create a new instance for each request instead of sharing the same instance for all requests.

Example:

<Window.Resources>
    <Canvas x:Key="Ampel" x:Shared="False">
        <Rectangle Fill="Black" HorizontalAlignment="Left" Height="52" Stroke="Black" VerticalAlignment="Top" Width="50"/>
        <Ellipse x:Name="RedGreen" Fill="Red" HorizontalAlignment="Left" Height="27" Margin="11,12,0,0" Stroke="Black" VerticalAlignment="Top" Width="28" />
    </Canvas>
</Window.Resources>

<Grid>
    <ContentControl Name="MyContentControl" Content="{StaticResource Ampel}" HorizontalAlignment="Left" />        
    <Label Name="MyLabel" Content="{StaticResource Ampel}" HorizontalAlignment="Center" />
    <ContentPresenter Name="MyContentPresenter" Content="{StaticResource Ampel}" HorizontalAlignment="Center" VerticalAlignment="Center" />
</Grid>

To change the Fill of Ellipse in code-behind, you can like this:

private void ChangeBackground_Click(object sender, RoutedEventArgs e)
{
    var canvas = MyContentControl.Content as Canvas;

    if (canvas != null)
    {
        foreach (var item in canvas.Children)
        {
            if (item is Ellipse)
            {
                ((Ellipse)item).Fill = Brushes.Green;
            }
        }
    }
}

Answer 2

You can use C# code by heritage:

public class customBottum : Buttom
{
        int var1;
        bool var2;

        public customBottum()
        {
            InitializeComponent();
        }

        other function ...
}

Answer 3

canvas is not having template property thats why we are using contencontrol here.

<Window.Resources>
    <ControlTemplate x:Key="Ampel" TargetType="ContentControl">
        <Canvas>
            <Rectangle Fill="Black" HorizontalAlignment="Left" Height="52" Stroke="Black" VerticalAlignment="Top" Width="50"/>
            <Ellipse x:Name="RedGreen" Fill="{Binding Path=Tag, RelativeSource={RelativeSource TemplatedParent}}" HorizontalAlignment="Left" Height="27" Margin="11,12,0,0" Stroke="Black" VerticalAlignment="Top" Width="28" RenderTransformOrigin="0.214,0.256"/>
        </Canvas>
    </ControlTemplate>
</Window.Resources >

<ContentControl  Template="{StaticResource Ampel}" Tag="Red" ></ContentControl>
<ContentControl  Template="{StaticResource Ampel}" Tag="Green" ></ContentControl>
<ContentControl  Template="{StaticResource Ampel}" Tag="Blue" ></ContentControl>

Output