how can I do this with C# code?

Do you want to be able to define the control template in C# or just assign it in C#? If its the latter you can just define that control template in your xaml resources (maybe in App.xaml?). And then assign it using something like xamChart1.Template = Resources["chartTemplate"]; where chartTemplate is the key you assigned to the resource.

If you want to create the entire template in code, then you should either:

1) Use that xaml as a string in your application and use XamlReader to hydrate it. Then assign it to the template property of the chart.

2) Create the template programmatically using FrameworkElementFactory, then assign it.

The second option there is more complex. A control template must create its content many times, and each time the content must be a distinct instance, thus it is defined as a factory that produces a new instance of the content on demand. When you define one in xaml, the transformation from an "instance" of what you want to create to a factory that produces an instance of the described is done automatically, so things are a bit more complicated if you want to do it by hand. What is the reason you want to define this in C#?

-Graham

This should obviously be a native feature of the XamChart

Why aren't such labels provided in the xamchart?  A caption is provided, why not these labels?

thanks, now it really looks nice.

When you set the chart's template the theme change is not allowed to override the chart's template, so some details of the neon theme at the level of the chart are lost. You can adjust for this by reconciling the template you are specifying with the neon theme's template. Here's the modified version:

<Window.Resources>
        <SolidColorBrush x:Key="CaptionForegroundBrush" Color="#FFFFFFFF"/>
        <Style x:Key="captionStyle" TargetType="TextBlock">
            <Setter Property="Foreground" Value="{StaticResource CaptionForegroundBrush}"/>
            <Setter Property="FontFamily" Value="/xamFeatureBrowserResources;Component/fonts/#Avenir"/>
            <Setter Property="FontSize" Value="16"/>
            <Setter Property="FontWeight" Value="Bold" />
        </Style>
        <ControlTemplate x:Key="chartTemplate" TargetType="igChart:XamChart">
            <Border 
                Background="{TemplateBinding Background}" 
                BorderBrush="{TemplateBinding BorderBrush}" 
                BorderThickness="{TemplateBinding BorderThickness}" 
                CornerRadius="0,0,0,0">
            <Grid >
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto" />
                    <ColumnDefinition />
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition />
                    <RowDefinition Height="Auto" />
                </Grid.RowDefinitions>
                <ContentPresenter Name="PART_Default_Chart" 
                                  Grid.Row="0" Grid.Column="1" />
                <TextBlock Grid.Row="0" Grid.RowSpan="2" 
                           Grid.Column="0" TextAlignment="Center"
                           Style="{StaticResource captionStyle}"
                           Text="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(local:AxisInfo.YAxisTitle)}">
                    <TextBlock.LayoutTransform>
                        <RotateTransform Angle="90" />
                    </TextBlock.LayoutTransform>
                </TextBlock>
                <TextBlock Grid.Row="1" Grid.ColumnSpan="2" 
                           Style="{StaticResource captionStyle}"
                           Text="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(local:AxisInfo.XAxisTitle)}"
                           TextAlignment="Center" />
            </Grid>
            </Border>
        </ControlTemplate>
    </Window.Resources>

Hope this helps!

-Graham