ControlTemplate defines the visual elements tree that is applied as the control template for a control.
ContentPresenter it is a placeholder for any XAML content and it can be used to insert content at runtime.
Example: Create Ellipse Button
<Window x:Class="WPF_Tutorial.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1">
<Window.Resources>
<ControlTemplate TargetType="Button" x:Key="ctButton" >
<Grid>
<Ellipse Fill="{ TemplateBinding Background }" Height="{TemplateBinding Height }">
</Ellipse>
<ContentPresenter VerticalAlignment="Center" HorizontalAlignment="Center" Content="{TemplateBinding Button.Content}" />
</Grid>
</ControlTemplate>
</Window.Resources>
<Grid>
<Button Content="Ellipse Button" HorizontalAlignment="Left" VerticalAlignment="Top"
Background="BlueViolet"
Width="100" Height="100" Template="{ StaticResource ctButton}" Foreground="#FFF3E2E2">
</Button>
</Grid>
</Window>
