WPF / Xaml, vertical aligment of LineGeomtry inside grid not working properly - wpf

Question

I try to get into creation of custom controls with for WPF. I found many good
tutorials and advises on the web so I started width a really simple example to get
my hands dirty and get some practice. I figured out that the issue stumbled across
is not really related to the subject of custom controls. So I extracted the xaml code to a simple wpf form.
<Window x:Class="WpfVerticalAigmentTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="200" Width="200">
<Grid>
<Grid Height="40" Background="LightCyan" VerticalAlignment="Center">
<Path Stroke="Red"
StrokeThickness="20" VerticalAlignment="Center" >
<Path.Data>
<LineGeometry StartPoint="0,0" EndPoint="100,0"></LineGeometry>
</Path.Data>
</Path>
</Grid>
</Grid>
My expectation was to get a line centered in the grid and claiming the half of the stroke thickness on each side from the center. But as the linked image shows differs from my expectation.
"Resulting visualization"
So it look like I missed a detail about the line shape or linegeomtry. How do I get the the line displayed as shown in the following image?
"Expected result"

Answer 1

You need to match the Width and Height of the LineGeometry to the Width and Height of the Path and set the VerticalAlignment property to Bottom:
<Grid Height="20" Width="200" Background="LightCyan" VerticalAlignment="Center">
<Path Stroke="Red" StrokeThickness="20" VerticalAlignment="Bottom">
<Path.Data>
<LineGeometry StartPoint="0,0" EndPoint="200,0"></LineGeometry>
</Path.Data>
</Path>
</Grid>

Answer 2

If your goal is your the expectaions, and not the way how u have reached this, I could prefer to you this:
<Grid>
<Grid Height="40" Background="LightCyan" VerticalAlignment="Center">
<Border BorderThickness="10" VerticalAlignment="Center" BorderBrush="Red" />
</Grid>
</Grid>

Answer 3

The problem here is that the starting point of the XY Coordinates of the Path starts on the top left, and the stroke expands in both directions but thereby only makes the Path bigger to the bottom (I can't really tell you why, but that's just what seems to happen).
You can see this pretty good in the Design View:
To work around this simply move your Y Coordinates down half of the stroke size.
<Grid Height="40"
VerticalAlignment="Center"
Background="LightCyan">
<Path VerticalAlignment="Center"
Stroke="Red"
StrokeThickness="20">
<Path.Data>
<LineGeometry StartPoint="0,10" EndPoint="100,10" />
</Path.Data>
</Path>
</Grid>
Or wrap it in another control (Canvas is the commonly used controls for Paths) with the desired height:
<Grid Height="40"
VerticalAlignment="Center"
Background="LightCyan">
<Canvas Height="20" VerticalAlignment="Center">
<Path Stroke="Red"
StrokeThickness="20">
<Path.Data>
<LineGeometry StartPoint="0,10" EndPoint="100,10" />
</Path.Data>
</Path>
</Canvas>
</Grid>
And you are good to go: