Center label around anchor point in RelativeLayout with Xamarin - xamarin.forms

Question

I have a RelativeLayout, and multiple polygons/labels in it. Now I want to place the labels inside the polygons, in the center of it. However, I don't know the width and height of the label, so placing them in the center results in something like this:
However, this is wrong, as I want the label to be in the exact middle of the polygon (of which the width and height is known), no matter what the text is.
I've looked into methods to try to center it, for example using HorizontalTextAlignment and VerticalTextAlignment, but so far no success. What is the right way to do that? HorizontalOptions doesn't work either, as it's not relative to a parent or something.
Code I'm currently using:
var MainGrid = new RelativeLayout();
var path = new PointCollection();
// add points to path
var coords = new Point(100, 100);
var TILE_WIDTH = 70;
var TILE_HEIGHT = 80;
// Here the real code begins
polygon = new Polygon
{
Points = path,
<other arguments>
};
var text = new Label
{
Text = "5",
HorizontalTextAlignment = TextAlignment.Center,
VerticalTextAlignment = TextAlignment.Center,
TextColor = Color.Black,
};
MainGrid.Children.Add(
polygon,
Constraint.Constant(coords.X),
Constraint.Constant(coords.Y)
);
MainGrid.Children.Add(
text,
Constraint.Constant(coords.X + TILE_WIDTH / 2),
Constraint.Constant(coords.Y + TILE_HEIGHT / 2)
);

Answer 1

set an arbitrary width and height on the label, as long as it is big enough to fit your text and smaller than the polygon. Also set a background color to help visualize the placement of the label (remove this once you get the alignment right)
var text = new Label
{
Text = "5",
HorizontalTextAlignment = TextAlignment.Center,
VerticalTextAlignment = TextAlignment.Center,
TextColor = Color.Black,
BackgroundColor = Color.White,
HeightRequest = 50,
WidthRequest = 50
};
then factor in the label width and height when placing it
MainGrid.Children.Add(
text,
Constraint.Constant(coords.X + (TILE_WIDTH / 2) - 25),
Constraint.Constant(coords.Y + (TILE_HEIGHT / 2) - 25)
);