RowSpan and ColumnSpan in Xamarin.Forms

Question

Is there anyone out there who can explain to me how RowSpan and ColumnSpan work in Xamarin.Forms?
The parameters right, left, top, and bottom are a little bit confusing.

Let's use this code snippet for RowSpan:

grid.Children.Add(new Label
{
   Text = "Span two rows (or more if you want)",
   TextColor = Color.Yellow,
   BackgroundColor = Color.Navy,
   XAlign = TextAlignment.Center,
   YAlign = TextAlignment.Center
}, 2, 3, 1, 3);

What do the numbers 2, 3, 1, 3 mean in terms of columns and rows here?
This is for a grid with four rows and three columns.

Answer 1

This answer is copied and pasted from this answer at Xamarin's forums (archived) by Till Balandat, but is useful here since Xamarin's documentation doesn't seem to explain the additional parameters to the Add method.

The overload for Add that takes 4 parameters is a little confusing, but in the end lets you define Row, RowSpan, Column and Columnspan: So the above example

var label = new Label { Text = "Row 1" };
myGrid.Children.Add(label,0,0);
Grid.SetColumnSpan(label,2);

translates to:

var label = new Label { Text = "Row 1" };
myGrid.Children.Add(label, 0, 2, 0, 1);

This is what Xamarin does internally:

public void Add(View view, int left, int right, int top, int bottom)
{
    //..exceptionhandling removed
    Grid.SetRow((BindableObject) view, top);
    Grid.SetRowSpan((BindableObject) view, bottom - top);
    Grid.SetColumn((BindableObject) view, left);
    Grid.SetColumnSpan((BindableObject) view, right - left);
    this.Add(view);
}

So you might be more comfortable with something like this:

public static class GridExtension
{
    public static void AddChild(this Grid grid, View view, int row, int column, int rowspan = 1, int columnspan = 1)
    {
        if (row < 0)
            throw new ArgumentOutOfRangeException("row");
        if (column < 0)
            throw new ArgumentOutOfRangeException("column");
        if (rowspan <= 0)
            throw new ArgumentOutOfRangeException("rowspan");
        if (columnspan <= 0)
            throw new ArgumentOutOfRangeException("columnspan");
        if (view == null)
          throw new ArgumentNullException("view");
        Grid.SetRow((BindableObject)view, row);
        Grid.SetRowSpan((BindableObject) view, rowspan);
        Grid.SetColumn((BindableObject) view, column);
        Grid.SetColumnSpan((BindableObject) view, columnspan);
        grid.Children.Add(view);      
    }
}