WPF GridHelper to easily define RowDefinitions and ColumnDefinitions

GridHelper.cs

using System.Windows;
using System.Windows.Controls;

public class GridHelper
{
    #region Rows & Columns

    public static string GetRows(DependencyObject obj)
    {
        return (string)obj.GetValue(RowsProperty);
    }

    public static void SetRows(DependencyObject obj, string value)
    {
        obj.SetValue(RowsProperty, value);
    }

    /// <summary>
    /// 自动为 Grid 控件添加 RowDefinitions
    /// </summary>
    /// <remarks>
    /// 支持的写法包括：<br/>
    /// - Star: 1*, *<br/>
    /// - Auto: auto, Auto<br/>
    /// - Pixel: 100, 10.5, 0
    /// </remarks>
    public static readonly DependencyProperty RowsProperty =
        DependencyProperty.RegisterAttached(
            "Rows",
            typeof(string),
            typeof(GridHelper),
            new FrameworkPropertyMetadata(
                "",
                FrameworkPropertyMetadataOptions.AffectsRender
                    | FrameworkPropertyMetadataOptions.AffectsMeasure
                    | FrameworkPropertyMetadataOptions.NotDataBindable,
                OnRowsChanged
            )
        );

    private static void OnRowsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is not Grid grid || e.NewValue is not string rows)
            throw new ArgumentException($"Invalid Rows property value: {e.NewValue}");

        grid.RowDefinitions.Clear();

        foreach (var row in rows.Split(',').Select(r => r.Trim()))
        {
            var gridLength = ParseGridLength(row);
            grid.RowDefinitions.Add(new RowDefinition { Height = gridLength });
        }
    }

    public static string GetColumns(DependencyObject obj)
    {
        return (string)obj.GetValue(ColumnsProperty);
    }

    public static void SetColumns(DependencyObject obj, string value)
    {
        obj.SetValue(ColumnsProperty, value);
    }

    /// <summary>
    /// 自动为 Grid 控件添加 ColumnDefinitions。详见 <seealso cref="RowsProperty"/>
    /// </summary>
    public static readonly DependencyProperty ColumnsProperty =
        DependencyProperty.RegisterAttached(
            "Columns",
            typeof(string),
            typeof(GridHelper),
            new FrameworkPropertyMetadata(
                "",
                FrameworkPropertyMetadataOptions.AffectsRender
                    | FrameworkPropertyMetadataOptions.AffectsMeasure
                    | FrameworkPropertyMetadataOptions.NotDataBindable,
                OnColumnsChanged
            )
        );

    private static void OnColumnsChanged(
        DependencyObject d,
        DependencyPropertyChangedEventArgs e
    )
    {
        if (d is not Grid grid || e.NewValue is not string rows)
            throw new ArgumentException($"Invalid Rows property value: {e.NewValue}");

        grid.ColumnDefinitions.Clear();

        foreach (var row in rows.Split(',').Select(r => r.Trim()))
        {
            var gridLength = ParseGridLength(row);
            grid.ColumnDefinitions.Add(new ColumnDefinition { Width = gridLength });
        }
    }

    private static GridLength ParseGridLength(string length)
    {
        // *, 1*, 2.5*
        if (length.EndsWith("*"))
        {
            double star = 1;
            if (length.Length > 1)
                star = double.Parse(length.Substring(0, length.Length - 1));
            return new GridLength(star, GridUnitType.Star);
        }
        // a, auto, A, Auto
        else if (length.Equals("auto", StringComparison.OrdinalIgnoreCase))
        {
            return GridLength.Auto;
        }
        // 100
        else if (double.TryParse(length, out var height))
        {
            return new GridLength(height);
        }

        throw new ArgumentException($"Invalid height value: {length}");
    }

    #endregion
}