Avalonia/src/Avalonia.Controls/RowDefinitions.cs

// Copyright (c) The Avalonia Project. All rights reserved.
// Licensed under the MIT license. See licence.md file in the project root for full license information.

using System.Collections.Specialized;
using System.Linq;
using Avalonia.Collections;

namespace Avalonia.Controls
{
    /// <summary>
    /// A collection of <see cref="RowDefinition"/>s.
    /// </summary>
    public class RowDefinitions : AvaloniaList<RowDefinition>
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="RowDefinitions"/> class.
        /// </summary>
        public RowDefinitions()
        {
            ResetBehavior = ResetBehavior.Remove;
            CollectionChanged += OnCollectionChanged;
            this.TrackItemPropertyChanged(delegate { IsDirty = true; });
        }

        internal bool IsDirty { get; set; } = true;
        internal Grid Parent { get; set; }

        private void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            foreach (var nI in this.Select((d, i) => (d, i)))
                nI.d._parentIndex = nI.i;

            foreach (var nD in e.NewItems?.Cast<DefinitionBase>()
                            ?? Enumerable.Empty<DefinitionBase>())
            {
                nD.Parent = this.Parent;
                nD.OnEnterParentTree();
            }

            foreach (var oD in e.OldItems?.Cast<DefinitionBase>()
                            ?? Enumerable.Empty<DefinitionBase>())
            {
                oD.Parent = null;
                oD.OnExitParentTree();
            }

            IsDirty = true;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="RowDefinitions"/> class.
        /// </summary>
        /// <param name="s">A string representation of the row definitions.</param>
        public RowDefinitions(string s)
            : this()
        {
            AddRange(GridLength.ParseLengths(s).Select(x => new RowDefinition(x)));
        }

        /// <summary>
        /// Parses a string representation of row definitions collection.
        /// </summary>
        /// <param name="s">The row definitions string.</param>
        /// <returns>The <see cref="RowDefinitions"/>.</returns>
        public static RowDefinitions Parse(string s) => new RowDefinitions(s);
    }
}