CSSNode.cs

using System;

namespace CSSLayoutApp
{
    public class CSSNode : IDisposable
    {
        private bool _isDisposed;
        private readonly IntPtr _cssNode;

        public CSSNode()
        {
            _cssNode = Native.CSSNodeNew();
            Native.CSSNodeInit(_cssNode);
        }

        public CSSNode(IntPtr cssNode)
        {
            _cssNode = cssNode;
        }

        private void CheckDisposed()
        {
            if (_isDisposed)
            {
                throw new ObjectDisposedException("CSSNode");
            }
        }

        public void Dispose()
        {
            if (!_isDisposed)
            {
                _isDisposed = true;
                Native.CSSNodeFree(_cssNode);
            }
        }

        public CSSNode this[int index]
        {
            get
            {
                CheckDisposed();
                var ptr = Native.CSSNodeGetChild(_cssNode, (uint)index);
                return new CSSNode(ptr);
            }
        }

        public int Count
        {
            get
            {
                CheckDisposed();
                return (int)Native.CSSNodeChildCount(_cssNode);
            }
        }
    }
}