ITreeSelector.cs

namespace BreadcrumbTestLib.ViewModels.Interfaces
{
    using System.ComponentModel;

    /// <summary>
    /// Implement Tree based structure and support LookupProcessing.
    /// </summary>
    /// <typeparam name="VM">Sub-node viewmodel type.</typeparam>
    /// <typeparam name="M">Type to identify a node, commonly string.</typeparam>
    public interface ITreeSelector<VM, M> : INotifyPropertyChanged
    {
        #region properties
        /// <summary>
        /// Whether current view model is selected.
        /// </summary>
        bool IsSelected { get; set; }

        /// <summary>
        /// This is marked by TreeRootSelector, for overflow menu support.
        /// </summary>
        bool IsRoot { get; set; }

        /// <summary>
        /// Based on IsRoot and IsChildSelected
        /// </summary>
        bool IsRootAndIsChildSelected { get; }

        /// <summary>
        /// Gets whether a child of current view model is selected.
        /// </summary>
        bool IsChildSelected { get; }

        /// <summary>
        /// Gets the model of the selected child item.
        /// </summary>
        M SelectedChild { get; set; }

        /// <summary>
        /// Gets the instance of the model object that represents this selection helper.
        /// The model backs the ViewModel property and should be in sync
        /// with it.
        /// </summary>
        M Value { get; }

        /// <summary>
        /// Gets the owning ViewModel of this selection helper.
        /// </summary>
        VM ViewModel { get; }

        /// <summary>
        /// Gets All sub-entries of the current tree item
        /// to support loading tree items.
        /// </summary>
        IBreadcrumbTreeItemHelperViewModel<VM> EntryHelper { get; }

        /// <summary>
        /// Gets whether this entry is currently overflowed (should be hidden
        /// because its to large for display) or a root element, or both.
        /// 
        /// This can be used by binding system to determine whether an element should
        /// be visble in the root drop down list, because overflowed or root
        /// items should be visible in the root drop down list for
        /// overflowed and root items.
        /// </summary>
        bool IsOverflowedOrRoot { get; }

        /// <summary>
        /// Gets/sets whether the BreadCrumb Tree item is currently overflowed
        /// (does not fit into the view display area) or not.
        /// </summary>
        bool IsOverflowed { get; }
        #endregion properties

        #region methods
        #endregion methods
    }
}