Item-Level Presentation Models for WPF

using System;
using System.IO;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Markup;
using System.Windows.Media;
using System.Xml;

namespace HappyNomad {
	public static class WPFUtil {

		#region 'FindAncestor' Methods

		/// <summary>
		/// Finds the nearest ancestor of the given item, that has the given type.
		/// </summary>
		/// <typeparam name="T">The type of the desired result</typeparam>
		/// <param name="startNode">A descendant of the desired result,
		/// from where to begin the search</param>
		/// <returns>The first ancestor of type T encountered, or null if no match found</returns>
		public static T FindAncestor<T>( DependencyObject startNode ) where T : DependencyObject {
			if ( startNode == null ) return null; //we�ve reached the root of the tree
			T startNodeAsT = startNode as T;

			if ( startNodeAsT != null )
				return startNodeAsT; //return current level if of target type
			else
				return FindAncestor<T>( GetParent(startNode) ); //recurse to the next level
		}

		/// <summary>
		/// GetParent method that traverses through the visual tree, as well as content elements.
		/// [Source: http://code.logos.com/blog/2008/02/finding_ancestor_elements_in_w.html ]
		/// </summary>
		public static DependencyObject GetParent( DependencyObject obj ) {
			if ( obj == null )
				return null;

			ContentElement ce = obj as ContentElement;
			if ( ce != null ) {
				DependencyObject parent = ContentOperations.GetParent( ce );
				if ( parent != null )
					return parent;

				FrameworkContentElement fce = ce as FrameworkContentElement;
				return fce != null ? fce.Parent : null;
			}

			return VisualTreeHelper.GetParent( obj );
		}

		#endregion

		#region 'FindDescendant' Methods

		/// <summary>
		/// Finds the nearest visual descendant of the given item, that satisfies the given condition.
		/// [Source: http://blogs.msdn.com/wpfsdk/archive/2007/04/16/how-do-i-programmatically-interact-with-template-generated-elements-part-ii.aspx ]
		/// </summary>
		/// <param name="ancestor">An ancestor of the desired result, from where to begin the search</param>
		/// <param name="testNode">The condition which the result must satisfy</param>
		/// <returns>The first descendant that satisfies the given condition.
		/// If no matching item can be found, a null reference is returned.</returns>
		public static object FindDescendant( DependencyObject ancestor, Predicate<DependencyObject> testNode ) {
			for ( int i = 0; i < VisualTreeHelper.GetChildrenCount( ancestor ); i++ ) {
				DependencyObject child = VisualTreeHelper.GetChild( ancestor, i );
				if ( child != null && testNode(child) ) //child is T )
					return child;
				else {
					object childOfChild = FindDescendant( child, testNode );
					if ( childOfChild != null )
						return childOfChild;
				}
			}
			return null;
		}

		public static OfType FindDescendant<OfType>( DependencyObject ancestor )
		  where OfType : DependencyObject {
			Predicate<DependencyObject> testNode = delegate( DependencyObject nodeToTest ) {
				return nodeToTest is OfType;
			};
			return (OfType)FindDescendant( ancestor, testNode );
		}

		public static OfType FindDescendant<OfType>( DependencyObject ancestor, string withName )
		  where OfType : FrameworkElement {
			Predicate<DependencyObject> testNode = delegate( DependencyObject nodeToTest ) {
				OfType n = nodeToTest as OfType;
				return n == null ? false : n.Name == withName;
			};
			return (OfType)FindDescendant( ancestor, testNode );
		}

		#endregion
	}

}