using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Media;

using System.Collections.Specialized;

using System.Collections;

using System.ComponentModel;

using System.Windows.Controls;



namespace Microsoft.Research.DynamicDataDisplay.Common

{

	/// <summary>

	/// Represents a custom Panel, which performs Arrange of its children independently, and does not remeasure or rearrange itself or all children when one child is

	/// added or removed.

	/// Is intended to be a base class for special layout panels, in which each childr is arranged independently from each other child,

	/// e.g. panel with child's position viewport bound to a rectangle in viewport coordinates.

	/// </summary>

	public abstract class IndividualArrangePanel : Panel

	{

		private bool inBatchAdd = false;



		/// <summary>

		/// Initializes a new instance of the <see cref="IndependentArrangePanel"/> class.

		/// </summary>

		protected IndividualArrangePanel() { }



		private UIChildrenCollection children;

		/// <summary>

		/// Creates a new <see cref="T:System.Windows.Controls.UIElementCollection"/>.

		/// </summary>

		/// <param name="logicalParent">The logical parent element of the collection to be created.</param>

		/// <returns>

		/// An ordered collection of elements that have the specified logical parent.

		/// </returns>

		protected sealed override UIElementCollection CreateUIElementCollection(FrameworkElement logicalParent)

		{

			children = new UIChildrenCollection(this, logicalParent);

			children.IsAddingMany = inBatchAdd;

			return children;

		}



		public bool InBatchAdd

		{

			get { return children.IsAddingMany; }

		}



		public virtual void BeginBatchAdd()

		{

			if (children == null)

			{

				inBatchAdd = true;

				return;

			}



			children.IsAddingMany = true;

		}



		public virtual void EndBatchAdd()

		{

			children.IsAddingMany = false;

		}



		/// <summary>

		/// Called when child is added.

		/// </summary>

		/// <param name="child">The added child.</param>

		protected internal virtual void OnChildAdded(FrameworkElement child) { }



		#region Overrides



		/// <summary>

		/// Overrides <see cref="M:System.Windows.Media.Visual.GetVisualChild(System.Int32)"/>, and returns a child at the specified index from a collection of child elements.

		/// </summary>

		/// <param name="index">The zero-based index of the requested child element in the collection.</param>

		/// <returns>

		/// The requested child element. This should not return null; if the provided index is out of range, an exception is thrown.

		/// </returns>

		protected sealed override Visual GetVisualChild(int index)

		{

			return Children[index];

		}



		/// <summary>

		/// Gets the number of visual child elements within this element.

		/// </summary>

		/// <value></value>

		/// <returns>

		/// The number of visual child elements for this element.

		/// </returns>

		protected sealed override int VisualChildrenCount

		{

			get { return Children.Count; }

		}



		/// <summary>

		/// Gets an enumerator for logical child elements of this element.

		/// </summary>

		/// <value></value>

		/// <returns>

		/// An enumerator for logical child elements of this element.

		/// </returns>

		protected sealed override IEnumerator LogicalChildren

		{

			get

			{

				return Children.GetEnumerator();

			}

		}



		#endregion

	}

}