using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Controls;



namespace Microsoft.Research.DynamicDataDisplay.Charts

{

	/// <summary>

	/// Represents a kind of 'spring' that makes width of one plotter's LeftPanel equal to other plotter's LeftPanel.

	/// </summary>

	public class WidthSpring : FrameworkElement, IPlotterElement

	{

		/// <summary>

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

		/// </summary>

		public WidthSpring()

		{

		}



		#region Properties



		/// <summary>

		/// Gets or sets panel which is a source of width.

		/// </summary>

		/// <value>The source panel.</value>

		public Panel SourcePanel

		{

			get { return (Panel)GetValue(SourcePanelProperty); }

			set { SetValue(SourcePanelProperty, value); }

		}



		public static readonly DependencyProperty SourcePanelProperty = DependencyProperty.Register(

		  "SourcePanel",

		  typeof(Panel),

		  typeof(WidthSpring),

		  new FrameworkPropertyMetadata(null, OnSourcePanelReplaced));



		private static void OnSourcePanelReplaced(DependencyObject d, DependencyPropertyChangedEventArgs e)

		{

			WidthSpring owner = (WidthSpring)d;

			owner.OnSourcePanelReplaced((Panel)e.OldValue, (Panel)e.NewValue);

		}



		private void OnSourcePanelReplaced(Panel prevPanel, Panel currPanel)

		{

			if (prevPanel != null)

			{

				prevPanel.SizeChanged -= OnPanel_SizeChanged;

			}

			if (currPanel != null)

			{

				currPanel.SizeChanged += OnPanel_SizeChanged;

			}

			UpdateWidth();

		}



		void OnPanel_SizeChanged(object sender, SizeChangedEventArgs e)

		{

			UpdateWidth();

		}



		private void UpdateWidth()

		{

			Panel parentPanel = Parent as Panel;

			if (parentPanel != null && SourcePanel != null)

			{

				Width = Math.Max(SourcePanel.ActualWidth - (parentPanel.ActualWidth - ActualWidth), 0);

			}

		}



		#endregion // end of Properties



		#region IPlotterElement Members



		private Plotter plotter;

		public void OnPlotterAttached(Plotter plotter)

		{

			this.plotter = plotter;

			plotter.LeftPanel.Children.Insert(0, this);

		}



		public void OnPlotterDetaching(Plotter plotter)

		{

			plotter.LeftPanel.Children.Remove(this);

			this.plotter = null;

		}



		public Plotter Plotter

		{

			get { return plotter; }

		}



		#endregion

	}

}