Equation Calculator with Graphing

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Controls;
using System.Windows;
using System.Windows.Input;


namespace CommonUtils
{
	public class DockWrapPanel : Panel
	{
		class RowInfo
		{
			public double TotalWidth {get; set;}
			public double Height { get; set; }
			public FrameworkElement StretchItem {get; set;}
			public List<FrameworkElement> LeftItems { get; set; }
			public List<FrameworkElement> RightItems { get; set; }
			public void Add(FrameworkElement child)
			{
				if (DockPanel.GetDock(child) == Dock.Right)
					RightItems.Add(child);
				else
					LeftItems.Add(child);
				if (child.HorizontalAlignment == HorizontalAlignment.Stretch && double.IsNaN(child.Width))
					StretchItem = child;
				TotalWidth += child.DesiredSize.Width;
			}
			public int Count
			{
				get { return LeftItems.Count + RightItems.Count; }
			}
			public RowInfo()
			{
				LeftItems = new List<FrameworkElement>();
				RightItems = new List<FrameworkElement>();
				Height = 0;
				TotalWidth = 0;
			}
		}
		protected override Size MeasureOverride(System.Windows.Size availableSize)
		{
			double xOffset = 0;
			double rowHeight = 0;
			double totalHeight = 0;
			foreach (UIElement child in this.Children)
			{
				child.Measure(availableSize);
				// move to new row
				if (xOffset + child.DesiredSize.Width > availableSize.Width)
				{
					totalHeight += rowHeight;
					xOffset = 0;
					rowHeight = 0;
				}
				if (child.DesiredSize.Height > rowHeight)
					rowHeight = child.DesiredSize.Height;
				xOffset += child.DesiredSize.Width;
			}
			totalHeight += rowHeight;
			return new Size(availableSize.Width, totalHeight);
		}
		protected override Size ArrangeOverride(System.Windows.Size finalSize)
		{
			double x = 0;
			List<RowInfo> rows = new List<RowInfo>();
			RowInfo currow = new RowInfo();
			foreach (FrameworkElement child in this.Children)
			{
				if (currow.Count > 0 && x + child.DesiredSize.Width > finalSize.Width)
				{
					rows.Add(currow);
					currow = new RowInfo();
					x = 0;
				}
				if (child.DesiredSize.Height > currow.Height)
					currow.Height = child.DesiredSize.Height;
				currow.Add(child);
				x += child.DesiredSize.Width;
			}
			rows.Add(currow);
			double y = 0;
			foreach (RowInfo row in rows)
			{
				x = 0;
				foreach (FrameworkElement child in row.LeftItems)
				{
					Rect r = new Rect();
					r.X = x;
					r.Y = y;
					double childHeight = child.DesiredSize.Height;
					if (double.IsNaN(child.Height))
						childHeight = row.Height;
					if (child.VerticalAlignment == VerticalAlignment.Center)
						r.Y = y + row.Height/2 - childHeight/2;
					if (child.VerticalAlignment == VerticalAlignment.Bottom)
						r.Y = y + row.Height - childHeight;
					if (object.Equals(child, row.StretchItem))
						r.Width = child.DesiredSize.Width + (finalSize.Width - row.TotalWidth);
					else
						r.Width = child.DesiredSize.Width;
					r.Height = childHeight;
					child.Arrange(r);
					x = r.Right;
				}
				row.RightItems.Reverse();
				x = finalSize.Width;
				foreach (FrameworkElement child in row.RightItems)
				{
					Rect r = new Rect();
					r.X = x - child.DesiredSize.Width;
					if (r.X < 0)
						r.X = 0;
					r.Y = y;
					if (child.VerticalAlignment == VerticalAlignment.Center)
						r.Y = y + row.Height/2 - child.Height/2;
					if (child.VerticalAlignment == VerticalAlignment.Bottom)
						r.Y = y + row.Height - child.Height;
					if (object.Equals(child, row.StretchItem))
					{
						r.Width = child.DesiredSize.Width + (finalSize.Width - row.TotalWidth);
						r.X -= (finalSize.Width - row.TotalWidth);
					}
					else
						r.Width = child.DesiredSize.Width;
					r.Height = child.DesiredSize.Height;
					child.Arrange(r);
					x = r.Left;
				}
				y += row.Height;
			}

			finalSize.Height = y;
			return finalSize;
		}
	}
}