/*
 * NPlot - A charting library for .NET
 * 
 * Windows.PlotSurface2d.cs
 * Copyright (C) 2003-2006 Matt Howlett and others.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. Neither the name of NPlot nor the names of its contributors may
 *    be used to endorse or promote products derived from this software without
 *    specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using System;
using System.Collections;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Printing;
using System.Text;
using System.Windows.Forms;

namespace NPlot.Windows
{
    /// <summary>
    /// A Windows.Forms PlotSurface2D control.
    /// </summary>
    /// <remarks>
    /// Unfortunately it's not possible to derive from both Control and NPlot.PlotSurface2D.
    /// </remarks>
    [ToolboxBitmap(typeof (PlotSurface2D), "PlotSurface2D.ico")]
    public class PlotSurface2D : Control, IPlotSurface2D, ISurface
    {
        /// <summary>
        /// This is the signature of the function used for InteractionOccurred events.
        /// TODO: expand this to include information about the event.
        /// </summary>
        /// <param name="sender"></param>
        public delegate void InteractionHandler(object sender);

        /// <summary>
        /// This is the signature of the function used for PreRefresh events.
        /// </summary>
        /// <param name="sender"></param>
        public delegate void PreRefreshHandler(object sender);

        private readonly ArrayList interactions_ = new ArrayList();
        private readonly NPlot.PlotSurface2D ps_;
        private IContainer components;

        private ToolTip coordinates_;
        private KeyEventArgs lastKeyEventArgs_;
        private PlotContextMenu rightMenu_;

        //private ArrayList selectedObjects_;

        private Axis xAxis1ZoomCache_;
        private Axis xAxis2ZoomCache_;
        private Axis yAxis1ZoomCache_;
        private Axis yAxis2ZoomCache_;

        /// <summary>
        /// Default constructor.
        /// </summary>
        public PlotSurface2D()
        {
            // This call is required by the Windows.Forms Form Designer.
            InitializeComponent();

            // double buffer, and update when resize.
            base.SetStyle(ControlStyles.AllPaintingInWmPaint, true);
            base.SetStyle(ControlStyles.DoubleBuffer, true);
            base.SetStyle(ControlStyles.UserPaint, true);
            base.ResizeRedraw = true;

            ps_ = new NPlot.PlotSurface2D();

            InteractionOccured += OnInteractionOccured;
            PreRefresh += OnPreRefresh;
        }

        /// <summary>
        /// Flag to display a coordinates in a tooltip.
        /// </summary>
        [
            Category("PlotSurface2D"),
            Description("Whether or not to show coordinates in a tool tip when the mouse hovers above the plot area."),
            Browsable(true),
            Bindable(true)
        ]
        public bool ShowCoordinates
        {
            get { return coordinates_.Active; }
            set { coordinates_.Active = value; }
        }

        /// <summary>
        /// The physical XAxis1 that was last drawn.
        /// </summary>
        [
            Browsable(false)
        ]
        public PhysicalAxis PhysicalXAxis1Cache
        {
            get { return ps_.PhysicalXAxis1Cache; }
        }

        /// <summary>
        /// The physical YAxis1 that was last drawn.
        /// </summary>
        [
            Browsable(false)
        ]
        public PhysicalAxis PhysicalYAxis1Cache
        {
            get { return ps_.PhysicalYAxis1Cache; }
        }

        /// <summary>
        /// The physical XAxis2 that was last drawn.
        /// </summary>
        [
            Browsable(false)
        ]
        public PhysicalAxis PhysicalXAxis2Cache
        {
            get { return ps_.PhysicalXAxis2Cache; }
        }

        /// <summary>
        /// The physical YAxis2 that was last drawn.
        /// </summary>
        [
            Browsable(false)
        ]
        public PhysicalAxis PhysicalYAxis2Cache
        {
            get { return ps_.PhysicalYAxis2Cache; }
        }

        /// <summary>
        /// When true, tool tip will display x value as a DateTime. Quick hack - this will probably be
        /// changed at some point.
        /// </summary>
        [Bindable(true), Browsable(true), Category("PlotSurface2D"),
         Description("When true, tool tip will display x value as a DateTime. Quick hack - this will probably be changed at some point.")]
        public bool DateTimeToolTip { get; set; }

        /// <summary>
        /// Sets the right context menu. Custom menus can be designed by overriding
        /// NPlot.Windows.PlotSurface2D.ContextMenu.
        /// </summary>
        [
            Browsable(false),
            Bindable(false)
        ]
        public PlotContextMenu RightMenu
        {
            get { return rightMenu_; }
            set
            {
                rightMenu_ = value;
                if (rightMenu_ != null)
                {
                    rightMenu_.PlotSurface2D = this;
                }
            }
        }

        /// <summary>
        /// Gets an instance of a NPlot.Windows.PlotSurface2D.ContextMenu that
        /// is useful in typical situations.
        /// </summary>
        public static PlotContextMenu DefaultContextMenu
        {
            get { return new PlotContextMenu(); }
        }

        /// <summary>
        /// Allows access to the PlotSurface2D.
        /// </summary>
        [
            Browsable(false),
            Bindable(false)
        ]
        public NPlot.PlotSurface2D Inner
        {
            get { return ps_; }
        }

        /// <summary>
        /// Clears the plot and resets to default values.
        /// </summary>
        public void Clear()
        {
            xAxis1ZoomCache_ = null;
            yAxis1ZoomCache_ = null;
            xAxis2ZoomCache_ = null;
            yAxis2ZoomCache_ = null;
            ps_.Clear();
            interactions_.Clear();
        }

        /// <summary>
        /// Adds a drawable object to the plot surface. If the object is an IPlot,
        /// the PlotSurface2D axes will also be updated.
        /// </summary>
        /// <param name="p">The IDrawable object to add to the plot surface.</param>
        public void Add(IDrawable p)
        {
            ps_.Add(p);
        }

        /// <summary>
        /// Adds a drawable object to the plot surface against the specified axes. If
        /// the object is an IPlot, the PlotSurface2D axes will also be updated.
        /// </summary>
        /// <param name="p">the IDrawable object to add to the plot surface</param>
        /// <param name="xp">the x-axis to add the plot against.</param>
        /// <param name="yp">the y-axis to add the plot against.</param>
        public void Add(IDrawable p, NPlot.PlotSurface2D.XAxisPosition xp, NPlot.PlotSurface2D.YAxisPosition yp)
        {
            ps_.Add(p, xp, yp);
        }

        /// <summary>
        /// Adds a drawable object to the plot surface. If the object is an IPlot,
        /// the PlotSurface2D axes will also be updated.
        /// </summary>
        /// <param name="p">The IDrawable object to add to the plot surface.</param>
        /// <param name="zOrder">The z-ordering when drawing (objects with lower numbers are drawn first)</param>
        public void Add(IDrawable p, int zOrder)
        {
            ps_.Add(p, zOrder);
        }

        /// <summary>
        /// Adds a drawable object to the plot surface against the specified axes. If
        /// the object is an IPlot, the PlotSurface2D axes will also be updated.
        /// </summary>
        /// <param name="p">the IDrawable object to add to the plot surface</param>
        /// <param name="xp">the x-axis to add the plot against.</param>
        /// <param name="yp">the y-axis to add the plot against.</param>
        /// <param name="zOrder">The z-ordering when drawing (objects with lower numbers are drawn first)</param>
        public void Add(IDrawable p, NPlot.PlotSurface2D.XAxisPosition xp,
                        NPlot.PlotSurface2D.YAxisPosition yp, int zOrder)
        {
            ps_.Add(p, xp, yp, zOrder);
        }

        /// <summary>
        /// Gets or Sets the legend to use with this plot surface.
        /// </summary>
        [
            Browsable(false),
            Bindable(false)
        ]
        public Legend Legend
        {
            get { return ps_.Legend; }
            set { ps_.Legend = value; }
        }

        /// <summary>
        /// Gets or Sets the legend z-order.
        /// </summary>
        [
            Browsable(true),
            Bindable(true),
            Category("PlotSurface2D"),
            Description("Determines the order with respect to other IDrawables on the plot surface in which the legend is drawn. " +
                        "The higher this value, the higher the position in the draw order.")
        ]
        public int LegendZOrder
        {
            get { return ps_.LegendZOrder; }
            set { ps_.LegendZOrder = value; }
        }

        /// <summary>
        /// Whether or not the title will be scaled according to size of the plot
        /// surface.
        /// </summary>
        [
            Browsable(true),
            Bindable(true),
            Description("Whether or not the title will be scaled according to size of the plot surface."),
            Category("PlotSurface2D")
        ]
        public bool AutoScaleTitle
        {
            get { return ps_.AutoScaleTitle; }
            set { ps_.AutoScaleTitle = value; }
        }

        /// <summary>
        /// When plots are added to the plot surface, the axes they are attached to
        /// are immediately modified to reflect data of the plot. If
        /// AutoScaleAutoGeneratedAxes is true when a plot is added, the axes will
        /// be turned in to auto scaling ones if they are not already [tick marks,
        /// tick text and label size scaled to size of plot surface]. If false,
        /// axes will not be autoscaling.
        /// </summary>
        [
            Browsable(true),
            Bindable(true),
            Description("When plots are added to the plot surface, the axes they are attached to are immediately modified " +
                        "to reflect data of the plot. If AutoScaleAutoGeneratedAxes is true when a plot is added, the axes will be " +
                        "turned in to auto scaling ones if they are not already [tick marks, tick text and label size scaled to size " +
                        "of plot surface]. If false, axes will not be autoscaling."),
            Category("PlotSurface2D")
        ]
        public bool AutoScaleAutoGeneratedAxes
        {
            get { return ps_.AutoScaleAutoGeneratedAxes; }
            set { ps_.AutoScaleAutoGeneratedAxes = value; }
        }

        /// <summary>
        /// The plot surface title.
        /// </summary>
        [
            Category("PlotSurface2D"),
            Description("The plot surface title"),
            Browsable(true),
            Bindable(true)
        ]
        public string Title
        {
            get { return ps_.Title; }
            set
            {
                ps_.Title = value;
                //helpful in design view. But crap in applications!
                //this.Refresh();
            }
        }

        /// <summary>
        /// The font used to draw the title.
        /// </summary>
        [
            Category("PlotSurface2D"),
            Description("The font used to draw the title."),
            Browsable(true),
            Bindable(false)
        ]
        public Font TitleFont
        {
            get { return ps_.TitleFont; }
            set { ps_.TitleFont = value; }
        }

        /// <summary>
        /// Padding of this width will be left between what is drawn and the control border.
        /// </summary>
        [
            Category("PlotSurface2D"),
            Description("Padding of this width will be left between what is drawn and the control border."),
            Browsable(true),
            Bindable(true)
        ]
        public new int Padding
        {
            get { return ps_.Padding; }
            set { ps_.Padding = value; }
        }

        /// <summary>
        /// The first abscissa axis.
        /// </summary>
        [
            Browsable(false)
        ]
        public Axis XAxis1
        {
            get { return ps_.XAxis1; }
            set { ps_.XAxis1 = value; }
        }

        /// <summary>
        /// The first ordinate axis.
        /// </summary>
        [
            Browsable(false)
        ]
        public Axis YAxis1
        {
            get { return ps_.YAxis1; }
            set { ps_.YAxis1 = value; }
        }

        /// <summary>
        /// The second abscissa axis.
        /// </summary>
        [
            Browsable(false)
        ]
        public Axis XAxis2
        {
            get { return ps_.XAxis2; }
            set { ps_.XAxis2 = value; }
        }

        /// <summary>
        /// The second ordinate axis.
        /// </summary>
        [
            Browsable(false)
        ]
        public Axis YAxis2
        {
            get { return ps_.YAxis2; }
            set { ps_.YAxis2 = value; }
        }

        /// <summary>
        /// A color used to paint the plot background. Mutually exclusive with PlotBackImage and PlotBackBrush
        /// </summary>
        /// <remarks>not browsable or bindable because only set method.</remarks>
        [
            Category("PlotSurface2D"),
            Description("Set the plot background color."),
            Browsable(true),
            Bindable(false)
        ]
        public Color PlotBackColor
        {
            set { ps_.PlotBackColor = value; }
        }

        /// <summary>
        /// An imaged used to paint the plot background. Mutually exclusive with PlotBackColor and PlotBackBrush
        /// </summary>
        /// <remarks>not browsable or bindable because only set method.</remarks>
        [
            Browsable(false),
            Bindable(false)
        ]
        public System.Drawing.Bitmap PlotBackImage
        {
            set { ps_.PlotBackImage = value; }
        }

        /// <summary>
        /// A Rectangle brush used to paint the plot background. Mutually exclusive with PlotBackColor and PlotBackBrush
        /// </summary>
        /// <remarks>not browsable or bindable because only set method.</remarks>
        [
            Browsable(false),
            Bindable(false)
        ]
        public IRectangleBrush PlotBackBrush
        {
            set { ps_.PlotBackBrush = value; }
        }

        /// <summary>
        /// Sets the title to be drawn using a solid brush of this color.
        /// </summary>
        /// <remarks>not browsable or bindable because only set method.</remarks>
        [
            Browsable(false),
            Bindable(false)
        ]
        public Color TitleColor
        {
            set { ps_.TitleColor = value; }
        }

        /// <summary>
        /// The brush used for drawing the title.
        /// </summary>
        [
            Browsable(true),
            Bindable(true),
            Description("The brush used for drawing the title."),
            Category("PlotSurface2D")
        ]
        public Brush TitleBrush
        {
            get { return ps_.TitleBrush; }
            set { ps_.TitleBrush = value; }
        }

        /// <summary>
        /// Set smoothing mode for drawing plot objects.
        /// </summary>
        [
            Category("PlotSurface2D"),
            Description("Set smoothing mode for drawing plot objects."),
            Browsable(true),
            Bindable(true)
        ]
        public SmoothingMode SmoothingMode
        {
            get { return ps_.SmoothingMode; }
            set { ps_.SmoothingMode = value; }
        }

        /// <summary>
        /// Add an axis constraint to the plot surface. Axis constraints can
        /// specify relative world-pixel scalings, absolute axis positions etc.
        /// </summary>
        /// <param name="c">The axis constraint to add.</param>
        public void AddAxesConstraint(AxesConstraint c)
        {
            ps_.AddAxesConstraint(c);
        }

        /// <summary>
        /// Remove a drawable object from the plot surface.
        /// </summary>
        /// <param name="p">the drawable to remove</param>
        /// <param name="updateAxes">whether or not to update the axes after removing the idrawable.</param>
        public void Remove(IDrawable p, bool updateAxes)
        {
            ps_.Remove(p, updateAxes);
        }

        /// <summary>
        /// Gets an array list containing all drawables currently added to the PlotSurface2D.
        /// </summary>
        [
            Browsable(false),
            Bindable(false)
        ]
        public ArrayList Drawables
        {
            get { return ps_.Drawables; }
        }

        /// <summary>
        /// All functionality of the OnPaint method is provided by this function.
        /// This allows use of the all encompasing PlotSurface.
        /// </summary>
        /// <param name="pe">the PaintEventArgs from paint event.</param>
        /// <param name="width">width of the control</param>
        /// <param name="height">height of the control</param>
        public void DoPaint(PaintEventArgs pe, int width, int height)
        {
            PreRefresh(this);

            foreach (Interactions.Interaction i in interactions_)
            {
                i.DoPaint(pe, width, height);
            }

            /*
            // make sure don't redraw after a refresh.
            this.horizontalBarPos_ = -1;
            this.verticalBarPos_ = -1;
            */

            Graphics g = pe.Graphics;

            Rectangle border = new Rectangle(0, 0, width, height);

            if (g == null)
            {
                throw (new NPlotException("null graphics context!"));
            }

            if (ps_ == null)
            {
                throw (new NPlotException("null NPlot.PlotSurface2D"));
            }

            if (border == Rectangle.Empty)
            {
                throw (new NPlotException("null border context"));
            }

            Draw(g, border);
        }

        /// <summary>
        /// All functionality of the OnMouseDown function is contained here.
        /// This allows use of the all encompasing PlotSurface.
        /// </summary>
        /// <param name="e">The mouse event args from the window we are drawing to.</param>
        public void DoMouseDown(MouseEventArgs e)
        {
            bool dirty = false;
            foreach (Interactions.Interaction i in interactions_)
            {
                i.DoMouseDown(e, this);
                dirty |= i.DoMouseDown(e, this);
            }
            if (dirty)
            {
                Refresh();
            }
        }

        /// <summary>
        /// All functionality of the OnMouseMove function is contained here.
        /// This allows use of the all encompasing PlotSurface.
        /// </summary>
        /// <param name="e">The mouse event args from the window we are drawing to.</param>
        /// <param name="ctr">The control that the mouse event happened in.</param>
        public void DoMouseMove(MouseEventArgs e, Control ctr)
        {
            bool dirty = false;
            foreach (Interactions.Interaction i in interactions_)
            {
                i.DoMouseMove(e, ctr, lastKeyEventArgs_);
                dirty |= i.DoMouseMove(e, ctr, lastKeyEventArgs_);
            }
            if (dirty)
            {
                Refresh();
            }

            // Update coordinates if necessary. 

            if (coordinates_.Active)
            {
                // we are here
                Point here = new Point(e.X, e.Y);
                if (ps_.PlotAreaBoundingBoxCache.Contains(here))
                {
                    coordinates_.ShowAlways = true;

                    // according to Måns Erlandson, this can sometimes be the case.
                    if (PhysicalXAxis1Cache == null)
                        return;
                    if (PhysicalYAxis1Cache == null)
                        return;

                    double x = PhysicalXAxis1Cache.PhysicalToWorld(here, true);
                    double y = PhysicalYAxis1Cache.PhysicalToWorld(here, true);
                    string s = "";
                    if (!DateTimeToolTip)
                    {
                        s = "(" + x.ToString("g4") + "," + y.ToString("g4") + ")";
                    }
                    else
                    {
                        DateTime dateTime = new DateTime((long) x);
                        s = dateTime.ToShortDateString() + " " + dateTime.ToLongTimeString() + Environment.NewLine + y.ToString("f4");
                    }
                    coordinates_.SetToolTip(this, s);
                }
                else
                {
                    coordinates_.ShowAlways = false;
                }
            }
        }

        /// <summary>
        /// All functionality of the OnMouseUp function is contained here.
        /// This allows use of the all encompasing PlotSurface.
        /// </summary>
        /// <param name="e">The mouse event args from the window we are drawing to.</param>
        /// <param name="ctr">The control that the mouse event happened in.</param>
        public void DoMouseUp(MouseEventArgs e, Control ctr)
        {
            bool dirty = false;

            ArrayList local_interactions = (ArrayList) interactions_.Clone();
            foreach (Interactions.Interaction i in local_interactions)
            {
                dirty |= i.DoMouseUp(e, ctr);
            }
            if (dirty)
            {
                Refresh();
            }

            if (e.Button == MouseButtons.Right)
            {
                Point here = new Point(e.X, e.Y);
                //selectedObjects_ = ps_.HitTest(here);
                if (rightMenu_ != null)
                    rightMenu_.Menu.Show(ctr, here);
            }
        }

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        /// <remarks>Modified! :-)</remarks>
        private void InitializeComponent()
        {
            components = new Container();
            coordinates_ = new ToolTip(components);
            // 
            // PlotSurface2D
            // 
            BackColor = SystemColors.ControlLightLight;
            Size = new Size(328, 272);
        }

        /// <summary>
        /// the key down callback
        /// </summary>
        /// <param name="e">information pertaining to the event</param>
        protected override void OnKeyDown(KeyEventArgs e)
        {
            lastKeyEventArgs_ = e;
        }

        /// <summary>
        /// The key up callback.
        /// </summary>
        /// <param name="e">information pertaining to the event</param>
        protected override void OnKeyUp(KeyEventArgs e)
        {
            lastKeyEventArgs_ = e;
        }

        /// <summary>
        /// the paint event callback.
        /// </summary>
        /// <param name="pe">the PaintEventArgs</param>
        protected override void OnPaint(PaintEventArgs pe)
        {
            DoPaint(pe, Width, Height);
            base.OnPaint(pe);
        }

        /// <summary>
        /// Draws the plot surface on the supplied graphics surface [not the control surface].
        /// </summary>
        /// <param name="g">The graphics surface on which to draw</param>
        /// <param name="bounds">
        /// A bounding box on this surface that denotes the area on the
        /// surface to confine drawing to.
        /// </param>
        public void Draw(Graphics g, Rectangle bounds)
        {
            // If we are not in design mode then draw as normal.
            if (LicenseManager.UsageMode == LicenseUsageMode.Designtime)
            {
                drawDesignMode(g, bounds);
            }

            ps_.Draw(g, bounds);
        }

        /// <summary>
        /// Draw a lightweight representation of us for design mode.
        /// </summary>
        private void drawDesignMode(Graphics g, Rectangle bounds)
        {
            g.DrawRectangle(new Pen(Color.Black), bounds.X + 2, bounds.Y + 2, bounds.Width - 4, bounds.Height - 4);
            g.DrawString("PlotSurface2D: " + Title, TitleFont, TitleBrush, bounds.X + bounds.Width/2.0f, bounds.Y + bounds.Height/2.0f);
        }

        /// <summary>
        /// Mouse down event handler.
        /// </summary>
        /// <param name="e">the event args.</param>
        protected override void OnMouseDown(MouseEventArgs e)
        {
            DoMouseDown(e);
            base.OnMouseDown(e);
        }

        /// <summary>
        /// Mouse Wheel event handler.
        /// </summary>
        /// <param name="e">the event args</param>
        protected override void OnMouseWheel(MouseEventArgs e)
        {
            DoMouseWheel(e);
            base.OnMouseWheel(e);
        }

        /// <summary>
        /// All functionality of the OnMouseWheel function is containd here.
        /// This allows use of the all encompasing PlotSurface.
        /// </summary>
        /// <param name="e">the event args.</param>
        public void DoMouseWheel(MouseEventArgs e)
        {
            bool dirty = false;
            foreach (Interactions.Interaction i in interactions_)
            {
                i.DoMouseWheel(e, this);
                dirty |= i.DoMouseWheel(e, this);
            }
            if (dirty)
            {
                Refresh();
            }
        }

        /// <summary>
        /// MouseMove event handler.
        /// </summary>
        /// <param name="e">The event arguments.</param>
        protected override void OnMouseMove(MouseEventArgs e)
        {
            DoMouseMove(e, this);
            base.OnMouseMove(e);
        }

        /// <summary>
        /// MouseLeave event handler. It has to invalidate the control to get rid of
        /// any remnant of vertical and horizontal guides.
        /// </summary>
        /// <param name="e">The event arguments.</param>
        protected override void OnMouseLeave(EventArgs e)
        {
            DoMouseLeave(e, this);
            base.OnMouseLeave(e);
        }

        /// <summary>
        /// </summary>
        /// <param name="e"></param>
        /// <param name="ctr"></param>
        public void DoMouseLeave(EventArgs e, Control ctr)
        {
            bool dirty = false;
            foreach (Interactions.Interaction i in interactions_)
            {
                dirty = i.DoMouseLeave(e, this) || dirty;
            }
            if (dirty)
                Refresh();
        }

        /// <summary>
        /// mouse up event handler.
        /// </summary>
        /// <param name="e">The event arguments.</param>
        protected override void OnMouseUp(MouseEventArgs e)
        {
            DoMouseUp(e, this);
            base.OnMouseUp(e);
        }

        /// <summary>
        /// sets axes to be those saved in the cache.
        /// </summary>
        public void OriginalDimensions()
        {
            if (xAxis1ZoomCache_ != null)
            {
                XAxis1 = xAxis1ZoomCache_;
                XAxis2 = xAxis2ZoomCache_;
                YAxis1 = yAxis1ZoomCache_;
                YAxis2 = yAxis2ZoomCache_;

                xAxis1ZoomCache_ = null;
                xAxis2ZoomCache_ = null;
                yAxis1ZoomCache_ = null;
                yAxis2ZoomCache_ = null;
            }
            Refresh();
        }

        private void DrawHorizontalSelection(Point start, Point end, UserControl ctr)
        {
            // the clipping rectangle in screen coordinates
            Rectangle clip = ctr.RectangleToScreen(
                new Rectangle(
                    ps_.PlotAreaBoundingBoxCache.X,
                    ps_.PlotAreaBoundingBoxCache.Y,
                    ps_.PlotAreaBoundingBoxCache.Width,
                    ps_.PlotAreaBoundingBoxCache.Height));

            start = ctr.PointToScreen(start);
            end = ctr.PointToScreen(end);

            ControlPaint.FillReversibleRectangle(
                new Rectangle(Math.Min(start.X, end.X), clip.Y, Math.Abs(end.X - start.X), clip.Height),
                Color.White);
        }

        /// <summary>
        /// Print the chart as currently shown by the control
        /// </summary>
        /// <param name="preview">If true, show print preview window.</param>
        public void Print(bool preview)
        {
            PrintDocument printDocument = new PrintDocument();
            printDocument.PrintPage += NPlot_PrintPage;
            printDocument.DefaultPageSettings.Landscape = true;

            DialogResult result;
            if (!preview)
            {
                PrintDialog dlg = new PrintDialog();
                dlg.Document = printDocument;
                result = dlg.ShowDialog();
            }
            else
            {
                PrintPreviewDialog dlg = new PrintPreviewDialog();
                dlg.Document = printDocument;
                result = dlg.ShowDialog();
            }
            if (result == DialogResult.OK)
            {
                try
                {
                    printDocument.Print();
                }
                catch
                {
                    Console.WriteLine("caught\n");
                }
            }
        }

        private void NPlot_PrintPage(object sender, PrintPageEventArgs ev)
        {
            Rectangle r = ev.MarginBounds;
            Draw(ev.Graphics, r);
            ev.HasMorePages = false;
        }

        /// <summary>
        /// Coppies the chart currently shown in the control to the clipboard as an image.
        /// </summary>
        public void CopyToClipboard()
        {
            System.Drawing.Bitmap b = new System.Drawing.Bitmap(Width, Height);
            Graphics g = Graphics.FromImage(b);
            g.Clear(Color.White);
            Draw(g, new Rectangle(0, 0, b.Width - 1, b.Height - 1));
            Clipboard.SetDataObject(b, true);
        }

        /// <summary>
        /// Coppies data in the current plot surface view window to the clipboard
        /// as text.
        /// </summary>
        public void CopyDataToClipboard()
        {
            StringBuilder sb = new StringBuilder();

            for (int i = 0; i < ps_.Drawables.Count; ++i)
            {
                IPlot plot = ps_.Drawables[i] as IPlot;
                if (plot != null)
                {
                    Axis xAxis = ps_.WhichXAxis(plot);
                    Axis yAxis = ps_.WhichYAxis(plot);

                    RectangleD region = new RectangleD(
                        xAxis.WorldMin,
                        yAxis.WorldMin,
                        xAxis.WorldMax - xAxis.WorldMin,
                        yAxis.WorldMax - yAxis.WorldMin);

                    plot.WriteData(sb, region, true);
                }
            }

            Clipboard.SetDataObject(sb.ToString(), true);
        }

        /// <summary>
        /// Remembers the current axes - useful in interactions.
        /// </summary>
        public void CacheAxes()
        {
            if (xAxis1ZoomCache_ == null && xAxis2ZoomCache_ == null &&
                yAxis1ZoomCache_ == null && yAxis2ZoomCache_ == null)
            {
                if (XAxis1 != null)
                {
                    xAxis1ZoomCache_ = (Axis) XAxis1.Clone();
                }
                if (XAxis2 != null)
                {
                    xAxis2ZoomCache_ = (Axis) XAxis2.Clone();
                }
                if (YAxis1 != null)
                {
                    yAxis1ZoomCache_ = (Axis) YAxis1.Clone();
                }
                if (YAxis2 != null)
                {
                    yAxis2ZoomCache_ = (Axis) YAxis2.Clone();
                }
            }
        }

        /// <summary>
        /// Adds and interaction to the plotsurface that adds functionality that responds
        /// to a set of mouse / keyboard events.
        /// </summary>
        /// <param name="i">the interaction to add.</param>
        public void AddInteraction(Interactions.Interaction i)
        {
            interactions_.Add(i);
        }

        /// <summary>
        /// Remove a previously added interaction
        /// </summary>
        /// <param name="i">interaction to remove</param>
        public void RemoveInteraction(Interactions.Interaction i)
        {
            interactions_.Remove(i);
        }

        /// <summary>
        /// Event is fired when an interaction happens with the plot that causes it to be modified.
        /// </summary>
        public event InteractionHandler InteractionOccured;

        /// <summary>
        /// Default function called when plotsurface modifying interaction occured.
        /// Override this, or add method to InteractionOccured event.
        /// </summary>
        /// <param name="sender"></param>
        protected void OnInteractionOccured(object sender)
        {
            // do nothing.
        }

        /// <summary>
        /// Event fired when we are about to paint.
        /// </summary>
        public event PreRefreshHandler PreRefresh;

        /// <summary>
        /// Default function called just before a refresh happens.
        /// </summary>
        /// <param name="sender"></param>
        protected void OnPreRefresh(object sender)
        {
            // do nothing.
        }

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (components != null)
                    components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region class PlotContextMenu

        /// <summary>
        /// Summary description for ContextMenu.
        /// </summary>
        public class PlotContextMenu
        {
            #region IPlotMenuItem

            /// <summary>
            /// elements of the MenuItems array list must implement this interface.
            /// </summary>
            public interface IPlotMenuItem
            {
                /// <summary>
                /// Gets the Windows.Forms.MenuItem associated with the PlotMenuItem
                /// </summary>
                MenuItem MenuItem { get; }

                /// <summary>
                /// This method is called for each menu item before the menu is
                /// displayed. It is useful for implementing check marks, disabling
                /// etc.
                /// </summary>
                /// <param name="plotContextMenu"></param>
                void OnPopup(PlotContextMenu plotContextMenu);
            }

            #endregion

            #region PlotMenuSeparator

            /// <summary>
            /// A plot menu item for separators.
            /// </summary>
            public class PlotMenuSeparator : IPlotMenuItem
            {
                private readonly int index_;

                private readonly MenuItem menuItem_;

                /// <summary>
                /// Constructor
                /// </summary>
                /// <param name="index"></param>
                public PlotMenuSeparator(int index)
                {
                    menuItem_ = new MenuItem();
                    index_ = index;

                    menuItem_.Index = index_;
                    menuItem_.Text = "-";
                }

                /// <summary>
                /// Index of this menu item in the menu.
                /// </summary>
                public int Index
                {
                    get { return index_; }
                }

                /// <summary>
                /// The Windows.Forms.MenuItem associated with this IPlotMenuItem
                /// </summary>
                public MenuItem MenuItem
                {
                    get { return menuItem_; }
                }

                /// <summary>
                /// </summary>
                /// <param name="plotContextMenu"></param>
                public void OnPopup(PlotContextMenu plotContextMenu)
                {
                    // do nothing.
                }
            }

            #endregion

            #region PlotMenuItem

            /// <summary>
            /// A Plot menu item suitable for specifying basic menu items
            /// </summary>
            public class PlotMenuItem : IPlotMenuItem
            {
                private readonly EventHandler callback_;
                private readonly int index_;
                private readonly MenuItem menuItem_;
                private readonly string text_;

                /// <summary>
                /// Constructor
                /// </summary>
                /// <param name="text">Menu item text</param>
                /// <param name="index">Index in the manu</param>
                /// <param name="callback">EventHandler to call if menu selected.</param>
                public PlotMenuItem(string text, int index, EventHandler callback)
                {
                    text_ = text;
                    index_ = index;
                    callback_ = callback;

                    menuItem_ = new MenuItem();

                    menuItem_.Index = index;
                    menuItem_.Text = text;
                    menuItem_.Click += callback;
                }

                /// <summary>
                /// The text to put in the menu for this menu item.
                /// </summary>
                public string Text
                {
                    get { return text_; }
                }

                /// <summary>
                /// Index of this menu item in the menu.
                /// </summary>
                public int Index
                {
                    get { return index_; }
                }

                /// <summary>
                /// EventHandler to call if menu selected.
                /// </summary>
                public EventHandler Callback
                {
                    get { return callback_; }
                }

                /// <summary>
                /// The Windows.Forms.MenuItem associated with this IPlotMenuItem
                /// </summary>
                public MenuItem MenuItem
                {
                    get { return menuItem_; }
                }

                /// <summary>
                /// Called before menu drawn.
                /// </summary>
                /// <param name="plotContextMenu">The plot menu this item is a member of.</param>
                public virtual void OnPopup(PlotContextMenu plotContextMenu)
                {
                    // do nothing.
                }
            }

            #endregion

            #region PlotZoomBackMenuItem

            /// <summary>
            /// A Plot Menu Item that provides necessary functionality for the
            /// zoom back menu item (graying out if zoomed right out in addition
            /// to basic functionality).
            /// </summary>
            public class PlotZoomBackMenuItem : PlotMenuItem
            {
                /// <summary>
                /// Constructor
                /// </summary>
                /// <param name="text">Text associated with this item in the menu.</param>
                /// <param name="index">Index of this item in the menu.</param>
                /// <param name="callback">EventHandler to call when menu item is selected.</param>
                public PlotZoomBackMenuItem(string text, int index, EventHandler callback)
                    : base(text, index, callback)
                {
                }

                /// <summary>
                /// Called before menu drawn.
                /// </summary>
                /// <param name="plotContextMenu">The plot menu this item is a member of.</param>
                public override void OnPopup(PlotContextMenu plotContextMenu)
                {
                    MenuItem.Enabled = plotContextMenu.plotSurface2D_.xAxis1ZoomCache_ != null;
                }
            }

            #endregion

            #region PlotShowCoordinatesMenuItem

            /// <summary>
            /// A Plot Menu Item that provides necessary functionality for the
            /// show coordinates menu item (tick mark toggle in addition to basic
            /// functionality).
            /// </summary>
            public class PlotShowCoordinatesMenuItem : PlotMenuItem
            {
                /// <summary>
                /// Constructor
                /// </summary>
                /// <param name="text">Text associated with this item in the menu.</param>
                /// <param name="index">Index of this item in the menu.</param>
                /// <param name="callback">EventHandler to call when menu item is selected.</param>
                public PlotShowCoordinatesMenuItem(string text, int index, EventHandler callback)
                    : base(text, index, callback)
                {
                }

                /// <summary>
                /// Called before menu drawn.
                /// </summary>
                /// <param name="plotContextMenu">The plot menu this item is a member of.</param>
                public override void OnPopup(PlotContextMenu plotContextMenu)
                {
                    MenuItem.Checked = plotContextMenu.plotSurface2D_.ShowCoordinates;
                }
            }

            #endregion

            private ArrayList menuItems_;

            /// <summary>
            /// The PlotSurface2D associated with the context menu. Classes inherited
            /// from PlotContextMenu will likely use this to implement their functionality.
            /// </summary>
            protected PlotSurface2D plotSurface2D_;

            private ContextMenu rightMenu_;

            /// <summary>
            /// Constructor creates
            /// </summary>
            public PlotContextMenu()
            {
                ArrayList menuItems = new ArrayList();

                menuItems = new ArrayList();
                menuItems.Add(new PlotZoomBackMenuItem("Original Dimensions", 0, mnuOriginalDimensions_Click));
                menuItems.Add(new PlotShowCoordinatesMenuItem("Show World Coordinates", 1, mnuDisplayCoordinates_Click));
                menuItems.Add(new PlotMenuSeparator(2));
                menuItems.Add(new PlotMenuItem("Print", 3, mnuPrint_Click));
                menuItems.Add(new PlotMenuItem("Print Preview", 4, mnuPrintPreview_Click));
                menuItems.Add(new PlotMenuItem("Copy To Clipboard", 5, mnuCopyToClipboard_Click));
                menuItems.Add(new PlotMenuItem("Copy Data To Clipboard", 6, mnuCopyDataToClipboard_Click));

                SetMenuItems(menuItems);
            }

            /// <summary>
            /// Gets an arraylist of all PlotMenuItems that comprise the
            /// menu. If this list is changed, this class must be told to
            /// update using the Update method.
            /// </summary>
            public ArrayList MenuItems
            {
                get { return menuItems_; }
            }

            /// <summary>
            /// The PlotSurface2D associated with the context menu. Generally, the user
            /// should not set this. It is used internally by PlotSurface2D.
            /// </summary>
            public PlotSurface2D PlotSurface2D
            {
                set { plotSurface2D_ = value; }
            }

            /// <summary>
            /// Gets the Windows.Forms context menu managed by this object.
            /// </summary>
            public ContextMenu Menu
            {
                get { return rightMenu_; }
            }

            /// <summary>
            /// Sets the context menu according to the IPlotMenuItem's in the provided
            /// ArrayList. The current menu items can be obtained using the MenuItems
            /// property and extended if desired.
            /// </summary>
            /// <param name="menuItems"></param>
            public void SetMenuItems(ArrayList menuItems)
            {
                menuItems_ = menuItems;

                rightMenu_ = new ContextMenu();

                foreach (IPlotMenuItem item in menuItems_)
                {
                    rightMenu_.MenuItems.Add(item.MenuItem);
                }

                rightMenu_.Popup += rightMenu__Popup;
            }

            private void mnuOriginalDimensions_Click(object sender, EventArgs e)
            {
                plotSurface2D_.OriginalDimensions();
            }

            private void mnuCopyToClipboard_Click(object sender, EventArgs e)
            {
                plotSurface2D_.CopyToClipboard();
            }

            private void mnuCopyDataToClipboard_Click(object sender, EventArgs e)
            {
                plotSurface2D_.CopyDataToClipboard();
            }

            private void mnuPrint_Click(object sender, EventArgs e)
            {
                plotSurface2D_.Print(false);
            }

            private void mnuPrintPreview_Click(object sender, EventArgs e)
            {
                plotSurface2D_.Print(true);
            }

            private void mnuDisplayCoordinates_Click(object sender, EventArgs e)
            {
                plotSurface2D_.ShowCoordinates = !plotSurface2D_.ShowCoordinates;
            }

            private void rightMenu__Popup(object sender, EventArgs e)
            {
                foreach (IPlotMenuItem item in menuItems_)
                {
                    item.OnPopup(this);
                }
            }
        }

        #endregion

        /// <summary>
        /// Encapsulates a number of separate "Interactions". An interaction is basically
        /// a set of handlers for mouse and keyboard events that work together in a
        /// specific way.
        /// </summary>
        public abstract class Interactions
        {
            /// <summary>
            /// Base class for an interaction. All methods are virtual. Not abstract as not all interactions
            /// need to use all methods. Default functionality for each method is to do nothing.
            /// </summary>
            public class Interaction
            {
                /// <summary>
                /// Handler for this interaction if a mouse down event is received.
                /// </summary>
                /// <param name="e">event args</param>
                /// <param name="ctr">reference to the control</param>
                /// <returns>true if plot surface needs refreshing.</returns>
                public virtual bool DoMouseDown(MouseEventArgs e, Control ctr)
                {
                    return false;
                }

                /// <summary>
                /// Handler for this interaction if a mouse up event is received.
                /// </summary>
                /// <param name="e">event args</param>
                /// <param name="ctr">reference to the control</param>
                /// <returns>true if plot surface needs refreshing.</returns>
                public virtual bool DoMouseUp(MouseEventArgs e, Control ctr)
                {
                    return false;
                }

                /// <summary>
                /// Handler for this interaction if a mouse move event is received.
                /// </summary>
                /// <param name="e">event args</param>
                /// <param name="ctr">reference to the control</param>
                /// <param name="lastKeyEventArgs"></param>
                /// <returns>true if plot surface needs refreshing.</returns>
                public virtual bool DoMouseMove(MouseEventArgs e, Control ctr, KeyEventArgs lastKeyEventArgs)
                {
                    return false;
                }

                /// <summary>
                /// Handler for this interaction if a mouse move event is received.
                /// </summary>
                /// <param name="e">event args</param>
                /// <param name="ctr">reference to the control</param>
                /// <returns>true if plot surface needs refreshing.</returns>
                public virtual bool DoMouseWheel(MouseEventArgs e, Control ctr)
                {
                    return false;
                }

                /// <summary>
                /// Handler for this interaction if a mouse Leave event is received.
                /// </summary>
                /// <param name="e">event args</param>
                /// <param name="ctr">reference to the control</param>
                /// <returns>true if the plot surface needs refreshing.</returns>
                public virtual bool DoMouseLeave(EventArgs e, Control ctr)
                {
                    return false;
                }

                /// <summary>
                /// Handler for this interaction if a paint event is received.
                /// </summary>
                /// <param name="pe">paint event args</param>
                /// <param name="width"></param>
                /// <param name="height"></param>
                public virtual void DoPaint(PaintEventArgs pe, int width, int height)
                {
                }
            }

            #region RubberBandSelection

            /// <summary>
            /// </summary>
            public class RubberBandSelection : Interaction
            {
                private readonly Point unset_ = new Point(-1, -1);
                private Point endPoint_ = new Point(-1, -1);
                private bool selectionInitiated_;
                private Point startPoint_ = new Point(-1, -1);

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseDown(MouseEventArgs e, Control ctr)
                {
                    // keep track of the start point and flag that select initiated.
                    selectionInitiated_ = true;
                    startPoint_.X = e.X;
                    startPoint_.Y = e.Y;

                    // invalidate the end point
                    endPoint_ = unset_;

                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                /// <param name="lastKeyEventArgs"></param>
                public override bool DoMouseMove(MouseEventArgs e, Control ctr, KeyEventArgs lastKeyEventArgs)
                {
                    if ((e.Button == MouseButtons.Left) && selectionInitiated_)
                    {
                        // we are here
                        Point here = new Point(e.X, e.Y);

                        // delete the previous box
                        if (endPoint_ != unset_)
                        {
                            DrawRubberBand(startPoint_, endPoint_, ctr);
                        }
                        endPoint_ = here;

                        // and redraw the last one
                        DrawRubberBand(startPoint_, endPoint_, ctr);
                    }

                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseUp(MouseEventArgs e, Control ctr)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    // handle left button (selecting region).
                    if ((e.Button == MouseButtons.Left) && selectionInitiated_)
                    {
                        endPoint_.X = e.X;
                        endPoint_.Y = e.Y;

                        // flag stopped selecting.
                        selectionInitiated_ = false;

                        if (endPoint_ != unset_)
                        {
                            DrawRubberBand(startPoint_, endPoint_, ctr);
                        }

                        Point minPoint = new Point(0, 0);
                        minPoint.X = Math.Min(startPoint_.X, endPoint_.X);
                        minPoint.Y = Math.Min(startPoint_.Y, endPoint_.Y);

                        Point maxPoint = new Point(0, 0);
                        maxPoint.X = Math.Max(startPoint_.X, endPoint_.X);
                        maxPoint.Y = Math.Max(startPoint_.Y, endPoint_.Y);

                        Rectangle r = ps.PlotAreaBoundingBoxCache;
                        if (minPoint != maxPoint && (r.Contains(minPoint) || r.Contains(maxPoint)))
                        {
                            ((PlotSurface2D) ctr).CacheAxes();

                            ((PlotSurface2D) ctr).PhysicalXAxis1Cache.SetWorldLimitsFromPhysical(minPoint, maxPoint);
                            ((PlotSurface2D) ctr).PhysicalXAxis2Cache.SetWorldLimitsFromPhysical(minPoint, maxPoint);
                            ((PlotSurface2D) ctr).PhysicalYAxis1Cache.SetWorldLimitsFromPhysical(maxPoint, minPoint);
                            ((PlotSurface2D) ctr).PhysicalYAxis2Cache.SetWorldLimitsFromPhysical(maxPoint, minPoint);

                            // reset the start/end points
                            startPoint_ = unset_;
                            endPoint_ = unset_;

                            ((PlotSurface2D) ctr).InteractionOccured(this);

                            return true;
                        }
                    }

                    return false;
                }

                /// <summary>
                /// Draws a rectangle representing selection area.
                /// </summary>
                /// <param name="start">a corner of the rectangle.</param>
                /// <param name="end">a corner of the rectangle diagonally opposite the first.</param>
                /// <param name="ctr">
                /// The control to draw to - this may not be us, if we have
                /// been contained by a PlotSurface.
                /// </param>
                private void DrawRubberBand(Point start, Point end, Control ctr)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    Rectangle rect = new Rectangle();

                    // the clipping rectangle in screen coordinates
                    Rectangle clip = ctr.RectangleToScreen(
                        new Rectangle(
                            ps.PlotAreaBoundingBoxCache.X,
                            ps.PlotAreaBoundingBoxCache.Y,
                            ps.PlotAreaBoundingBoxCache.Width,
                            ps.PlotAreaBoundingBoxCache.Height));

                    // convert to screen coords
                    start = ctr.PointToScreen(start);
                    end = ctr.PointToScreen(end);

                    // now, "normalize" the rectangle
                    if (start.X < end.X)
                    {
                        rect.X = start.X;
                        rect.Width = end.X - start.X;
                    }
                    else
                    {
                        rect.X = end.X;
                        rect.Width = start.X - end.X;
                    }
                    if (start.Y < end.Y)
                    {
                        rect.Y = start.Y;
                        rect.Height = end.Y - start.Y;
                    }
                    else
                    {
                        rect.Y = end.Y;
                        rect.Height = start.Y - end.Y;
                    }
                    rect = Rectangle.Intersect(rect, clip);

                    ControlPaint.DrawReversibleFrame(
                        new Rectangle(rect.X, rect.Y, rect.Width, rect.Height),
                        Color.White, FrameStyle.Dashed);
                }
            }

            #endregion

            #region HorizontalGuideline

            /// <summary>
            /// Horizontal line interaction
            /// </summary>
            public class HorizontalGuideline : Interaction
            {
                private readonly Color color_;
                private int barPos_;

                /// <summary>
                /// Constructor
                /// </summary>
                public HorizontalGuideline()
                {
                    color_ = Color.Black;
                }

                /// <summary>
                /// Constructor
                /// </summary>
                /// <param name="lineColor"></param>
                public HorizontalGuideline(Color lineColor)
                {
                    color_ = lineColor;
                }

                /// <summary>
                /// </summary>
                /// <param name="pe"></param>
                /// <param name="width"></param>
                /// <param name="height"></param>
                public override void DoPaint(PaintEventArgs pe, int width, int height)
                {
                    barPos_ = -1;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                /// <param name="lastKeyEventArgs"></param>
                public override bool DoMouseMove(MouseEventArgs e, Control ctr, KeyEventArgs lastKeyEventArgs)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    // if mouse isn't in plot region, then don't draw horizontal line
                    if (e.X > ps.PlotAreaBoundingBoxCache.Left && e.X < ps.PlotAreaBoundingBoxCache.Right &&
                        e.Y > ps.PlotAreaBoundingBoxCache.Top && e.Y < (ps.PlotAreaBoundingBoxCache.Bottom - 1))
                    {
                        if (ps.PhysicalXAxis1Cache != null)
                        {
                            // the clipping rectangle in screen coordinates
                            Rectangle clip = ctr.RectangleToScreen(
                                new Rectangle(
                                    ps.PlotAreaBoundingBoxCache.X,
                                    ps.PlotAreaBoundingBoxCache.Y,
                                    ps.PlotAreaBoundingBoxCache.Width,
                                    ps.PlotAreaBoundingBoxCache.Height));

                            Point p = ctr.PointToScreen(new Point(e.X, e.Y));

                            if (barPos_ != -1)
                            {
                                ControlPaint.DrawReversibleLine(
                                    new Point(clip.Left, barPos_),
                                    new Point(clip.Right, barPos_), color_);
                            }

                            if (p.Y < clip.Bottom && p.Y > clip.Top)
                            {
                                ControlPaint.DrawReversibleLine(
                                    new Point(clip.Left, p.Y),
                                    new Point(clip.Right, p.Y), color_);

                                barPos_ = p.Y;
                            }
                            else
                            {
                                barPos_ = -1;
                            }
                        }
                    }
                    else
                    {
                        if (barPos_ != -1)
                        {
                            Rectangle clip = ctr.RectangleToScreen(
                                new Rectangle(
                                    ps.PlotAreaBoundingBoxCache.X,
                                    ps.PlotAreaBoundingBoxCache.Y,
                                    ps.PlotAreaBoundingBoxCache.Width,
                                    ps.PlotAreaBoundingBoxCache.Height));

                            ControlPaint.DrawReversibleLine(
                                new Point(clip.Left, barPos_),
                                new Point(clip.Right, barPos_), color_);
                            barPos_ = -1;
                        }
                    }

                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                /// <returns></returns>
                public override bool DoMouseLeave(EventArgs e, Control ctr)
                {
                    if (barPos_ != -1)
                    {
                        NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                        Rectangle clip = ctr.RectangleToScreen(
                            new Rectangle(
                                ps.PlotAreaBoundingBoxCache.X,
                                ps.PlotAreaBoundingBoxCache.Y,
                                ps.PlotAreaBoundingBoxCache.Width,
                                ps.PlotAreaBoundingBoxCache.Height));

                        ControlPaint.DrawReversibleLine(
                            new Point(clip.Left, barPos_),
                            new Point(clip.Right, barPos_), color_);

                        barPos_ = -1;
                    }
                    return false;
                }
            }

            #endregion

            #region VerticalGuideline

            /// <summary>
            /// </summary>
            public class VerticalGuideline : Interaction
            {
                private readonly Color color_;
                private int barPos_;

                /// <summary>
                /// </summary>
                public VerticalGuideline()
                {
                    color_ = Color.Black;
                }

                /// <summary>
                /// </summary>
                /// <param name="lineColor"></param>
                public VerticalGuideline(Color lineColor)
                {
                    color_ = lineColor;
                }

                /// <summary>
                /// </summary>
                /// <param name="pe"></param>
                /// <param name="width"></param>
                /// <param name="height"></param>
                public override void DoPaint(PaintEventArgs pe, int width, int height)
                {
                    barPos_ = -1;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                /// <param name="lastKeyEventArgs"></param>
                public override bool DoMouseMove(MouseEventArgs e, Control ctr, KeyEventArgs lastKeyEventArgs)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    // if mouse isn't in plot region, then don't draw horizontal line
                    if (e.X > ps.PlotAreaBoundingBoxCache.Left && e.X < (ps.PlotAreaBoundingBoxCache.Right - 1) &&
                        e.Y > ps.PlotAreaBoundingBoxCache.Top && e.Y < ps.PlotAreaBoundingBoxCache.Bottom)
                    {
                        if (ps.PhysicalXAxis1Cache != null)
                        {
                            // the clipping rectangle in screen coordinates
                            Rectangle clip = ctr.RectangleToScreen(
                                new Rectangle(
                                    ps.PlotAreaBoundingBoxCache.X,
                                    ps.PlotAreaBoundingBoxCache.Y,
                                    ps.PlotAreaBoundingBoxCache.Width,
                                    ps.PlotAreaBoundingBoxCache.Height));

                            Point p = ctr.PointToScreen(new Point(e.X, e.Y));

                            if (barPos_ != -1)
                            {
                                ControlPaint.DrawReversibleLine(
                                    new Point(barPos_, clip.Top),
                                    new Point(barPos_, clip.Bottom), color_);
                            }

                            if (p.X < clip.Right && p.X > clip.Left)
                            {
                                ControlPaint.DrawReversibleLine(
                                    new Point(p.X, clip.Top),
                                    new Point(p.X, clip.Bottom), color_);
                                barPos_ = p.X;
                            }
                            else
                            {
                                barPos_ = -1;
                            }
                        }
                    }
                    else
                    {
                        if (barPos_ != -1)
                        {
                            Rectangle clip = ctr.RectangleToScreen(
                                new Rectangle(
                                    ps.PlotAreaBoundingBoxCache.X,
                                    ps.PlotAreaBoundingBoxCache.Y,
                                    ps.PlotAreaBoundingBoxCache.Width,
                                    ps.PlotAreaBoundingBoxCache.Height)
                                );

                            ControlPaint.DrawReversibleLine(
                                new Point(barPos_, clip.Top),
                                new Point(barPos_, clip.Bottom), color_);

                            barPos_ = -1;
                        }
                    }

                    return false;
                }

                /// <summary>
                /// Handler for mouse leave event
                /// </summary>
                /// <param name="e">event args</param>
                /// <param name="ctr"></param>
                /// <returns></returns>
                public override bool DoMouseLeave(EventArgs e, Control ctr)
                {
                    if (barPos_ != -1)
                    {
                        NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                        Rectangle clip = ctr.RectangleToScreen(
                            new Rectangle(
                                ps.PlotAreaBoundingBoxCache.X,
                                ps.PlotAreaBoundingBoxCache.Y,
                                ps.PlotAreaBoundingBoxCache.Width,
                                ps.PlotAreaBoundingBoxCache.Height));

                        ControlPaint.DrawReversibleLine(
                            new Point(barPos_, clip.Top),
                            new Point(barPos_, clip.Bottom), color_);
                        barPos_ = -1;
                    }
                    return false;
                }
            }

            #endregion

            #region HorizontalDrag

            /// <summary>
            /// </summary>
            public class HorizontalDrag : Interaction
            {
                private readonly Point unset_ = new Point(-1, -1);
                private bool dragInitiated_;
                private Point lastPoint_ = new Point(-1, -1);

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseDown(MouseEventArgs e, Control ctr)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    if (e.X > ps.PlotAreaBoundingBoxCache.Left && e.X < (ps.PlotAreaBoundingBoxCache.Right) &&
                        e.Y > ps.PlotAreaBoundingBoxCache.Top && e.Y < ps.PlotAreaBoundingBoxCache.Bottom)
                    {
                        dragInitiated_ = true;

                        lastPoint_.X = e.X;
                        lastPoint_.Y = e.Y;
                    }

                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                /// <param name="lastKeyEventArgs"></param>
                public override bool DoMouseMove(MouseEventArgs e, Control ctr, KeyEventArgs lastKeyEventArgs)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    if ((e.Button == MouseButtons.Left) && dragInitiated_)
                    {
                        int diffX = e.X - lastPoint_.X;

                        ((PlotSurface2D) ctr).CacheAxes();

                        // original code was using PixelWorldLength of the physical axis
                        // but it was not working for non-linear axes - the code below works
                        // in all cases
                        if (ps.XAxis1 != null)
                        {
                            Axis axis = ps.XAxis1;
                            PointF pMin = ps.PhysicalXAxis1Cache.PhysicalMin;
                            PointF pMax = ps.PhysicalXAxis1Cache.PhysicalMax;

                            PointF physicalWorldMin = pMin;
                            PointF physicalWorldMax = pMax;
                            physicalWorldMin.X -= diffX;
                            physicalWorldMax.X -= diffX;
                            double newWorldMin = axis.PhysicalToWorld(physicalWorldMin, pMin, pMax, false);
                            double newWorldMax = axis.PhysicalToWorld(physicalWorldMax, pMin, pMax, false);
                            axis.WorldMin = newWorldMin;
                            axis.WorldMax = newWorldMax;
                        }
                        if (ps.XAxis2 != null)
                        {
                            Axis axis = ps.XAxis2;
                            PointF pMin = ps.PhysicalXAxis2Cache.PhysicalMin;
                            PointF pMax = ps.PhysicalXAxis2Cache.PhysicalMax;

                            PointF physicalWorldMin = pMin;
                            PointF physicalWorldMax = pMax;
                            physicalWorldMin.X -= diffX;
                            physicalWorldMax.X -= diffX;
                            double newWorldMin = axis.PhysicalToWorld(physicalWorldMin, pMin, pMax, false);
                            double newWorldMax = axis.PhysicalToWorld(physicalWorldMax, pMin, pMax, false);
                            axis.WorldMin = newWorldMin;
                            axis.WorldMax = newWorldMax;
                        }

                        lastPoint_ = new Point(e.X, e.Y);

                        ((PlotSurface2D) ctr).InteractionOccured(this);

                        return true;
                    }

                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseUp(MouseEventArgs e, Control ctr)
                {
                    if ((e.Button == MouseButtons.Left) && dragInitiated_)
                    {
                        lastPoint_ = unset_;
                        dragInitiated_ = false;
                    }
                    return false;
                }
            }

            #endregion

            #region VerticalDrag

            /// <summary>
            /// </summary>
            public class VerticalDrag : Interaction
            {
                private readonly Point unset_ = new Point(-1, -1);
                private bool dragInitiated_;
                private Point lastPoint_ = new Point(-1, -1);

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseDown(MouseEventArgs e, Control ctr)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    if (e.X > ps.PlotAreaBoundingBoxCache.Left && e.X < (ps.PlotAreaBoundingBoxCache.Right) &&
                        e.Y > ps.PlotAreaBoundingBoxCache.Top && e.Y < ps.PlotAreaBoundingBoxCache.Bottom)
                    {
                        dragInitiated_ = true;

                        lastPoint_.X = e.X;
                        lastPoint_.Y = e.Y;
                    }

                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                /// <param name="lastKeyEventArgs"></param>
                public override bool DoMouseMove(MouseEventArgs e, Control ctr, KeyEventArgs lastKeyEventArgs)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    if ((e.Button == MouseButtons.Left) && dragInitiated_)
                    {
                        int diffY = e.Y - lastPoint_.Y;

                        ((PlotSurface2D) ctr).CacheAxes();

                        if (ps.YAxis1 != null)
                        {
                            Axis axis = ps.YAxis1;
                            PointF pMin = ps.PhysicalYAxis1Cache.PhysicalMin;
                            PointF pMax = ps.PhysicalYAxis1Cache.PhysicalMax;

                            PointF physicalWorldMin = pMin;
                            PointF physicalWorldMax = pMax;
                            physicalWorldMin.Y -= diffY;
                            physicalWorldMax.Y -= diffY;
                            double newWorldMin = axis.PhysicalToWorld(physicalWorldMin, pMin, pMax, false);
                            double newWorldMax = axis.PhysicalToWorld(physicalWorldMax, pMin, pMax, false);
                            axis.WorldMin = newWorldMin;
                            axis.WorldMax = newWorldMax;
                        }
                        if (ps.YAxis2 != null)
                        {
                            Axis axis = ps.YAxis2;
                            PointF pMin = ps.PhysicalYAxis2Cache.PhysicalMin;
                            PointF pMax = ps.PhysicalYAxis2Cache.PhysicalMax;

                            PointF physicalWorldMin = pMin;
                            PointF physicalWorldMax = pMax;
                            physicalWorldMin.Y -= diffY;
                            physicalWorldMax.Y -= diffY;
                            double newWorldMin = axis.PhysicalToWorld(physicalWorldMin, pMin, pMax, false);
                            double newWorldMax = axis.PhysicalToWorld(physicalWorldMax, pMin, pMax, false);
                            axis.WorldMin = newWorldMin;
                            axis.WorldMax = newWorldMax;
                        }

                        lastPoint_ = new Point(e.X, e.Y);

                        ((PlotSurface2D) ctr).InteractionOccured(this);

                        return true;
                    }

                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseUp(MouseEventArgs e, Control ctr)
                {
                    if ((e.Button == MouseButtons.Left) && dragInitiated_)
                    {
                        lastPoint_ = unset_;
                        dragInitiated_ = false;
                    }

                    return false;
                }
            }

            #endregion

            #region HorizontalRangeSelection

            /// <summary>
            /// This plot intraction allows the user to select horizontal regions.
            /// </summary>
            public class HorizontalRangeSelection : Interaction
            {
                private readonly Point unset_ = new Point(-1, -1);
                private Point endPoint_ = new Point(-1, -1);
                private int minimumPixelDistanceForSelect_ = 5;
                private Point previousPoint_ = new Point(-1, -1);
                private bool selectionInitiated_;
                private double smallestAllowedRange_ = double.Epsilon*100.0;
                private Point startPoint_ = new Point(-1, -1);

                /// <summary>
                /// Default constructor
                /// </summary>
                public HorizontalRangeSelection()
                {
                }

                /// <summary>
                /// Constructor
                /// </summary>
                /// <param name="smallestAllowedRange">the smallest distance between the selected xmin and xmax for the selection to be performed.</param>
                public HorizontalRangeSelection(double smallestAllowedRange)
                {
                    smallestAllowedRange_ = smallestAllowedRange;
                }

                /// <summary>
                /// The minimum width of the selected region (in pixels) for the interaction to zoom.
                /// </summary>
                public int MinimumPixelDistanceForSelect
                {
                    get { return minimumPixelDistanceForSelect_; }
                    set { minimumPixelDistanceForSelect_ = value; }
                }

                /// <summary>
                /// The smallest range (distance between world min and world max) selectable.
                /// If a smaller region is selected, the selection will do nothing.
                /// </summary>
                public double SmallestAllowedRange
                {
                    get { return smallestAllowedRange_; }
                    set { smallestAllowedRange_ = value; }
                }

                /// <summary>
                /// Handler for mouse down event for this interaction
                /// </summary>
                /// <param name="e">the mouse event args</param>
                /// <param name="ctr">the plot surface this event applies to</param>
                public override bool DoMouseDown(MouseEventArgs e, Control ctr)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    if (e.X > ps.PlotAreaBoundingBoxCache.Left && e.X < ps.PlotAreaBoundingBoxCache.Right &&
                        e.Y > ps.PlotAreaBoundingBoxCache.Top && e.Y < ps.PlotAreaBoundingBoxCache.Bottom)
                    {
                        // keep track of the start point and flag that select initiated.
                        selectionInitiated_ = true;
                        startPoint_.X = e.X;
                        startPoint_.Y = e.Y;

                        previousPoint_.X = e.X;
                        previousPoint_.Y = e.Y;

                        // invalidate the end point
                        endPoint_ = unset_;

                        return false;
                    }

                    selectionInitiated_ = false;
                    endPoint_ = unset_;
                    startPoint_ = unset_;
                    return false;
                }

                /// <summary>
                /// Handler for mouse move event for this interaction
                /// </summary>
                /// <param name="e">the mouse event args</param>
                /// <param name="ctr">the plot surface this event applies to</param>
                /// <param name="lastKeyEventArgs"></param>
                public override bool DoMouseMove(MouseEventArgs e, Control ctr, KeyEventArgs lastKeyEventArgs)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    // if dragging on axis to zoom.
                    if ((e.Button == MouseButtons.Left) && selectionInitiated_)
                    {
                        Point endPoint_ = previousPoint_;
                        if (e.X > ps.PlotAreaBoundingBoxCache.Left && e.X < ps.PlotAreaBoundingBoxCache.Right &&
                            e.Y > ps.PlotAreaBoundingBoxCache.Top && e.Y < ps.PlotAreaBoundingBoxCache.Bottom)
                        {
                            endPoint_ = new Point(e.X, e.Y);
                            DrawHorizontalSelection(previousPoint_, endPoint_, ctr);
                            previousPoint_ = endPoint_;
                        }
                        else
                        {
                            endPoint_ = new Point(e.X, e.Y);
                            if (e.X < ps.PlotAreaBoundingBoxCache.Left) endPoint_.X = ps.PlotAreaBoundingBoxCache.Left + 1;
                            if (e.X > ps.PlotAreaBoundingBoxCache.Right) endPoint_.X = ps.PlotAreaBoundingBoxCache.Right - 1;
                            DrawHorizontalSelection(previousPoint_, endPoint_, ctr);
                            previousPoint_ = endPoint_;
                        }
                    }

                    return false;
                }

                /// <summary>
                /// Handler for mouse up event for this interaction
                /// </summary>
                /// <param name="e">the mouse event args</param>
                /// <param name="ctr">the plot surface this event applies to</param>
                public override bool DoMouseUp(MouseEventArgs e, Control ctr)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    if ((e.Button == MouseButtons.Left) && selectionInitiated_)
                    {
                        endPoint_.X = e.X;
                        endPoint_.Y = e.Y;
                        if (e.X < ps.PlotAreaBoundingBoxCache.Left) endPoint_.X = ps.PlotAreaBoundingBoxCache.Left + 1;
                        if (e.X > ps.PlotAreaBoundingBoxCache.Right) endPoint_.X = ps.PlotAreaBoundingBoxCache.Right - 1;

                        // flag stopped selecting.
                        selectionInitiated_ = false;

                        if (endPoint_ != unset_)
                        {
                            DrawHorizontalSelection(startPoint_, endPoint_, ctr);
                        }

                        // ignore very small selections
                        if (Math.Abs(endPoint_.X - startPoint_.X) < minimumPixelDistanceForSelect_)
                        {
                            return false;
                        }

                        ((PlotSurface2D) ctr).CacheAxes();

                        // determine the new x axis 1 world limits (and check to see if they are far enough appart).
                        double xAxis1Min = double.NaN;
                        double xAxis1Max = double.NaN;
                        if (ps.XAxis1 != null)
                        {
                            int x1 = Math.Min(endPoint_.X, startPoint_.X);
                            int x2 = Math.Max(endPoint_.X, startPoint_.X);
                            int y = ps.PhysicalXAxis1Cache.PhysicalMax.Y;

                            xAxis1Min = ps.PhysicalXAxis1Cache.PhysicalToWorld(new Point(x1, y), true);
                            xAxis1Max = ps.PhysicalXAxis1Cache.PhysicalToWorld(new Point(x2, y), true);
                            if (xAxis1Max - xAxis1Min < smallestAllowedRange_)
                            {
                                return false;
                            }
                        }

                        // determine the new x axis 2 world limits (and check to see if they are far enough appart).
                        double xAxis2Min = double.NaN;
                        double xAxis2Max = double.NaN;
                        if (ps.XAxis2 != null)
                        {
                            int x1 = Math.Min(endPoint_.X, startPoint_.X);
                            int x2 = Math.Max(endPoint_.X, startPoint_.X);
                            int y = ps.PhysicalXAxis2Cache.PhysicalMax.Y;

                            xAxis2Min = ps.PhysicalXAxis2Cache.PhysicalToWorld(new Point(x1, y), true);
                            xAxis2Max = ps.PhysicalXAxis2Cache.PhysicalToWorld(new Point(x2, y), true);
                            if (xAxis2Max - xAxis2Min < smallestAllowedRange_)
                            {
                                return false;
                            }
                        }

                        // now actually update the world limits.

                        if (ps.XAxis1 != null)
                        {
                            ps.XAxis1.WorldMax = xAxis1Max;
                            ps.XAxis1.WorldMin = xAxis1Min;
                        }

                        if (ps.XAxis2 != null)
                        {
                            ps.XAxis2.WorldMax = xAxis2Max;
                            ps.XAxis2.WorldMin = xAxis2Min;
                        }

                        ((PlotSurface2D) ctr).InteractionOccured(this);

                        return true;
                    }

                    return false;
                }

                private void DrawHorizontalSelection(Point start, Point end, Control ctr)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    // the clipping rectangle in screen coordinates
                    Rectangle clip = ctr.RectangleToScreen(
                        new Rectangle(
                            ps.PlotAreaBoundingBoxCache.X,
                            ps.PlotAreaBoundingBoxCache.Y,
                            ps.PlotAreaBoundingBoxCache.Width,
                            ps.PlotAreaBoundingBoxCache.Height));

                    start = ctr.PointToScreen(start);
                    end = ctr.PointToScreen(end);

                    ControlPaint.FillReversibleRectangle(
                        new Rectangle(Math.Min(start.X, end.X), clip.Y, Math.Abs(end.X - start.X), clip.Height),
                        Color.White);
                }
            }

            #endregion

            #region AxisDrag

            /// <summary>
            /// </summary>
            public class AxisDrag : Interaction
            {
                private readonly bool enableDragWithCtr_;

                private Axis axis_;
                private bool doing_;
                private Point lastPoint_;
                private PhysicalAxis physicalAxis_;
                private float sensitivity_ = 200.0f;
                private Point startPoint_;

                /// <summary>
                /// </summary>
                /// <param name="enableDragWithCtr"></param>
                public AxisDrag(bool enableDragWithCtr)
                {
                    enableDragWithCtr_ = enableDragWithCtr;
                }

                /// <summary>
                /// </summary>
                /// <value></value>
                public float Sensitivity
                {
                    get { return sensitivity_; }
                    set { sensitivity_ = value; }
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseDown(MouseEventArgs e, Control ctr)
                {
                    // if the mouse is inside the plot area [the tick marks are here and part of the 
                    // axis], then don't invoke drag. 
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;
                    if (e.X > ps.PlotAreaBoundingBoxCache.Left && e.X < ps.PlotAreaBoundingBoxCache.Right &&
                        e.Y > ps.PlotAreaBoundingBoxCache.Top && e.Y < ps.PlotAreaBoundingBoxCache.Bottom)
                    {
                        return false;
                    }

                    if ((e.Button == MouseButtons.Left))
                    {
                        // see if hit with axis.
                        ArrayList objects = ps.HitTest(new Point(e.X, e.Y));

                        foreach (object o in objects)
                        {
                            if (o is Axis)
                            {
                                doing_ = true;
                                axis_ = (Axis) o;

                                //PhysicalAxis[] physicalAxisList = new[]
                                //    {ps.PhysicalXAxis1Cache, ps.PhysicalXAxis2Cache, ps.PhysicalYAxis1Cache, ps.PhysicalYAxis2Cache};

                                if (ps.PhysicalXAxis1Cache.Axis == axis_)
                                    physicalAxis_ = ps.PhysicalXAxis1Cache;
                                else if (ps.PhysicalXAxis2Cache.Axis == axis_)
                                    physicalAxis_ = ps.PhysicalXAxis2Cache;
                                else if (ps.PhysicalYAxis1Cache.Axis == axis_)
                                    physicalAxis_ = ps.PhysicalYAxis1Cache;
                                else if (ps.PhysicalYAxis2Cache.Axis == axis_)
                                    physicalAxis_ = ps.PhysicalYAxis2Cache;

                                lastPoint_ = startPoint_ = new Point(e.X, e.Y);

                                return false;
                            }
                        }
                    }

                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                /// <param name="lastKeyEventArgs"></param>
                public override bool DoMouseMove(MouseEventArgs e, Control ctr, KeyEventArgs lastKeyEventArgs)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    // if dragging on axis to zoom.
                    if ((e.Button == MouseButtons.Left) && doing_ && physicalAxis_ != null)
                    {
                        if (enableDragWithCtr_ && lastKeyEventArgs != null && lastKeyEventArgs.Control)
                        {
                        }
                        else
                        {
                            float dist =
                                (e.X - lastPoint_.X) +
                                (-e.Y + lastPoint_.Y);

                            lastPoint_ = new Point(e.X, e.Y);

                            if (dist > sensitivity_/3.0f)
                            {
                                dist = sensitivity_/3.0f;
                            }

                            PointF pMin = physicalAxis_.PhysicalMin;
                            PointF pMax = physicalAxis_.PhysicalMax;
                            double physicalWorldLength = Math.Sqrt((pMax.X - pMin.X)*(pMax.X - pMin.X) + (pMax.Y - pMin.Y)*(pMax.Y - pMin.Y));

                            float prop = (float) (physicalWorldLength*dist/sensitivity_);
                            prop *= 2;

                            ((PlotSurface2D) ctr).CacheAxes();

                            float relativePosX = (startPoint_.X - pMin.X)/(pMax.X - pMin.X);
                            float relativePosY = (startPoint_.Y - pMin.Y)/(pMax.Y - pMin.Y);

                            if (float.IsInfinity(relativePosX) || float.IsNaN(relativePosX)) relativePosX = 0.0f;
                            if (float.IsInfinity(relativePosY) || float.IsNaN(relativePosY)) relativePosY = 0.0f;

                            PointF physicalWorldMin = pMin;
                            PointF physicalWorldMax = pMax;

                            physicalWorldMin.X += relativePosX*prop;
                            physicalWorldMax.X -= (1 - relativePosX)*prop;
                            physicalWorldMin.Y -= relativePosY*prop;
                            physicalWorldMax.Y += (1 - relativePosY)*prop;

                            double newWorldMin = axis_.PhysicalToWorld(physicalWorldMin, pMin, pMax, false);
                            double newWorldMax = axis_.PhysicalToWorld(physicalWorldMax, pMin, pMax, false);
                            axis_.WorldMin = newWorldMin;
                            axis_.WorldMax = newWorldMax;

                            ((PlotSurface2D) ctr).InteractionOccured(this);

                            return true;
                        }
                    }

                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseUp(MouseEventArgs e, Control ctr)
                {
                    if (doing_)
                    {
                        doing_ = false;
                        axis_ = null;
                        physicalAxis_ = null;
                        lastPoint_ = new Point();
                    }

                    return false;
                }
            }

            #endregion

            #region MouseWheelZoom

            /// <summary>
            /// </summary>
            public class MouseWheelZoom : Interaction
            {
                //private Point point_ = new Point(-1, -1);
                private float sensitivity_ = 60.0f;

                /// <summary>
                /// Number of screen pixels equivalent to one wheel step.
                /// </summary>
                public float Sensitivity
                {
                    get { return sensitivity_; }
                    set { sensitivity_ = value; }
                }

                //private bool mouseDown_ = false;

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseUp(MouseEventArgs e, Control ctr)
                {
                    //mouseDown_ = false;
                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseDown(MouseEventArgs e, Control ctr)
                {
                    //NPlot.PlotSurface2D ps = ((Windows.PlotSurface2D)ctr).Inner;

                    //if (e.X > ps.PlotAreaBoundingBoxCache.Left && e.X < ps.PlotAreaBoundingBoxCache.Right &&
                    //    e.Y > ps.PlotAreaBoundingBoxCache.Top && e.Y < ps.PlotAreaBoundingBoxCache.Bottom)
                    //{
                    //    point_.X = e.X;
                    //    point_.Y = e.Y;
                    //    mouseDown_ = true;
                    //}
                    return false;
                }

                /// <summary>
                /// </summary>
                /// <param name="e"></param>
                /// <param name="ctr"></param>
                public override bool DoMouseWheel(MouseEventArgs e, Control ctr)
                {
                    NPlot.PlotSurface2D ps = ((PlotSurface2D) ctr).Inner;

                    ((PlotSurface2D) ctr).CacheAxes();

                    float delta = e.Delta/(float) e.Delta;
                    delta *= sensitivity_;

                    Axis axis = null;
                    PointF pMin = PointF.Empty;
                    PointF pMax = PointF.Empty;
                    KeyEventArgs keyArgs = ((PlotSurface2D) ctr).lastKeyEventArgs_;
                    bool zoom = (keyArgs != null && keyArgs.Control);

                    if (keyArgs != null && keyArgs.Shift)
                    {
                        axis = ps.YAxis1;
                        pMin = ps.PhysicalYAxis1Cache.PhysicalMin;
                        pMax = ps.PhysicalYAxis1Cache.PhysicalMax;
                    }
                    else
                    {
                        axis = ps.XAxis1;
                        pMin = ps.PhysicalXAxis1Cache.PhysicalMin;
                        pMax = ps.PhysicalXAxis1Cache.PhysicalMax;
                    }
                    if (axis == null) return false;

                    PointF physicalWorldMin = pMin;
                    PointF physicalWorldMax = pMax;
                    physicalWorldMin.X -= delta;
                    physicalWorldMax.X -= (zoom) ? -delta : delta;
                    physicalWorldMin.Y += delta;
                    physicalWorldMax.Y += (zoom) ? -delta : delta;
                    double newWorldMin = axis.PhysicalToWorld(physicalWorldMin, pMin, pMax, false);
                    double newWorldMax = axis.PhysicalToWorld(physicalWorldMax, pMin, pMax, false);
                    axis.WorldMin = newWorldMin;
                    axis.WorldMax = newWorldMax;

                    ((PlotSurface2D) ctr).InteractionOccured(this);

                    return true;
                }
            }

            #endregion
        }
    }
}