First, amazing library, I was able to swap out core-plot and had OxyPlot up and running in my iOS application in a couple of hours.

I am having a bit of an issue with the generated graphs, and maybe I'm missing something simple, but all of the graphs created on the simulator and on the devices appear blurry. See the attached screen shot:



Thoughts? Thanks!

I think the problem was that the example used an UIScrollView to show the plot. I am currently refactoring the iOS port. A much better Plot view will be available soon!

Excited to see it!

Let me know if you need help with device testing.

Yes, help on device testing (particularly older iOS devices) would be great.
I am currently trying to fix the image rendering (having some issues on partial image drawing) and touch events (depends on https://oxyplot.codeplex.com/workitem/9625) on the iOS control.

I have pushed the current version of the iOS control to default. The new version should not be blurry, and should also render aliased (e.g. axis/grid lines) much nicer. Can you check this on your devices?
There are still some issues remaining on image drawing and text rendering (should use Core Text). Also the touch events are not handled (waiting for #9625 to be pulled in).

I just pulled down the latest default, and my graphs now look great using the new iOS control PlotView. The example app looks great, as well as my own app where I swapped out core-plot for Oxyplot.

As for hardware I tested with what I had on hand, a 5s and iPad3.

I ran Instruments against the iPad3 in debug mode, and was happy to see memory and CPU usage were both super low. As a comparison, doing the same exact work using core-plot on the iPad would either result in a soft reset because I consumed 300 MB of memory, or 100% CPU usage for a prolonged period of time while rendering three plots.

Did the Xamarin.Android project get the same treatment, or was this not a problem on the Android side?

I have not tested Xamarin.Android yet, will do this when I am finished with iOS.

Hi,

First of all, thank you very much for this great chart library.
I'm having a problem while attempting to change the color of the selected marker in a line series. Is this possible at all, or it is a not-supported feature?

I've tried to modify the "LineSeries and PlotModel MouseDown event" example, simply adding the following lines

        model.SelectionColor = OxyColors.Red;
        s1.SelectionMode = SelectionMode.Single;
        s1.ItemsSource = s1.Points;

and inside the MouseDown event handler

                // Check if we are near a point
                if ((nearestPoint - e.Position).Length < 10)
                {
                    // Start editing this point
                    indexOfPointToMove = indexOfNearestPoint;
                    s1.SelectItem(indexOfPointToMove);
                }

This doesn't seem to work. Is there something that I'm missing?

Last thing, why do we have to change the color at model level? Isn't more flexible doing it a series level? That is we could also have more control on the stroke of the selected item.

Thanks,
Fabio

After tracing it back through the source, it does seem to flag the item properly (all the way back in Selection.cs). Are you refreshing the plot after you select the item? (InvalidatePlot(false) on the view or model). The mouse event will change the flag but it won't actually display anything on it's own unless you tell the view to update manually.

Also imo at least selection colour should be global to the model itself, not series. I can't really think of a reason you'd want multiple different selection colours unless you're selecting different items for different actions.

Yes, the model get invalidated (the lines of code I've added are from on of the examples).
If you see that the flag set properly. then, or it is ignored, or the color is overwritten when the line series get rendered, I imagine.

The reason was for aesthetics, as I might have 2 or more series on the same plot, and I might want to highlight each marker based on the original marker color, or with different colors for quick distinguish with a quick look. (I'm assuming here that you can have multiple items selected on the same plot from different series)

Anyway I solved it creating a scattered series that "clones" some information from the selected marker's series and paint a scattered item on top of it.

Thank you for the help.

Well when it's the Selection object itself then it just has a boolean flag, but when it's a point in it, the Selection object has an array of bools that it flags with the index given to it. (Source Link).

That sounds more like a use for highlighting, not selection, although I do agree, I think highlighting should be drawn around (probably harder than it sounds or based on the original colour). It does look a bit weird in the Toolbar example I put together when you change the colour of an annotation and it just remains shiny yellow, would be nice to have it based on the colour it is, as you mention.

Hello,
Thank for your free code. It's seem to be very beautiful.
I've to make an application for an hydraulic bench. It's write under vb.net 2012 WPF.
I've not found any example under vb.net.
I try this :
xaml.vb
Private Sub Window_SourceInitialized_1(sender As Object, e As EventArgs)

    Dim Mesures As New ObservableCollection(Of Mesure)

    For j As Integer = 0 To 25
        Dim Mes As New Mesure
        Mes.Temps = 10 * j
        Mes.Value = 2 * j
        Mes.Maximum = 2 * j + 1
        Mes.Maximum = 2 * j - 1
        Mesures.Add(Mes)
    Next j

    Courb.DataContext = Mesures
End Sub

XAML
<Window x:Class="Fene_Courbe"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:oxy="clr-namespace:OxyPlot.Wpf;assembly=OxyPlot.Wpf"
      Title="COURBES" Height="600" Width="800" Closing="Window_Closing_1" Topmost="True" SourceInitialized="Window_SourceInitialized_1" ContentRendered="Window_ContentRendered_1">

    <Grid>
    <oxy:Plot x:Name="Courb" Title="Courbes" LegendPlacement="Outside" LegendPosition="RightTop" LegendOrientation="Vertical">
        <oxy:Plot.Series>
            <oxy:LineSeries x:Name="CPR1" DataContext="Mesures" Title="PR1"  DataFieldX="Temps" DataFieldY="Value"  ItemsSource="{Binding Items}" StrokeThickness="2" Color="Red" ></oxy:LineSeries>
            <oxy:LineSeries x:Name="CMax" DataContext="Mesures"  Title="Max"  DataFieldX="Temps" DataFieldY="Maximum"  ItemsSource="{Binding Items}" StrokeThickness="2"  Color="Green" ></oxy:LineSeries>
            <oxy:LineSeries x:Name="CMin" DataContext="Mesures"  Title="Min"  DataFieldX="Temps" DataFieldY="Minimum"  ItemsSource="{Binding Items}" StrokeThickness="2"  Color="Violet" ></oxy:LineSeries>
        </oxy:Plot.Series>
    </oxy:Plot>
</Grid>

</Window>

I have a frame with axis and legends for the 3 curves, but no curve.
1- Is anyone can help me ?
2- Can i use also data from a dataset ?
3- Where can i find an vb.net WPF example ?

Thanks by advance
Laurent

Sorry, there are no VB.NET examples here, I have no experience with VB.
I have not tried with a DataSet yet, but it would be interesting to see if that works! Will add an example (in C#) later.

Thanks for answer,

i continue my tries...

Laurent

Find, i've find. It's very fun and very easy. Thank a lot for this library.

I give you my vb code

Public Class Mesure

    Implements INotifyPropertyChanged

    Private _Temps As Double
    Private _Mesure1 As Double
    Private _Mesure2 As Double
    Private _Mesure3 As Double

    Public Sub New()
        _Temps = 0.0
        _Mesure1 = 0.0
        _Mesure2 = 0.0
        _Mesure3 = 0.0
    End Sub

    Public Overrides Function ToString() As String
        Return Format(_Temps, "{0:##0.00}") & " " & Format(_Mesure1, "{1:# ##0.00}") & " " & Format(_Mesure2, "{2:# ##0.00}") & " " & Format(_Mesure3, "{3:# ##0.00}") 
    End Function

    Private Sub NotifyPropertyChanged(<CallerMemberName()> Optional ByVal propertyName As String = Nothing)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
    End Sub

    Public Property Temps() As Double
        Get
            Return _Temps
        End Get

        Set(ByVal value As Double)
            _Temps = value
            NotifyPropertyChanged()
        End Set
    End Property
    Public Property Mesure1() As Double
        Get
            Return _Mesure1
        End Get

        Set(ByVal value As Double)
            _Mesure1 = value
            NotifyPropertyChanged()
        End Set
    End Property
    Public Property Mesure2() As Double
        Get
            Return _Mesure2
        End Get

        Set(ByVal value As Double)
            _Mesure2 = value
            NotifyPropertyChanged()
        End Set
    End Property
    Public Property Mesure3() As Double
        Get
            Return _Mesure3
        End Get

        Set(ByVal value As Double)
            _Mesure3 = value
            NotifyPropertyChanged()
        End Set
    End Property

    Public Event PropertyChanged(sender As Object, e As PropertyChangedEventArgs) Implements INotifyPropertyChanged.PropertyChanged
End Class

MainWindow.xaml.vb

  Public Mesures As New Collection(Of Mesure)


.....
  For k As Double = 0 To 1 Step 0.00001
    Mesures.Add(New Mesure With {.Temps = k, .Mesure1 = Sin(15 * k) * 500, .Mesure2 = Cos(10 * k) * 250, .Mesure3 = Sin(8 * k) * 100)
  Next k
......

Fene_Courbe.xaml

<Window x:Class="Fene_Courbe"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="COURBES" Height="600" Width="800" Closing="Window_Closing_1" Topmost="True"
    xmlns:oxy="clr-namespace:OxyPlot;assembly=OxyPlot"
    xmlns:oxywpf="clr-namespace:OxyPlot.Wpf;assembly=OxyPlot.Wpf" SourceInitialized="Window_SourceInitialized_1">
<Grid>
    <oxywpf:Plot x:Name="Courbes" Title="Courbes" Background="Beige">
        <oxywpf:LineSeries x:Name="PR1" Color="Red" Title="PR1" DataFieldX="Temps" DataFieldY="Mesure1" ItemsSource="{Binding Mesures}" ></oxywpf:LineSeries>
        <oxywpf:LineSeries x:Name="PR2" Color="Blue"  Title="PR2" DataFieldX="Temps" DataFieldY="Mesure2" ItemsSource="{Binding Mesures}" ></oxywpf:LineSeries>
        <oxywpf:LineSeries x:Name="DB1" Color="Green"  Title="DB1" DataFieldX="Temps" DataFieldY="Mesure3" ItemsSource="{Binding Mesures}" ></oxywpf:LineSeries>
    </oxywpf:Plot>
</Grid>

</Window>



Fene_Courbe.xaml.vb

Imports OxyPlot
Imports OxyPlot.Series
Imports System.Collections
Imports System.Collections.Generic
Imports System.Linq
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Navigation
Imports System.Windows.Shapes

Public Class Fene_Courbe

Private Sub Window_SourceInitialized_1(sender As Object, e As EventArgs)
    Courbes.Series().Item(0).ItemsSource = Mesures
    Courbes.Series().Item(1).ItemsSource = Mesures
    Courbes.Series().Item(2).ItemsSource = Mesures
End Sub

End Class

Hello again,

I have observe a misbehavior when I set
PlotType = PlotType.Cartesian

When my application re-sizes reducing it's size, the plot also re size with proper proportion.
But when the application re-sizes increasing it's size, the plot re size itself but keeps proportion as it is.

Kindly let me know how can I avoid this issue.

Thanks.

From the Axes documentation:

Adding axes in XAML
<oxy:Plot Title="Linear axes">
    <oxy:Plot.Axes>
        <oxy:LinearAxis Position="Bottom" Minimum="-20" Maximum="80" />
        <oxy:LinearAxis Position="Left" Minimum="-10" Maximum="10" />
     </oxy:Plot.Axes>
</oxy:Plot>

Adding axes to a PlotModel
var model=new PlotModel();
model.Axes.Add(new LinearAxis(AxisPosition.Bottom,-20,80));
model.Axes.Add(new LinearAxis(AxisPosition.Left,-10,10));

But, what if I want to bind from the XAML to an axis ?!

more to the point, the reason was I wanted to see if I can make two charts share an axis, so moving one will move the other ...

Ideas? Suggestions?

To do this with binding, we need to add ActualMinimum and ActualMaximum dependency properties (one-way).
https://oxyplot.codeplex.com/workitem/10096

In the current implementation, you can subscribe to the AxisChanged event on the axis (not yet available on the Wpf.Axis class), read the ActualMinimum and ActualMaximum and use the Zoom(x0,x1) method to set the range on the other axis.

The AxisChanged routed event is registered at
https://oxyplot.codeplex.com/workitem/9992

Also remember to invalidate the plot every time the values are changed.

when using DateTimeAxis,I found a question.
bottomAxis[i] = new DateTimeAxis(AxisPosition.Bottom, "时间", "yyyy/MM/dd\nhh:mm:ss", DateTimeIntervalType.Milliseconds);
bottomAxis[i].MajorStep = 1.0 / 3600 / 24;
bottomAxis[i].MinorStep = 1.0 / 3600 / 24 / 10;
bottomAxis[i].ShowMinorTicks = true;
I want to set MajorStep=1 second and Minorstep=0.1 second.when I started,the DateTimeInterval was correct.
But when I set :
bottomAxis[i].Maximum = DateTimeAxis.ToDouble(DateTime.Now);
bottomAxis[i].Minimum = DateTimeAxis.ToDouble(DateTime.Now.AddMinutes(-1));
the DateTimeInterval become 9 Second per step.Why?
Please revert. Thanks in advance.

Regards

Hello,

I don't know if this bug has already been reported.

I'm currently using OxyPlot with .net 3.5 with Windows Forms and I'm using the heatmapseries with contour series. (The bug happens with the heatmapseries)

When I plot a grid of 400x400, it takes a few seconds to plot and the user has time to interact with the application.

So I reveive an Unhandled Exception everytime I try to Pan the plot before the chart was actually plotted :

System.NullReferenceException: Object reference not set to an instance of an object.
at OxyPlot.Series.XYAxisSeries.InverseTransform(ScreenPoint p) in c:\Users\jmbegin\Desktop\Oxyplot\oxyplot_36df819096f6\Source\OxyPlot\Series\XYAxisSeries.cs:line 126
at OxyPlot.Series.HeatMapSeries.GetNearestPoint(ScreenPoint point, Boolean interpolate) in c:\Users\jmbegin\Desktop\Oxyplot\oxyplot_36df819096f6\Source\OxyPlot\Series\HeatMapSeries.cs:line 252
at OxyPlot.Series.Series.HitTest(ScreenPoint point, Double tolerance) in c:\Users\jmbegin\Desktop\Oxyplot\oxyplot_36df819096f6\Source\OxyPlot\Series\Series.cs:line 123
at OxyPlot.PlotModel.HandleMouseDown(Object sender, OxyMouseEventArgs e) in c:\Users\jmbegin\Desktop\Oxyplot\oxyplot_36df819096f6\Source\OxyPlot\PlotModel\PlotModel.MouseEvents.cs:line 82
at OxyPlot.WindowsForms.Plot.OnMouseDown(MouseEventArgs e) in c:\Users\jmbegin\Desktop\Oxyplot\oxyplot_36df819096f6\Source\OxyPlot.WindowsForms\Plot.cs:line 482
at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Using a debugger, I tracked the source of the bug. As the exception info said, it happens in HeatMapSeries.GetNearestPoint when it calls this.InverseTransform

    public DataPoint InverseTransform(ScreenPoint p)
    {
           return this.XAxis.InverseTransform(p.X, p.Y, this.YAxis);
    }

Where my XAxis and YAxis are null, which explains the NullReferenceException

I solved this problem for my project by adding

        if (this.XAxis == null || this.YAxis == null) return null;

In the HeatMapSeries.GetNearestPoint so we don't encounter the null reference exception.

This does not have the exact behavior I wanted as it seem to execute all the pans done while not plotted once it plotted, so it's a weird animation.
But for my project, it is enough as it's a rare condition and it still gives the result I want.

Are you updating/rendering on multiple threads?
I could not reproduce this bug in the example browser (using WinForms and .NET 4.0).

We can add the test to the HeatMapSeries.GetNearestPoint, but I suspect this is not the only place.
Maybe it would be better to handle this in the PlotModel.HandleMouseDown method - if the plot model is not updated it should not try to perform the hit testing. It is probably more code than the single null reference test, but could solve similar problems in other series.

Humm yes, I added added recently code to generate my PlotModel in a different thread to try and reduce the time the application is hanging.
Although, I'm adding the PlotModel to the Plot.Model only after the thread joined the main one.

I tried removing all the threading I added and the bug still happens.
I also got the same issue with ContourSeries.GetNearestPoint where I added the same fix "if (this.XAxis == null || this.YAxis == null) return null;"

I also tried to reproduce with the example browser and I didn't reproduce it, I'm still investigating on my side to see what is wrong,

Hello objo,
after a lot of searching and testing, it really seems like a timing problem where the mousedown event gets triggered before the plotModel is fully updated.
I've had tests that if I stopped the application the problem would not happen like if the delay I gave was enough to let the update get done before the mousedown event.

I've also suceeded in reproducing the bug with the createpeaks exemple in .net 4.5 by adding calculating delay before the update.

To reproduce you can add the loop before adding the model. I saw it happened like that if you can pan before it's plotted.

        private void InitPlot()
        {
            int count = 0;
            for (int i = 0; i < 10000; i++)
            {
                count += i;
                for (int j = 0; j < 10000; j++)
                {
                    if (count > 0)
                        count -= j;
                    else
                        count += j;
                }
            }
            plot1.Model = vm.SelectedExample != null ? vm.SelectedExample.PlotModel : null;
            plot1.BackColor = vm.PlotBackground;
        }

Else what I did first was to modify the WindowsFormsDemo by adding a button to refresh and the calculating Delay :

namespace WindowsFormsDemo
{
    using System;
    using System.Drawing;
    using System.Windows.Forms;

    using OxyPlot;
    using OxyPlot.Axes;
    using OxyPlot.Series;

    public partial class Form1 : Form
    {
        Button refreshButton;
        public Form1()
        {
            InitializeComponent();

            refreshButton = new Button();
            refreshButton.Location = new Point(this.Width / 2, 30);
            refreshButton.Click += refreshButton_Click;
            this.Controls.Add(refreshButton);
            plot1.SendToBack();

            plot1.Model = CreatePeaks();
        }

        public void refreshButton_Click(object sender, EventArgs e)
        {
            int count = 0;
            for (int i = 0; i < 10000; i++)
            { 
                count += i;
                for (int j = 0; j < 10000; j++)
                {
                    if (count > 0)
                        count -= j;
                    else
                        count += j;
                }
            }
            refreshButton.Text = count.ToString();
            plot1.Model = CreatePeaks();
        }

        public static PlotModel CreatePeaks(OxyPalette palette = null, bool includeContours = true)
        {
            double x0 = -3.1;
            double x1 = 3.1;
            double y0 = -3;
            double y1 = 3;
            Func<double, double, double> peaks = (x, y) => 3 * (1 - x) * (1 - x) * Math.Exp(-(x * x) - (y + 1) * (y + 1)) - 10 * (x / 5 - x * x * x - y * y * y * y * y) * Math.Exp(-x * x - y * y) - 1.0 / 3 * Math.Exp(-(x + 1) * (x + 1) - y * y);
            var xvalues = ArrayHelper.CreateVector(x0, x1, 400);
            var yvalues = ArrayHelper.CreateVector(y0, y1, 400);
            var peaksData = ArrayHelper.Evaluate(peaks, xvalues, yvalues);

            var model = new PlotModel("Peaks");
            model.Axes.Add(new LinearColorAxis { Position = AxisPosition.Right, Palette = palette ?? OxyPalettes.Jet(500), HighColor = OxyColors.Gray, LowColor = OxyColors.Black });

            var hms = new HeatMapSeries { X0 = x0, X1 = x1, Y0 = y0, Y1 = y1, Data = peaksData };
            model.Series.Add(hms);
            if (includeContours)
            {
                var cs = new ContourSeries
                {
                    Color = OxyColors.Black,
                    FontSize = 0,
                    ContourLevelStep = 1,
                    LabelBackground = OxyColors.Undefined,
                    ColumnCoordinates = yvalues,
                    RowCoordinates = xvalues,
                    Data = peaksData
                };
                model.Series.Add(cs);
            }

            return model;
        }
    }
}

I think i have an issue with something related to this.

<Exception><ExceptionType>System.NullReferenceException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Referencia a objeto no establecida como instancia de un objeto.</Message><StackTrace>   en OxyPlot.ScreenPointHelper.FindNearestPointOnPolyline(ScreenPoint point, IList`1 points) en c:\TeamCity\buildAgent\work\3b9fcf1ba397d0ed\Source\OxyPlot\Rendering\ScreenPointHelper.cs:línea 56
   en OxyPlot.Annotations.PathAnnotation.HitTest(ScreenPoint point, Double tolerance) en c:\TeamCity\buildAgent\work\3b9fcf1ba397d0ed\Source\OxyPlot\Annotations\PathAnnotation.cs:línea 424
   en OxyPlot.PlotModel.HandleMouseDown(Object sender, OxyMouseEventArgs e) en c:\TeamCity\buildAgent\work\3b9fcf1ba397d0ed\Source\OxyPlot\PlotModel\PlotModel.MouseEvents.cs:línea 86
   en OxyPlot.WindowsForms.Plot.OnMouseDown(MouseEventArgs e) en c:\TeamCity\buildAgent\work\3b9fcf1ba397d0ed\Source\OxyPlot.WindowsForms\Plot.cs:línea 397
   en System.Windows.Forms.Control.WmMouseDown(Message&amp;amp; m, MouseButtons button, Int32 clicks)
   en System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
   en System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   en System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
   en System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   en System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   en System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   en QCEP.Program.Main() en c:\Users\gbaquedano\Documents\Visual Studio 2013\Projects\QCEP\QCEP\Program.cs:línea 20
   en System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   en System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext, String[] activationCustomData)
   en Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone()
   en System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   en System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   en System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   en System.Threading.ThreadHelper.ThreadStart()</StackTrace><ExceptionString>System.NullReferenceException: Referencia a objeto no establecida como instancia de un objeto.
   en OxyPlot.ScreenPointHelper.FindNearestPointOnPolyline(ScreenPoint point, IList`1 points) en c:\TeamCity\buildAgent\work\3b9fcf1ba397d0ed\Source\OxyPlot\Rendering\ScreenPointHelper.cs:línea 56
   en OxyPlot.Annotations.PathAnnotation.HitTest(ScreenPoint point, Double tolerance) en c:\TeamCity\buildAgent\work\3b9fcf1ba397d0ed\Source\OxyPlot\Annotations\PathAnnotation.cs:línea 424
   en OxyPlot.PlotModel.HandleMouseDown(Object sender, OxyMouseEventArgs e) en c:\TeamCity\buildAgent\work\3b9fcf1ba397d0ed\Source\OxyPlot\PlotModel\PlotModel.MouseEvents.cs:línea 86
   en OxyPlot.WindowsForms.Plot.OnMouseDown(MouseEventArgs e) en c:\TeamCity\buildAgent\work\3b9fcf1ba397d0ed\Source\OxyPlot.WindowsForms\Plot.cs:línea 397
   en System.Windows.Forms.Control.WmMouseDown(Message&amp;amp; m, MouseButtons button, Int32 clicks)
   en System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
   en System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   en System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
   en System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   en System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   en System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)

Issue happens when you click the plot when it is drawing and hasn't finished. The click event gets triggered even the model is not fully updated.
If you wait for it to finish (like 100ms in my current test) you dont get the crash.

It does sound exactly like what I had.
I also specified how to solve this quickly and locally by adding null reference checks directly in the library in the getNearestPoint functions or in your case FindNearestPointOnPolyline.

The ideal solution would be as objo said :

Maybe it would be better to handle this in the PlotModel.HandleMouseDown method - if the plot model is not updated it should not try to perform the hit testing.

You can see for yourself which one you want to implement.

I don't have time to look into this myself, but if I'm not the only one that had this bug it would be a good idea to create an issue about it.

jmprog: thanks for providing the code to reproduce the error. I have added the issue: https://oxyplot.codeplex.com/workitem/10138