This examples showcases the performance of SciChart when rendering a real-time FIFO chart on 50 SciChartSurface instances at the same time.

SciChartSurface controls are loaded in an ItemsControl (using DataTemplates, MVVM) and bound to a real-time source of data. The data is pushed in at a phenomenal rate and the chart updates in real-time.

The scrolling effect is achieved by using FIFO Dataseries, which automatically discard old points once a threshold is met. Useful for ECG style monitoring applications!

Documentation Links

• DataSeries.FifoCapacity property
• Performance Tips and Tricks

// EEGExampleView.xaml

<UserControl x:Class="SciChart.Examples.Examples.CreateRealtimeChart.EEGChannelsDemo.EEGExampleView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:ext="http://schemas.abtsoftware.co.uk/scichart/exampleExternals"
             xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             xmlns:s="http://schemas.abtsoftware.co.uk/scichart"
             d:DesignHeight="400"
             d:DesignWidth="600"
             mc:Ignorable="d">

    <i:Interaction.Triggers>
        <i:EventTrigger EventName="Loaded">
            <i:InvokeCommandAction Command="{Binding StartCommand}" />
        </i:EventTrigger>

        <i:EventTrigger EventName="Unloaded">
            <i:InvokeCommandAction Command="{Binding StopCommand}" />
        </i:EventTrigger>
    </i:Interaction.Triggers>

    <UserControl.Resources>

        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="/SciChart.Examples.ExternalDependencies;component/Resources/Styles/MergedResources.xaml" />
                <ResourceDictionary Source="/SciChart.Examples.ExternalDependencies;component/Resources/Styles/ToolbarButtonsCommon.xaml" />
            </ResourceDictionary.MergedDictionaries>

            <!--  ItemTemplate for EEG Channels. Create a single SciChartSurface instance per EEGChannelViewModel  -->
            <DataTemplate x:Key="ChannelItemTemplate">

                <Grid IsHitTestVisible="False">
                  <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto" SharedSizeGroup="Name" />
                    <ColumnDefinition Width="*" />
                  </Grid.ColumnDefinitions>

                  <TextBlock Margin="10,0"
                             Foreground="White"
                             Text="{Binding ChannelName}" />

                  <!-- Declare the SciChartSurface. We use RenderPriority=Low to put rendering below mouse input and keep the app responsive -->
                  <s:SciChartSurface Grid.Column="1"
                                     Height="20"
                                     HorizontalAlignment="Stretch"
                                     Padding="0">

                    <!--  Declare RenderableSeries, which are mapped to DataSet Series 1:1 and in order  -->
                    <s:SciChartSurface.RenderableSeries>
                      <s:FastLineRenderableSeries AntiAliasing="False"
                                                  DataSeries="{Binding ChannelDataSeries}"
                                                  ResamplingMode="None"
                                                  Stroke="{Binding Stroke,
                                                                              Mode=OneWay}">
                        <s:FastLineRenderableSeries.RolloverMarkerTemplate>
                          <ControlTemplate>
                            <Ellipse Width="7"
                                     Height="7"
                                     Fill="White" />
                          </ControlTemplate>
                        </s:FastLineRenderableSeries.RolloverMarkerTemplate>
                      </s:FastLineRenderableSeries>
                    </s:SciChartSurface.RenderableSeries>

                    <!--  Axes are created implicitly when a dataset is created, but we override them here so we can style them  -->
                    <s:SciChartSurface.XAxis>
                      <s:NumericAxis AutoRange="Always"
                                     DrawMajorGridLines="False"
                                     DrawMinorGridLines="False"
                                     DrawMajorBands="False"
                                     Visibility="Collapsed">
                        <s:NumericAxis.GrowBy>
                          <s:DoubleRange Max="0" Min="0" />
                        </s:NumericAxis.GrowBy>
                      </s:NumericAxis>
                    </s:SciChartSurface.XAxis>
                    <s:SciChartSurface.YAxis>
                      <s:NumericAxis AutoRange="Always"
                                     DrawMajorGridLines="False"
                                     DrawMinorGridLines="False"
                                     DrawMajorBands="False"
                                     Visibility="Collapsed" />
                    </s:SciChartSurface.YAxis>

                  </s:SciChartSurface>
                </Grid>
            </DataTemplate>

            <!--  Style per ListBoxItem to ensure the chart stretches to fit  -->
            <Style x:Key="ChannelListBoxItemStyle" TargetType="ListBoxItem">
                <Setter Property="HorizontalContentAlignment" Value="Stretch" />
                <Setter Property="Margin" Value="3,0,3,0"/>
                <Setter Property="Padding" Value="0"/>
            </Style>

            <!--  Style for Stats  -->
            <Style x:Key="StatsStyle" TargetType="TextBlock">
                <Setter Property="FontSize" Value="26" />
                <Setter Property="Margin" Value="0" />
                <Setter Property="FontWeight" Value="Normal" />
                <Setter Property="Foreground" Value="#BBFC9C29" />
                <Setter Property="FontFamily" Value="/Resources/Fonts/#Neuropol Regular" />
            </Style>

            <s:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
        </ResourceDictionary>

    </UserControl.Resources>

    <Grid x:Name="LayoutRoot">

        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>

        <Border Panel.ZIndex="9999"
                Background="#FF232426"
                BorderBrush="#323539"
                BorderThickness="0,0,2,0">
            <WrapPanel HorizontalAlignment="Right" Orientation="Vertical">

                <!--  Define the Toolbar  -->
                <ToggleButton Command="{Binding StartCommand}"
                              Content="Play"
                              Style="{StaticResource PlayButtonStyle}"
                              ToolTip="Play"
                              s:ToggleButtonExtensions.GroupName="RealTimeEEG" />

                <ToggleButton Command="{Binding StopCommand}"
                              x:Name="StopButton"
                              Content="Pause"
                              Style="{StaticResource PauseButtonStyle}"
                              ToolTip="Pause"
                              s:ToggleButtonExtensions.GroupName="RealTimeEEG" />

                <ToggleButton Command="{Binding ResetCommand}"
                              x:Name="ResetButton"
                              Content="Stop"
                              Style="{StaticResource StopButtonStyle}"
                              ToolTip="Stop"
                              s:ToggleButtonExtensions.GroupName="RealTimeEEG" />

                <ext:FlyoutMenuButton x:Name="IntervalFlyoutMenuButton"
                                      HorizontalAlignment="Left"
                                      Content="Interval"
                                      Style="{StaticResource FlyoutMenuButtonStyle}"
                                      ToolTipService.ToolTip="Interval (ms)">

                    <ext:FlyoutMenuButton.PopupContent>
                        <StackPanel MinWidth="150" Orientation="Vertical">

                            <TextBlock Margin="3"
                                       HorizontalAlignment="Left"
                                       Foreground="White"
                                       Text="Interval (ms): " />

                            <Slider MinWidth="100"
                                    DataContext="{Binding}"
                                    IsEnabled="{Binding IsRunning,
                                                        Converter={StaticResource BooleanToVisibilityConverter},
                                                        ConverterParameter=INVERSE}"
                                    Maximum="100"
                                    Minimum="10"
                                    Value="{Binding TimerInterval,
                                                    Mode=TwoWay}">
                                <ToolTipService.ToolTip>
                                    <StackPanel Orientation="Horizontal">
                                        <TextBlock Foreground="#222222" Text="{Binding TimerInterval}" />
                                        <TextBlock Foreground="#222222" Text=" ms" />
                                    </StackPanel>
                                </ToolTipService.ToolTip>
                            </Slider>

                        </StackPanel>
                    </ext:FlyoutMenuButton.PopupContent>
                </ext:FlyoutMenuButton>

                <ext:FlyoutMenuButton x:Name="PointsFlyoutMenuButton"
                                      HorizontalAlignment="Left"
                                      Content="Points"
                                      Style="{StaticResource FlyoutMenuButtonStyle}"
                                      ToolTipService.ToolTip="Points per Tick">

                    <ext:FlyoutMenuButton.PopupContent>
                        <StackPanel MinWidth="150" Orientation="Vertical">

                            <TextBlock Margin="3"
                                       VerticalAlignment="Center"
                                       Foreground="White"
                                       Text="Points per Tick: " />

                            <Slider MinWidth="100"
                                    DataContext="{Binding}"
                                    IsEnabled="{Binding IsRunning,
                                                        Converter={StaticResource BooleanToVisibilityConverter},
                                                        ConverterParameter=INVERSE}"
                                    Maximum="100"
                                    Minimum="10"
                                    Value="{Binding BufferSize,
                                                    Mode=TwoWay}">
                                <ToolTipService.ToolTip>
                                    <StackPanel Orientation="Horizontal">
                                        <TextBlock Foreground="#222222" Text="{Binding BufferSize}" />
                                        <TextBlock Foreground="#222222" Text=" Points/Tick" />
                                    </StackPanel>
                                </ToolTipService.ToolTip>
                            </Slider>

                        </StackPanel>
                    </ext:FlyoutMenuButton.PopupContent>
                </ext:FlyoutMenuButton>

            </WrapPanel>
        </Border>

        <!--  Define the listbox which will host the N channels of the EEG  -->
        <ListBox Grid.Column="1"
                 Background="#1c1c1e"
                 BorderThickness="0"
                 ItemContainerStyle="{StaticResource ChannelListBoxItemStyle}"
                 ItemTemplate="{StaticResource ChannelItemTemplate}"
                 ItemsSource="{Binding ChannelViewModels}"
                 Grid.IsSharedSizeScope="True"
                 ScrollViewer.HorizontalScrollBarVisibility="Disabled" />

        <!--  Define the Stats Panel  -->
        <Grid Grid.Column="1"
              Margin="40,40,0,0"
              HorizontalAlignment="Left"
              VerticalAlignment="Top">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto" />
                <ColumnDefinition Width="60" />
                <ColumnDefinition Width="Auto" />
                <ColumnDefinition Width="Auto" />
            </Grid.ColumnDefinitions>
            <TextBlock Grid.Column="0"
                       HorizontalAlignment="Left"
                       VerticalAlignment="Top"
                       Style="{StaticResource StatsStyle}"
                       Text="FPS: " />
            <TextBlock Name="fpsCounter"
                       Grid.Column="1"
                       HorizontalAlignment="Left"
                       VerticalAlignment="Top"
                       Style="{StaticResource StatsStyle}" />
            <TextBlock Grid.Column="2"
                       Margin="10,0,0,0"
                       HorizontalAlignment="Left"
                       VerticalAlignment="Top"
                       Style="{StaticResource StatsStyle}"
                       Text="Point Count: " />
            <TextBlock Name="pointCount"
                       Grid.Column="3"
                       HorizontalAlignment="Left"
                       VerticalAlignment="Top"
                       Style="{StaticResource StatsStyle}" />
        </Grid>

    </Grid>

</UserControl>

// EEGExampleView.xaml.cs

// *************************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2017. All rights reserved.
//  
// Web: http://www.scichart.com
//   Support: support@scichart.com
//   Sales:   sales@scichart.com
// 
// EEGExampleView.xaml.cs is part of the SCICHART® Examples. Permission is hereby granted
// to modify, create derivative works, distribute and publish any part of this source
// code whether for commercial, private or personal use. 
// 
// The SCICHART® examples are distributed in the hope that they will be useful, but
// without any warranty. It is provided "AS IS" without warranty of any kind, either
// expressed or implied. 
// *************************************************************************************
using System;
using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using SciChart.Examples.ExternalDependencies.Data;

namespace SciChart.Examples.Examples.CreateRealtimeChart.EEGChannelsDemo
{
    /// <summary>
    /// Interaction logic for EEGExampleView.xaml
    /// </summary>
    public partial class EEGExampleView : UserControl
    {
        private Stopwatch _stopWatch;
        private double _lastFrameTime;
        private MovingAverage _fpsAverage;

        public EEGExampleView()
        {
            InitializeComponent();

            _stopWatch = Stopwatch.StartNew();
            _fpsAverage = new MovingAverage(5);         
   
            this.Loaded += OnLoaded;
            this.Unloaded += OnUnloaded;
        }

        private void OnUnloaded(object sender, RoutedEventArgs routedEventArgs)
        {
            CompositionTarget.Rendering -= CompositionTarget_Rendering;            
        }

        private void OnLoaded(object sender, RoutedEventArgs routedEventArgs)
        {
            CompositionTarget.Rendering -= CompositionTarget_Rendering;         
            CompositionTarget.Rendering += CompositionTarget_Rendering;            
        }


        /// <summary>
        /// Purely for stats reporting (FPS). Not needed for SciChart rendering
        /// </summary>
        private void CompositionTarget_Rendering(object sender, EventArgs e)
        {
            if (StopButton.IsChecked != true && ResetButton.IsChecked != true)
            {
                // Compute the render time
                double frameTime = _stopWatch.ElapsedMilliseconds;
                double delta = frameTime - _lastFrameTime;
                double fps = 1000.0 / delta;

                // Push the fps to the movingaverage, we want to average the FPS to get a more reliable reading
                _fpsAverage.Push(fps);

                // Render the fps to the screen
                fpsCounter.Text = double.IsNaN(_fpsAverage.Current) ? "-" : string.Format("{0:0}", _fpsAverage.Current);

                // Render the total point count (all series) to the screen
                var eegExampleViewModel = (DataContext as EEGExampleViewModel);
                pointCount.Text = eegExampleViewModel != null ? eegExampleViewModel.PointCount.ToString() : "Na";

                _lastFrameTime = frameTime;
            }
        }
    }
}

// EEGExampleViewModel.cs

// *************************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2017. All rights reserved.
//  
// Web: http://www.scichart.com
//   Support: support@scichart.com
//   Sales:   sales@scichart.com
// 
// EEGExampleViewModel.cs is part of the SCICHART® Examples. Permission is hereby granted
// to modify, create derivative works, distribute and publish any part of this source
// code whether for commercial, private or personal use. 
// 
// The SCICHART® examples are distributed in the hope that they will be useful, but
// without any warranty. It is provided "AS IS" without warranty of any kind, either
// expressed or implied. 
// *************************************************************************************
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Timers;
using System.Windows.Input;
using System.Windows.Media;
using SciChart.Charting.Common.Helpers;
using SciChart.Core.Helpers;
using SciChart.Core.Utility;
using SciChart.Examples.ExternalDependencies.Common;

namespace SciChart.Examples.Examples.CreateRealtimeChart.EEGChannelsDemo
{
    public class EEGExampleViewModel : BaseViewModel
    {
        private ObservableCollection<EEGChannelViewModel> _channelViewModels;

        private readonly IList<Color> _colors = new[]
                                                    {
                                                        Colors.White, Colors.Yellow, Color.FromArgb(255, 0, 128, 128), Color.FromArgb(255, 176, 196, 222),
                                                        Color.FromArgb(255, 255, 182, 193), Colors.Purple, Color.FromArgb(255, 245, 222, 179),Color.FromArgb(255, 173, 216, 230),
                                                        Color.FromArgb(255, 250, 128, 114), Color.FromArgb(255, 144, 238, 144), Colors.Orange, Color.FromArgb(255, 192, 192, 192), 
                                                        Color.FromArgb(255, 255, 99, 71), Color.FromArgb(255, 205, 133, 63), Color.FromArgb(255, 64, 224, 208), Color.FromArgb(255, 244, 164, 96)
                                                    };

        private readonly FasterRandom _random = new FasterRandom();
        private const int ChannelCount = 50; // Number of channels to render
        private const int Size = 1000;       // Size of each channel in points (FIFO Buffer)
        private volatile int _currentSize = 0;
        private uint _timerInterval = 20;// Interval of the timer to generate data in ms        
        private int _bufferSize = 15; // Number of points to append to each channel each timer tick
        private Timer _timer;        
        private object _syncRoot = new object();

        // X, Y buffers used to buffer data into the Scichart instances in blocks of BufferSize
        private double[] xBuffer;
        private double[] yBuffer;
        private bool _running;
        private bool _isReset;

        private readonly ActionCommand _startCommand;
        private readonly ActionCommand _stopCommand;
        private readonly ActionCommand _resetCommand;
        private TimedMethod _startDelegate;

        public EEGExampleViewModel()
        {
            _startCommand = new ActionCommand(Start, () => !IsRunning);
            _stopCommand = new ActionCommand(Stop, () => IsRunning);
            _resetCommand = new ActionCommand(Reset, () => !IsRunning && !IsReset);         
        }

        public ObservableCollection<EEGChannelViewModel> ChannelViewModels
        {
            get { return _channelViewModels; }
            set 
            { 
                _channelViewModels = value;
                OnPropertyChanged("ChannelViewModels");
            }
        }        

        public ICommand StartCommand { get { return _startCommand; } }
        public ICommand StopCommand { get { return _stopCommand; } }
        public ICommand ResetCommand { get { return _resetCommand; } }

        public int PointCount { get { return _currentSize * ChannelCount; } }

        public double TimerInterval
        {
            get { return _timerInterval; }
            set
            {
                _timerInterval = (uint)value;
                OnPropertyChanged("TimerInterval");
                Stop();
            }
        }

        public double BufferSize
        {
            get { return _bufferSize; }
            set
            {
                _bufferSize = (int)value;
                OnPropertyChanged("BufferSize");
                Stop();
            }
        }

        public bool IsReset
        {
            get { return _isReset; }
            set
            {
                _isReset = value;

                _startCommand.RaiseCanExecuteChanged();
                _stopCommand.RaiseCanExecuteChanged();
                _resetCommand.RaiseCanExecuteChanged();

                OnPropertyChanged("IsReset");
            }
        }

        public bool IsRunning
        {
            get { return _running; }
            set 
            { 
                _running = value;

                _startCommand.RaiseCanExecuteChanged();
                _stopCommand.RaiseCanExecuteChanged();
                _resetCommand.RaiseCanExecuteChanged();

                OnPropertyChanged("IsRunning");                
            }
        }

        private void Start()
        {
            if (_channelViewModels == null || _channelViewModels.Count == 0)
            {
                Reset();
            }

            if (!IsRunning)
            {
                IsRunning = true;
                IsReset = false;
                xBuffer = new double[_bufferSize];
                yBuffer = new double[_bufferSize];
                _timer = new Timer(_timerInterval);
                _timer.Elapsed += OnTick;
                _timer.AutoReset = true;
                _timer.Start();
            }
        }

        private void Stop()
        {
            if (IsRunning)
            {
                _timer.Stop();
                IsRunning = false;
            }
        }

        private void Reset()
        {
            Stop();

            // Initialize N EEGChannelViewModels. Each of these will be represented as a single channel
            // of the EEG on the view. One channel = one SciChartSurface instance
            ChannelViewModels = new ObservableCollection<EEGChannelViewModel>();
            for (int i = 0; i < ChannelCount; i++)
            {
                var channelViewModel = new EEGChannelViewModel(Size, _colors[i%16]) {ChannelName = "Channel " + i};
                ChannelViewModels.Add(channelViewModel);
            }

            IsReset = true;
        }        

        private void OnTick(object sender, EventArgs e)
        {
            // Ensure only one timer Tick processed at a time
            lock (_syncRoot)
            {
                for (int i = 0; i < _channelViewModels.Count; i++)
                {
                    // Get the dataseries created for this channel
                    var channel = _channelViewModels[i];
                    var dataseries = channel.ChannelDataSeries;

                    // Preload previous value with k-1 sample, or 0.0 if the count is zero
                    double xValue = dataseries.Count > 0 ? dataseries.XValues[dataseries.Count - 1] : 0.0;
                    
                    // Add points 10 at a time for efficiency   
                    for (int j = 0; j < BufferSize; j++)
                    {
                        // Generate a new X,Y value in the random walk
                        xValue = xValue + 1;
                        double yValue = _random.NextDouble();

                        xBuffer[j] = xValue;
                        yBuffer[j] = yValue;
                    }

                    // Append block of values
                    dataseries.Append(xBuffer, yBuffer);

                    // For reporting current size to GUI
                    _currentSize = dataseries.Count;
                }
            }
        }
    }
}

// EEGChannelViewModel.cs

// *************************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2017. All rights reserved.
//  
// Web: http://www.scichart.com
//   Support: support@scichart.com
//   Sales:   sales@scichart.com
// 
// EEGChannelViewModel.cs is part of the SCICHART® Examples. Permission is hereby granted
// to modify, create derivative works, distribute and publish any part of this source
// code whether for commercial, private or personal use. 
// 
// The SCICHART® examples are distributed in the hope that they will be useful, but
// without any warranty. It is provided "AS IS" without warranty of any kind, either
// expressed or implied. 
// *************************************************************************************
using System.Windows.Media;
using SciChart.Charting.Model.DataSeries;
using SciChart.Examples.ExternalDependencies.Common;

namespace SciChart.Examples.Examples.CreateRealtimeChart.EEGChannelsDemo
{
    public class EEGChannelViewModel : BaseViewModel
    {
        private readonly int _size;
        private Color _color;
        private IXyDataSeries<double, double> _channelDataSeries;

        public EEGChannelViewModel(int size, Color color)
        {
            _size = size;
            Stroke = color;

            // Add an empty First In First Out series. When the data reaches capacity (int size) then old samples
            // will be pushed out of the series and new appended to the end. This gives the appearance of 
            // a scrolling chart window
            ChannelDataSeries = new XyDataSeries<double, double>() {FifoCapacity = _size};                

            // Pre-fill with NaN up to size. This stops the stretching effect when Fifo series are filled with AutoRange
            for(int i = 0; i < _size; i++)
                ChannelDataSeries.Append(i, double.NaN);
        }

        public string ChannelName { get; set; }

        public Color Stroke 
        { 
            get { return _color; }
            set 
            { 
                _color = value;
                OnPropertyChanged("Stroke");
            }
        }

        public IXyDataSeries<double, double> ChannelDataSeries
        {
            get { return _channelDataSeries; }
            set
            {
                _channelDataSeries = value;
                OnPropertyChanged("ChannelDataSeries");
            }
        }

        public void Reset()
        {            
            _channelDataSeries.Clear();         
        }
    }
}

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