This example demonstrates how to create a Histogram with Labels on columns in SciChart. This is achieved by combining the FastColumnRenderableSeries with a custom modifier which creates TextAnnotation and positions them over the individual columns.

Take a look at the source-code to see how we’ve achieved this.

// CustomAnnotationModifier.cs

// *************************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2017. All rights reserved.
//  
// Web: http://www.scichart.com
//   Support: support@scichart.com
//   Sales:   sales@scichart.com
// 
// CustomAnnotationModifier.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.Collections;
using System.Windows;
using SciChart.Charting.ChartModifiers;

namespace SciChart.Examples.Examples.SeeFeaturedApplication.Histogram
{
    public class CustomAnnotationModifier : ChartModifierBase
    {
        public static readonly DependencyProperty LabelsSourceProperty = DependencyProperty.Register("LabelsSource", typeof(IEnumerable), typeof(CustomAnnotationModifier), new PropertyMetadata(null, OnLabelsSourceChanged));

        public IEnumerable LabelsSource
        {
            get { return (IEnumerable)GetValue(LabelsSourceProperty); }
            set { SetValue(LabelsSourceProperty, value); }
        }

        /// <summary>
        /// Called when the Chart Modifier is attached to the Chart Surface
        /// </summary>
        public override void OnAttached()
        {
            base.OnAttached();

            // Catch the condition where LabelsSource binds before chart is shown. Rebuild annotations
            if (LabelsSource != null && base.ParentSurface.Annotations.Count == 0)
            {
                RebuildAnnotations();
            }
        }

        private static void OnLabelsSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var modifier = (CustomAnnotationModifier) d;
            var newValue = e.NewValue as IEnumerable;
            if (newValue != null)
            {
                modifier.RebuildAnnotations();
            }
        }

        private void RebuildAnnotations()
        {
            if (base.ParentSurface != null && LabelsSource != null)
            {
                // Take a look at the base class, ChartModifierBase for a wealth of API methods and properties to manipulate the SciChartSurface
                var annotationCollection = base.ParentSurface.Annotations;
                annotationCollection.Clear();

                foreach (var item in LabelsSource)
                {
                    annotationCollection.Add(new HistogramLabelAnnotation { DataContext = item });
                }
            }
        }
    }
}

// HistogramLabelAnnotation.xaml

<s:TextAnnotation x:Class="SciChart.Examples.Examples.SeeFeaturedApplication.Histogram.HistogramLabelAnnotation"
                  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                  xmlns:s="http://schemas.abtsoftware.co.uk/scichart"
                  Foreground="#ffdddddd"
                  FontWeight="Bold"
                  FontSize="12"
                  HorizontalAnchorPoint="Center"
                  Text="{Binding LabelText}"
                  VerticalAnchorPoint="Bottom"
                  X1="{Binding X1}"
                  Y1="{Binding Y1}" />

// HistogramLabelAnnotation.xaml.cs

// *************************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2017. All rights reserved.
//  
// Web: http://www.scichart.com
//   Support: support@scichart.com
//   Sales:   sales@scichart.com
// 
// HistogramLabelAnnotation.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 SciChart.Charting.Visuals.Annotations;

namespace SciChart.Examples.Examples.SeeFeaturedApplication.Histogram
{
    /// <summary>
    /// Interaction logic for CustomTextAnnotation.xaml
    /// </summary>
    public partial class HistogramLabelAnnotation : TextAnnotation
    {
        public HistogramLabelAnnotation()
        {
            InitializeComponent();
        }
    }
}

// HistogramLabelViewModel.cs

// *************************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2017. All rights reserved.
//  
// Web: http://www.scichart.com
//   Support: support@scichart.com
//   Sales:   sales@scichart.com
// 
// HistogramLabelViewModel.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;

namespace SciChart.Examples.Examples.SeeFeaturedApplication.Histogram
{
    public class HistogramLabelViewModel
    {
        public HistogramLabelViewModel(IComparable x1, IComparable y1, string text)
        {
            X1 = x1;
            Y1 = y1;
            LabelText = text;
        }

        /// <summary>
        /// LabelText will allow us to bind to TextAnnotation.Text
        /// </summary>
        public string LabelText { get; set; }

        /// <summary>
        /// X1 defines the X Data-Value for positioning the annotation
        /// </summary>
        public IComparable X1 { get; set; }

        /// <summary>
        /// Y1 defines the Y Data-Value for positioning the annotation
        /// </summary>
        public IComparable Y1 { get; set; }
    }
}

// HistogramView.xaml

<UserControl x:Class="SciChart.Examples.Examples.SeeFeaturedApplication.Histogram.HistogramView"
             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:ex="http://schemas.abtsoftware.co.uk/scichart/exampleExternals"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             xmlns:s="http://schemas.abtsoftware.co.uk/scichart"
             xmlns:histogram="clr-namespace:SciChart.Examples.Examples.SeeFeaturedApplication.Histogram"
             d:DesignHeight="400"
             d:DesignWidth="600"
             mc:Ignorable="d">

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

        <!--  The SciChartInteractionToolbar adds zoom, pan, zoom extents and rotate functionality  -->
        <!--  to the chart and is included for example purposes.  -->
        <!--  If you wish to know how to zoom and pan a chart then do a search for Zoom Pan in the Examples suite!  -->
        <ex:SciChartInteractionToolbar TargetSurface="{Binding ElementName=SciChart}" />

        <!--  Shows the SciChartSurface and binds ZoomHistoryManager to the instance in the viewmodel  -->
        <!--  This is what we use to control zoom history as well as Undo Redo  -->
        <s:SciChartSurface x:Name="SciChart"
                           Grid.Column="1"
                           RenderableSeries="{s:SeriesBinding RenderableSeriesViewModels}">
            <!--  Styles.xaml resource keys must match StyleKey in RenderableSeriesViewModel  -->
            <s:SciChartSurface.Resources>
                <ResourceDictionary Source="Styles.xaml" />
            </s:SciChartSurface.Resources>

            <s:SciChartSurface.XAxis>
                <s:NumericAxis />
            </s:SciChartSurface.XAxis>

            <s:SciChartSurface.YAxis>
                <s:NumericAxis GrowBy="0, 0.1" />
            </s:SciChartSurface.YAxis>

            <s:SciChartSurface.ChartModifier>
                <histogram:CustomAnnotationModifier LabelsSource="{Binding ChartLabels}" />
            </s:SciChartSurface.ChartModifier>

        </s:SciChartSurface>

    </Grid>
</UserControl>

// HistogramView.xaml.cs

// *************************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2016. All rights reserved.
//  
// Web: http://www.scichart.com
//   Support: support@scichart.com
//   Sales:   sales@scichart.com
// 
// HistogramView.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.Windows.Controls;

namespace SciChart.Examples.Examples.SeeFeaturedApplication.Histogram
{
    /// <summary>
    /// Interaction logic for HistogramView.xaml
    /// </summary>
    public partial class HistogramView : UserControl
    {
        public HistogramView()
        {
            InitializeComponent();
        }
    }
}

// HistogramViewModel.cs

// *************************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2016. All rights reserved.
//  
// Web: http://www.scichart.com
//   Support: support@scichart.com
//   Sales:   sales@scichart.com
// 
// HistogramViewModel.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.Collections.Generic;
using System.Globalization;
using SciChart.Charting.Model.ChartSeries;
using SciChart.Charting.Model.DataSeries;
using SciChart.Examples.ExternalDependencies.Common;
using SciChart.Examples.ExternalDependencies.Data;

namespace SciChart.Examples.Examples.SeeFeaturedApplication.Histogram
{
    public class HistogramViewModel : BaseViewModel
    {
        private static readonly double[] BlueSeriesData = {1, 1, 0, 2, 3, 1, 1, 6, 3, 12, 15, 6, 10, 4, 8, 5, 3, 2, 3, 2};
        private static readonly double[] RedSeriesData = {0, 0, 1, 2, 3, 1, 2, 6, 9, 9, 10, 6, 5, 13, 4, 8, 8, 4, 3, 4};
        private static readonly double[] GreenSeriesData = {1, 2, 4, 4, 5, 8, 7, 10, 10, 6, 8, 6, 11, 3, 7, 4, 1, 0, 0, 1};

        public HistogramViewModel()
        {
            ChartLabels = new List<HistogramLabelViewModel>();

            // StyleKey in RenderableSeriesViewModel must match style resource keys in XAML 
            RenderableSeriesViewModels = new List<IRenderableSeriesViewModel>
            {
                GenerateColumn(-2.5, BlueSeriesData, "BlueColumnStyle"),
                GenerateAvarage(-2.5, BlueSeriesData, "BlueLineStyle"),
                GenerateColumn(0, RedSeriesData, "RedColumnStyle"),
                GenerateAvarage(0, BlueSeriesData, "RedLineStyle"),
                GenerateColumn(2.5, GreenSeriesData, "GreenColumnStyle"),
                GenerateAvarage(2.5, BlueSeriesData, "GreenLineStyle"),
            };
        }

        public List<IRenderableSeriesViewModel> RenderableSeriesViewModels { get; set; }

        public List<HistogramLabelViewModel> ChartLabels { get; set; }

        private IRenderableSeriesViewModel GenerateColumn(double startsAt, double[] data, string styleKey)
        {
            var dataSeries = new XyDataSeries<double, double>();
            
            var xValues = GeneratexValues(startsAt, data.Length);
            dataSeries.Append(xValues, data);

            // Annotations for text labels
            for (var i = 0; i < data.Length; i++)
            {
                ChartLabels.Add(new HistogramLabelViewModel(xValues[i], data[i],data[i].ToString(CultureInfo.InvariantCulture)));
            }

            return new ColumnRenderableSeriesViewModel
            {
                DataSeries = dataSeries,
                StyleKey = styleKey,
            };
        }

        private IRenderableSeriesViewModel GenerateAvarage(double startsAt, double[] data, string styleKey)
        {
            var dataSeries = new XyDataSeries<double, double>();

            var xValues = GeneratexValues(startsAt, data.Length);
            dataSeries.Append(xValues, data.MovingAverage(3));

            return new LineRenderableSeriesViewModel
            {
                DataSeries = dataSeries,
                StyleKey = styleKey,
            };
        }

        private double[] GeneratexValues(double startsAt, int count)
        {
            var xValues = new double[count];
            for (var i = 0; i < count; i++)
            {
                xValues[i] = startsAt;
                startsAt += 0.25;
            }

            return xValues;
        }
    }
}

// Styles.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:s="http://schemas.abtsoftware.co.uk/scichart">

    <Style x:Key="BaseColumnStyle" TargetType="s:FastColumnRenderableSeries">
        <Setter Property="Opacity" Value="0.3" />
        <Setter Property="StrokeThickness" Value="2" />
        <Setter Property="DataPointWidth" Value="0.9" />
    </Style>

    <Style x:Key="BlueColumnStyle"
           BasedOn="{StaticResource BaseColumnStyle}"
           TargetType="s:FastColumnRenderableSeries">
        <Setter Property="Fill" Value="CornflowerBlue" />
    </Style>
    <Style x:Key="RedColumnStyle"
           BasedOn="{StaticResource BaseColumnStyle}"
           TargetType="s:FastColumnRenderableSeries">
        <Setter Property="Fill" Value="DarkRed" />
    </Style>
    <Style x:Key="GreenColumnStyle"
           BasedOn="{StaticResource BaseColumnStyle}"
           TargetType="s:FastColumnRenderableSeries">
        <Setter Property="Fill" Value="ForestGreen" />
    </Style>

    <Style x:Key="BaseLineStyle" TargetType="s:FastLineRenderableSeries">
        <Setter Property="StrokeThickness" Value="3" />
    </Style>

    <Style x:Key="BlueLineStyle"
           BasedOn="{StaticResource BaseLineStyle}"
           TargetType="s:FastLineRenderableSeries">
        <Setter Property="Stroke" Value="CornflowerBlue" />
    </Style>
    <Style x:Key="RedLineStyle"
           BasedOn="{StaticResource BaseLineStyle}"
           TargetType="s:FastLineRenderableSeries">
        <Setter Property="Stroke" Value="DarkRed" />
    </Style>
    <Style x:Key="GreenLineStyle"
           BasedOn="{StaticResource BaseLineStyle}"
           TargetType="s:FastLineRenderableSeries">
        <Setter Property="Stroke" Value="ForestGreen" />
    </Style>

</ResourceDictionary>

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