CustomDrawSeriesEventArgsBase.DXLegendMarkerImage Property

Gets or sets the image of the legend item marker of the series or series point that is currently being painted.

Namespace: DevExpress.XtraCharts

Assembly: DevExpress.XtraCharts.v24.1.dll

NuGet Package: DevExpress.Charts

Declaration

C#

public DXImage DXLegendMarkerImage { get; set; }

VB.NET

Public Property DXLegendMarkerImage As DXImage

Property Value

Type	Description
DXImage	The image of the legend item marker.

Remarks

Use this property instead of e.LegendMarkerImage to specify an image of the legend item marker.

Example

This example demonstrates how to use the ChartControl.CustomDrawSeries event to modify the legend markers of bar series.

View Example

Assign a custom legend marker to the e.LegendMarkerImage property. Set the e.DisposeLegendMarkerImage property to true to avoid memory leaks. To customize options used to draw the series, cast e.SeriesDrawOptions to the DrawOptions class descendant that stores draw options of the required series view type.

Form1.cs

using CustomDrawingSample.Model;
using DevExpress.Drawing;
using DevExpress.XtraCharts;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Linq;

namespace CustomDrawingSample {
    public partial class Form1 : DevExpress.XtraEditors.XtraForm {
        string trackedSeriesName;
        Dictionary<string, DXImage> photoCache = new Dictionary<string, DXImage>();

        #region #Constants
        const int borderSize = 5;
        const int scaledPhotoWidth = 48;
        const int scaledPhotoHeight = 51;
        // Width and height of scaled photo with border.
        const int totalWidth = 58;
        const int totalHeight = 61;

        // Rects required to create a custom legend series marker.
        static readonly Rectangle photoRect = new Rectangle(
                borderSize, borderSize,
                scaledPhotoWidth, scaledPhotoHeight);
        static readonly Rectangle totalRect = new Rectangle(
                0, 0,
                totalWidth, totalHeight);
        #endregion

        public Form1() {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e) {
            using (var context = new NwindDbContext()) {
                InitPhotoCache(context.Employees);
                chart.DataSource = context.Orders.ToList();
            }

            chart.SeriesDataMember = "Employee.FullName";
            chart.SeriesTemplate.ArgumentDataMember = "OrderDate";
            chart.SeriesTemplate.ValueDataMembers.AddRange("Freight");

            XYDiagram diagram = chart.Diagram as XYDiagram;
            if (diagram != null) {
                diagram.AxisX.DateTimeScaleOptions.AggregateFunction = AggregateFunction.Sum;
                diagram.AxisX.DateTimeScaleOptions.MeasureUnit = DateTimeMeasureUnit.Year;
            }

            chart.CustomDrawSeries += OnCustomDrawSeries;
            chart.ObjectHotTracked += OnObjectHotTracked;
        }

        private void OnObjectHotTracked(object sender, HotTrackEventArgs e) {
            trackedSeriesName = e.HitInfo.InSeries ? ((Series)e.HitInfo.Series).Name : null;
        }

        void InitPhotoCache(IEnumerable<Employee> employees) {
            photoCache.Clear();
            foreach (var employee in employees) {
                using (MemoryStream stream = new MemoryStream(employee.Photo)) {
                    if (!photoCache.ContainsKey(employee.FullName))
                        photoCache.Add(employee.FullName, DXImage.FromStream(stream));
                }
            }
        }

        #region #CustomDrawSeriesImplementation
        private void OnCustomDrawSeries(object sender, CustomDrawSeriesEventArgs e) {
            bool isSelected = e.Series.Name.Equals(trackedSeriesName);
            // Design a series marker image.
            DXBitmap image = new DXBitmap(totalWidth, totalHeight);
            using (DXGraphics graphics = DXGraphics.FromImage(image)) {
                using (var fillBrush = isSelected ? (DXBrush)new DXHatchBrush(DXHatchStyle.DarkDownwardDiagonal,
                                                                          e.LegendDrawOptions.Color,
                                                                          e.LegendDrawOptions.ActualColor2)
                                                  : (DXBrush)new DXSolidBrush(e.LegendDrawOptions.Color)) {
                    graphics.FillRectangle(fillBrush, totalRect);
                }
                DXImage photo;
                if (photoCache.TryGetValue(e.Series.Name, out photo))
                    graphics.DrawImage(photo, photoRect);
            }
            e.DXLegendMarkerImage = image;
            e.DisposeLegendMarkerImage = true;

            BarDrawOptions options = e.SeriesDrawOptions as BarDrawOptions;
            if (options != null && isSelected) {
                options.FillStyle.FillMode = DevExpress.XtraCharts.FillMode.Hatch;
                ((HatchFillOptions)options.FillStyle.Options).HatchStyle = HatchStyle.DarkDownwardDiagonal;
            }
        }
        #endregion
    }
}

Form1.vb

Imports CustomDrawingSample.Model
Imports DevExpress.Drawing
Imports DevExpress.XtraCharts
Imports System
Imports System.Collections.Generic
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.IO
Imports System.Linq

Namespace CustomDrawingSample

    Public Partial Class Form1
        Inherits DevExpress.XtraEditors.XtraForm

        Private trackedSeriesName As String

        Private photoCache As Dictionary(Of String, DXImage) = New Dictionary(Of String, DXImage)()

#Region "#Constants"
        Const borderSize As Integer = 5

        Const scaledPhotoWidth As Integer = 48

        Const scaledPhotoHeight As Integer = 51

        ' Width and height of scaled photo with border.
        Const totalWidth As Integer = 58

        Const totalHeight As Integer = 61

        ' Rects required to create a custom legend series marker.
        Private Shared ReadOnly photoRect As Rectangle = New Rectangle(borderSize, borderSize, scaledPhotoWidth, scaledPhotoHeight)

        Private Shared ReadOnly totalRect As Rectangle = New Rectangle(0, 0, totalWidth, totalHeight)

#End Region
        Public Sub New()
            InitializeComponent()
        End Sub

        Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
            Using context = New NwindDbContext()
                InitPhotoCache(context.Employees)
                chart.DataSource = context.Orders.ToList()
            End Using

            chart.SeriesDataMember = "Employee.FullName"
            chart.SeriesTemplate.ArgumentDataMember = "OrderDate"
            chart.SeriesTemplate.ValueDataMembers.AddRange("Freight")
            Dim diagram As XYDiagram = TryCast(chart.Diagram, XYDiagram)
            If diagram IsNot Nothing Then
                diagram.AxisX.DateTimeScaleOptions.AggregateFunction = AggregateFunction.Sum
                diagram.AxisX.DateTimeScaleOptions.MeasureUnit = DateTimeMeasureUnit.Year
            End If

            AddHandler chart.CustomDrawSeries, AddressOf OnCustomDrawSeries
            AddHandler chart.ObjectHotTracked, AddressOf OnObjectHotTracked
        End Sub

        Private Sub OnObjectHotTracked(ByVal sender As Object, ByVal e As HotTrackEventArgs)
            trackedSeriesName = If(e.HitInfo.InSeries, CType(e.HitInfo.Series, Series).Name, Nothing)
        End Sub

        Private Sub InitPhotoCache(ByVal employees As IEnumerable(Of Employee))
            photoCache.Clear()
            For Each employee In employees
                Using stream As MemoryStream = New MemoryStream(employee.Photo)
                    If Not photoCache.ContainsKey(employee.FullName) Then photoCache.Add(employee.FullName, DXImage.FromStream(stream))
                End Using
            Next
        End Sub

#Region "#CustomDrawSeriesImplementation"
        Private Sub OnCustomDrawSeries(ByVal sender As Object, ByVal e As CustomDrawSeriesEventArgs)
            Dim isSelected As Boolean = e.Series.Name.Equals(trackedSeriesName)
            ' Design a series marker image.
            Dim image As DXBitmap = New DXBitmap(totalWidth, totalHeight)
            Using graphics As DXGraphics = DXGraphics.FromImage(image)
                Using fillBrush = If(isSelected, CType(New DXHatchBrush(DXHatchStyle.DarkDownwardDiagonal, e.LegendDrawOptions.Color, e.LegendDrawOptions.ActualColor2), DXBrush), CType(New DXSolidBrush(e.LegendDrawOptions.Color), DXBrush))
                    graphics.FillRectangle(fillBrush, totalRect)
                End Using

                Dim photo As DXImage
                If photoCache.TryGetValue(e.Series.Name, photo) Then graphics.DrawImage(photo, photoRect)
            End Using

            e.DXLegendMarkerImage = image
            e.DisposeLegendMarkerImage = True
            Dim options As BarDrawOptions = TryCast(e.SeriesDrawOptions, BarDrawOptions)
            If options IsNot Nothing AndAlso isSelected Then
                options.FillStyle.FillMode = DevExpress.XtraCharts.FillMode.Hatch
                CType(options.FillStyle.Options, HatchFillOptions).HatchStyle = HatchStyle.DarkDownwardDiagonal
            End If
        End Sub
#End Region
    End Class
End Namespace

Related GitHub Examples

The following code snippets (auto-collected from DevExpress Examples) contain references to the DXLegendMarkerImage property.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

winforms-chart-create-custom-legend-radio-buttons-to-control-visibility-of-a-chart-series/CS/MainForm.cs#L63

    e.DisposeLegendMarkerImage = true;
    e.DXLegendMarkerImage = bitmap;
}

winforms-chart-draw-a-custom-legend-marker-for-a-series-point/CS/CustomSeriesPointDrawingSample/Form1.cs#L84

e.DXLegendMarkerImage = image;
e.DisposeLegendMarkerImage = true;

winforms-chart-draw-a-custom-legend-marker-for-a-series/CS/CustomDrawingSample/Form1.cs#L87

}
e.DXLegendMarkerImage = image;
e.DisposeLegendMarkerImage = true;

VB.NET

winforms-chart-create-custom-legend-radio-buttons-to-control-visibility-of-a-chart-series/VB/MainForm.vb#L74

    e.DisposeLegendMarkerImage = True
    e.DXLegendMarkerImage = bitmap
End Sub

winforms-chart-draw-a-custom-legend-marker-for-a-series-point/VB/CustomSeriesPointDrawingSample/Form1.vb#L87

e.DXLegendMarkerImage = image
e.DisposeLegendMarkerImage = True

winforms-chart-draw-a-custom-legend-marker-for-a-series/VB/CustomDrawingSample/Form1.vb#L88

e.DXLegendMarkerImage = image
e.DisposeLegendMarkerImage = True