HeatmapControl.Legend Property

Returns heatmap legend options.

Namespace : DevExpress.XtraCharts.Heatmap

Assembly : DevExpress.XtraCharts.v25.2.UI.dll

NuGet Package : DevExpress.Win.Charts

Declaration

C#
VB.NET

csharp

public HeatmapLegend Legend { get; }

Public ReadOnly Property Legend As HeatmapLegend

Property Value

Type	Description
HeatmapLegend

Contains options for the heatmap legend.

Example

How to Bind a Heatmap to a Data Source (XML File)

The following example shows how to create a heatmap and bind it to a data source. In this example, the heatmap obtains data from an XML file.

Add the HeatmapControl to the Form.
Create a HeatmapDataSourceAdapter object and assign it to the HeatmapControl.DataAdapter property.
Define the adapter’s DataSource property.
Use the ColorDataMember property to define a data member that is used to determine cell colors.
Specify the following adapter properties to define data members that store heatmap arguments:
Create a HeatmapRangeColorProvider object and assign it to the heatmap’s ColorProvider property. The HeatmapRangeColorProvider paints cells based on a value range to which the cell value belongs.
Add a HeatmapTitle to the heatmap’s Titles collection. Specify the title’s Text property.
Use the heatmap’s Label property to configure cell label options. This example shows how to configure label text format.
Set the HeatmapControl.ToolTipEnabled property to true to enable tooltips. Specify the HeatmapControl.ToolTipTextPattern property to define tooltip text display format.

View Example

C#
VB.NET

csharp

using DevExpress.XtraCharts;
using DevExpress.XtraCharts.Heatmap;
using System.Data;
using System.Drawing;
using DevExpress.Drawing;
using System.IO;
using System.Windows.Forms;

namespace BindHeatmapToDataSource {
    public partial class Form1 : Form {
        public Form1() {
            InitializeComponent();
            DataTable data = CreateDataSet("BalanceOfTrade.xml");

            heatmap.DataAdapter = new HeatmapDataSourceAdapter() {
                XArgumentDataMember = "Country",
                YArgumentDataMember = "Product",
                ColorDataMember = "Value",
                DataSource = data
            };

            Palette palette = new Palette("Custom") { Color.Red, Color.White, Color.Green };

            HeatmapRangeColorProvider colorProvider = new HeatmapRangeColorProvider() {
                Palette = palette,
                ApproximateColors = true,
                LegendItemPattern = "{V1} .. {V2}"
            };

            heatmap.ColorProvider = colorProvider;

            colorProvider.RangeStops.Add(new HeatmapRangeStop(0, HeatmapRangeStopType.Percentage));
            colorProvider.RangeStops.Add(new HeatmapRangeStop(-10));
            colorProvider.RangeStops.Add(new HeatmapRangeStop(-2.5));
            colorProvider.RangeStops.Add(new HeatmapRangeStop(0));
            colorProvider.RangeStops.Add(new HeatmapRangeStop(2.5));
            colorProvider.RangeStops.Add(new HeatmapRangeStop(10));
            colorProvider.RangeStops.Add(new HeatmapRangeStop(1, HeatmapRangeStopType.Percentage));

            heatmap.Titles.Add(new HeatmapTitle { Text = "Balance of Trade" });

            heatmap.Legend.Visibility = DevExpress.Utils.DefaultBoolean.True;

            heatmap.Label.Visible = true;
            heatmap.Label.DXFont = new DXFont("SegoeUI", 6);
            heatmap.Label.Pattern = "{V}";
            heatmap.Label.Color = Color.Black;

            heatmap.ToolTipEnabled = true;
            heatmap.ToolTipController = new DevExpress.Utils.ToolTipController {
                AllowHtmlText = true,
                ToolTipLocation = DevExpress.Utils.ToolTipLocation.RightTop,
                ShowBeak = true
            };
            heatmap.ToolTipTextPattern = "X: <b>{X}</b>\nY: <b>{Y}</b>";

            heatmap.EnableAxisXScrolling = true;
            heatmap.EnableAxisYScrolling = true;
            heatmap.EnableAxisXZooming = true;
            heatmap.EnableAxisYZooming = true;

            heatmap.AxisX.Title.Text = "Region";
            heatmap.AxisX.Title.Visibility = DevExpress.Utils.DefaultBoolean.True;
            heatmap.AxisX.Label.Staggered = false;
            heatmap.AxisX.Label.ResolveOverlappingOptions.AllowStagger = false;
            heatmap.AxisX.Label.ResolveOverlappingOptions.AllowRotate = false;
            heatmap.AxisX.Label.ResolveOverlappingOptions.AllowHide = false;
            heatmap.AxisY.Title.Text = "Product Category";
            heatmap.AxisY.Title.Visibility = DevExpress.Utils.DefaultBoolean.True;
        }

        public static DataTable CreateDataSet(string xmlFileName) {
            string filePath = GetRelativePath(xmlFileName);
            if (!string.IsNullOrWhiteSpace(filePath)) {
                DataSet dataSet = new DataSet();
                dataSet.ReadXml(filePath);
                if (dataSet.Tables.Count > 0)
                    return dataSet.Tables[0];
            }
            return null;
        }
        public static string GetRelativePath(string name) {
            name = "Data\\" + name;
            DirectoryInfo dir = new DirectoryInfo(Application.StartupPath);
            for (int i = 0; i <= 10; i++) {
                string filePath = Path.Combine(dir.FullName, name);
                if (File.Exists(filePath))
                    return filePath;
                dir = Directory.GetParent(dir.FullName);
            }
            return string.Empty;
        }
    }
}

Imports System.Data
Imports DevExpress.Drawing
Imports DevExpress.XtraCharts
Imports DevExpress.XtraCharts.Heatmap

Namespace BindHeatmapToDataSource

    Public Partial Class Form1
        Inherits System.Windows.Forms.Form

        Public Sub New()
            Me.InitializeComponent()
            Dim data As System.Data.DataTable = BindHeatmapToDataSource.Form1.CreateDataSet("BalanceOfTrade.xml")
            Me.heatmap.DataAdapter = New HeatmapDataSourceAdapter() With {.XArgumentDataMember = "Country", .YArgumentDataMember = "Product", .ColorDataMember = "Value", .DataSource = data}
            Dim palette As Palette = New Palette("Custom") From {System.Drawing.Color.Red, System.Drawing.Color.White, System.Drawing.Color.Green}
            Dim colorProvider As HeatmapRangeColorProvider = New HeatmapRangeColorProvider() With {.Palette = palette, .ApproximateColors = True, .LegendItemPattern = "{V1} .. {V2}"}
            Me.heatmap.ColorProvider = colorProvider
            colorProvider.RangeStops.Add(New HeatmapRangeStop(0, HeatmapRangeStopType.Percentage))
            colorProvider.RangeStops.Add(New HeatmapRangeStop(-10))
            colorProvider.RangeStops.Add(New HeatmapRangeStop(-2.5))
            colorProvider.RangeStops.Add(New HeatmapRangeStop(0))
            colorProvider.RangeStops.Add(New HeatmapRangeStop(2.5))
            colorProvider.RangeStops.Add(New HeatmapRangeStop(10))
            colorProvider.RangeStops.Add(New HeatmapRangeStop(1, HeatmapRangeStopType.Percentage))
            Me.heatmap.Titles.Add(New HeatmapTitle With {.Text = "Balance of Trade"})
            Me.heatmap.Legend.Visibility = DevExpress.Utils.DefaultBoolean.[True]
            Me.heatmap.Label.Visible = True
            Me.heatmap.Label.DXFont = New DXFont("SegoeUI", 6)
            Me.heatmap.Label.Pattern = "{V}"
            Me.heatmap.Label.Color = System.Drawing.Color.Black
            Me.heatmap.ToolTipEnabled = True
            Me.heatmap.ToolTipController = New DevExpress.Utils.ToolTipController With {.AllowHtmlText = True, .ToolTipLocation = DevExpress.Utils.ToolTipLocation.RightTop, .ShowBeak = True}
            Me.heatmap.ToolTipTextPattern = "X: <b>{X}</b>" & Global.Microsoft.VisualBasic.Constants.vbLf & "Y: <b>{Y}</b>"
            Me.heatmap.EnableAxisXScrolling = True
            Me.heatmap.EnableAxisYScrolling = True
            Me.heatmap.EnableAxisXZooming = True
            Me.heatmap.EnableAxisYZooming = True
            Me.heatmap.AxisX.Title.Text = "Region"
            Me.heatmap.AxisX.Title.Visibility = DevExpress.Utils.DefaultBoolean.[True]
            Me.heatmap.AxisX.Label.Staggered = False
            Me.heatmap.AxisX.Label.ResolveOverlappingOptions.AllowStagger = False
            Me.heatmap.AxisX.Label.ResolveOverlappingOptions.AllowRotate = False
            Me.heatmap.AxisX.Label.ResolveOverlappingOptions.AllowHide = False
            Me.heatmap.AxisY.Title.Text = "Product Category"
            Me.heatmap.AxisY.Title.Visibility = DevExpress.Utils.DefaultBoolean.[True]
        End Sub

        Public Shared Function CreateDataSet(ByVal xmlFileName As String) As DataTable
            Dim filePath As String = BindHeatmapToDataSource.Form1.GetRelativePath(xmlFileName)
            If Not String.IsNullOrWhiteSpace(filePath) Then
                Dim dataSet As System.Data.DataSet = New System.Data.DataSet()
                dataSet.ReadXml(filePath)
                If dataSet.Tables.Count > 0 Then Return dataSet.Tables(0)
            End If

            Return Nothing
        End Function

        Public Shared Function GetRelativePath(ByVal name As String) As String
            name = "Data\" & name
            Dim dir As System.IO.DirectoryInfo = New System.IO.DirectoryInfo(System.Windows.Forms.Application.StartupPath)
            For i As Integer = 0 To 10
                Dim filePath As String = System.IO.Path.Combine(dir.FullName, name)
                If System.IO.File.Exists(filePath) Then Return filePath
                dir = System.IO.Directory.GetParent(dir.FullName)
            Next

            Return String.Empty
        End Function
    End Class
End Namespace

The XML file structure looks as follows:

Show XML

xml

<?xml version="1.0" standalone="yes"?>
<BalanceOfTrade xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="Item">
      <xs:complexType>
        <xs:sequence>
          <xs:element name="Country" type="xs:string"/>
          <xs:element name="Product" type="xs:string"/>
          <xs:element name="Value" type="xs:double"/>
        </xs:sequence>
      </xs:complexType>
    </xs:element>
  </xs:schema>
  <Item>
    <Country>China</Country>
    <Product>Computer</Product>
    <Value>-151.9</Value>
  </Item>
  <Item>
    <Country>China</Country>
    <Product>Oil, Gas, Minerals</Product>
    <Value>1.9</Value>
  </Item>
  <Item>
    <Country>China</Country>
    <Product>Transportation</Product>
    <Value>10.9</Value>
  </Item>
  <Item>
    <Country>China</Country>
    <Product>Apparel</Product>
    <Value>-56.3</Value>
  </Item>
  <!--...-->
</BalanceOfTrade>