HeatmapLegend Class

A heatmap legend.

Namespace: DevExpress.Xpf.Charts.Heatmap

Assembly: DevExpress.Xpf.Charts.v24.1.dll

NuGet Package: DevExpress.Wpf.Charts

Declaration

C#

public class HeatmapLegend :
    LegendBase

VB.NET

Public Class HeatmapLegend
    Inherits LegendBase

Related API Members

The following members return HeatmapLegend objects:

• HeatmapControl.Legend
• HeatmapHitInfo.Legend
• HeatmapLegendItem.Legend

Remarks

Assign a HeatmapLegend object to the Legend property to show a legend for the heatmap.

If you use HeatmapRangeColorProvider or HeatmapKeyColorProvider to paint heatmap, you can use the LegendItemPattern property to format legend item text.

Example

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.

1. Add the HeatmapControl to the project.

2. Create a HeatmapDataSourceAdapter object and assign it to the HeatmapControl.DataAdapter property.

3. Define the adapter’s DataSource property.

4. Use the ColorDataMember property to define a data member that is used to determine cell colors.

5. Specify the following adapter properties to define data members that store heatmap arguments:

   • XArgumentDataMember
   • YArgumentDataMember

6. Create a HeatmapRangeColorProvider object and assign it to the HeatmapControl.ColorProvider property. The Range Color Provider paints cells based on a value range to which the cell value belongs.

7. To display cell labels, initialize the HeatmapControl.Label property with a HeatmapLabel object.

8. Set the HeatmapControl.Legend property to a HeatmapLegend object to add a legend to the heatmap.

9. Set the HeatmapControl.ToolTipEnabled property to true to enable tooltips. Specify the HeatmapToolTipOptions.Pattern property to define tooltip text display format.

10. Use the HeatmapControl.AxisX and HeatmapControl.AxisY properties to customize heatmap axes.

    In this example, the x-axis AutoGrid property is disabled and GridSpacing is set to 1 to display all axis labels (without gaps). The Angle property defines axis label rotation to avoid overlapped labels.

View Example

XAML

<dx:ThemedWindow
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
    xmlns:dxh="http://schemas.devexpress.com/winfx/2008/xaml/heatmap" 
    xmlns:dxc="http://schemas.devexpress.com/winfx/2008/xaml/charts"
    x:Class="HeatmapDataSource.MainWindow"
    Title="Heatmap Control" Height="500" Width="800">
    <Grid>
        <dxh:HeatmapControl ToolTipEnabled="True">
            <dxh:HeatmapControl.ToolTipOptions>
                <dxh:HeatmapToolTipOptions Pattern="X: {X}&#x0a;Y: {Y}" />
            </dxh:HeatmapControl.ToolTipOptions>
            <dxh:HeatmapControl.Titles>
                <dxc:Title Content="Balance of Trade" HorizontalAlignment="Center"/>
            </dxh:HeatmapControl.Titles>
            <dxh:HeatmapControl.DataAdapter>
                <dxh:HeatmapDataSourceAdapter
                    DataSource="{Binding}"
                    XArgumentDataMember="Country"
                    YArgumentDataMember="Product"
                    ColorDataMember="Value"/>
            </dxh:HeatmapControl.DataAdapter>
            <dxh:HeatmapControl.ColorProvider>
                <dxh:HeatmapRangeColorProvider ApproximateColors="true" 
                                               LegendItemPattern="{}{VP1:0%} - {VP2:0%}">
                    <dxh:HeatmapRangeColorProvider.Palette>
                        <dxc:CustomPalette>
                            <dxc:CustomPalette.Colors>
                                <Color>Red</Color>
                                <Color>White</Color>
                                <Color>Green</Color>
                            </dxc:CustomPalette.Colors>
                        </dxc:CustomPalette>
                    </dxh:HeatmapRangeColorProvider.Palette>
                    <dxh:HeatmapRangeColorProvider.RangeStops>
                        <dxh:HeatmapRangeStop Value="0" Type="Percentage"/>
                        <dxh:HeatmapRangeStop Value="-10"/>
                        <dxh:HeatmapRangeStop Value="-2.5"/>
                        <dxh:HeatmapRangeStop Value="0"/>
                        <dxh:HeatmapRangeStop Value="2.5"/>
                        <dxh:HeatmapRangeStop Value="10"/>
                        <dxh:HeatmapRangeStop Value="1" Type="Percentage"/>
                    </dxh:HeatmapRangeColorProvider.RangeStops>
                </dxh:HeatmapRangeColorProvider>
            </dxh:HeatmapControl.ColorProvider>
            <dxh:HeatmapControl.Label>
                <dxh:HeatmapLabel FontSize="8"/>
            </dxh:HeatmapControl.Label>
            <dxh:HeatmapControl.Legend>
                <dxh:HeatmapLegend/>
            </dxh:HeatmapControl.Legend>
            <dxh:HeatmapControl.AxisX>
                <dxh:HeatmapAxis AutoGrid="False" 
                                 GridSpacing="1">
                    <dxh:HeatmapAxis.Label>
                        <dxc:AxisLabel Angle="30"/>
                    </dxh:HeatmapAxis.Label>
                </dxh:HeatmapAxis>
            </dxh:HeatmapControl.AxisX>
            <dxh:HeatmapControl.AxisY>
                <dxh:HeatmapAxis/>
            </dxh:HeatmapControl.AxisY>
        </dxh:HeatmapControl>
    </Grid>
</dx:ThemedWindow>

C#

using DevExpress.Xpf.Core;
using System;
using System.Data;
using System.IO;
using System.Windows;
using System.Xml;
using System.Xml.Linq;

namespace HeatmapDataSource {

    public partial class MainWindow : ThemedWindow {
        public MainWindow() {
            InitializeComponent();
            DataContext = DataLoader.CreateDataSet("/Data/BalanceOfTrade.xml");
        }
    }
    public static class DataLoader {
        static Stream GetStream(string fileName) {
            Uri uri = new Uri(fileName, UriKind.RelativeOrAbsolute);
            return Application.GetResourceStream(uri).Stream;
        }
        public static XDocument LoadXDocumentFromResources(string fileName) {
            try {
                return XDocument.Load(GetStream(fileName));
            } catch {
                return null;
            }
        }
        public static XmlDocument LoadXmlDocumentFromResources(string fileName) {
            XmlDocument document = new XmlDocument();
            try {
                document.Load(GetStream(fileName));
                return document;
            } catch {
                return null;
            }
        }
        public static DataTable CreateDataSet(string fileName) {
            if (!string.IsNullOrWhiteSpace(fileName)) {
                DataSet dataSet = new DataSet();
                dataSet.ReadXml(GetStream(fileName));
                if (dataSet.Tables.Count > 0)
                    return dataSet.Tables[0];
            }
            return null;
        }
    }
}

VB.NET

Imports DevExpress.Xpf.Core
Imports System
Imports System.Data
Imports System.IO
Imports System.Windows
Imports System.Xml
Imports System.Xml.Linq

Namespace HeatmapDataSource

    Public Partial Class MainWindow
        Inherits ThemedWindow

        Public Sub New()
            Me.InitializeComponent()
            DataContext = CreateDataSet("/Data/BalanceOfTrade.xml")
        End Sub
    End Class

    Public Module DataLoader

        Private Function GetStream(ByVal fileName As String) As Stream
            Dim uri As Uri = New Uri(fileName, UriKind.RelativeOrAbsolute)
            Return Application.GetResourceStream(uri).Stream
        End Function

        Public Function LoadXDocumentFromResources(ByVal fileName As String) As XDocument
            Try
                Return XDocument.Load(GetStream(fileName))
            Catch
                Return Nothing
            End Try
        End Function

        Public Function LoadXmlDocumentFromResources(ByVal fileName As String) As XmlDocument
            Dim document As XmlDocument = New XmlDocument()
            Try
                document.Load(GetStream(fileName))
                Return document
            Catch
                Return Nothing
            End Try
        End Function

        Public Function CreateDataSet(ByVal fileName As String) As DataTable
            If Not String.IsNullOrWhiteSpace(fileName) Then
                Dim dataSet As DataSet = New DataSet()
                dataSet.ReadXml(GetStream(fileName))
                If dataSet.Tables.Count > 0 Then Return dataSet.Tables(0)
            End If

            Return Nothing
        End Function
    End Module
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>     

Inheritance

Show 12 items

Object

DispatcherObject

DependencyObject

Visual

UIElement

FrameworkElement

Control

ChartElementBase

ChartElement

DevExpress.Xpf.Charts.ChartNotificationElement

LegendBase

HeatmapLegend