HeatmapControl.CustomizeHeatmapToolTip Event

Occurs before a tooltip is invoked and allows to customize tooltip content based on heatmap cell arguments and values.

Namespace: DevExpress.XtraCharts.Heatmap

Assembly: DevExpress.XtraCharts.v21.2.UI.dll

NuGet Packages: DevExpress.Win.Charts, DevExpress.Win.Design

Declaration

C#

public event CustomizeHeatmapToolTipEventHandler CustomizeHeatmapToolTip

VB.NET

Public Event CustomizeHeatmapToolTip As CustomizeHeatmapToolTipEventHandler

Event Data

The CustomizeHeatmapToolTip event's data class is CustomizeHeatmapToolTipEventArgs. The following properties provide information specific to this event:

Property	Description
HeatmapCell	Returns a heatmap cell for which a tooltip is shown.
Text	Gets or sets the cell tooltip text.
Title	Gets or sets the cell tooltip title.

Remarks

The following example shows how to use the HeatmapControl.CustomizeHeatmapToolTip event to modify tooltip content based on the cell value for which the tooltip is shown.

Follow the steps below to enable and customize tooltips:

• Set the HeatmapControl.ToolTipEnabled property to true.
• Initialize the HeatmapControl.ToolTipController property with a ToolTipController object. Enable the controller’s AllowHtmlText property to apply HTML tags to tooltip content.
• In the HeatmapControl.CustomizeHeatmapToolTip event handler, specify the e.Title and e.Text properties to format tooltip text.

The code below applies a custom format to tooltip text if a heatmap cell value is more than the specified value:

C#

const int ThresholdValue = 50;

public Form1() {
    InitializeComponent();
    // ...
    heatmap.ToolTipEnabled = true;
    heatmap.ToolTipController = new DevExpress.Utils.ToolTipController { AllowHtmlText = true };
    heatmap.CustomizeHeatmapToolTip += OnHeatmapCustomizeHeatmapToolTip;
}

private void OnHeatmapCustomizeHeatmapToolTip(object sender, CustomizeHeatmapToolTipEventArgs e) {
    double cellValue = (double)e.HeatmapCell.ColorValue;
    if (cellValue > ThresholdValue) {
        e.Title = "Sale Info";
        e.Text = $"Total: <color=green>${cellValue}K</color>";
    }
}

VB.NET

Const ThresholdValue As Integer = 50

Public Sub New()
    heatmap.ToolTipEnabled = True
    heatmap.ToolTipController = New DevExpress.Utils.ToolTipController With {
        .AllowHtmlText = True
    }
    heatmap.CustomizeHeatmapToolTip += AddressOf OnHeatmapCustomizeHeatmapToolTip
End Sub

Private Sub OnHeatmapCustomizeHeatmapToolTip(ByVal sender As Object, ByVal e As CustomizeHeatmapToolTipEventArgs)
    Dim cellValue As Double = CDbl(e.HeatmapCell.ColorValue)

    If cellValue > ThresholdValue Then
        e.Title = "Sale Info"
        e.Text = $"Total: <color=green>${cellValue}K</color>"
    End If
End Sub