Setting ToolTip Text for GridViewSparklineColumn in RadGridView for WinForms

Environment

Product Version	Product	Author
2025.1.211	RadGridView for WinForms	Dinko Krastev

Description

In the following tutorial, we will demonstrate how to add a ToolTip to the DataPoints inside the GridViewSparklineColumn.

Solution

To customize the ToolTip text for the GridViewSparklineColumn, handle the DataPointTooltipTextNeeded event of the SparkTooltipController. Access the controller by handling the CellFormatting event of the RadGridView. Below is the implementation:

Steps to Customize ToolTip Text

1. Add a GridViewSparklineColumn to your RadGridView.
2. Handle the CellFormatting event of the RadGridView to access the SparkTooltipController.
3. Subscribe to the DataPointTooltipTextNeeded event of the SparkTooltipController.
4. Customize the ToolTip text in the DataPointTooltipTextNeeded event based on your requirements.

Example Code

public partial class GridSparkForm : RadForm
    {
        public GridSparkForm()
        {
            InitializeComponent();

            GridViewDecimalColumn idColumn = new GridViewDecimalColumn("Id");
            this.radGridView1.Columns.Add(idColumn);

            GridViewTextBoxColumn nameColumn = new GridViewTextBoxColumn("Name");
            this.radGridView1.Columns.Add(nameColumn);

            GridViewDateTimeColumn dateColumn = new GridViewDateTimeColumn("Date");
            this.radGridView1.Columns.Add(dateColumn);

            GridViewCheckBoxColumn boolColumn = new GridViewCheckBoxColumn("Bool");
            this.radGridView1.Columns.Add(boolColumn);

            GridViewSparklineColumn column = new GridViewSparklineColumn("SparkColumn") { Width = 400 };
            column.SeriesType = SparkSeriesType.Line;
            column.ShowMarkers = true;
            column.ShowTooltip = true;
            column.ShowHighPointIndicator = true;
            column.ShowLowPointIndicator = true;
            column.ShowNegativePointIndicators = true;
            column.ShowFirstPointIndicator = true;
            column.ShowLastPointIndicator = true;

            column.SparkDataNeeded += this.Column_SparkDataNeeded;
            this.radGridView1.DataSource = this.GetData();
            this.radGridView1.Columns.Add(column);

            this.radGridView1.CellFormatting += this.RadGridView1_CellFormatting;


        }

        private void RadGridView1_CellFormatting(object sender, CellFormattingEventArgs e)
        {
            var cell = e.CellElement as GridSparklineCellElement;
            if (cell == null || cell.SparklineElement.View.Controllers.Count == 0)
            {
                return;
            }

            var controller = cell.SparklineElement.View.Controllers.Where(c => c is SparkTooltipController).First() as SparkTooltipController;
            if (controller != null)
            {
                controller.DataPointTooltipTextNeeded -= Controller_DataPointTooltipTextNeeded;
                controller.DataPointTooltipTextNeeded += Controller_DataPointTooltipTextNeeded;
            }
        }

        private void Controller_DataPointTooltipTextNeeded(object sender, SparkDataPointTooltipTextNeededEventArgs e)
        {
            var point = e.DataPoint as CategoricalSparkDataPoint;
            if (point.Value > 10)
            {
                e.Text = "Value Critical";
            }
        }

        private void Column_SparkDataNeeded(object sender, SparkDataNeededEventArgs e)
        {
            GridSparklineCellElement cell = sender as GridSparklineCellElement;
            if (cell == null)
            {
                return;
            }

            e.Cancel = true;
            BindingList<ChartDataObject> data = new BindingList<ChartDataObject>();
            for (int i = 1; i < 25; i++)
            {
                data.Add(new ChartDataObject
                {
                    //Value = i,
                    Value = i % 2 == 0 ? i : -i,
                    Category = DateTime.Now.AddDays(i)
                });
            }

            ((SparkCartesianSeries)cell.SparklineElement.Series).ValueMember = "Value";
            ((SparkCartesianSeries)cell.SparklineElement.Series).CategoryMember = "Category";
            cell.SparklineElement.Series.DataSource = data;
        }

        private DataTable GetData()
        {
            DataTable dt = new DataTable();

            dt.Columns.Add("Id", typeof(int));
            dt.Columns.Add("Name", typeof(string));
            dt.Columns.Add("Date", typeof(DateTime));
            dt.Columns.Add("Bool", typeof(bool));

            Random rand = new Random();

            for (int i = 0; i < 100; i++)
            {
                dt.Rows.Add(i, "Name " + i, DateTime.Now.AddDays(i), i % 2 == 0);
            }

            return dt;
        }
    }

    public class ChartDataObject
    {
        public DateTime? Category { get; set; }

        public double? Value { get; set; }
    }

See Also

• Sparkline Tooltips Documentation
• RadGridView Documentation