XtraCharts > 示例 > 如何： 确定哪个系列点位于测试点下面

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在 DevExpress Code Central 数据库中可以找到完整的示例项目，网址是 http://www.devexpress.com/example=E2717。 取决于目标平台类型 (ASP.NET、WinForms 等)，可以在线运行本示例，或者下载自动可执行的示例。

这个示例展示了如何接管 ChartControl.MouseMove 事件，从而确定哪个 系列点 位于测试点下面，并且使用 ToolTipController 在工具提示中显示它的参数和取值信息。

要在运行时刻启用点击测试，以便于让本示例正确工作，则把 ChartControl.RuntimeHitTesting 属性设置为 true。

C#CopyCode image复制代码
 (Form1.cs)
using System;
using System.Windows.Forms;
using DevExpress.XtraCharts;
// ...

private void chartControl1_MouseMove(object sender, MouseEventArgs e) {
    // Obtain hit information under the test point.
    ChartHitInfo hi = chartControl1.CalcHitInfo(e.X, e.Y);

    // Obtain the series point under the test point.
    SeriesPoint point = hi.SeriesPoint;

    // Check whether the series point was clicked or not.
    if (point != null) {
        // Obtain the series point argument.
        string argument = "Argument: " + point.Argument.ToString();

        // Obtain series point values.
        string values = "Value(s): " + point.Values[0].ToString();
        if (point.Values.Length > 1) {
            for (int i = 1; i < point.Values.Length; i++) {
                values = values + ", " + point.Values[i].ToString();
            }
        }

        // Show the tooltip.
        toolTipController1.ShowHint(argument + "\n" + values, "SeriesPoint Data");
    }
    else {
        // Hide the tooltip.
        toolTipController1.HideHint();
    }
}
Visual BasicCopyCode image复制代码
 (Form1.vb)
Imports System
Imports System.Windows.Forms
Imports DevExpress.XtraCharts
' ...

Private Sub chartControl1_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs) Handles chartControl1.MouseMove
    ' Obtain hit information under the test point.
    Dim hi As ChartHitInfo = chartControl1.CalcHitInfo(e.X, e.Y)

    ' Obtain the series point under the test point.
    Dim point As SeriesPoint = hi.SeriesPoint

    ' Check whether the series point was clicked or not.
    If point IsNot Nothing Then
        ' Obtain the series point argument.
        Dim argument As String = "Argument: " & point.Argument.ToString()

        ' Obtain series point values.
        Dim values As String = "Value(s): " & point.Values(0).ToString()
        If point.Values.Length > 1 Then
            For i As Integer = 1 To point.Values.Length - 1
                values = values & ", " & point.Values(i).ToString()
            Next i
        End If

        ' Show the tooltip.
        toolTipController1.ShowHint(argument & Constants.vbLf & values, "SeriesPoint Data")
    Else
        ' Hide the tooltip.
        toolTipController1.HideHint()
    End If
End Sub

不能使用 ChartControl.HitTest 方法来实现此目的，因为此方法返回鼠标单击的 ChartElement (图表元素)。 SeriesPoint (系列点) 对象不是图表元素，而 Series、XYDiagram 和 ChartControl 对象都是图表元素。

在下面的插图中显示了结果。

Expand image参阅