XtraCharts > 示例 > 如何： 把常数线添加到轴上

本示例演示了在运行时刻如何创建并定制 常数线。

因为常数线从属于图像的 轴，因此首先需要把 图象 对象转换为适当的图象类型。 此后，就可以访问轴，并管理它们的常数线集合。

C#CopyCode image复制代码
// Cast the chart's diagram to the XYDiagram type, to access its axes.
XYDiagram diagram = (XYDiagram)chartControl1.Diagram;

// Create a constant line.
ConstantLine constantLine1 = new ConstantLine("Constant Line 1");
diagram.AxisY.ConstantLines.Add(constantLine1);

// Define its axis value.
constantLine1.AxisValue = 7;

// Customize the behavior of the constant line.
constantLine1.Visible = true;
constantLine1.ShowInLegend = true;
constantLine1.LegendText = "Some Threshold";
constantLine1.ShowBehind = false;

// Customize the constant line's title.
constantLine1.Title.Visible = true;
constantLine1.Title.Text = "Constant Line Title";
constantLine1.Title.TextColor = Color.Red;
constantLine1.Title.Antialiasing = false;
constantLine1.Title.Font = new Font("Tahoma", 14, FontStyle.Bold);
constantLine1.Title.ShowBelowLine = true;
constantLine1.Title.Alignment = ConstantLineTitleAlignment.Far;

// Customize the appearance of the constant line.
constantLine1.Color = Color.Red;
constantLine1.LineStyle.DashStyle = DashStyle.Dash;
constantLine1.LineStyle.Thickness = 2;
Visual BasicCopyCode image复制代码
' Cast the chart's diagram to the XYDiagram type, to access its axes.
Dim diagram As XYDiagram = CType(chartControl1.Diagram, XYDiagram)

' Create a constant line.
Dim constantLine1 As New ConstantLine("Constant Line 1")
diagram.AxisY.ConstantLines.Add(constantLine1)

' Define its axis value.
constantLine1.AxisValue = 7

' Customize the behavior of the constant line.
constantLine1.Visible = True
constantLine1.ShowInLegend = True
constantLine1.LegendText = "Some Threshold"
constantLine1.ShowBehind = False

' Customize the constant line's title.
constantLine1.Title.Visible = True
constantLine1.Title.Text = "Constant Line Title"
constantLine1.Title.TextColor = Color.Red
constantLine1.Title.Antialiasing = False
constantLine1.Title.Font = New Font("Tahoma", 14, FontStyle.Bold)
constantLine1.Title.ShowBelowLine = True
constantLine1.Title.Alignment = ConstantLineTitleAlignment.Far

' Customize the appearance of the constant line.
constantLine1.Color = Color.Red
constantLine1.LineStyle.DashStyle = DashStyle.Dash
constantLine1.LineStyle.Thickness = 2

在下面的插图中显示了结果。

CodeCentralShow Me

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=E1370。 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。

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