Nevron .NET Vision
Chart for .NET / User's Guide / Styling / Custom Style Sheets

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    Custom Style Sheets
    In This Topic

    You can use style sheets for a variety of purposes. One of them is to apply dynamic coloring depending on the data in the chart. In this topic we’ll show how to create a custom style sheet that will dynamically change the fill style of gauge indicators if it they enter a specified range of values.

    The first task is to create an applicator that will change the fill style of a gauge indicator if it falls in a specified range. The following code shows how to do this:

    Copy Code
    public class NRangeValueApplicator : NRuleApplicator
    public NRangeValueApplicator(double startVal, double endVal, Color inRange, Color outRange)
    StartValue = startVal;
    EndValue = endVal;
    InRangeColor = inRange;
    OutRangeColor = outRange;
    public override void Apply(NChartElement element)
     NNeedleValueIndicator indicator = element as NNeedleValueIndicator;
     if (indicator == null)
     if (indicator.Value > StartValue && indicator.Value < EndValue)
      // indicator is in range
      indicator.Shape.FillStyle = new NColorFillStyle(InRangeColor);
      indicator.Shape.FillStyle = new NColorFillStyle(OutRangeColor);
    double StartValue;
    double EndValue;
    Color InRangeColor;
    Color OutRangeColor;
    Visual Basic
    Copy Code
    Public Class NRangeValueApplicator
      Inherits NRuleApplicator
    Public Sub New(ByVal startVal As Double, ByVal endVal As Double, ByVal inRange As Color, ByVal outRange As Color)
     StartValue = startVal
     EndValue = endVal
     InRangeColor = inRange
     OutRangeColor = outRange
    End Sub
    Public Overrides Sub Apply(ByVal element As NChartElement)
     Dim indicator As NNeedleValueIndicator = TryCast(element, NNeedleValueIndicator)
     If indicator Is Nothing Then
     End If
     If indicator.Value > StartValue AndAlso indicator.Value < EndValue Then
      ' indicator is in range
      indicator.Shape.FillStyle = New NColorFillStyle(InRangeColor)
      indicator.Shape.FillStyle = New NColorFillStyle(OutRangeColor)
     End If
    End Sub
    Private StartValue As Double
    Private EndValue As Double
    Private InRangeColor As Color
    Private OutRangeColor As Color
    End Class

    The next step is to create a style sheet that uses this applicator:

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    // create selector
    NTypeOfSelector selector = new NTypeOfSelector(typeof(NNeedleValueIndicator));
    NRangeValueApplicator customApplicator = new NRangeValueApplicator(10, 20, Color.Green, Color.Red);
    // create a style sheet
    NStyleSheet sheet = new NStyleSheet();
    sheet.Rules.Add(new NStyleSheetRule(selector, customApplicator));
    // apply to document
    nChartControl1.Document.StyleSheet = sheet;
    Visual Basic
    Copy Code
    ' create selector
    Dim selector As NTypeOfSelector = New NTypeOfSelector(GetType(NNeedleValueIndicator))
    Dim customApplicator As NRangeValueApplicator = New NRangeValueApplicator(10, 20, Color.Green, Color.Red)
    ' create a style sheet
    Dim sheet As NStyleSheet = New NStyleSheet()
    sheet.Rules.Add(New NStyleSheetRule(selector, customApplicator))
    ' apply to document
    nChartControl1.Document.StyleSheet = sheet

    Note that we used a “type of” selector to create the style sheet rule. This ensures that only objects of type “NNeedleValueIndicator” will be processed in the Apply override of the applicator.

    Finally you should know that you can also extend selectors by deriving from the abstract NSelector class.