This topic introduces custom axis scaling feature of the XamDataChart™ control and explains, with code examples, how to use it to create custom axis scaler.
The topic is organized as follows:
The XamDataChart control is designed to allow application developers to implement custom axis scales in their applications. This is accomplished by applying the custom axis scaler to the Scaler property of a numeric axis. Refer to the Configuring Axis Scales topic for basic information on using axis scale feature of the XamDataChart control.
Table 1 – List of types of axes that support custom axis scaling feature.
An example of custom axis scaler is the ProbabilityVerticalScaler which scales values plotted along y-axis between 0% to 100% values in the XamDataChart control.
Figure 1 – Preview of the XamDataChart control with ProbabilityVerticalScaler applied to y-axis.
In order to implement custom axis scaler, you must create a class that inherits from the NumericScaler base class and override the following abstract methods of the base class:
The following code snippet shows how to create custom ProbabilityVerticalScaler by inheriting from NumericScaler class and overriding above methods with code for setting actual range of y-axis to 0-100% and scaling/un-scaling data values.
In Visual Basic:
Imports Infragistics.Controls.Charts
Namespace Infragistics.Samples.Common
''' <summary>
''' Represents the probability scaler for vertical numeric axis
''' </summary>
Public Class ProbabilityVerticalScaler
Inherits NumericScaler
''' <summary>
''' Absolute minimum for probability value on a numeric axis
''' </summary>
Public Const AbsoluteProbabiltyMinimumValue As Double = 0.0
''' <summary>
''' Absolute maximum for probability value on a numeric axis
''' </summary>
Public Const AbsoluteProbabiltyMaximumValue As Double = 100.0
Protected Mu As Double = 0.5
Protected Sigma As Double = 0.075
''' <summary>
''' Calculates the actual minimum and actual maximum values for the axis scale
''' </summary>
Public Overrides Sub CalculateRange(target As NumericAxisBase, minimumValue As Double, maximumValue As Double, ByRef actualMinimumValue As Double, ByRef actualMaximumValue As Double)
' for this scaler the actual axis range is always between 0 and 100 percent
actualMinimumValue = AbsoluteProbabiltyMinimumValue
actualMaximumValue = AbsoluteProbabiltyMaximumValue
End Sub
''' <summary>
''' Returns the display (pixel) position corresponding with a numeric value on the axis
''' </summary>
Public Overrides Function GetScaledValue(unscaledValue As Double, p As ScalerParams) As Double
Dim scaledValue As Double = (unscaledValue - ActualMinimumValue) / (ActualMaximumValue - ActualMinimumValue)
If Not p.IsInverted Then
scaledValue = 1.0 - scaledValue
End If
scaledValue = Me.Mu + Me.Sigma * System.Math.Tan(System.Math.PI * (scaledValue - 0.5))
Return p.ViewportRect.Top + p.ViewportRect.Height * (scaledValue - p.WindowRect.Top) / p.WindowRect.Height
End Function
''' <summary>
''' Returns the numeric value corresponding to the display or "pixel" position on the axis
''' </summary>
Public Overrides Function GetUnscaledValue(scaledValue As Double, p As ScalerParams) As Double
Dim unscaledValue As Double = p.WindowRect.Top + p.WindowRect.Height * (scaledValue - p.ViewportRect.Top) / p.ViewportRect.Height
If Not p.IsInverted Then
unscaledValue = 1.0 - unscaledValue
End If
unscaledValue = 0.5 + 0.318309886183791 * System.Math.Atan2(unscaledValue - Me.Mu, Me.Sigma)
Return ActualMinimumValue + unscaledValue * (ActualMaximumValue - ActualMinimumValue)
End Function
End Class
End NamespaceIn C#:
using Infragistics.Controls.Charts;
namespace Infragistics.Samples.Common
{
/// <summary>
/// Represents the probability scaler for vertical numeric axis
/// </summary>
public class ProbabilityVerticalScaler : NumericScaler
{
/// <summary>
/// Absolute minimum for probability value on a numeric axis
/// </summary>
public const double AbsoluteProbabiltyMinimumValue = 0.0;
/// <summary>
/// Absolute maximum for probability value on a numeric axis
/// </summary>
public const double AbsoluteProbabiltyMaximumValue = 100.0;
protected double Mu = 0.5;
protected double Sigma = 0.075;
/// <summary>
/// Calculates the actual minimum and actual maximum values for the axis scale
/// </summary>
public override void CalculateRange(NumericAxisBase target, double minimumValue, double maximumValue,
out double actualMinimumValue,
out double actualMaximumValue)
{
// for this scaler the actual axis range is always between 0 and 100 percent
actualMinimumValue = AbsoluteProbabiltyMinimumValue;
actualMaximumValue = AbsoluteProbabiltyMaximumValue;
}
/// <summary>
/// Returns the display (pixel) position corresponding with a numeric value on the axis
/// </summary>
public override double GetScaledValue(double unscaledValue, ScalerParams p)
{
double scaledValue = (unscaledValue - ActualMinimumValue)/(ActualMaximumValue - ActualMinimumValue);
if (!p.IsInverted)
{
scaledValue = 1.0 - scaledValue;
}
scaledValue = this.Mu + this.Sigma * System.Math.Tan(System.Math.PI * (scaledValue - 0.5));
return p.ViewportRect.Top + p.ViewportRect.Height * (scaledValue - p.WindowRect.Top) / p.WindowRect.Height;
}
/// <summary>
/// Returns the numeric value corresponding to the display or "pixel" position on the axis
/// </summary>
public override double GetUnscaledValue(double scaledValue, ScalerParams p)
{
double unscaledValue = p.WindowRect.Top + p.WindowRect.Height * (scaledValue - p.ViewportRect.Top) / p.ViewportRect.Height;
if (!p.IsInverted)
{
unscaledValue = 1.0 - unscaledValue;
}
unscaledValue = 0.5 + 0.318309886183790671 * System.Math.Atan2(unscaledValue - this.Mu, this.Sigma);
return ActualMinimumValue + unscaledValue * (ActualMaximumValue - ActualMinimumValue);
}
}
}Optionally, custom tick mark values can be implemented for the ProbabilityVerticalScaler as it is demonstrated in the following code snippet
In Visual Basic:
Imports System.Collections.Generic
Imports System.Linq
Imports Infragistics.Controls.Charts
Namespace Infragistics.Samples.Common
Public Class ProbabilityTickmarkValues
Inherits TickmarkValues
Public Sub New()
' define probability tickmark values
Me.ProbabilityValues = New DoubleCollection() From { 0, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 100 }
End Sub
Protected First As Double
Protected Last As Double
Protected ProbabilityValues As DoubleCollection
''' <summary>
''' Initializes tickmark values prior to rendering axis labels, striplines, and gridlines
''' </summary>
''' <param name="initializationParameters"></param>
Public Overrides Sub Initialize(initializationParameters As TickmarkValuesInitializationParameters)
MyBase.Initialize(initializationParameters)
' Initialize is overridden in order to store the minimum and maximum values,
' which will be later used in the MajorValues() and MinorValues() methods.
Me.First = initializationParameters.VisibleMinimum
Me.Last = initializationParameters.VisibleMaximum
End Sub
''' <summary>
''' Returns values of major tickmarks
''' </summary>
''' <returns></returns>
Public Overrides Function MajorValues() As IEnumerable(Of Double)
Dim values As IEnumerable(Of Double) = ProbabilityValues.Where(Function(value) value >= Me.First AndAlso value <= Me.Last)
Return values
End Function
''' <summary>
''' Returns values of minor tickmarks
''' </summary>
''' <returns></returns>
Public Overrides Function MinorValues() As IEnumerable(Of Double)
' no minor tickmarks
Return New Double() {}
End Function
End Class
End NamespaceIn C#:
using System.Collections.Generic;
using System.Linq;
using Infragistics.Controls.Charts;
namespace Infragistics.Samples.Common
{
public class ProbabilityTickmarkValues : TickmarkValues
{
public ProbabilityTickmarkValues()
{
// define probability tickmark values
this.ProbabilityValues = new DoubleCollection { 0, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 100 };
}
protected double First;
protected double Last;
protected DoubleCollection ProbabilityValues;
/// <summary>
/// Initializes tickmark values prior to rendering axis labels, striplines, and gridlines
/// </summary>
/// <param name="initializationParameters"></param>
public override void Initialize(TickmarkValuesInitializationParameters initializationParameters)
{
base.Initialize(initializationParameters);
// Initialize is overridden in order to store the minimum and maximum values,
// which will be later used in the MajorValues() and MinorValues() methods.
this.First = initializationParameters.VisibleMinimum;
this.Last = initializationParameters.VisibleMaximum;
}
/// <summary>
/// Returns values of major tickmarks
/// </summary>
/// <returns></returns>
public override IEnumerable<double> MajorValues()
{
IEnumerable<double> values = ProbabilityValues.Where((value) => value >= this.First && value <= this.Last);
return values;
}
/// <summary>
/// Returns values of minor tickmarks
/// </summary>
/// <returns></returns>
public override IEnumerable<double> MinorValues()
{
return new double[] { /* no minor tickmarks */ };
}
}
}The following code snippet shows how to apply custom ProbabilityVerticalScaler to the y-axis in the XamDataChart control.
In XAML:
<ig:XamDataChart.Axes>
<ig:NumericYAxis Name="yAxis" MinimumValue="0" MaximumValue="100" Label="{}{} %" >
<!-- ========================================================================== -->
<ig:NumericYAxis.Scaler>
<custom:ProbabilityVerticalScaler />
</ig:NumericYAxis.Scaler>
<!-- ========================================================================== -->
<ig:NumericYAxis.TickmarkValues>
<custom:ProbabilityTickmarkValues />
</ig:NumericYAxis.TickmarkValues>
</ig:NumericYAxis>
</ig:XamDataChart.Axes>