Questions

Hi Stuart,

If you want one axis to draw gridlines, and the other not, you need to set AxisBase.IsPrimaryAxis to true (to draw gridlines) or to false (to not draw gridlines). That will solve the problem.

However, I think what you’re looking for is a good way to switch between linear and logarithmic axis. So, here is one way you can do this, with attached behaviours:

SwitchYAxisTypeBehavior

Dynamically Switches an axis instance on a chart depending on a bound boolean property

// Note this could be extended to deal with XAxis quite easily
public class SwitchYAxisTypeBehavior
{
    // Define the Default YAxis -- this can be done in XAML
    public static readonly DependencyProperty DefaultYAxisProperty = DependencyProperty.RegisterAttached(
        "DefaultYAxis", typeof(AxisBase), typeof(SwitchYAxisTypeBehavior), new PropertyMetadata(default(AxisBase), OnPropertyChanged));

    public static void SetDefaultYAxis(DependencyObject element, AxisBase value)
    {
        element.SetValue(DefaultYAxisProperty, value);
    }

    public static AxisBase GetDefaultYAxis(DependencyObject element)
    {
        return (AxisBase)element.GetValue(DefaultYAxisProperty);
    }

    // Define the Alternative YAxis -- this can be done in XAML
    public static readonly DependencyProperty AlternativeYAxisProperty = DependencyProperty.RegisterAttached(
        "AlternativeYAxis", typeof(AxisBase), typeof(SwitchYAxisTypeBehavior), new PropertyMetadata(default(AxisBase), OnPropertyChanged));

    public static void SetAlternativeYAxis(DependencyObject element, AxisBase value)
    {
        element.SetValue(AlternativeYAxisProperty, value);
    }

    public static AxisBase GetAlternativeYAxis(DependencyObject element)
    {
        return (AxisBase)element.GetValue(AlternativeYAxisProperty);
    }

    // Define a boolean attached property which switches between default and alternative YAxis
    public static readonly DependencyProperty UseAlternateYAxisProperty = DependencyProperty.RegisterAttached(
        "UseAlternateYAxis", typeof(bool), typeof(SwitchYAxisTypeBehavior), new PropertyMetadata(default(bool), OnPropertyChanged));

    public static void SetUseAlternateYAxis(DependencyObject element, bool value)
    {
        element.SetValue(UseAlternateYAxisProperty, value);
    }

    public static bool GetUseAlternateYAxis(DependencyObject element)
    {
        return (bool)element.GetValue(UseAlternateYAxisProperty);
    }

    private static void OnPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // This is where we switch the axis type depending on boolean
        var scs = d as SciChartSurface;
        if (scs == null) return;

        bool useAlternateYAxis = GetUseAlternateYAxis(scs);
        scs.YAxis = useAlternateYAxis ? GetAlternativeYAxis(scs) : GetDefaultYAxis(scs);
    }
}

Usage (XAML):

    <s:SciChartSurface x:Name="sciChart" Grid.Row="1" m:SwitchYAxisTypeBehavior.UseAlternateYAxis="{Binding UseLogarithmicAxis}">

        <m:SwitchYAxisTypeBehavior.DefaultYAxis>
            <s:NumericAxis AxisTitle="Numeric Axis" DrawMajorBands="True" VisibleRange="0, 10" AutoRange="Never"/>
        </m:SwitchYAxisTypeBehavior.DefaultYAxis>

        <m:SwitchYAxisTypeBehavior.AlternativeYAxis>
            <s:LogarithmicNumericAxis AxisTitle="Logarithmic Axis" LogarithmicBase="10" TextFormatting="0.0" CursorTextFormatting="0.0"  
                                      DrawMajorBands="True" VisibleRange="0.1, 10000"/>
        </m:SwitchYAxisTypeBehavior.AlternativeYAxis>

  ...
  </s:SciChartSurface>

Alternatively, if not using MVVM

Attached properties can be set in code as well. The C# equivalent for setting an attached property is:

var scs = new SciChartSurface();
// ... 
SwitchYAxisTypeBehavior.SetDefaultYAxis(scs, new NumericAxis() { ... } );
SwitchYAxisTypeBehavior.SetAlternateYAxis(scs, new LogarithmicNumericAxis() { ... } );
SwitchYAxisTypeBehavior.SetUseAlternateYAxis(scs, true);

Best regards,
Andrew