WPF custom ValueFormatter fails in 2015

[eugenem]

This code worked at MS 2013:

public class MyGeneralValueFormatter : GeneralValueFormatter
{

return Engineering.ToFormattedString(Convert.ToDouble(value), this.Format, _units);

}

protected override UIElement VisualizeCore<TData>(TData value, ValuePresenterArgs args, UIElement existingVisual)
{
UIElement element = base.VisualizeCore<TData>(value, args, existingVisual);

if (args.Context is Axis<TData>)
{
var axis = (Axis<TData>)args.Context;

if (axis.Orientation == System.Windows.Controls.Orientation.Horizontal)
{
if (_showOnlyMinMaxAtX)
{
Range<TData> range = axis.Range;
var comparer = range.Comparer;
RelativeAlignment alignment =
comparer.Compare(range.Minimum, value) == 0 ? RelativeAlignment.Near :
comparer.Compare(range.Maximum, value) == 0 ? RelativeAlignment.Far :
RelativeAlignment.Center;
//RegionPanel.SetRelativeHorizontalAlignment(element, alignment);

element.Opacity = comparer.Compare(range.Minimum, value) == 0 || comparer.Compare(range.Maximum, value) == 0 ? 1.0 : 0.0;
}
}
else
{
element = new Viewbox { MaxWidth = 60, Width = 60, Stretch = System.Windows.Media.Stretch.None, Child = element };
}
}

return element;
}
}

1. This doesn't even compile:

RegionPanel.SetRelativeHorizontalAlignment(element, alignment);

2. This crashes with error: Specified element is already the logical child of another element. Disconnect it first.

element = new Viewbox { MaxWidth = 60, Width = 60, Stretch = System.Windows.Media.Stretch.None, Child = element };

[D-Cubed]

Hi, eugenem

I can address one of your concerns immediately. In Measurement Studio 2015, RegionPanel was changed to RelativePanel, which is why that line no longer compiles.

To address your other concern, I will need more context for this code. Syntactically, I don't believe your code (as is) would have compiled in any version of Visual Studio. It is also unclear how the value formatter class relates to the VisualizeCore<TData> override method. Can you please provide a more complete snippet? Please see the following copy of the code you provided, where I have added comments with questions. I also highlighted the place I changed RegionPanel to RelativePanel.

// This is a class definition. Why is it returning a value?
public class MyGeneralValueFormatter : GeneralValueFormatter
{
    return Engineering.ToFormattedString(Convert.ToDouble(value), this.Format, _units);
}

// Where does this method belong? Currently it does not have a containing class.
protected override UIElement VisualizeCore<TData>(TData value, ValuePresenterArgs args, UIElement existingVisual)
{
    UIElement element = base.VisualizeCore<TData>(value, args, existingVisual);

    if (args.Context is Axis<TData>)
    {
        var axis = (Axis<TData>)args.Context;
        if (axis.Orientation == System.Windows.Controls.Orientation.Horizontal)
        {
            if (_showOnlyMinMaxAtX)
            {
                Range<TData> range = axis.Range;
                var comparer = range.Comparer;
                RelativeAlignment alignment =
                comparer.Compare(range.Minimum, value) == 0 ? RelativeAlignment.Near :
                comparer.Compare(range.Maximum, value) == 0 ? RelativeAlignment.Far :
                RelativeAlignment.Center;
                RelativePanel.SetRelativeHorizontalAlignment(element, alignment);
                element.Opacity = comparer.Compare(range.Minimum, value) == 0 || comparer.Compare(range.Maximum, value) == 0 ? 1.0 : 0.0;
            }
        }
        else
        {
            element = new Viewbox { MaxWidth = 60, Width = 60, Stretch = System.Windows.Media.Stretch.None, Child = element };
        }
    }

    return element;
}
}

[eugenem]

sorry, I've deleted too much of the class. there is the full version:

  public class RCAGeneralValueFormatter : GeneralValueFormatter 
  {
    private string _units;
    private bool _showOnlyMinMaxAtX;

    public RCAGeneralValueFormatter(string format, string units, bool showOnlyMinMaxAtX)
      : base(format)
    {
      _units = units;
      _showOnlyMinMaxAtX = showOnlyMinMaxAtX;
    }

    protected override string FormatCore<TData>(TData value, ValuePresenterArgs args)
    {
      if (args.Context is Axis<TData>)
      {
        var axis = (Axis<TData>)args.Context;

        if (axis.Orientation == System.Windows.Controls.Orientation.Horizontal)
        {
            Range<TData> range = axis.Range;
            var comparer = range.Comparer;
            if( comparer.Compare(range.Minimum, value) != 0 && comparer.Compare(range.Maximum, value) != 0)
              return Engineering.ToFormattedString(Convert.ToDouble(value), this.Format, "");
        }
      }
      
      return Engineering.ToFormattedString(Convert.ToDouble(value), this.Format, _units);
    }

    protected override UIElement VisualizeCore<TData>(TData value, ValuePresenterArgs args, UIElement existingVisual)
    {
      UIElement element = base.VisualizeCore<TData>(value, args, existingVisual);
        
      if (false && args.Context is Axis<TData>)
      {
        var axis = (Axis<TData>)args.Context;

        if (axis.Orientation == System.Windows.Controls.Orientation.Horizontal)
        {
          if (_showOnlyMinMaxAtX)
          {
            Range<TData> range = axis.Range;
            var comparer = range.Comparer;
            RelativeAlignment alignment =
                    comparer.Compare(range.Minimum, value) == 0 ? RelativeAlignment.Near :
                    comparer.Compare(range.Maximum, value) == 0 ? RelativeAlignment.Far :
                    RelativeAlignment.Center;
            //RegionPanel.SetRelativeHorizontalAlignment(element, alignment);

            element.Opacity = comparer.Compare(range.Minimum, value) == 0 || comparer.Compare(range.Maximum, value) == 0 ? 1.0 : 0.0;
          }
        }
        else
        {
          element = new Viewbox { MaxWidth = 60, Width = 60, Stretch = System.Windows.Media.Stretch.None, Child = element };
        }
      }
        
      return element;
    }
  }

[D-Cubed · Accepted solution]

Thank you for posting the rest of the code.

It looks like instead of using your override for VisualizeCore<TData>, you can make use of the new properties, RangeLabeledDivisions.MaximumLabelAlignment and RangeLabeledDivisions.MinimumLabelAlignment. For example:

<ni:Graph>
    <ni:Graph.Axes>
        <ni:AxisDouble Orientation="Horizontal">
            <ni:AxisDouble.MajorDivisions>
                <ni:RangeLabeledDivisions MaximumLabelAlignment="Far" MinimumLabelAlignment="Near" />
            </ni:AxisDouble.MajorDivisions>
        </ni:AxisDouble>
    </ni:Graph.Axes>
</ni:Graph>

As for creating a new ViewBox, is there a reason you don't just set the UIElement properties directly on element? It seems like setting the MaxWidth on element would have the same effect as what you are doing there.