Question

How does one swap the axes in a WPF Toolkit line chart? I have the following xaml:

<chartingToolkit:Chart  Name="lineChart" Title="Line Series Demo" Margin="0,0,0,0">
     <chartingToolkit:LineSeries  DependentValuePath="Key" IndependentValuePath="Value" ItemsSource="{Binding}" IsSelectionEnabled="True" />
  </chartingToolkit:Chart>

The dependent values always appear as the Y-axis. I need them as the X-axis. Is this possible with WPF Toolkit charts? If I can’t do this with WPF Toolkit, are there other free WPF charting libraries I can use instead? All I need is line chart that can handle multiple series with time on X-Axis and Strings on Y-Axis.

Answer 1

After unsuccessfully trying to find an answer to my problem with the original WPF Toolkit, I decided to edit the Charting toolkit source myself. Here are the changes that I did in order to get it working:

(Showing source code changes, to see original source, look at the original post prior to edit)

1. Get the source. I am using VS2010 and since some of the components
   from WPF Toolkit have become a part of .NET4, I had to modify WPF
   Toolkit solution. Thankfully, that legwork was already done for me.
   Get the source here

2. Change LineSeries.cs:115 To

                   if (axis == null)
                   {
                      axis = new CategoryAxis();
                   } 
   

3. Change LineAreaBaseSeries.cs:243 To

      double x = ActualIndependentAxis.GetPlotAreaCoordinate(dataPoint.ActualIndependentValue).Value;
      double y = this.InternalActualDependentAxis.GetPlotAreaCoordinate(dataPoint.ActualDependentValue).Value;
   
      if (ValueHelper.CanGraph(x) && ValueHelper.CanGraph(y))
      {
         dataPoint.Visibility = Visibility.Visible;
   
         double coordinateY = Math.Round(y - (dataPoint.ActualHeight / 2));
         Canvas.SetTop(dataPoint, coordinateY);
         double coordinateX = Math.Round(x - (dataPoint.ActualWidth / 2));
         Canvas.SetLeft(dataPoint, coordinateX);
      }
      else
      {
         dataPoint.Visibility = Visibility.Collapsed;
      }
   

Change LineAreaBaseSeries.cs:298 To

       Func<DataPoint, Point> createPoint =
           dataPoint =>
               new Point(
                   ActualIndependentAxis.GetPlotAreaCoordinate(dataPoint.ActualIndependentValue).Value,
                   this.InternalActualDependentAxis.GetPlotAreaCoordinate(dataPoint.ActualDependentValue).Value);
       IEnumerable<Point> points = Enumerable.Empty<Point>();
       if (ActualIndependentAxis is IRangeAxis)
       {
          points = DataPointsByIndependentValue.Select(createPoint);
       }
       else
       {
          points =
             ActiveDataPoints
                   .Select(createPoint)
                   .OrderBy(point => point.X);
       }

After these changes you can use a dependent source of strings.

Cheers!