ScottPlot does not plot when data template is used

Question

When ScottPlot WPF control is placed inside a data template and used for plotting, nothing gets rendered. I'm puzzled as to why the following code would not work:

This is my view:

<Window x:Class="Client.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Client"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Window.Resources>
        <DataTemplate x:Key="DataPlotTemplate">
            <StackPanel>
                <TextBlock Text="{Binding Title}"/>
                <WpfPlot MinHeight="300" MinWidth="300" Content="{Binding DataPlot}"/>
                <TextBlock Text="{Binding Description}"/>
            </StackPanel>
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <StackPanel>
            <ContentControl Content="{Binding DataPlotVm0}"
                            ContentTemplate="{StaticResource DataPlotTemplate}"/>
            <ContentControl Content="{Binding DataPlotVm1}"
                            ContentTemplate="{StaticResource DataPlotTemplate}"/>
        </StackPanel>
    </Grid>
</Window>

This is my view model:

public class DataPlotViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChange(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    private string title = "";
    public string Title
    {
        get { return title; }
        set
        {
            title = value;
            OnPropertyChange("Title");
        }
    }

    public ScottPlot.WpfPlot DataPlot { get; set; } = new ScottPlot.WpfPlot();

    private string description = "";
    public string Description
    {
        get { return description; }
        set
        {
            description = value;
            OnPropertyChange("Description");
        }
    }
}

When DataPlot of the view model is used for plotting, nothing appears.

score 3 · Accepted Answer · answered Dec 09 '20 at 08:36

Scott Plot is not implemented as a proper WPF control that supports data-binding and MVVM.

ScottPlot aims to be easy to use by data scientists new to C#, so its API favors the simplicity of one-line method calls (with optional, named arguments) and intentionally avoids complex paradigms (data binding, MVVM, inheritance) commonly seen in similar libraries available for the .NET platform.

There is a similar issue on GitHub that describes what you can do.

You can create WpfPlot in ViewModel [...] and bind it in you view [...]
It's bad pattern bring control to VM, but it should work.

As the author already states, this is a bad pattern as your view model will contain a UI control. However, there is currently no support for data-binding for WpfPlot. According to the issue, although breaking MVVM, this works:

<DataTemplate x:Key="DataPlotTemplate">
   <StackPanel>
      <TextBlock Text="{Binding Title}"/>
      <ContentControl MinHeight="300" MinWidth="300" Content="{Binding DataPlot}"/>
      <TextBlock Text="{Binding Description}"/>
   </StackPanel>
</DataTemplate>

You could of course derive a custom control and adapt it or use other workarounds for binding, but I do not think that is advisable, as the control itself does offcially not offer any support for this anyway.

ScottPlot does not plot when data template is used

1 Answers1