Example of OxyPlot.Wpf renders blank

JanDotNet · February 2022

Hi,

first of all thanks for the great work, LinqPad is just awesome!

I am trying to display the default example of a WPF OxyPlot line chart with the code below, but the output remains white.
I've also tried to put it into a Grid and set the width/height, but the result didn't change.

var model = new PlotModel { Title = "Example 1" };
model.Series.Add(new FunctionSeries(Math.Cos, 0, 10, 0.1, "cos(x)"));
var plotView = new PlotView();
plotView.Model = model;
PanelManager.DisplayWpfElement(plotView);

I am using LinqPad 5.44.02 (Premium Edition). Any Ideas?

Thanks
Jan

JoeAlbahari · February 2022

There's some dodgy code in OxyPlot.Wpf. In PlotViewBase:

private bool IsInVisualTree()
{
    DependencyObject dependencyObject = this;
    while ((dependencyObject = VisualTreeHelper.GetParent(dependencyObject)) != null)
        if (dependencyObject is Window)
            return true;
    return false;
}

If the parent is not a Window, OxyPlot assumes that the control is not in a visual tree. LINQPad doesn't use a Window to host WPF controls; it uses an ElementHost.

I suggest you run the OxyPlot.WindowsForms instead. It seems to perform quite well in LINQPad:

var model = new PlotModel { Title = "Example 1" };
var series = new FunctionSeries(Math.Cos, 0, 10, 0.1, "cos(x)");
model.Series.Add(series);
var plotView = new PlotView { Model = model }.Dump();

for (int i = 0; i < 100; i++)
{
    await Task.Delay (10);
    series.StrokeThickness++;
    model.InvalidatePlot(true);
}

Edit: it looks like this problem has been fixed in the OxyPlot.Wpf source code, but the NuGet package hasn't yet been updated. They don't seem to release too often.

JanDotNet · February 2022

A similar issue seems to be fixed last month for rendering within SkiaSharp:

https://github.com/oxyplot/oxyplot/blame/196bb74bd8105bc1b5730389ec779996e57156a9/Source/OxyPlot.Wpf.Shared/PlotViewBase.cs#L448

I will try to extend OxyPlot to check for ElementHost as well.... otherwise using WinForms is also an acceptable solution. Thanks!

JanDotNet · February 2022

Checking for ElementHost in IsInVisualTree seems not to work either... doesen't matter, I'll continue with the WinForms solution. Thanks again .

Example of OxyPlot.Wpf renders blank

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