Performance: interactivity is slow if Visual.Render() is overridden

Bug Description: When display a huge amount of points, ScottPlot is lagging a lot, especially when you’re trying to move in the graph

Reproducing:

AvaPlot plot = this.FindControl<AvaPlot>("Plot");
var random = new Random();
plot.Plot.AddScatter(
    xs: Enumerable.Range(0, 10000).Select(x => (double)x).ToArray(),
    ys: Enumerable.Range(0, 10000).Select(x => (double)random.Next()).ToArray()
);

System Information

• ScottPlot Version: 4.1.16
• Operating System: Windows 11 / Ubuntu 20.04
• Application Type: Avalonia

[bclehmann]

I am unfamiliar with your overriding of Visual.Render(DrawingContext context) in MainWindow.axaml.cs. I wonder if Visual.Render is called everytime that the control needs to be redrawn. This is bad, because you’re initializing a lot of data in this function.

I would move all of it to the constructor, or another function guaranteed to be called only once on startup.

[swharden]

Also I’m a little confused about an AvaPlot being used in a Windows WPF project. I would have expected to see a WpfPlot 🤔

I don’t have much Avalonia experience though. Is this a mistake, or is there some cross-platform fanciness going on here?

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net5.0</TargetFramework>
    <Nullable>enable</Nullable>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Avalonia" Version="0.10.6" />
    <PackageReference Include="Avalonia.Desktop" Version="0.10.6" />
    <PackageReference Include="Avalonia.Diagnostics" Version="0.10.6" />
    <PackageReference Include="ScottPlot.Avalonia" Version="4.1.16" />
   </ItemGroup>
</Project>

EDIT: I was mistaken. This isn’t a WPF project, and the original issue says this is an Avalonia project. The WinExe line threw me off. My bad!