We analyzed several performance issues in real-time charting scenarios and we found that the rendering speed of the Line Series was worse than expected in certain cases. Specifically, we noticed a big performance decrease when rendering a Line Series that contained many vertical segments. We investigated this behavior and developed a deeper understanding of the origin of the issues: in a nutshell, the WPF rendering system can be inefficient at times.
We decided to implement a custom rendering method to improve performance in the relevant use cases. The new implementation uses a D3DImage object to display a Direct3D surface. We write Direct2D content to that surface.
The new functionality is included in the upcoming v19.1 release. You enable it by setting the property ChartControl.IsDirectXSurfaceRendering to true. In our tests, Line Series rendering speed increased between 1.8 and 5 times in different scenarios, and in extreme cases the rendering speed was about 25 times faster than before. The Spline Series rendering speed improved as well, up to 2.5 times.
Note that series types other than Line and Spline don’t benefit from the new feature. At this point we recommend to activate the IsDirectXSurfaceRendering option only for Line and Spline series, since we haven’t fully ascertained compatibility with all other series types.
Performance Comparison
We created a sample with 20000 input points. Using the old rendering mode, the Line Series rendered around 5 FPS. At High DPI resolutions, the speed even dropped to 1 FPS. All interactive operations, such as zooming and scrolling, were slowed down considerably.
Running the same sample with the IsDirectXSurfaceRendering option enabled, we saw an impressive boost to around 50 FPS – even at High DPI resolutions. At the same time, scroll and zoom operations remained very smooth.
In the screenshot, the bottom chart also displays a Spline Series. This uses 800 points and shows an improvement from ~8 to ~45 FPS.
You can download the sample project from our GitHub repository
Your Feedback Is Valuable
If you use Line or Spline series in your data visualization applications, we suggest you try the new rendering method and let us know how it works for you. In case you notice any problems, please contact us via the Support Center. We would also appreciate it if you could take a moment to complete the short survey below.