1

In our WPF application, we have a need to display about 64 real-time level meters for an audio application. The tests we've thrown at WPF, even when rendering basic primitives as efficiently as we can still show it to be nowhere near where our application needs to be, often times bogging down the main thread so much to the point that it's non-responsive to input.

As such, we have to go with something more optimized for graphics performance such as DirectX (via SlimDX or SharpDX) or OpenGL/ES (via Atlas which converts it to DirectX calls.)

My question is if it's possible to create multiple, small DirectX-based areas, each representing an individual meter, or for that matter, is that even the right approach? I was under the understanding that you have to run it as at a minimum, the entire window, not a portion thereof.

The issues I see with the latter are airspace issues wherein you can't have WPF content in front of DirectX content in the same window, and we really don't want to have to redo all of our controls in DirectX since for the other non-meter 95% of our UI WPF is great!

I have read that you can render DirectX to a brush, then use that inside WPF, or using the WriteableBitmap class which gives you direct access to the buffers WPF then uses in its Render thread, both of which don't seem to suffer from the Airspace issues, but that seems we'd be right back at the same place with WPF being the bottleneck since it still has to do the rendering.

We are of course going to dedicate a few weeks to sample applications testing all of the above, but I'm wondering if I'm even headed in the right direction, and/or if there are any caveats we can avoid by talking to people with experience doing something like this to avoid common pitfalls, etc. As such, any comments will be appreciated.

I'm hoping we can perhaps even start a wiki somewhere to discuss this topic as it seems to be a popular one, albeit spread all over the place making it hard for new entrants to get the information they seek.

Mark A. Donohoe
  • 28,442
  • 25
  • 137
  • 286

2 Answers2

1

With wpf / d3d interop, You should always try to create the smallest number of interop calls. So you should prefer rendering all 64 level meters in a single render target (also it allows you to batch your primitive rendering and draw everything in the smallest number of gpu calls).

you should try to use the D3DImage API that allows you to share your own D3D texture with the wpf renderer.

Simon Ferquel
  • 366
  • 1
  • 3
  • Can you comment more on the D3DImage API? Are you saying that will allow D3D renderings to be part of the WPF render/composter so we won't have airspace issues? – Mark A. Donohoe Sep 26 '13 at 22:09
0

If WPF can't really handle these 64 moving bars, you could go with a single D3DImage and use Direct3D9 for rendering all bars at once directly to it. For your specific scenario, you shouldn't have any performance problem.

xoofx
  • 3,682
  • 1
  • 17
  • 32