Best way to display an incrementally-updating image

[edyoung]

Hi, I'm writing a program which renders images - think fractals or ray-tracing. Multiple background threads will update a buffer as the computation progresses, and I'd like the user to be able to see what is going on while this happens. Drawing the image takes multiple seconds in most cases, so I'd like this to be efficient but don't need 60fps responsiveness. I'm trying to understand the best way to do this in WinUI. I'd prefer to keep most of this in C#.

So far the options I am aware of:

• Create a SoftwareBitmap, SoftwareBitmapSource, and BitmapBuffer. Background threads call LockBuffer then update chunks of the bitmap. In this case I am not sure how to signal that some part of the image should be redrawn on screen when it changes?
• From https://docs.microsoft.com/en-us/windows/uwp/gaming/directx-and-xaml-interop it appears I can create a SurfaceImageSource and render to it using Direct2D. This looks more complicated to do from C# but doable.
• Or from the same article I could use a SwapChainPanel. That sounds a bit like overkill.

So my question is: given the constraints above, can you suggest how best to do this? Could be one of the above or something else entirely. Also, if you are aware of open source code or samples which demonstrate using that approach, pointers would be much appreciated.

Thanks!