Is it possible to disable double buffering or otherwise debug overdrawing?

[dswitkin]

I have a suspicion that our app is overdrawing, e.g. drawing the same thing too often, drawing invisible items needlessly, etc. Are there any debugging tools or flags I can use to disable double buffering so that I see the flickering? Or to see each Visual/Control/Panel draw one by one to observe how much work is being done? This is an ordinary 2D desktop app for Mac and Windows, no 3D or direct frame buffer access. Thanks!

[stevemonaco]

Use the debug overlays in DevTools (the legacy ones have it). Overlays -> Dirty Rects.

The Accelerate dev tools have some additional profiling options, but AFAIK, there's no toggle for the overlays. Maybe I'm not seeing them. Edit: I missed them.

You can also enable the overlays yourself by setting TopLevel.RendererDiagnostics or such.

Also, the renderer shouldn't be drawing invisible (as in IsVisible="False" or Opacity="0") controls. Beware of things like infinite animations, unnecessary updates, etc. Not enough details to provide other ideas.

[dswitkin]

Thanks, I was able to turn on DirtyRects via TopLevel and get a sense of things updating. I can't find any documentation on what the DirtyRects colors mean though:

https://api-docs.avaloniaui.net/docs/T_Avalonia_Rendering_RendererDebugOverlays

On my mostly grey UI it seems like just some slightly purple, grey, and green values which cycle through. Are they arbitrary?

Also, I'm concerned that some background views may be drawing behind an opaque foreground object. Is there any way to disable double buffering so that I can see if this is happening?

[stevemonaco]

AFAIK, those colors cycle so that it works on a variety of bgs (and so subsequent updates look different).

I don't think double buffering should be your concern. AFAIK, there's no way to adjust frame buffering.

Keeping background views (ie. full pages stacked) isn't a winning recipe, especially if they don't have IsVisible="False" to prevent extra work. The easy thing to do here is to use the render overlays (or Avalonia logging) to get render/layout times, remove said background views, and repeat.

[maxkatz6]

but AFAIK, there's no toggle for the overlays

Old overlays are still there. Historically these were part of Avalonia renderer itself, with public API to toggle. Old and new devtools just provided menu options to tottle them.

[stevemonaco]

Aha, the context options are only (?) available on the TopLevel element which makes sense (since that's where the properties live), but kind of unintuitive for discoverability. Thanks Max.

[maxkatz6]

Yeah, this is definitely something that can be designed in a better way.