Use new NativeWindow::lock() API in dummy_render()

[MarijnS95]

No description provided.

[rib]

It could be good to have a comment explaining what this is for.

This is intended to be a bare-bones example of how to use android-activity so it's quite likely someone looking at this isn't going to be familiar with what set_buffers_geometry does (and the name from the NDK isn't very self documenting when we're using it to set the format and not the 'geometry' as such).

Maybe we can just note that, since this example is going to clear the window from the CPU then we want to ensure the buffer is in a known format that we will be able to write to from dummy_render()

[MarijnS95]

Sure, still a draft as I wanted to share progress and show what's possible with the new bindings.

[rib]

Yep, I'd be happy to have a convenient way to at least show something other than a black screen, but without needing to pull in a full-blown graphics API.

[MarijnS95]

Cool cool, this already shows a gradient instead of a black screen, as a sign of life.

We can probably drop the draft status now, IIRC this is mostly ready.

[rib]

Yeah don't mind if it's taken out of draft and will just want to wait until it doesn't depend on [patches] before landing.

[MarijnS95]

Sure, expect that to take ±1month though. That should be enough time to see if there are any issues with this patch though, pretty helpful to test compatibility with the ecosystem meanwhile.

[rib]

Sorry this didn't land sooner but I rebased and just tweaked it to add a format assertion in dummy_render and made it also explicitly write to the blue + alpha channels.

I'm not quite sure what just happened though with the follow up force push of the previous branch @MarijnS95 ?

[MarijnS95]

A bunch of my changes went missing but you're right, you also added some changes that are now missing in my force-push. Working on reconverging (was still on this branch and instead intended to first rebase/fix #9).

[rib]

okey - I didn't mean to discard other changes but just guessed the other lint changes might be out of date by now.

maybe I can try and open a separate PR with just your previous lint fixes so this one just deals with the dummy_render changes?

[MarijnS95]

Moved to #24, now restoring this PR.

[MarijnS95]

Since the buffer is """maybeuninit""", setting all channels to valid values is "required" (hoping Android doesn't read the skipped padding/stride bytes).

Not too keen on the assert but let's keep it. I rather allow RGBX8 too, but might be a bit of a hassle to support now. This is the only format I set in softbuffer:

https://github.com/rust-windowing/softbuffer/blob/fb3bc8df4f338685816886774867691e9f6064ad/src/backends/android.rs#L76

But then allow RGBA8 too in case the user changed it:

https://github.com/rust-windowing/softbuffer/blob/fb3bc8df4f338685816886774867691e9f6064ad/src/backends/android.rs#L101-L114

(The new Alpha code came after my changes, I haven't touched softbuffer since due to constraints)