nm_custom_draw should provide a mutable reference? about winsafe

[rodrigocfd]

It seems you are correct, NMLVCUSTOMDRAW should me mutable. Let me know if it's working for you now.

I'm unsure about all other nm_custom_draw being mutable, though.

[mattg23]

That was fast, thank you @rodrigocfd !

I can confirm, it works as expected.

One note: I needed to assign the colors this way:

let txt_clr = COLORREF::new(highlight.fg_color.0, highlight.fg_color.1, highlight.fg_color.2);
unsafe {
    *draw.clrText.as_mut() = txt_clr.raw();
}

If i do it any other way the compiler optimizes it away in release mode 🤷. But i assume that's a skill issue on my side.

[rodrigocfd]

Won't this work for you?

self.lst_entries.on().nm_custom_draw(|p| {

	let blue = w::COLORREF::new(0x00, 0x00, 0xff);

	p.clrText = blue; // simple assignment!

	// ...

	Ok(co::CDRF::DODEFAULT)
});

[mattg23]

Unfortunately not.
I made a quick repo reproducing the behavior if you want to try it out.
Do you have any ideas what is happening here?

This is a learning project for me, so it's not a problem if i have to use unsafe.
But it would be nice to understand what exactly is going on here.

Edit: Added a profile with lto to the repo. This removes all colors, even the unsafe version doesn't work.

[rodrigocfd]

The root cause was way deeper than the message handling itself. The lambda parameter was originally const, then later cast to mutable, thus causing undefined behavior.This is a rule that comes from C++, which I fortunately already faced in my C++ days.

I still don't know how this change will propagate throughout all WM_NOTIFY events, but so far everything seems fine.

Your example is working for me with all profiles now. Let me know if it works for you.

[mattg23]

I've done some small testing with max optimizations enabled.
So far everything works fine. Thank you so much for the support!

Also thanks for the info. I checked your changes and the stackoverflow post you linked.
This makes sense to me now.

I still have a bunch of features to implement, so i keep an eye out for anything suspicious.