Large resoluton issues (u16 integer overflow and rendering artefacts)

[karolinepauls]

I started playing around resizing the terminal and looking what happens. For now I've only fixed a couple of panics with higher resolutions: karolinepauls@bd33c04

However, I could still see some rendering artefacts and I'm investigating some right now. Artefacts appear when the number of characters exceeds 2^16 (resolution over 256x256). 2^16 characters is quite a lot but e.g. tmux continues working fine.

$ git grep ' as u16' shows the lib generally assumes u16.

I haven't fixed the gauge demo is panicking so far because here the root of the problem is using integer percentages instead of floating points:

tui-rs/src/widgets/gauge.rs

Line 81 in 56fc434

let width = (gauge_area.width * self.percent) / 100;

Limiting fractional sizes to 0-100 also likely makes scaling choppy.

One way would be to (A) hardcode max resolution to be X:Y where X * Y < 2^16. Another (B) - promote u16 dimensions to u32 (and limit the resolution to 2^32 in case someone's that crazy).

(C) Regarding percentages, I would rather see them as [0, 1] floating points, which would make slicing more precise (3 panes with a ratio of 0.33333333333... will leave a smaller gap than 3 panes with percentage being 33).

I'm looking for some input on that.

[fdehau]

First of all thank you for taking the time to look into this since I've overlooked this issue until now.

Regarding your first point while I think that solution (A) is an easier path for the fix, solution (B) appears to be more future proof.

Regarding percentages you are making a very good point and moving to floats for better precision is ok for me.

I'm also interested in your setup for testing those cases if you don't mind sharing.

[karolinepauls]

The setup is me rescaling a console window way over what my screen is (and getting frustrated doing so). 2^16 is not that much. At work my console window is stretched across 2 HD screens, which is halfway there.

In order to properly test conditions like that a virtual terminal backend may come in handy.

This issue is a bit about too many things at once, so for now I'll play with the ideas here and then I may come up with some PRs. Otherwise - feel free to split it.

[karolinepauls]

#92 "resolves" artefacts with backends over 2^16 characters.

Percentage remains unresolved (I may look into it but last time I tried to do something, it took me so long that meanwhile you implemented an equivalent :D).

[fdehau]

That's great 👍. As you suggested earlier, I think promoting dimensions to u32 might be the next step to cover most use cases. In the meantime, thanks to your work, we have an elegant solution to this problem =).