Add optional line to Points PlotItem

[jsalort]

This is a proposal to add the option to connect the points in the Points PlotItem, similar to "o-" in Matlab or Python Matplotlib.
I don't know if such addition would be welcome in egui_plot, but I needed this in a project, and initially thought about defining a custom PlotItem. But it is not straightforward to implement custom PlotItem, as some methods are private, so it was simpler to just add the options I needed in the existing Points struct. Besides, other people may want to do this.

It is not the same thing as adding two PlotItem: a Line and a Points, because then clicking on the name in the legend would mask only the Points. There are surely workarounds, but I found simpler to just have the option the connect the points in the Points PlotItem.

[emilk]

this is paying the price of the collect wether or not we have a line

[emilk]

This adds a "line" feature to egui_plot::Points.
We could instead add a marker feature to egui_plot::Line

But better yet would probably be to combine Points and Line into one thing, instead of replicating features between them. What do you think?

[jsalort]

This adds a "line" feature to egui_plot::Points. We could instead add a marker feature to egui_plot::Line

But better yet would probably be to combine Points and Line into one thing, instead of replicating features between them. What do you think?

Well yes, I agree completely. In the analogy with other plotting tools like Matplotlib, both kinds of plots are just obtained with plt.plot, with option for markers and/or line. Providing both features within the same PlotItem makes sense to me, but deprecating one of the existing things would be a backward-incompatible change (for people using the one that would be removed).
Or maybe it is possible to have just one thing, perhaps something like egui_plot::Chart, but keep both previous names, egui_plot::Points and egui_plot::Line which would be aliases for Chart only with different defaults, e.g. Points with only markers by default, and Line with only a line by default (if such a thing is possible with the Rust type system, I am too new to Rust to know).

[emilk]

egui_plot has recently been moved to its own repository, at https://github.com/emilk/egui_plot

This will hopefully speed up its development by having more reviewers and maintainers.

Please re-open this PR at https://github.com/emilk/egui_plot/pulls

See also:

• Looking for maintainer egui_plot#58
• Move egui_plot to its own repo #4828