Interacting with lines

[burhangul]

Hello everyone,
Is there any way to interacting with lines instead of points?
We want to select dataset with click on the line. I tried the interactions of the chart options and "getElementsAtEventForMode" method but none of them didn't give me the line. Has anyone tried this before?
Thanks in advance

[stockiNail]

AFAIK that's not possible because line charts are using points as data elements. Maybe it could be an enhancement, I guess

[kadnan]

but can't i figure out line element on hover or on click? after all it is a DOM element?

[stockiNail]

but can't i figure out line element on hover or on click? after all it is a DOM element?

@kadnan No, it isn't. Chartjs is drawing everything on canvas (DOM element) and therefore all items (scales, title, legend, data elements, and so on) are drawn on the canvas but they are not DOM element.

[LeeLenaleee]

If you don't use any tension you could parse the datasets, get the point where the x coordinate is left of your click, get the point right of the x coordinate where you clicked, use math to make a y=ax+b formula, then you enter for the x the x where you clicked and then you can check if the y is the same or approximately the same as the y where you clicked

[stockiNail]

@LeeLenaleee do you think this could be an enhancement, leveraging on Path2D (already use in the line element) like did in annotation plugin [PR] (chartjs/chartjs-plugin-annotation#754)? This will affect the interactions because line element is a dataset element and not a data element.

[LeeLenaleee]

I guess we can always open an enhancement issue for it, then you have the information at 1 place where you expect it and if we don't want it there is the place to put it.

Don't know the underlying codebase well enough from my head to say that we can do it right now in a nice way since like you said its not a data element