Selection size

[ninetailedtori]

Heyo, so I'm tryna add some customisation to the main statusbar, really, and I'm trying to get it to display the size of any current selection if there is a selection. That's including rectangular selections, and single-line selections. I want to know the length and thus char count, in a single-line selection, and in multiline rect selections, I wanna know the length and width, and perhaps char count. Not too sure how to impl something like this, would value advice :]

[niten94]

I assume you're using the init.lua file and called micro.SetStatusInfoFn("initlua.fn_name_here") there, although I don't think both are documented well. If not, you may try looking at the following:

• built-in status plugin code as an example
• this section about using init.lua
• the plugin API documented in > help plugins
  • I plan to try slightly reorganizing and add more details in this help topic

Also, the function named in the SetStatusInfoFn() call only receives a buffer as its parameter, which I'll be referring to as b.

I have some questions:

1. What do you specifically mean by the length of a selection? Do you mean the number of lines?
2. Rectangular selections in Micro are technically multiple cursors. It's easier to handle rectangular selections, so would it be enough for you to only consider those?
3. By width, do you mean the displayed width?

As for the character count, you could use this loop:

local cursors = b:GetCursors()
for _, c in cursors() do end

You can then use micro/util which has CharacterCountInString() and String(), together with b:Substr() which is an embedded method from LineArray.

[ninetailedtori]

By length, I mean the length in characters, lengthwise, compared to height/width of selection, which is number of lines selected!

[niten94]

Right sorry, it doesn't make much sense to think of selection length as the number of lines. I also remember that width is always horizontal in the context of UIs, so I was confused why it was mentioned together with length

About my 2nd question, I meant to say that rect selections are technically one cursor per line. Here, b:NumCursors() might be enough to determine the no. of lines selected.

For the displayed length, plugins don't have a reliable way to determine it when considering factors like wide characters and \t. The return value of CharacterCountInString() is good enough if there are no such characters. (edited, counting bytes is worse)

A function or method like StringWidth() could be provided to plugins, but I'm not good at coming up with APIs

[Andriamanitra]

For the displayed length, plugins don't have a reliable way to determine it when considering factors like wide characters and \t.

Cursor.GetVisualX should work for that, except when softwrapping (in which case you can't really have a rectangular selection anyway).

I think visual X would be the length metric most closely aligned with rectangular selections because you could have selected a rectangular region like this:

a🧑‍🚒
xyz

In this case the lengths of the selections on the two lines would be:

• in grapheme clusters: 2, 3
• in code points: 4, 3 (this is what you'd get from CharacterCountInString)
• in bytes (UTF-8): 12, 3
• in characters: It could be any of the above depending on who you ask: it is not well defined. Humans usually mean grapheme clusters, but C calls bytes char, and Rust calls code points char. This causes confusion when dealing with non-ASCII text.
• with visual X: 3, 3

[niten94]

Visual X indeed looks like the metric Micro uses to determine the displayed length. I was thinking about GetVisualX too and it can be used, but I'm not sure it's appropiate.

The only approach I could come up with now uses GetVisualX on start and end X by temporarily setting Cursor.X prior. This relies on an implementation detail, which I feel is less guaranteed to remain than the majority of the internal API.

• with visual X: 3, 3

$(status.vcol) indicated 5 at the end of the 1st line in v2.0.15-rc1, but Micro seems to display it in 6 columns. I think there's a bug somewhere, but I belive visual X is usually correct

[Andriamanitra]

$(status.vcol) indicated 5 at the end of the 1st line in v2.0.15-rc1, but Micro seems to display it in 6 columns. I think there's a bug somewhere, but I belive visual X is usually correct

Right, that was not a good example because micro actually doesn't render emojis such as the firefighter as one but rather renders each of its parts (person + zero-width joiner + fire engine) in their own cell. I should have used a simpler double wide character to demonstrate the point.