Number of line as you'd get moving down the buffer with C-n

Question

In a buffer in Emacs, a line is the text you get from the first character after you press "Enter" to the last character before the next "Enter". And so, this is the line numbers one gets to the left of the buffer when you are in the display-line-numbers-mode.

Is there any way to get not these line numbers, but the "number of line" you get by counting the number of times you press C-n when moving down the buffer from the beginning? Namely, counting the numbers of lines (as I see in the screen) from the beginning of the buffer till the current position, and showing them in the screen as display-line-numbers-mode does.

I have tried using M-q on the line, but this is not what I am looking for as this command truncates the line into multiple lines.

[Edited in order to make the question clearer.]

I'd like to get the kind of thing you get when (in the windowed version of Emacs) you activate "Options → Show/Hide → Line Numbers for All Lines → Visual Line Numbers". But I don't quite understand this option, because it's not counting the lines from the first one in the buffer. Instead, the number in front of each line changes depending on the line in which the cursor is.

[Edit 2]

Example:

In this image I have two lines (I am using word wrapping). Well, the idea is that I'd like to show a number in each line I see, that is, from 1 (at the beginning) to 12 (at the end of the buffer). Of course, if I change the width of the window I'd get a different number of lines.

Answer 1

There is no built-in functionality to provide line numbers based on visual lines. First of all, compared to buffer lines (e.g. \n, \r\n), visual lines need to get recounted on every window width-change, which can bring Emacs down to its knees. Compared to normal buffer lines, visual lines are only second-class citizens in that regard.

However, the old linum-mode provides a starting point to get your desired behaviour. We can change linum-mode in a way that counts visual line modes, but we will disregard some warnings.

Here are the necessary steps:

1. Copy linum.el to another file. For this demonstration, let's call it vinum.el
2. Open vinum.el and M-x replace-string RET linum RET vinum RET
3. Replace forward-line with next-line (warning: next-line is only meant for interactive use, however, C-n is next-line and you want to use its behaviour)
4. M-x eval-buffer
5. Open a buffer with long lines and enable both visual-line-mode and vinum-mode.

This will still use the correct line number for the first line. If you always want to start the numbers by 1, then replace (line-number-at-pos) by 1. If you want to count all visual lines, then replace (window-start win) by (point-min) and (window-end win t) by (point-max) instead.