More straightforward newline handling

[tempoz]

This PR ensures that every newline: true corresponds to an actual newline character, and conversely that every newline character has a newline: true field somewhere.

This:

• Lets us distinguish between an input that ends with a newline and one that does not on render
• Allows us to render input that ends with multiple newlines correctly
• Allows us to scroll out one line at a time, which greatly simplifies the scroll out logic
• Eliminates the awkward new line that would appear in the middle of a line when scrolling out a line that was too large for the window (see huge-line.sh)

[tempoz]

Hey, just checking in on the status of this PR since I have another one I would like to submit that stacks on this one :D

[DrJosh9000]

Thanks @tempoz, I'm a bit busy lately, haven't been able to give this the time it deserves. From a quick skim this looks good though. I'll aim to do a proper review this week.

[tempoz]

No problem; I greatly appreciate your time and consideration whenever you have the bandwidth to give it.

[DrJosh9000]

Apologies for the delay in getting around to it, but this looks great! Thanks!

[DrJosh9000]

Would you mind rebasing this / merging from main? I would do it if GitHub showed me the button (I probably don't have rights to make changes directly to your repo.)

[tempoz]

done!

[philwo]

Hi!

I noticed that the first line rendered into the screen gets truncated under circumstances that I'm not fully sure yet how to describe... but I found an easy minimal repro that I'm curious what you both think about:

• Check out the latest main of terminal-to-html.
• Comment out or remove the line screen.ScrollOutFunc = wc.WriteString in cmd/terminal-to-html/terminal-to-html.go.
• Run the following command and observe the output. Note that the "hello world" line is 82 chars long:

$ go build cmd/terminal-to-html
$ for i in $(seq -w 0 50); do echo "[$i] hello world hello world hello world hello world hello world hello world hello"; done | \
  ./terminal-to-html --window-max-cols=80 --buffer-max-lines=50 --window-cols=80 --window-lines=50

[26] hello world hello world hello world hello world hello world hello world hello
[27] hello world hello world hello world hello world hello world hello world hello
[28] hello world hello world hello world hello world hello world hello world hello
[29] hello world hello world hello world hello world hello world hello world hello
[30] hello world hello world hello world hello world hello world hello world hello
[31] hello world hello world hello world hello world hello world hello world hello
[32] hello world hello world hello world hello world hello world hello world hello
[33] hello world hello world hello world hello world hello world hello world hello
[34] hello world hello world hello world hello world hello world hello world hello
[35] hello world hello world hello world hello world hello world hello world hello
[36] hello world hello world hello world hello world hello world hello world hello
[37] hello world hello world hello world hello world hello world hello world hello
[38] hello world hello world hello world hello world hello world hello world hello
[39] hello world hello world hello world hello world hello world hello world hello
[40] hello world hello world hello world hello world hello world hello world hello
[41] hello world hello world hello world hello world hello world hello world hello
[42] hello world hello world hello world hello world hello world hello world hello
[43] hello world hello world hello world hello world hello world hello world hello
[44] hello world hello world hello world hello world hello world hello world hello
[45] hello world hello world hello world hello world hello world hello world hello
[46] hello world hello world hello world hello world hello world hello world hello
[47] hello world hello world hello world hello world hello world hello world hello
[48] hello world hello world hello world hello world hello world hello world hello
[49] hello world hello world hello world hello world hello world hello world hello
[50] hello world hello world hello world hello world hello world hello world hello%

• Patch in this PR and try again. Note that the first line printed is now truncated to "lo", while the same line number was still fully printed in the previous run:

$ go build cmd/terminal-to-html
$ for i in $(seq -w 0 50); do echo "[$i] hello world hello world hello world hello world hello world hello world hello"; done | \
  ./terminal-to-html --window-max-cols=80 --buffer-max-lines=50 --window-cols=80 --window-lines=50

lo
[27] hello world hello world hello world hello world hello world hello world hello
[28] hello world hello world hello world hello world hello world hello world hello
[29] hello world hello world hello world hello world hello world hello world hello
[30] hello world hello world hello world hello world hello world hello world hello
[31] hello world hello world hello world hello world hello world hello world hello
[32] hello world hello world hello world hello world hello world hello world hello
[33] hello world hello world hello world hello world hello world hello world hello
[34] hello world hello world hello world hello world hello world hello world hello
[35] hello world hello world hello world hello world hello world hello world hello
[36] hello world hello world hello world hello world hello world hello world hello
[37] hello world hello world hello world hello world hello world hello world hello
[38] hello world hello world hello world hello world hello world hello world hello
[39] hello world hello world hello world hello world hello world hello world hello
[40] hello world hello world hello world hello world hello world hello world hello
[41] hello world hello world hello world hello world hello world hello world hello
[42] hello world hello world hello world hello world hello world hello world hello
[43] hello world hello world hello world hello world hello world hello world hello
[44] hello world hello world hello world hello world hello world hello world hello
[45] hello world hello world hello world hello world hello world hello world hello
[46] hello world hello world hello world hello world hello world hello world hello
[47] hello world hello world hello world hello world hello world hello world hello
[48] hello world hello world hello world hello world hello world hello world hello
[49] hello world hello world hello world hello world hello world hello world hello
[50] hello world hello world hello world hello world hello world hello world hello%

I'm not sure what the correct fix for this - any idea?