Tom,

That analysis has been performed, many times over. Literally tens if not hundreds of hours at this point.

I do not know how to convey that in other ways than what I already tried.

All the terminal tested match the behavior of what is proposed in the paper modulo tofu and other rendering bugs

I looked at code of all these terminal too, it's also in the paper. The codepoints in the screenshot are the codepoints that sg-16 specifically asked about at the last meeting.

I am glad to see that your observations concur.

On Wed, Dec 14, 2022, 19:30 Tom Honermann <tom@honermann.net> wrote:

On 11/30/22 5:26 PM, Corentin via SG16 wrote:

Hello folks.

Here is a list of all the codepoint that change

https://gist.githubusercontent.com/cor3ntin/b7f4f52893b0b54890e970f7bbec6118/raw/720a910585d78c9ceb4e0458dcef87af2a436121/width.md

Just a note: the gist has 8570 characters and that count matches the ranges specified in the D2675R1 annex.

Simply cat that file in the terminal.

The screenshot below is a render on ITerm2

You will notice the tofu for reserved codepoints is considered narrow

but doesn't quite fit so it overlaps with the next cell, same for the number in square.

As discussed previously, a single screen shot that only shows a small subset of the relevant characters is not sufficient to demonstrate that the conclusions of the paper are consistent with existing behavior. I continue to have reservations about the screen shots in the paper for this reason; I don't see how they provide useful information at all. I think they are actively misleading since they do not appear to show behavior that is consistent with the intent of the paper.

I spent some time analyzing the behavior of all 8570 characters in the terminal I use (Konsole 12.12.3 with the Hack 10pt font). Here is what I found:

For the characters that the paper changes from width 1 to width 2 (based on the listings in the annex), the following are displayed with a width other than 2:

Width 0:

U+016FE4 (KHITAN SMALL SCRIPT FILLER)

Width 1: (These were all displayed as tofu; some are probably unassigned characters, others are probably unknown by the font)

U+01AFF0 .. U+01AFFE

U+01B11F ..

U+01F6DC .. U+01F6DF

U+01F7F0

U+01FA75 .. U+01FA77

U+01FA7B .. U+01FA7C

U+01FA87 .. U+01FA88

U+01FAA9 .. U+01FAAF

U+01FAB7 .. U+01FABF

U+01FAC3 .. U+01FACF

U+01FAD7 .. U+01FAF8

For the characters that the paper changes from width 1 to width 2 (based on the listings in the annex), the following are displayed with a width other than 1:

Width 2:

U+003248 .. U+00324F (CIRCLED NUMBER TEN ON BLACK SQUARE .. CIRCLED NUMBER EIGHTY ON BLACK SQUARE)

These results strongly match the intent of the paper and that the open question regarding the last group of characters should be answered such that they do not change width.

This is the kind of analysis I would like to see performed for other terminals so that we can qualitatively compare behavior between them. I attached C++ source code I used to display the characters.

Tom.

FYI Iterm2 also uses Unicode UAX 44

https://github.com/gnachman/iTerm2/blob/master/sources/NSCharacterSet+iTerm.m#L464