On Fri, 04 Feb 2022 09:37:03 +0200 Eli Zaretskii wrote: > > From: Lars Ingebrigtsen > > Date: Thu, 03 Feb 2022 22:21:28 +0100 > > Cc: 20140@debbugs.gnu.org > > > > Richard Wordingham writes: > > > > > I am running Emacs 24.4 in a Ubuntu 12.04 Precise Pangolin > > > installation, for which the version of libm17n-0 is 1.6.3-1. I am > > > attempting to induce Emacs to render the Tai Tham script. There > > > appears to be a bug/feature in Emacs which makes this > > > unnecessarily difficult. > > > > (I'm going through old bug reports that unfortunately weren't > > resolved at the time.) > > > > I vaguely remember there having been some fixes in this area since > > this bug report was opened -- does this work better for you in more > > recent versions of Emacs? I'm currently using the vanilla emacs on Ubuntu Focal, which is described as 'GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.14) of 2020-03-26, modified by Debian'. The key good news is that the commands forward-char-intrusive and backward-char-intrusive are now standard, so I can position the cursor by dead-reckoning. You can reasonably mark the issue as solved. > The most important change is that we now use HarfBuzz by default. Isn't that only true for Emacs 27.1 and above? > Richard didn't contribute the Tai Tham composition rules to us > (AFAIR), so I cannot test what happens now in Emacs with HarfBuzz. > Maybe we should revisit this issue, but first I hope Richard could > tell whether the issue still exists, and if so, what composition rules > he uses or suggests to use for Tai Tham. Sad to see that Khaled Hosny's suggestion not to use composition rules seems not to have been taken. You're welcome to include my composition rules. They're complicated by the facts that the 'regular expressions' are not interpreted as regular expressions and they are not interpreted as closed under canonical equivalence. I therefore calculate the regular expression. My composition rules are attached as tai-tham.el, which was last modified on 20 March 2015. (It would need reformatting to paste into this email.) There are some deficiencies; I've a feeling there may be a problem with adding ZWNJ and CGJ as marks; ZWJ should also be added for completeness. I need ZWNJ to write 4-column ᨴᩣᩴᨶ᩠ᩅ‌ᩣ᩠ᨿ as opposed to 3-column ᨴᩣᩴᨶ᩠ᩅᩣ᩠ᨿ, and even with my font, HarfBuzz will need CGJ for the suppression of jack-booted dotted circles. Additionally, for didactic text, what can I do for U+25CC for explicit display of marks and their equivalents on a dotted circle, and for that matter, for display on NBSP? Richard. Richard.