[j-devel] 0.18.1.1

[Peter G. <pe...@ar...>]

This morning's development snapshot (j 0.18.1.1, lisp 0.0.0.22) is up:

    http://armedbear.org/j.zip          (source)
    http://armedbear.org/j-jar.zip      (just j.jar)

This snapshot fixes an important display-related bug (I hope).

For a long time, j has been very close to working acceptably with
proportional fonts, but there was an annoying bug that caused the caret
to be positioned incorrectly, usually on the proper character but
somewhere in the middle of it rather than at its left edge (where it
belongs).

I was motivated to look into this (again) by a question from the field:

> I just have a quick question for you, if you edit Asia text in J, why
> the cursor is always in the middle of character, and how to fix it.

It turns out that the display code suffered from an off-by-one bug,
which led (in effect) to the replacement of the character immediately
preceding the caret in the text that was fed to measureLine(). This
made no difference with a monospaced font, since the space was the same
width as the character it replaced, but it led to the aforementioned
problem with proportional fonts, and in all likelihood it was also
responsible for the problem with Asian text.

This bug is fixed in the current snapshot. I've tested all the corner
cases I could think of, and I've been running with the new code for a
couple of hours, so I think it's solid, but it's a complicated area, so
please let me know if you notice any anomalies.

(There are still a number of problems with proportional fonts in j that
have nothing to do with caret positioning, notably the alignment of
columns in mailboxes and directory buffers, so the use of proportional
fonts is not officially recommended or condoned.)

This snapshot also features a revised init.lisp in the examples
directory, showing how to check the hostname to decide which theme to
load, so you can use different themes on machines with different
display characteristics, all managed with the same init.lisp. Symlinks
are us... ;)

Thanks for your support.

-Peter