From: Keith David Bershatsky <esq@lawlist.com>
To: Emacs Devel <emacs-devel@gnu.org>
Subject: Is there an IT test for a tab-width spacer?
Date: Tue, 24 Oct 2017 17:59:47 -0700 [thread overview]
Message-ID: <m2o9owujng.wl%esq@lawlist.com> (raw)
I am working on implementing crosshairs (17684) and multiple fake cursors (22873).
it.c lets us know whether we are on the initial tab that has been assigned a character by the user with the buffer-display-table, e.g., 187/».
it.c also lets us know whether we have moved beyond that location to a tab without a character; i.e., 9, aka (char-to-string 9).
I am having trouble calculating the X and HPOS for each and every location between the initial tab and the next textual character. A buffer-display-table for a tab that is assigned a leading 187 followed by a 9 has a minimum tab-width of 2. Even though the buffer-local value for tab-width may be 2, that combination of 187/9 might be a total of 3 characters wide depending upon the circumstances. And as the user increases the buffer-local tab-width value, it seemingly becomes more difficult to predict the X and HPOS.
Inching along with a test similar to line 22682 in xdisp.c seems insufficient for this particular project: while (it.current_x + it.pixel_width <= target_x).
To analyze the width of the spacer and calculate the X and HPOS for each location within that space, is it necessary to go to the next character and then mathematically determine what the previous tab-width was?
Thanks,
Keith
next reply other threads:[~2017-10-25 0:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-25 0:59 Keith David Bershatsky [this message]
2017-10-25 15:02 ` Is there an IT test for a tab-width spacer? Eli Zaretskii
-- strict thread matches above, loose matches on Subject: below --
2017-10-28 17:10 Keith David Bershatsky
2017-10-28 17:23 ` Eli Zaretskii
2017-10-28 18:06 Keith David Bershatsky
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