this was the last piece of the puzzle, the case where we can't find any
font to draw the codepoint.
in such cases, we use XftFontMatch() which is INSANELY slow. but that's
not the real problem. the real problem was we were continuously trying
to match the same thing over and over again.
this patch introduces a small cache, which keeps track a couple
codepoints for which we know we won't find any matches.
with this, i can dump lots of emojies into dmenu where some of them
don't have any matching font, and still not have dmenu lag insanely or
FREEZE completely when scrolling up and down.
this also improves startup time, which will of course depend on the
system and all installed fonts; but on my system and test case i see the
following startup time drop:
before -> after
60ms -> 34ms
ref. https://git.suckless.org/dmenu/commit/22511c41d55a38a770541ae617a09383d5e6ad1c.html
a massive amount of time inside readstdin() is spent trying to get the
max input width and then put it into inputw, only for it to get clamped
down to mw/3 inside setup().
it makes more sense to calculate inputw inside setup() once we have mw
available. similar to the last patch, i see noticeable startup
performance improvement:
before -> after
160ms -> 60ms
additionally this will take fallback fonts into account compared to the
previous version, so it's not only more performant but also more correct.
ref. https://git.suckless.org/dmenu/commit/77526f756e23e362081ac807521f901f2e5cd5e6.html
Disclaimer: this may break the JSON patch
this replaces inefficient pattern of `MIN(TEXTW(..), n)` with
drw_fontset_getwidth_clamp() instead, which is far more efficient when
we only want up to a certain width.
dumping a decently sized (unicode) emoji file into dmenu, I see the
startup time drop significantly with this patch.
before -> after
360ms -> 160ms
this should also noticeably improve input latency (responsiveness) given
that calcoffsets() and drawmenu() are pretty hot functions.
ref. https://git.suckless.org/dmenu/commit/7269c5355d257dd2ad2c53f15dc9c1cf6796aea5.html
getting the width of a string is an O(n) operation, and in many cases
users only care about getting the width upto a certain number.
instead of calling drw_fontset_getwidth() and *then* clamping the
result, this patch introduces drw_fontset_getwidth_clamp() function,
similar to strnlen(), which will stop once we reach n.
the `invert` parameter was overloaded internally to preserve the API,
however library users should be calling drw_fontset_getwidth_clamp() and
not depend upon internal behavior of drw_text().
ref. https://git.suckless.org/dmenu/commit/6be057f060543bb0f3ed9423904263617cdffffe.html
this patch makes some non-trivial changes, which significantly improves
the performance of drawing large strings as well as fixes any issues
regarding the printing of the ellipsis when string gets truncated.
* performance:
before there were two O(n) loops, one which finds how long we can go
without changing font, and the second loop would (incorrectly) truncate
the string if it's too big.
this patch merges the overflow calculation into the first loop and exits
out when overflow is detected. when dumping lots of emojies into dmenu,
i see some noticeable startup time improvement:
before -> after
460ms -> 360ms
input latency when scrolling up/down is also noticeably better and can
be tested with the following:
for _ in $(seq 20); do
cat /dev/urandom | base64 | tr -d '\n' | head -c 1000000
echo
done | ./dmenu -l 10
* correctness:
the previous version would incorrectly assumed single byte chars and
would overwrite them with '.' , this caused a whole bunch of obvious
problems, including the ellipsis not getting rendered if then font
changed.
in addition to exiting out when we detect overflow, this patch also
keeps track of the last x-position where the ellipsis would fit. if we
detect overflow, we simply make a recursing call to drw_text() at the
ellipsis_x position and overwrite what was there.
so now the ellipsis will always be printed properly, regardless of
weather the font changes or if the string is single byte char or not.
the idea of rendering the ellipsis on top incase of overflow was
from Bakkeby <bakkeby@gmail.com>, thanks! however the original patch had
some issues incorrectly truncating the prompt (-p flag) and cutting off
emojies. those have been fixed in here.
Ref. https://git.suckless.org/dmenu/commit/41fdabbf7c517f8d524b70cbd78238cc319ccef3.html
