GopherProxy

	drw_text: improve both performance and correctness - dmenu - dynamic menu
	git clone git://git.suckless.org/dmenu
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	---
	commit 41fdabbf7c517f8d524b70cbd78238cc319ccef3
	parent 3a505cebe8adab204e5619357e0bfe3f9f3a92ff
	Author: NRK <[email protected]>
	Date: Thu, 24 Mar 2022 00:37:55 +0600

	drw_text: improve both performance and correctness

	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 <[email protected]>, thanks! however the original patch had
	some issues incorrectly truncating the prompt (-p flag) and cutting off
	emojies. those have been fixed in here.

	Diffstat:
	M drw.c \| 56 ++++++++++++++++-------------…

	1 file changed, 28 insertions(+), 28 deletions(-)
	---
	diff --git a/drw.c b/drw.c
	@@ -251,12 +251,10 @@ drw_rect(Drw *drw, int x, int y, unsigned int w, unsigned…
	int
	drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int …
	{
	- char buf[1024];
	- int ty;
	- unsigned int ew;
	+ int ty, ellipsis_x = 0;
	+ unsigned int tmpw, ew, ellipsis_w = 0, ellipsis_len, ellipsis_width;
	XftDraw *d = NULL;
	Fnt usedfont, curfont, *nextfont;
	- size_t i, len;
	int utf8strlen, utf8charlen, render = x \|\| y \|\| w \|\| h;
	long utf8codepoint = 0;
	const char *utf8str;
	@@ -264,7 +262,7 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned i…
	FcPattern *fcpattern;
	FcPattern *match;
	XftResult result;
	- int charexists = 0;
	+ int charexists = 0, overflow = 0;

	if (!drw \|\| (render && !drw->scheme) \|\| !text \|\| !drw->fonts)
	return 0;
	@@ -282,8 +280,9 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned i…
	}

	usedfont = drw->fonts;
	+ drw_font_getexts(usedfont, "...", 3, &ellipsis_width, NULL);
	while (1) {
	- utf8strlen = 0;
	+ ew = ellipsis_len = utf8strlen = 0;
	utf8str = text;
	nextfont = NULL;
	while (*text) {
	@@ -291,9 +290,21 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned …
	for (curfont = drw->fonts; curfont; curfont = curfont-…
	charexists = charexists \|\| XftCharExists(drw->…
	if (charexists) {
	- if (curfont == usedfont) {
	+ drw_font_getexts(curfont, text, utf8ch…
	+ if (ew + ellipsis_width <= w) {
	+ /* keep track where the ellips…
	+ ellipsis_x = x + ew;
	+ ellipsis_w = w - ew;
	+ ellipsis_len = utf8strlen;
	+ }
	+
	+ if (ew + tmpw > w) {
	+ overflow = 1;
	+ utf8strlen = ellipsis_len;
	+ } else if (curfont == usedfont) {
	utf8strlen += utf8charlen;
	text += utf8charlen;
	+ ew += tmpw;
	} else {
	nextfont = curfont;
	}
	@@ -301,36 +312,25 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned…
	}
	}

	- if (!charexists \|\| nextfont)
	+ if (overflow \|\| !charexists \|\| nextfont)
	break;
	else
	charexists = 0;
	}

	if (utf8strlen) {
	- drw_font_getexts(usedfont, utf8str, utf8strlen, &ew, N…
	- /* shorten text if necessary */
	- for (len = MIN(utf8strlen, sizeof(buf) - 1); len && ew…
	- drw_font_getexts(usedfont, utf8str, len, &ew, …
	-
	- if (len) {
	- memcpy(buf, utf8str, len);
	- buf[len] = '\0';
	- if (len < utf8strlen)
	- for (i = len; i && i > len - 3; buf[--…
	- ; /* NOP */
	-
	- if (render) {
	- ty = y + (h - usedfont->h) / 2 + usedf…
	- XftDrawStringUtf8(d, &drw->scheme[inve…
	- usedfont->xfont, x, …
	- }
	- x += ew;
	- w -= ew;
	+ if (render) {
	+ ty = y + (h - usedfont->h) / 2 + usedfont->xfo…
	+ XftDrawStringUtf8(d, &drw->scheme[invert ? Col…
	+ usedfont->xfont, x, ty, (Xft…
	}
	+ x += ew;
	+ w -= ew;
	}
	+ if (render && overflow)
	+ drw_text(drw, ellipsis_x, y, ellipsis_w, h, 0, "...", …

	- if (!*text) {
	+ if (!*text \|\| overflow) {
	break;
	} else if (nextfont) {
	charexists = 0;