GopherProxy

	drw_text: improve performance when there's no match - dmenu - dynamic menu
	git clone git://git.suckless.org/dmenu
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	---
	commit 22511c41d55a38a770541ae617a09383d5e6ad1c
	parent 77526f756e23e362081ac807521f901f2e5cd5e6
	Author: NRK <[email protected]>
	Date: Thu, 24 Mar 2022 00:37:55 +0600

	drw_text: improve performance when there's no match

	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

	Diffstat:
	M drw.c \| 13 ++++++++++++-

	1 file changed, 12 insertions(+), 1 deletion(-)
	---
	diff --git a/drw.c b/drw.c
	@@ -251,7 +251,7 @@ drw_rect(Drw *drw, int x, int y, unsigned int w, unsigned i…
	int
	drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int …
	{
	- int ty, ellipsis_x = 0;
	+ int i, ty, ellipsis_x = 0;
	unsigned int tmpw, ew, ellipsis_w = 0, ellipsis_len, ellipsis_width;
	XftDraw *d = NULL;
	Fnt usedfont, curfont, *nextfont;
	@@ -263,6 +263,9 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned i…
	FcPattern *match;
	XftResult result;
	int charexists = 0, overflow = 0;
	+ /* keep track of a couple codepoints for which we have no match. */
	+ enum { nomatches_len = 64 };
	+ static struct { long codepoint[nomatches_len]; unsigned int idx; } nom…

	if (!drw \|\| (render && !drw->scheme) \|\| !text \|\| !drw->fonts)
	return 0;
	@@ -346,6 +349,12 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned …
	* character must be drawn. */
	charexists = 1;

	+ for (i = 0; i < nomatches_len; ++i) {
	+ /* avoid calling XftFontMatch if we know we wo…
	+ if (utf8codepoint == nomatches.codepoint[i])
	+ goto no_match;
	+ }
	+
	fccharset = FcCharSetCreate();
	FcCharSetAddChar(fccharset, utf8codepoint);

	@@ -374,6 +383,8 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned i…
	curfont->next = usedfont;
	} else {
	xfont_free(usedfont);
	+ nomatches.codepoint[++nomatches.idx % …
	+no_match:
	usedfont = drw->fonts;
	}
	}