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authorNRK <nrk@disroot.org>2022-03-24 00:37:55 +0600
committerHiltjo Posthuma <hiltjo@codemadness.org>2022-03-25 22:49:07 +0100
commit41fdabbf7c517f8d524b70cbd78238cc319ccef3 (patch)
tree15ba06d8e243b2791323fa1770cded0d3a397c00
parent3a505cebe8adab204e5619357e0bfe3f9f3a92ff (diff)
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 <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.
-rw-r--r--drw.c56
1 files changed, 28 insertions, 28 deletions
diff --git a/drw.c b/drw.c
index 4cdbcbe..e65d069 100644
--- a/drw.c
+++ b/drw.c
@@ -251,12 +251,10 @@ drw_rect(Drw *drw, int x, int y, unsigned int w, unsigned int h, int filled, int
int
drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int lpad, const char *text, int invert)
{
- 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 int h, unsigned int lp
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 int h, unsigned int lp
}
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 int h, unsigned int lp
for (curfont = drw->fonts; curfont; curfont = curfont->next) {
charexists = charexists || XftCharExists(drw->dpy, curfont->xfont, utf8codepoint);
if (charexists) {
- if (curfont == usedfont) {
+ drw_font_getexts(curfont, text, utf8charlen, &tmpw, NULL);
+ if (ew + ellipsis_width <= w) {
+ /* keep track where the ellipsis still fits */
+ 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 int h, unsigned int lp
}
}
- if (!charexists || nextfont)
+ if (overflow || !charexists || nextfont)
break;
else
charexists = 0;
}
if (utf8strlen) {
- drw_font_getexts(usedfont, utf8str, utf8strlen, &ew, NULL);
- /* shorten text if necessary */
- for (len = MIN(utf8strlen, sizeof(buf) - 1); len && ew > w; len--)
- drw_font_getexts(usedfont, utf8str, len, &ew, NULL);
-
- if (len) {
- memcpy(buf, utf8str, len);
- buf[len] = '\0';
- if (len < utf8strlen)
- for (i = len; i && i > len - 3; buf[--i] = '.')
- ; /* NOP */
-
- if (render) {
- ty = y + (h - usedfont->h) / 2 + usedfont->xfont->ascent;
- XftDrawStringUtf8(d, &drw->scheme[invert ? ColBg : ColFg],
- usedfont->xfont, x, ty, (XftChar8 *)buf, len);
- }
- x += ew;
- w -= ew;
+ if (render) {
+ ty = y + (h - usedfont->h) / 2 + usedfont->xfont->ascent;
+ XftDrawStringUtf8(d, &drw->scheme[invert ? ColBg : ColFg],
+ usedfont->xfont, x, ty, (XftChar8 *)utf8str, utf8strlen);
}
+ x += ew;
+ w -= ew;
}
+ if (render && overflow)
+ drw_text(drw, ellipsis_x, y, ellipsis_w, h, 0, "...", invert);
- if (!*text) {
+ if (!*text || overflow) {
break;
} else if (nextfont) {
charexists = 0;