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implement Units;
include "sys.m";
sys: Sys;
include "units.m";
Dpi: con 100; # pixels per inch on an average display (pinched from tk)
init()
{
sys = load Sys Sys->PATH;
}
# return length in pixels, and string equivalent;
# makes sure that string equiv is specified in absolute units
# (not in terms of percentage or font size)
# XXX give this a proper testing.
length(s: string, emsize, xsize: int, relative: string): (int, string)
{
(n, units) := units(s);
case units {
Uem =>
px := (n * emsize);
return (px / SCALE, n2s(px) + "px");
Uex =>
px := (n * xsize);
return (px / SCALE, n2s(px) + "px");
Upx =>
return (n / SCALE, s);
Uin =>
return ((n * Dpi) / SCALE, s);
Ucm =>
return ((n * Dpi * 100) / (2540 * SCALE), s);
Umm =>
return ((n * Dpi * 10) / (254 * SCALE), s);
Upt =>
return ((n * Dpi) / (72 * SCALE), s);
Upc =>
return ((n * Dpi * 12) / (72 * SCALE), s);
Upercent or
Unone =>
# treat no units as relative factor.
# the only place this is used is for "line_height" in css, i believe;
# otherwise an unadorned number is not legal.
if (relative == nil)
return (0, nil);
(rn, rs) := length(relative, 0, 0, nil);
px := (n * rn) / SCALE;
if (units == Upercent)
px /= 100;
return (px, string px + "px");
}
return (n / SCALE, s);
}
# return non-relative for unadorned numbers, as it's not defined so anything's ok.
isrelative(s: string): int
{
n := len s;
if (n < 2)
return 0;
if (s[n - 1] == '%')
return 1;
case s[n - 2:] {
"em" or
"ex" =>
return 1;
}
return 0;
}
n2s(n: int): string
{
(i, f) := (n / SCALE, n % SCALE);
if (f == 0)
return string i;
if (f < 0)
f = -f;
return string i + "." + sys->sprint("%.3d", f);
}
Uem, Uex, Upx, Uin, Ucm, Umm, Upt, Upc, Upercent, Unone: con iota;
SCALE: con 1000;
units(s: string): (int, int)
{
# XXX what should we do on error?
if (s == nil)
return (0, -1);
i := 0;
# optional leading sign
neg := 0;
if (s[0] == '-' || s[0] == '+') {
neg = s[0] == '-';
i++;
}
n := 0;
for (; i < len s; i++) {
c := s[i];
if (c < '0' || c > '9')
break;
n = (n * 10) + (c - '0');
}
n *= SCALE;
if (i < len s && s[i] == '.') {
i++;
mul := 100;
for (; i < len s; i++) {
c := s[i];
if (c < '0' || c > '9')
break;
n += (c - '0') * mul;
mul /= 10;
}
}
units := Unone;
if (i < len s) {
case s[i:] {
"em" =>
units = Uem;
"ex" =>
units = Uex;
"px" =>
units = Upx;
"in" =>
units = Uin;
"cm" =>
units = Ucm;
"mm" =>
units = Umm;
"pt" =>
units = Upt;
"pc" =>
units = Upc;
"%" =>
units = Upercent;
* =>
return (0, -1);
}
}
if (neg)
n = -n;
return (n, units);
}
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