From: Mark Oteiza <mvoteiza@udel.edu>
To: Eli Zaretskii <eliz@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: Doc string and operation of color-distance
Date: Thu, 14 Sep 2017 15:43:28 -0400 [thread overview]
Message-ID: <874ls5xdzz.fsf@udel.edu> (raw)
In-Reply-To: <83mv5xm84m.fsf@gnu.org>
Eli Zaretskii <eliz@gnu.org> writes:
> Mark, the new color-distance says something strange in its doc string:
>
> (color-distance COLOR1 COLOR2 &optional FRAME METRIC)
>
> Return an integer distance between COLOR1 and COLOR2 on FRAME.
> COLOR1 and COLOR2 may be either strings containing the color name,
> or lists of the form (RED GREEN BLUE), each in the range 0 to 65535 inclusive.
> If FRAME is unspecified or nil, the current frame is used.
> If METRIC is unspecified or nil, a modified L*u*v* metric is used.
>
> The last sentence should say "non-nil", I think, and it should
> document that METRIC is supposed to be a function of 2 colors.
>
> Also, this is unexpected:
>
> (color-distance "red" "blue" nil 'lcms-cam02-ucs)
> => (error "Invalid color" "red")
>
> I think the new lcms2 functions should support colors specified as
> strings, because all the other color-related functions do.
At the very least we should feed metrics the translated RGBs.
Beyond that, in order to use (for example) lcms2-cam02-ucs with
color-distance, one has to translate RGB to XYZ, so the metric would be
(lambda (a b)
(lcms2-cam02-ucs (color-srgb-to-xyz a) (color-srgb-to-xyz b))
diff --git a/src/xfaces.c b/src/xfaces.c
index 012de4e7af..9804c96c39 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -4093,7 +4093,9 @@ DEFUN ("color-distance", Fcolor_distance, Scolor_distance, 2, 4, 0,
COLOR1 and COLOR2 may be either strings containing the color name,
or lists of the form (RED GREEN BLUE), each in the range 0 to 65535 inclusive.
If FRAME is unspecified or nil, the current frame is used.
-If METRIC is unspecified or nil, a modified L*u*v* metric is used. */)
+If METRIC is specified, it should be a function that accepts two
+lists of the form (RED GREEN BLUE). The default metric uses a
+modified L*u*v* space. */)
(Lisp_Object color1, Lisp_Object color2, Lisp_Object frame,
Lisp_Object metric)
{
@@ -4112,7 +4114,15 @@ If METRIC is unspecified or nil, a modified L*u*v* metric is used. */)
if (NILP (metric))
return make_number (color_distance (&cdef1, &cdef2));
else
- return call2 (metric, color1, color2);
+ {
+ Lisp_Object rgb1 = list3 (make_number (&cdef1.red),
+ make_number (&cdef1.green),
+ make_number (&cdef1.blue));
+ Lisp_Object rgb2 = list3 (make_number (&cdef2.red),
+ make_number (&cdef2.green),
+ make_number (&cdef2.blue));
+ return call2 (metric, rgb1, rgb2);
+ }
}
\f
next prev parent reply other threads:[~2017-09-14 19:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-14 18:45 Doc string and operation of color-distance Eli Zaretskii
2017-09-14 19:12 ` Mark Oteiza
2017-09-15 13:30 ` Eli Zaretskii
2017-09-15 16:45 ` Mark Oteiza
2017-09-15 17:24 ` Eli Zaretskii
2017-09-14 19:43 ` Mark Oteiza [this message]
2017-09-14 20:23 ` Mark Oteiza
2017-09-15 13:41 ` Eli Zaretskii
2017-09-15 13:40 ` Eli Zaretskii
2017-09-15 15:15 ` Mark Oteiza
2017-09-15 16:32 ` Mark Oteiza
2017-09-15 17:26 ` Eli Zaretskii
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=874ls5xdzz.fsf@udel.edu \
--to=mvoteiza@udel.edu \
--cc=eliz@gnu.org \
--cc=emacs-devel@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).