xterm-256color and face colors

xterm-256color and face colors

[Giorgos Keramidas]

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Hi all,

The version of Emacs I am currently running is ``GNU Emacs 23.1.90.1
(i386-unknown-freebsd9.0, GTK+ Version 2.18.4) of 2009-12-11 on kobe'',
built from a Git snapshot a couple of days ago.

A recent update to FreeBSD synchronized our termcap database entries for
"xterm*" terminals with the one in xterm's source distribution.  This
was the first step towards making Emacs really support more than 8 color
cells in xterm windows under FreeBSD.

Unfortunately this seems to have broken many face-colors that use X11
names in their face attributes.  With the current termcap database of
FreeBSD using a TERM value of "xterm" causes Emacs to fall back to 8
color cells, but most of the faces map into these color cells correctly.
The result is similar to the attached "emacs-23-xterm.png" screenshot,
also available at:

  http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm.png

Using a TERM value of "xterm-256color", on the other hand, causes Emacs
to have 256 color cells, but font-locking fails to pick up the color
definitions of many font faces, resulting in no color at all for those
faces.  For example the same `M-x ielm' session does not highlight
strings with any color at all.  The result is similar to the attached
"emacs-23-xterm-256color.png" screenshot, also available at:

  http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm-256color.png

Trying `M-x customize-face RET font-lock-string-face RET' shows that
strings should be using "LightSalmon" as their color, but the sample
text near the color definition uses no color at all.  The screenshot
attached as "emacs-23-xterm-256color-string-face.png" shows this, and is
also available online at:

  http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm-256color-string-face.png

The list of face-colors from `M-x list-colors-display' shows 256 colors
when TERM="xterm-256color" but the colors upwards of slot 16 are all
unnamed, as in the attached "emacs-23-xterm-256color-list.png"
screenshot, also available at:

  http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm-256color-list.png

I see that `color-name-rgb-alist' is populated with a list of X11 color
names, but these names are not used at all for face colors in xterm
windows that have TERM="xterm-256color".  Any ideas how I can make Emacs
use the already loaded colors from `color-name-rgb-alist' to populate
the 256 available color cells?


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Re: xterm-256color and face colors

[Dan Nicolaescu]

Giorgos Keramidas <keramida@ceid.upatras.gr> writes:

  > Hi all,
  > 
  > The version of Emacs I am currently running is ``GNU Emacs 23.1.90.1
  > (i386-unknown-freebsd9.0, GTK+ Version 2.18.4) of 2009-12-11 on kobe'',
  > built from a Git snapshot a couple of days ago.
  > 
  > A recent update to FreeBSD synchronized our termcap database entries for
  > "xterm*" terminals with the one in xterm's source distribution.  This
  > was the first step towards making Emacs really support more than 8 color
  > cells in xterm windows under FreeBSD.
  > 
  > Unfortunately this seems to have broken many face-colors that use X11
  > names in their face attributes.  With the current termcap database of
  > FreeBSD using a TERM value of "xterm" causes Emacs to fall back to 8
  > color cells, but most of the faces map into these color cells correctly.
  > The result is similar to the attached "emacs-23-xterm.png" screenshot,
  > also available at:
  > 
  >   http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm.png
  > 
  > Using a TERM value of "xterm-256color", on the other hand, causes Emacs
  > to have 256 color cells, but font-locking fails to pick up the color
  > definitions of many font faces, resulting in no color at all for those
  > faces.  For example the same `M-x ielm' session does not highlight
  > strings with any color at all.  The result is similar to the attached
  > "emacs-23-xterm-256color.png" screenshot, also available at:
  > 
  >   http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm-256color.png

Emacs considers xterm to have a light background by default, and it
chooses face colors based on that.
So first step in getting this solved you want to start 
"xterm -bg white -fg black".

  > Trying `M-x customize-face RET font-lock-string-face RET' shows that
  > strings should be using "LightSalmon" as their color, but the sample
  > text near the color definition uses no color at all.  The screenshot
  > attached as "emacs-23-xterm-256color-string-face.png" shows this, and is
  > also available online at:
  > 
  >   http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm-256color-string-face.png

This looks like a problem with xterm or the termcap/terminfo settings.  Emacs
things that there are 256 colors, but when it tries to use them they
don't work correctly.

Check if xterm is compiled with 256 colors support, there's a script in
the xterm sources called 256colors2.pl, run it and see if you can get
many colors displayed.

Also try
$ tput setaf 21
it should change the foreground to blue #0000ff

$ tput setab 196
it should change the background to red #ff0000

  > The list of face-colors from `M-x list-colors-display' shows 256 colors
  > when TERM="xterm-256color" but the colors upwards of slot 16 are all
  > unnamed, as in the attached "emacs-23-xterm-256color-list.png"
  > screenshot, also available at:
  > 
  >   http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm-256color-list.png
  > 
  > I see that `color-name-rgb-alist' is populated with a list of X11 color
  > names, but these names are not used at all for face colors in xterm
  > windows that have TERM="xterm-256color".  Any ideas how I can make Emacs
  > use the already loaded colors from `color-name-rgb-alist' to populate
  > the 256 available color cells?

That's not done.
But faces can still use any color name in `color-name-rgb-alist', and
the color get mapped to one of the 256 colors available.

Re: xterm-256color and face colors

[Giorgos Keramidas]

On Sat, 12 Dec 2009 18:51:33 -0800 (PST), Dan Nicolaescu <dann@ics.uci.edu> wrote:
>Giorgos Keramidas <keramida@ceid.upatras.gr> writes:
>> The version of Emacs I am currently running is ``GNU Emacs 23.1.90.1
>> (i386-unknown-freebsd9.0, GTK+ Version 2.18.4) of 2009-12-11 on kobe'',
>> built from a Git snapshot a couple of days ago.
>>
>> A recent update to FreeBSD synchronized our termcap database entries for
>> "xterm*" terminals with the one in xterm's source distribution.  This
>> was the first step towards making Emacs really support more than 8 color
>> cells in xterm windows under FreeBSD.
>> ...
>> Trying `M-x customize-face RET font-lock-string-face RET' shows that
>> strings should be using "LightSalmon" as their color, but the sample
>> text near the color definition uses no color at all.  The screenshot
>> attached as "emacs-23-xterm-256color-string-face.png" shows this,
>> and is also available online at:
>>
>>   http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm-256color-string-face.png
>
> This looks like a problem with xterm or the termcap/terminfo settings.  Emacs
> things that there are 256 colors, but when it tries to use them they
> don't work correctly.
>
> Check if xterm is compiled with 256 colors support, there's a script in
> the xterm sources called 256colors2.pl, run it and see if you can get
> many colors displayed.

Hi Dan,

Thanks!  Running the vttests/256colors.pl script from the source of
xterm itself shows that indeed this is an xterm problem with my local
xterm package.  I'll rebuild my xterm with the WITH_256_COLOR=1 option,
check again and report back :)

Re: xterm-256color and face colors

[Giorgos Keramidas]

On Sun, 13 Dec 2009 05:18:22 +0200, Giorgos Keramidas <keramida@ceid.upatras.gr> wrote:
> On Sat, 12 Dec 2009 18:51:33 -0800 (PST), Dan Nicolaescu <dann@ics.uci.edu> wrote:
>>Giorgos Keramidas <keramida@ceid.upatras.gr> writes:
>>> The version of Emacs I am currently running is ``GNU Emacs 23.1.90.1
>>> (i386-unknown-freebsd9.0, GTK+ Version 2.18.4) of 2009-12-11 on kobe'',
>>> built from a Git snapshot a couple of days ago.
>>>
>>> A recent update to FreeBSD synchronized our termcap database entries for
>>> "xterm*" terminals with the one in xterm's source distribution.  This
>>> was the first step towards making Emacs really support more than 8 color
>>> cells in xterm windows under FreeBSD.
>>> ...
>>> Trying `M-x customize-face RET font-lock-string-face RET' shows that
>>> strings should be using "LightSalmon" as their color, but the sample
>>> text near the color definition uses no color at all.  The screenshot
>>> attached as "emacs-23-xterm-256color-string-face.png" shows this,
>>> and is also available online at:
>>>
>>>   http://people.freebsd.org/~keramida/emacs-xterm256/emacs-23-xterm-256color-string-face.png
>>
>> This looks like a problem with xterm or the termcap/terminfo settings.  Emacs
>> things that there are 256 colors, but when it tries to use them they
>> don't work correctly.
>>
>> Check if xterm is compiled with 256 colors support, there's a script in
>> the xterm sources called 256colors2.pl, run it and see if you can get
>> many colors displayed.
>
> Hi Dan,
>
> Thanks!  Running the vttests/256colors.pl script from the source of
> xterm itself shows that indeed this is an xterm problem with my local
> xterm package.  I'll rebuild my xterm with the WITH_256_COLOR=1 option,
> check again and report back :)

Ok, that was the cause of the face problems.  Rebuilding xterm with the
256-color option fixed everything.  Thanks again.