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Re: background-print

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 11 Aug 2011 08:36:22 -0700
Message-ID: <CAAWBYDBPNKOe=PSksh82eGCvWggnySOGaAwfND3P4PhucL83LQ@mail.gmail.com>
To: Håkon Wium Lie <howcome@opera.com>
Cc: www-style list <www-style@w3.org>
On Thu, Aug 11, 2011 at 2:03 AM, Håkon Wium Lie <howcome@opera.com> wrote:
> Also sprach Tab Atkins Jr.:
>
>  > At the f2f I briefly discussed background printing at the end of
>  > Tuesday.  (minutes:
>  > <http://lists.w3.org/Archives/Public/www-style/2011Aug/0178.html>,
>  > thread: <http://lists.w3.org/Archives/Public/www-style/2011Jul/0341.html>).
>  >
>  > I had asked people to chime in, but not many people did.  Florian
>  > commented that he was in the camp that thought this should be
>  > triggered simply by the print stylesheet setting values.  (This has
>  > flaws, both purity-wise and technical*.)
>
> What's wrong with this?:
>
>  @media print {
>    * { background: none }
>  }

I'm not sure I understand.  Are you suggesting that the UA put that in
its UA stylesheet, such that it can be overridden by the author as
desired?

If so, then the suggestion has several problems, unfortunately.  For
one, UAs do more than suppress backgrounds; they also adjust text
colors to ensure that there is still adequate contrast.  For two, that
rule would get overridden by a background set in media=all, which is
the default for stylesheets that don't specify a @media.  This doesn't
reflect current behavior either, and would be an undesirable change
(it would mean that most backgrounds suddenly start printing).

It's the color-adjustment that really clinches the fact that we can't
solve this solely by fiddling with 'background'.  This really is a
separate control with unique behavior, and has to be addressed with
its own property (or some other entity, like an @-rule).  I still
suggest:

printer-safe-colors: _prefer_ | avoid;

The "prefer" value biases the UA toward suppressing backgrounds and
adjusting text colors so as to save ink.  The "avoid" value biases the
UA against that.  The user still has the ultimate choice; this is just
a suggestion, moreso than most other properties.

~TJ
Received on Thursday, 11 August 2011 15:37:09 GMT

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