Re: [PATCH] Re: About the :distant-foreground face attribute

[Daniel Colascione <dancol@dancol.org>]

On 01/13/2014 01:29 PM, Jan Djärv wrote:
> 13 jan 2014 kl. 19:41 skrev Daniel Colascione <dancol@dancol.org>:
>
>> On 01/13/2014 08:33 AM, Jan Djärv wrote:
>>> 13 jan 2014 kl. 14:13 skrev Daniel Colascione <dancol@dancol.org>:
>>>> The patch uses the CIE L*A*B colorspace algorithm by default.
>>>
>>> Do not change the defaults please. Reinstate the
>>> *_selection_fg_color.
>>> They are system defined and should be honored.
>>
>> There are two sane defaults: the 24.3 behavior, where we always use the system selection foreground and background, and my proposed behavior, where we use the fontified foreground and automatically adjust it so that it's legible. The current behavior is worse because it uses the system selection foreground only sometimes and doesn't preserve theme hues when possible.
>
> What theme hues? The default theme is not really a theme as
> selection
colors are taken from system settings. And this is correct IMHO, any
application that doesn't do so by default (i.e. no user configuration
has been set in the application) is seriously broken.

Yes, but font-lock colors are specified with explicit colors (even in 
the default "theme"), and we want to preserve these even in the presence 
of a selection. We are *already* not honoring the system-specified 
foreground selection color. At the same time, we want to make sure that 
highlighted text is legible against a background of whatever the system 
selection color happens to be. The best way to do that is to 
automatically shift the foreground colors in value, but not hue, so that 
they remain legible while being recognizably the same color.

I think the results are actually pretty good. If a particular theme 
doesn't want to use automatic color adjustment, it can specify its own 
:contrast-function and do whatever it wants.

I would also support a scheme where, by default, 'region' sets 
foreground *and* background colors to the system selection colors and 
other faces don't show through. But we didn't decide to go in that 
direction.

> If you talk about other themes, they can set :distant-foreground to
> a
real color of their choosing and not rely on some automatically
generated one which most probably don't fit the theme anyway.
Automatically generated colors are a crutch which should be avoided if
possible, certainly not recommended.

There's no way that themes can take into account all the possible colors 
users and packages might use. Automatic contrast adjustment can do that.

If you want the :distant-foreground behavior, it can be accommodated in 
this patch. This patch also permits other schemes that some users might 
find more useful. We should push policy to user customization when 
possible instead of hardcoding policy in the logic of face attributes.