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

[Daniel Colascione]

On 01/14/2014 03:44 AM, Jan D. wrote:
> Daniel Colascione skrev 2014-01-14 11:44:
> > On 01/14/2014 01:34 AM, Jan D. wrote:
> > > > > Given the use case at hand, we know for a fact that the background is
> > > > > the region background, so I don't understand why a calculated
> > > > > foreground
> > > > > is needed.  Just pick one that matches the background.
> > > > > There might be other use cases where a calculated foreground makes
> > > > > sense, but my imagination fails me here.
> > > >
> > > > Calculated foreground colors look better: they resemble the font-lock
> > > > colors on which they're based.
> > >
> > > For the region case, that would imply the possibility of different
> > > foregrounds for marked text, none which is the actual font-lock color.
> >
> > It *is* the same color in the sense that the code we generate has the
> > same hue. How on earth is that worse than changing arbitrary font-locked
> > pieces of text to the system selection foreground color?
>
> Because the system color foreground is (presumably) choosen to look good
> together with the system color background.

Yes, and a color we algorithmically generate from a font-lock face will 
*also* look good against that background color, but 1) will be distinct 
from other faces replaced for lack of contrast, and 2) will be visually 
similar to the pre-highlight face. Have you tried the patch?

> > But that's exactly what
> > happens when we put gtk_selection_bg_color in a color spec! Why are you
> > fine with allowing gtk_selection_bg_color as a color (producing a color
> > that's presumably workable but unknown to a theme writer) but adamantly
> > opposed to a feature that selects good colors another way?
>
> I'm objecting to having the system default colors replaced with
> generated colors for the default case.  What themes other than the
> default does is irrelevant.  We are just talking about defaults here.

We already replace the system default colors with colors from font-lock 
faces.

> > I've produced working code that allows Emacs to act how you prefer *and*
> > how I prefer based on user configuration. What is your problem with that
> > code?
>
> I have no problem with the code, just the defaults.
>
> > Have you responded to the numerous objections to
> > :distant-foreground with anything other than retrenchment?
>
> So far the objections have been mostly opinions.  If there was a
> concrete case or a bug it exposes that would be another issue.
> The most concrete objection is the case of inheriting faces Yidong
> brought up in another mail, which indeed is a real problem.

Problems with usability in UI or API design don't result in clear "bugs" 
in the same way that logic errors or crashes do. Fixing them relies on 
judgment, and that relies chiefly on informed opinion. You can't dismiss 
others' opinions about this feature while not subjecting your own to the 
same treatment.

> > And a theme designer can opt not to use the feature or to explicitly
> > turn it off --- but a theme designer should never have to bother,
> > because the feature only activates when the contrast is awful, which
> > happens only when a theme designer screws up or deliberately relies on
> > system colors.
>
> Why should a theme designer rely on system colors?  That does not sound
> like a good theme.  Again, the default should rely on system colors, not
> arbitrary themes.

You are not responding to the point I make in the text you quote. I 
don't know why a theme designer would use system colors either. That's 
not the point. I'm saying that explicitly-chosen themes should never 
trigger the code under discussion if they're well-designed.

> > > That is not a use case.  A use case describes what an actual user does
> > > and in what situation automatically calculates colors enters the
> > > picture.
> >
> > This entire thread describes the use case. There are abundant examples.
> > Your objection here is baseless.
>
> There is a lot of handwaving and describing of mechanisms, but not one
> real world example, i.e. what major mode and which font lock faces and
> possible other faces are involved, and what does the user do to trigger
> the generated color.

Message-ID: <address@hidden>
From: Daniel Colascione <address@hidden>
> So to put the discussion in more concrete terms: say I run a stock
> GTK3 Emacs on a system with a background color exactly equal to
> "Blue1", which is the color we use for font-lock-function-name-face.
> I visit xfaces.c, search for "UNSPECIFIEDP", and hit C-a C-SPC C-e.
> What colors do you propose we use for the text "UNSPECIFIEDP" on that
> line?

> > > > :distant-foreground has far too narrow a justification to warrant being
> > > > a face property by itself.
> > >
> > > Also, just an opinion, not based on some documented design rule in any
> > > Emacs or GNU document.
> >
> > So only GNU documents count now, not reasoned arguments?
>
> No, but if documentation of some design rule existed it would give
> weight to your argument.  But your statement about :distant-foreground
> being too narrow is just your personal opinion which you have not
> motivated with any reasoned argument, just asserted.

I'm not the only one who's expressed concerns about the design of the 
feature.