From: "Mark Bestley" <gnu@bestley.co.uk>
To: "Eli Zaretskii" <eliz@gnu.org>
Cc: stephen.berman@gmx.net, 61188@debbugs.gnu.org
Subject: bug#61188: 30.0.50; color-lighten-name seems not to work
Date: Thu, 02 Feb 2023 15:46:09 +0000 [thread overview]
Message-ID: <81E109CF-91D3-412A-87FC-2839ABFF4788@fastmail.co.uk> (raw)
In-Reply-To: <83o7qdz4lh.fsf@gnu.org>
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*
> On 1 Feb 2023, at 17:18, Eli Zaretskii <eliz@gnu.org> wrote:
>
>> Date: Wed, 01 Feb 2023 14:11:13 +0000
>> From: "Mark Bestley" <gnu@bestley.co.uk>
>> Cc: 61188@debbugs.gnu.org
>>
>>> So I guess the current behavior is the intended one, and we should
>>> close this bug as wontfix?
>>
>> No - I think the way 28.2 worked was correct. (for impact see highlight-indent.el which now does not work with a black background )
>
> But by changing the tests to match what Emacs does now we explicitly
> said that we disagree, and that the current behavior is the correct
> one.
>
>> What is the expected value of (color-lighten-name "Black" 100) as I don't know where that test is. I would think the test is wrong. Did it run for 28.2?
>
> The test is in test/lisp/color-tests.el. The expected value is
> exactly what you said is wrong.
>
>> Surely lightening Black fully should give white
>
> How so? The 100 is the percentage of the present luminance, and if
> that is zero, why do you expect it to become lighter?
>
> See also the discussion in bug#54514, which was exactly about that.
I don't see a discussion there.
But I do understand and accept the rationale for changing * color-lighten-hsl*
>
>> In 30 olor-lighten-name "Black" of any positive value gives Black - surely this cannot be correct.
>
> A zero multiplied by any percentage stays zero, no? If you want a
> non-zero result, start with something close to black, but not actually
> black.
The issue is more with color-lighten-name and the use it has in highlight-indent.el
Here the background colour is increased or darkened so that a new background is distinguishable from the original and it does that via varying the hue. In those terms increasing the hue from black to shades of grey and 100% takes you to white makes sense.
So just multiplying hue may not give the expected result here, The old reasoning for color-by-name might make some sense but I don't think we have the rationale why that was chosen.
So I understand why then change was made but I think that there will be broken code around which used color-lighten-name when emacs 29 is released.
Basically manipulation of coper values is more complex than at first thought.
I'll report this issue to highlight-indent.el and I think this bug can be closed,
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next prev parent reply other threads:[~2023-02-02 15:46 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-30 21:48 bug#61188: 30.0.50; color-lighten-name seems not to work Mark Bestley
2023-01-30 22:58 ` Stephen Berman
2023-01-31 18:39 ` Eli Zaretskii
2023-01-31 20:34 ` Stephen Berman
2023-02-01 13:21 ` Eli Zaretskii
2023-02-01 14:11 ` Mark Bestley
2023-02-01 17:18 ` Eli Zaretskii
2023-02-02 15:46 ` Mark Bestley [this message]
2023-02-02 18:32 ` Mark Bestley
2023-02-21 13:08 ` Bernd Rellermeyer
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