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From:   Jonathan Corbet <corbet@lwn.net>
To:     Akira Yokosawa <akiyks@gmail.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>
Cc:     linux-doc@vger.kernel.org,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        linux-kernel@vger.kernel.org, Akira Yokosawa <akiyks@gmail.com>
Subject: Re: [PATCH v2 2/3] docs/conf.py: Respect env variable SPHINX_IMGMATH
In-Reply-To: <736e39fd-b068-80dd-b383-70e061e71bf5@gmail.com>
References: <c41cab17-afd6-bc99-56a1-e4e73b8c1ef6@gmail.com>
 <736e39fd-b068-80dd-b383-70e061e71bf5@gmail.com>
Date:   Thu, 18 Aug 2022 11:24:49 -0600
Message-ID: <87sfltbh26.fsf@meer.lwn.net>
MIME-Version: 1.0
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Precedence: bulk

Akira Yokosawa <akiyks@gmail.com> writes:

> On some distros with coarse-grained packaging policy, dvipng is
> installed along with latex.  In such cases, math rendering will
> use imgmath by default.  It is possible to override the choice by
> specifying the option string of "-D html_math_renderer='mathjax'"
> to sphinx-build (Sphinx >= 1.8).
>
> To provide developers an easier-to-use knob, add code for an env
> variable "SPHINX_IMGMATH" which overrides the automatic choice
> of math renderer for html docs.
>
>     SPHINX_IMGMATH=yes : Load imgmath even if dvipng is not found
>     SPHINX_IMGMATH=no  : Don't load imgmath (fall back to mathjax)
>
> Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
> Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> ---
> Changes since v1:
>  - No logical changes.
>  - Renames:
>      LOAD_IMGMATH -> SPHINX_IMGMATH (Mauro),
>      opt_load_imgmath -> env_sphinx_imgmath.
>  - Acked-by from Mauro.
>
> --
>  Documentation/conf.py | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/conf.py b/Documentation/conf.py
> index 3ec1f845c839..0b8f20e8e22c 100644
> --- a/Documentation/conf.py
> +++ b/Documentation/conf.py
> @@ -128,8 +128,20 @@ autosectionlabel_maxdepth = 2
>  # mathjax is the default math renderer since Sphinx 1.8.
>  have_latex =  have_command('latex', '--version', 'pdfTeX')
>  have_dvipng = have_command('dvipng', '--version', 'dvipng')
> -load_imgmath = ((have_latex and have_dvipng)
> -                or (major == 1 and minor < 8)
> +load_imgmath = have_latex and have_dvipng
> +
> +# Respect SPHINX_IMGMATH (for html docs only)
> +if 'SPHINX_IMGMATH' in os.environ:
> +    env_sphinx_imgmath = os.environ['SPHINX_IMGMATH']
> +    if 'yes' in env_sphinx_imgmath:
> +        load_imgmath = True
> +    elif 'no' in env_sphinx_imgmath:
> +        load_imgmath = False
> +    else: # otherwide, auto selection
> +        pass

That "else: pass" sequence does nothing, of course, and could be taken
out.

Otherwise fine,

jon