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Message-ID: <e7e3cfb5-fc82-5ce4-b964-e3eec01dcc2c@gmail.com>
Date:   Sun, 28 Aug 2022 12:47:14 +0900
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Subject: Re: [PATCH v3 2/2] docs/conf.py: Respect env variable SPHINX_IMGMATH
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To:     Randy Dunlap <rdunlap@infradead.org>
Cc:     linux-doc@vger.kernel.org,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Akira Yokosawa <akiyks@gmail.com>
References: <9b8ff6d7-e97a-c03f-7d46-4b80ae3cf196@gmail.com>
 <5a582b2b-d51c-a062-36b2-19479cf68fab@gmail.com>
 <2032102a-e2d3-6105-f4e6-bba7decdbb66@infradead.org>
From:   Akira Yokosawa <akiyks@gmail.com>
In-Reply-To: <2032102a-e2d3-6105-f4e6-bba7decdbb66@infradead.org>
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Hi Randy,  thank you for looking into this!

On Sat, 27 Aug 2022 17:38:41 -0700, Randy Dunlap wrote:
> Hi Akira,
> 
> On 8/26/22 21:38, Akira Yokosawa wrote:
>> 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)
> 
> Please add SPHINX_IMGMATH to Documentation/doc-guide/sphinx.rst
> (I guess), where other Sphinx environment variables are listed.

Right.
As I mentioned in the coverletter, (quoted below):

> I mentioned in the thread of [3] that imgmath can generate scalable
> math images in SVG.
> 
> My plan was to implement that option as well.  But during tests under
> Fedora/CentOS/openSUSE, I encountered a couple of warnings from dvisvgm.
> That would be regressions on existing systems which happen to have
> not-working dvisvgm along with working dvipng.  I'm thinking of adding
> the SVG option later if I can figure out the minimal requirement for
> dvisvgm under imgmath.

, I'm working on follow-up changes related to SPHINX_IMGMATH.

My plan is to update related docs and help text in Makefile when I manage
the SVG option. At that time, SPHINX_IMGMATH will have additional options
like 'svg' and 'png'.

Hopefully, such follow-up changes can make the v6.1 merge window.

Does this plan work for you?

        Thanks, Akira
> 
>> Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
>> Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org>
>> ---
>> Changes since v2:
>>  - Emit warning on unknown setting of SPHINX_IMGMATH.
>>
>> 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 c4aaedd96220..9678a8215457 100644
>> --- a/Documentation/conf.py
>> +++ b/Documentation/conf.py
>> @@ -124,8 +124,20 @@ autosectionlabel_maxdepth = 2
>>  # mathjax is the default math renderer since Sphinx 1.8.
>>  have_latex =  have_command('latex')
>>  have_dvipng = have_command('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:
>> +        sys.stderr.write("Unknown env SPHINX_IMGMATH=%s ignored.\n" % env_sphinx_imgmath)
>> +
>> +# Always load imgmath for Sphinx <1.8 or for epub docs
>> +load_imgmath = (load_imgmath or (major == 1 and minor < 8)
>>                  or 'epub' in sys.argv)
>>  
>>  if load_imgmath:
> 
> thanks.