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Subject: [RFC PATCH v2 1/7] docs: pdfdocs: Refactor config for CJK document
To:     Jonathan Corbet <corbet@lwn.net>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        "Wu X.C." <bobwxc@email.cn>, SeongJae Park <sj38.park@gmail.com>
Cc:     Hu Haowen <src.res@email.cn>,
        Shinwoo Lee <shinwoo.lee.us@gmail.com>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        Akira Yokosawa <akiyks@gmail.com>
References: <20ff8a65-6a5c-c062-fe1a-0f5c5ddc813c@gmail.com>
From:   Akira Yokosawa <akiyks@gmail.com>
Message-ID: <ea17ce02-07f3-a34c-ced2-c585caa50607@gmail.com>
Date:   Mon, 19 Jul 2021 20:10:00 +0900
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To make generated LaTeX code portable across systems with different sets
of available fonts, convert font-availability check in python code to
LaTeX code by using a conditional command provided by the "fontspec"
package.

This will help those who run Sphinx on one machine/container and run
latexmk on other machines/containers.

Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
---
 Documentation/conf.py | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/Documentation/conf.py b/Documentation/conf.py
index 7d92ec3e5b6e..b440cb606d22 100644
--- a/Documentation/conf.py
+++ b/Documentation/conf.py
@@ -16,8 +16,6 @@ import sys
 import os
 import sphinx
 
-from subprocess import check_output
-
 # Get Sphinx version
 major, minor, patch = sphinx.version_info[:3]
 
@@ -355,15 +353,14 @@ latex_elements = {
      ''',
 }
 
-# At least one book (translations) may have Asian characters
-# with are only displayed if xeCJK is used
+# Translations have Asian (CJK) characters which are only displayed if
+# xeCJK is used
 
-cjk_cmd = check_output(['fc-list', '--format="%{family[0]}\n"']).decode('utf-8', 'ignore')
-if cjk_cmd.find("Noto Sans CJK SC") >= 0:
-    latex_elements['preamble']  += '''
+latex_elements['preamble']  += '''
+    \\IfFontExistsTF{Noto Sans CJK SC}{
 	% This is needed for translations
-        \\usepackage{xeCJK}
-        \\setCJKmainfont{Noto Sans CJK SC}
+	\\usepackage{xeCJK}
+	\\setCJKmainfont{Noto Sans CJK SC}
 	% Define custom macros to on/off CJK
 	\\newcommand{\\kerneldocCJKon}{\\makexeCJKactive}
 	\\newcommand{\\kerneldocCJKoff}{\\makexeCJKinactive}
@@ -371,13 +368,12 @@ if cjk_cmd.find("Noto Sans CJK SC") >= 0:
 	\\usepackage{etoolbox}
 	% Inactivate CJK after tableofcontents
 	\\apptocmd{\\sphinxtableofcontents}{\\kerneldocCJKoff}{}{}
-     '''
-else:
-    latex_elements['preamble']  += '''
+    }{ % No CJK font found
 	% Custom macros to on/off CJK (Dummy)
 	\\newcommand{\\kerneldocCJKon}{}
 	\\newcommand{\\kerneldocCJKoff}{}
-     '''
+    }
+'''
 
 # Fix reference escape troubles with Sphinx 1.4.x
 if major == 1:
-- 
2.17.1