[PATCH v4 6/9] docs: pdfdocs: One-half spacing for CJK translations

[Akira Yokosawa <akiyks@gmail.com>]

CJK documents are much easier to read with a wider baseline stretch.
Applying onehalfspacing option of "setspace" package looks reasonable.

Note: \usepackage{setspace} needs to be before that of hyperref in the
preamble.
The 'extrapackages' key (available since Sphinx 2.3) is for this purpose.
For systems with Sphinx < 2.3, dummy commands of \onehalfspacing and
\singlespacing are provided instead.
One-half spacing is not effective in LaTeX sources generated by such
revisions of Sphinx.

Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
---
 Documentation/conf.py                      | 12 ++++++++++--
 Documentation/translations/ja_JP/howto.rst |  8 ++++++++
 Documentation/translations/ko_KR/howto.rst |  8 ++++++++
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/Documentation/conf.py b/Documentation/conf.py
index 2ccfe4442acc..f219a7a41f48 100644
--- a/Documentation/conf.py
+++ b/Documentation/conf.py
@@ -341,6 +341,9 @@ latex_elements = {
         verbatimhintsturnover=false,
     ''',
 
+    # For CJK One-half spacing, need to be in front of hyperref
+    'extrapackages': r'\usepackage{setspace}',
+
     # Additional stuff for the LaTeX preamble.
     'preamble': '''
 	% Prevent column squeezing of tabulary.
@@ -404,9 +407,12 @@ latex_elements['preamble']  += '''
 	}
 	\\newCJKfontfamily[JPsans]\\jpsans{Noto Sans CJK JP}
 	\\newCJKfontfamily[JPmono]\\jpmono{Noto Sans Mono CJK JP}
+	% Dummy commands for Sphinx < 2.3 (no 'extrapackages' support)
+	\\providecommand{\\onehalfspacing}{}
+	\\providecommand{\\singlespacing}{}
 	% Define custom macros to on/off CJK
-	\\newcommand{\\kerneldocCJKon}{\\makexeCJKactive}
-	\\newcommand{\\kerneldocCJKoff}{\\makexeCJKinactive}
+	\\newcommand{\\kerneldocCJKon}{\\makexeCJKactive\\onehalfspacing}
+	\\newcommand{\\kerneldocCJKoff}{\\makexeCJKinactive\\singlespacing}
 	\\newcommand{\\kerneldocBeginSC}{%
 	    \\begingroup%
 	    \\scmain%
@@ -437,6 +443,8 @@ latex_elements['preamble']  += '''
 	    \\renewcommand{\\CJKttdefault}{JPmono}%
 	}
 	\\newcommand{\\kerneldocEndJP}{\\endgroup}
+	% Single spacing in literal blocks
+	\\fvset{baselinestretch=1}
 	% To customize \\sphinxtableofcontents
 	\\usepackage{etoolbox}
 	% Inactivate CJK after tableofcontents
diff --git a/Documentation/translations/ja_JP/howto.rst b/Documentation/translations/ja_JP/howto.rst
index 73ebdab4ced7..d667f9d8a02a 100644
--- a/Documentation/translations/ja_JP/howto.rst
+++ b/Documentation/translations/ja_JP/howto.rst
@@ -1,3 +1,7 @@
+.. raw:: latex
+
+	\kerneldocCJKoff
+
 NOTE:
 This is a version of Documentation/process/howto.rst translated into Japanese.
 This document is maintained by Tsugikazu Shibata <tshibata@ab.jp.nec.com>
@@ -11,6 +15,10 @@ try to update the original English file first.
 
 ----------------------------------
 
+.. raw:: latex
+
+	\kerneldocCJKon
+
 この文書は、
 Documentation/process/howto.rst
 の和訳です。
diff --git a/Documentation/translations/ko_KR/howto.rst b/Documentation/translations/ko_KR/howto.rst
index a2bdd564c907..e3cdf0c84892 100644
--- a/Documentation/translations/ko_KR/howto.rst
+++ b/Documentation/translations/ko_KR/howto.rst
@@ -1,3 +1,7 @@
+.. raw:: latex
+
+	\kerneldocCJKoff
+
 NOTE:
 This is a version of Documentation/process/howto.rst translated into korean
 This document is maintained by Minchan Kim <minchan@kernel.org>
@@ -11,6 +15,10 @@ try to update the original English file first.
 
 ----------------------------------
 
+.. raw:: latex
+
+	\kerneldocCJKon
+
 이 문서는
 Documentation/process/howto.rst
 의 한글 번역입니다.
-- 
2.17.1