[Emacs-diffs] master f75d189: Improve documentation of ':lang' in font specs

[Eli Zaretskii]

branch: master
commit f75d189ed87d4a5bcad5eb1b9c54382e6b7802dc
Author: Eli Zaretskii <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Improve documentation of ':lang' in font specs
    
    * src/font.c (Ffont_spec): Doc fix: elaborate on the values and
    use of the ':lang' property of the font spec.
    * doc/emacs/frames.texi (Fonts): Document the language names that
    can be in the STYLE part of XLFD.
    * doc/lispref/display.texi (Low-Level Font): Document the ':lang'
    property.
---
 doc/emacs/frames.texi    |    5 ++++-
 doc/lispref/display.texi |    9 +++++++++
 src/font.c               |    6 ++++--
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/doc/emacs/frames.texi b/doc/emacs/frames.texi
index f401c8f..de72d87 100644
--- a/doc/emacs/frames.texi
+++ b/doc/emacs/frames.texi
@@ -703,7 +703,10 @@ The font width---normally @samp{normal}, @samp{condensed},
 other values.
 @item style
 An optional additional style name.  Usually it is empty---most XLFDs
-have two hyphens in a row at this point.
+have two hyphens in a row at this point.  The style name can also
+specify a two-letter ISO-639 language name, like @samp{ja} or
address@hidden; some fonts that support CJK scripts have that spelled out
+in the style name part.
 @item pixels
 The font height, in pixels.
 @item height
diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 357a3c3..b4e2037 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -3419,6 +3419,15 @@ The charset registry and encoding of the font, such as
 @item :script
 The script that the font must support (a symbol).
 
address@hidden :lang
+The language that the font should support.  The value should be a
+symbol whose name is a two-letter ISO-639 language name.  On X, the
+value is matched against the ``Additional Style'' field of the XLFD
+name of a font, if it is non-empty.  On MS-Windows, fonts matching the
+spec are required to support codepages needed for the language.
+Currently, only a small set of CJK languages is supported with this
+property: @samp{ja}, @samp{ko}, and @samp{zh}.
+
 @item :otf
 @cindex OpenType font
 The font must be an OpenType font that supports these OpenType
diff --git a/src/font.c b/src/font.c
index 7aa0e85..564c53a 100644
--- a/src/font.c
+++ b/src/font.c
@@ -3857,8 +3857,10 @@ listed in the variable `script-representative-chars'.
 
 `:lang'
 
-VALUE must be a symbol of two-letter ISO-639 language names,
-e.g. `ja'.
+VALUE must be a symbol whose name is a two-letter ISO-639 language
+name, e.g. `ja'.  The value is matched against the "Additional Style"
+field of the XLFD spec of a font, if it's non-empty, on X, and
+against the codepages supported by the font on w32.
 
 `:otf'