Re: Rendering pi more nicely in PDF

[Alexander Lakhin]

>From the symbolic unit of the department...

Hello Tom,
26.04.2020 22:13, Tom Lane wrote:
> In the department of nitpickery ...
>
> "π" renders poorly in our PDF docs: as shown in the attached
> screenshot, it doesn't line up on the baseline.  I realized that
> this is the same problem I'd run into recently with right-arrow,
> and it can be solved in the same way, namely we have to specify
> use of the symbol font explicitly.  So attached is a proposed
> patch to fix it.
>
> Use of a new processing-instruction might not be the most elegant
> way to do this ... anyone have a better suggestion?
I would use the phrase tag, which is intended for such uses: [1] [2].
The "phrase" sounds too generic, but it doesn't require yet another
processing instruction e.g. for ∑ or a similar entity.

[1] http://www.sagehill.net/docbookxsl/CustomInlines.html
[2] https://tdg.docbook.org/tdg/4.5/phrase.html

Best regards,
Alexander

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index b0afaebf728..16a4a679d1c 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1365,7 +1365,7 @@ repeat('Pg', 4) <returnvalue>PgPgPgPg</returnvalue>
         <function>pi</function> (  )
         <returnvalue>double precision</returnvalue>
        <?br?>
-        Approximate value of &pi;
+        Approximate value of <phrase role="symbol">&pi;</phrase>
        <?br?>
         <literal>pi()</literal>
         <returnvalue>3.141592653589793</returnvalue>
diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
index 58a2aa3bf20..8c5bf18f79c 100644
--- a/doc/src/sgml/ref/pgbench.sgml
+++ b/doc/src/sgml/ref/pgbench.sgml
@@ -1528,7 +1528,7 @@ SELECT 4 AS four \; SELECT 5 AS five \aset
       <row>
        <entry><literal><function>pi()</function></literal></entry>
        <entry>double</entry>
-       <entry>value of the constant PI</entry>
+       <entry>value of the constant <phrase role="symbol">&pi;</phrase></entry>
        <entry><literal>pi()</literal></entry>
        <entry><literal>3.14159265358979323846</literal></entry>
       </row>
diff --git a/doc/src/sgml/stylesheet-fo.xsl b/doc/src/sgml/stylesheet-fo.xsl
index 6797e06a77c..3d3ab02ae9a 100644
--- a/doc/src/sgml/stylesheet-fo.xsl
+++ b/doc/src/sgml/stylesheet-fo.xsl
@@ -132,4 +132,8 @@
   </fo:bookmark>
 </xsl:template>
 
+<xsl:template match="phrase[@role='symbol']">
+  <fo:inline font-family="{$symbol.font.family}"><xsl:value-of select="." /></fo:inline>
+</xsl:template>
+
 </xsl:stylesheet>