Fix #3702: abstract LaTeX styling of figure legends into sphinxlegend

doc/latex.rst

@@ -438,7 +438,14 @@ Let us now list some macros from the package file
      the new macros are wrappers of the formerly hard-coded ``\texttt``,
      ``\emph``, ... The default definitions can be found in
      :file:`sphinx.sty`.
-- paragraph level environments: for each admonition type ``<foo>``, the
+- a :dudir:`figure` may have an optional legend with arbitrary body
+  elements: they are rendered in a ``sphinxlegend`` environment. The default
+  definition issues ``\small``, and ends with ``\par``.
+
+  .. versionadded:: 1.5.6
+     formerly, the ``\small`` was hardcoded in LaTeX writer and the ending
+     ``\par`` was lacking.
+- for each admonition type ``<foo>``, the
   used environment is named ``sphinx<foo>``. They may be ``\renewenvironment``
   'd individually, and must then be defined with one argument (it is the heading
   of the notice, for example ``Warning:`` for :dudir:`warning` directive, if

sphinx/texinputs/sphinx.sty

@@ -1383,6 +1383,8 @@
 \protected\def\sphinxstyleliteralstrong  {\sphinxbfcode}
 \protected\def\sphinxstyleabbreviation   {\textsc}
 \protected\def\sphinxstyleliteralintitle {\sphinxcode}
+% figure legend comes after caption and may contain arbitrary body elements
+\newenvironment{sphinxlegend}{\par\small}{\par}
 
 % LaTeX writer uses macros to hide double quotes from \sphinxcode's \@noligs
 \protected\def\sphinxquotedblleft{``}

sphinx/writers/latex.py

@@ -1599,10 +1599,10 @@ class LaTeXTranslator(nodes.NodeVisitor):
         self.unrestrict_footnote(node)
 
     def visit_legend(self, node):
-        self.body.append('{\\small ')
+        self.body.append('\n\\begin{sphinxlegend}')
 
     def depart_legend(self, node):
-        self.body.append('}')
+        self.body.append('\\end{sphinxlegend}\n')
 
     def visit_admonition(self, node):
         self.body.append('\n\\begin{sphinxadmonition}{note}')