Close #4550: All tables and figures without align option are displayed to center

CHANGES

@@ -65,6 +65,7 @@ Incompatible changes
 * LaTeX: graphics inclusion of oversized images rescales to not exceed
   the text width and height, even if width and/or height option were used.
   (refs: #5956)
+* #4550: All tables and figures without ``align`` option are displayed to center
 
 Deprecated
 ----------

sphinx/io.py

@@ -21,7 +21,7 @@
 from sphinx.deprecation import RemovedInSphinx30Warning
 from sphinx.transforms import (
     ApplySourceWorkaround, ExtraTranslatableNodes, CitationReferences,
-    DefaultSubstitutions, MoveModuleTargets, HandleCodeBlocks, SortIds,
+    DefaultSubstitutions, MoveModuleTargets, HandleCodeBlocks, SortIds, FigureAligner,
     AutoNumbering, AutoIndexUpgrader, FilterSystemMessages,
     UnreferencedFootnotesDetector, SphinxSmartQuotes, DoctreeReadEvent, ManpageLink
 )
@@ -96,7 +96,7 @@ class SphinxStandaloneReader(SphinxBaseReader):
     """
     transforms = [ApplySourceWorkaround, ExtraTranslatableNodes, PreserveTranslatableMessages,
                   Locale, CitationReferences, DefaultSubstitutions, MoveModuleTargets,
-                  HandleCodeBlocks, AutoNumbering, AutoIndexUpgrader, SortIds,
+                  HandleCodeBlocks, AutoNumbering, AutoIndexUpgrader, SortIds, FigureAligner,
                   RemoveTranslatableInline, FilterSystemMessages, RefOnlyBulletListTransform,
                   UnreferencedFootnotesDetector, SphinxSmartQuotes, ManpageLink,
                   SphinxDomains, SubstitutionDefinitionsRemover, DoctreeReadEvent,

sphinx/transforms/__init__.py

@@ -23,7 +23,7 @@
 from sphinx.util import logging
 from sphinx.util.docutils import new_document
 from sphinx.util.i18n import format_date
-from sphinx.util.nodes import apply_source_workaround, is_smartquotable
+from sphinx.util.nodes import NodeMatcher, apply_source_workaround, is_smartquotable
 
 if False:
     # For type annotation
@@ -309,6 +309,19 @@ def apply(self, **kwargs):
                                location=node)
 
 
+class FigureAligner(SphinxTransform):
+    """
+    Align figures to center by default.
+    """
+    default_priority = 700
+
+    def apply(self, **kwargs):
+        # type: (Any) -> None
+        matcher = NodeMatcher(nodes.table, nodes.figure)
+        for node in self.document.traverse(matcher):  # type: nodes.Element
+            node.setdefault('align', 'center')
+
+
 class FilterSystemMessages(SphinxTransform):
     """Filter system messages from a doctree."""
     default_priority = 999

tests/roots/test-latex-table/expects/longtable.tex

@@ -1,6 +1,6 @@
 \label{\detokenize{longtable:longtable}}
 
-\begin{savenotes}\sphinxatlongtablestart\begin{longtable}{|l|l|}
+\begin{savenotes}\sphinxatlongtablestart\begin{longtable}[c]{|l|l|}
 \hline
 \sphinxstyletheadfamily 
 header1

tests/roots/test-latex-table/expects/longtable_having_caption.tex

@@ -1,6 +1,6 @@
 \label{\detokenize{longtable:longtable-having-caption}}
 
-\begin{savenotes}\sphinxatlongtablestart\begin{longtable}{|l|l|}
+\begin{savenotes}\sphinxatlongtablestart\begin{longtable}[c]{|l|l|}
 \sphinxthelongtablecaptionisattop
 \caption{caption for longtable\strut}\label{\detokenize{longtable:id1}}\\*[\sphinxlongtablecapskipadjust]
 \hline

tests/roots/test-latex-table/expects/longtable_having_problematic_cell.tex

@@ -1,6 +1,6 @@
 \label{\detokenize{longtable:longtable-having-problematic-cell}}
 
-\begin{savenotes}\sphinxatlongtablestart\begin{longtable}{|*{2}{\X{1}{2}|}}
+\begin{savenotes}\sphinxatlongtablestart\begin{longtable}[c]{|*{2}{\X{1}{2}|}}
 \hline
 \sphinxstyletheadfamily 
 header1

tests/roots/test-latex-table/expects/longtable_having_stub_columns_and_problematic_cell.tex

@@ -1,6 +1,6 @@
 \label{\detokenize{longtable:longtable-having-both-stub-columns-and-problematic-cell}}
 
-\begin{savenotes}\sphinxatlongtablestart\begin{longtable}{|*{3}{\X{1}{3}|}}
+\begin{savenotes}\sphinxatlongtablestart\begin{longtable}[c]{|*{3}{\X{1}{3}|}}
 \hline
 \sphinxstyletheadfamily 
 header1

tests/roots/test-latex-table/expects/longtable_having_verbatim.tex

@@ -1,6 +1,6 @@
 \label{\detokenize{longtable:longtable-having-verbatim}}
 
-\begin{savenotes}\sphinxatlongtablestart\begin{longtable}{|*{2}{\X{1}{2}|}}
+\begin{savenotes}\sphinxatlongtablestart\begin{longtable}[c]{|*{2}{\X{1}{2}|}}
 \hline
 \sphinxstyletheadfamily 
 header1

tests/roots/test-latex-table/expects/longtable_having_widths.tex

@@ -1,6 +1,6 @@
 \label{\detokenize{longtable:longtable-having-widths-option}}
 
-\begin{savenotes}\sphinxatlongtablestart\begin{longtable}{|\X{30}{100}|\X{70}{100}|}
+\begin{savenotes}\sphinxatlongtablestart\begin{longtable}[c]{|\X{30}{100}|\X{70}{100}|}
 \hline\noalign{\phantomsection\label{\detokenize{longtable:namedlongtable}}\label{\detokenize{longtable:mylongtable}}}%
 \sphinxstyletheadfamily 
 header1

tests/roots/test-latex-table/expects/longtable_having_widths_and_problematic_cell.tex

@@ -1,6 +1,6 @@
 \label{\detokenize{longtable:longtable-having-both-widths-and-problematic-cell}}
 
-\begin{savenotes}\sphinxatlongtablestart\begin{longtable}{|\X{30}{100}|\X{70}{100}|}
+\begin{savenotes}\sphinxatlongtablestart\begin{longtable}[c]{|\X{30}{100}|\X{70}{100}|}
 \hline
 \sphinxstyletheadfamily 
 header1

tests/roots/test-latex-table/expects/longtable_with_tabularcolumn.tex

@@ -1,6 +1,6 @@
 \label{\detokenize{longtable:longtable-with-tabularcolumn}}
 
-\begin{savenotes}\sphinxatlongtablestart\begin{longtable}{|c|c|}
+\begin{savenotes}\sphinxatlongtablestart\begin{longtable}[c]{|c|c|}
 \hline
 \sphinxstyletheadfamily 
 header1