Support margin auto for table alignment #194

Author: onizet

src/Html2OpenXml/Expressions/Table/TableExpression.cs

@@ -201,12 +201,6 @@ protected override void ComposeStyles (ParsingContext context)
             }
         }
 
-        var align = Converter.ToParagraphAlign(tableNode.GetAttribute("align"));
-        if (!align.HasValue)
-            align = Converter.ToParagraphAlign(styleAttributes["justify-self"]);
-        if (align.HasValue)
-            tableProperties.TableJustification = new() { Val = align.Value.ToTableRowAlignment() };
-
         var dir = tableNode.GetTextDirection();
         if (dir.HasValue)
             tableProperties.BiDiVisual = new() { 
@@ -286,5 +280,22 @@ protected override void ComposeStyles (ParsingContext context)
                 };
             }
         }
+
+        var align = Converter.ToParagraphAlign(tableNode.GetAttribute("align"))
+            ?? Converter.ToParagraphAlign(styleAttributes["justify-self"]);
+        if (!align.HasValue)
+        {
+            var margin = styleAttributes.GetMargin("margin");
+            if (margin.Left.Type == UnitMetric.Auto)
+            {
+                if (margin.Right.Type == UnitMetric.Auto)
+                    align = JustificationValues.Center;
+                else
+                    align = JustificationValues.Right;
+            }
+        }
+
+        if (align.HasValue)
+            tableProperties.TableJustification = new() { Val = align.Value.ToTableRowAlignment() };
     }
 }

test/HtmlToOpenXml.Tests/TableTests.cs

@@ -352,6 +352,8 @@ public void TableCaption_ReturnsPositionedParagraph(string position, int caption
 
         [TestCase("align='right'", ExpectedResult = "right")]
         [TestCase("style='justify-self:center'", ExpectedResult = "center")]
+        [TestCase("style='margin-left:auto'", ExpectedResult = "right")]
+        [TestCase("style='margin-left:auto;margin-right:auto'", ExpectedResult = "center")]
         public string? TableAlign_ReturnsTableJustification(string style)
         {
             var elements = converter.Parse(@$"<table {style}>