Implemented the cell margins of Table

DocX/Table.cs

@@ -232,6 +232,38 @@ namespace Novacode
             return tblPr;
         }
 
+        /// <summary>
+        /// Set the specified cell margin for the table-level.
+        /// </summary>
+        /// <param name="type">The side of the cell margin.</param>
+        /// <param name="margin">The value for the specified cell margin.</param>
+        /// <remarks>More information can be found <see cref="http://msdn.microsoft.com/en-us/library/documentformat.openxml.wordprocessing.tablecellmargindefault.aspx">here</see></remarks>
+        public void SetTableCellMargin(TableCellMarginType type, double margin)
+        {
+            XElement tblPr = GetOrCreate_tblPr();
+
+            // find (or create) the element with the cell margins 
+            XElement tblCellMar = tblPr.Element(XName.Get("tblCellMar", DocX.w.NamespaceName));
+            if (tblCellMar == null)
+            {
+                tblPr.AddFirst(new XElement(XName.Get("tblCellMar", DocX.w.NamespaceName)));
+                tblCellMar = tblPr.Element(XName.Get("tblCellMar", DocX.w.NamespaceName));
+            }
+
+            // find (or create) the element with cell margin for the specified side
+            XElement tblMargin = tblCellMar.Element(XName.Get(type.ToString(), DocX.w.NamespaceName));
+            if (tblMargin == null)
+            {
+                tblCellMar.AddFirst(new XElement(XName.Get(type.ToString(), DocX.w.NamespaceName)));
+                tblMargin = tblCellMar.Element(XName.Get(type.ToString(), DocX.w.NamespaceName));
+            }
+            
+            tblMargin.RemoveAttributes();
+            // set the value for the cell margin
+            tblMargin.Add(new XAttribute(XName.Get("w", DocX.w.NamespaceName), margin));
+            // set the side of cell margin
+            tblMargin.Add(new XAttribute(XName.Get("type", DocX.w.NamespaceName), "dxa"));
+        }
 
         /// <summary>
         /// Gets the column width for a given column index.

DocX/_Enumerations.cs

@@ -663,6 +663,30 @@ namespace Novacode
   	Auto,
   	None
   }
+
+  /// <summary>
+  /// Cell margin for all sides of the table cell.
+  /// </summary>
+  public enum TableCellMarginType
+  {
+      /// <summary>
+      /// The left cell margin.
+      /// </summary>
+      left,
+      /// <summary>
+      /// The right cell margin.
+      /// </summary>
+      right,
+      /// <summary>
+      /// The bottom cell margin.
+      /// </summary>
+      bottom,
+      /// <summary>
+      /// The top cell margin.
+      /// </summary>
+      top
+  }
+
   public enum HeadingType
   {
       [Description("Heading1")]

UnitTests/DocXUnitTests.cs

@@ -2768,6 +2768,65 @@ namespace UnitTests
                 Assert.AreEqual("22", szCsValue);
             }
         }
+
+        [TestMethod]
+        public void SetTableCellMargin_WhenSetTwoCellMargins_ContainsTwoCellMargins()
+        {
+            using (var document = DocX.Create("Set table cell margins.docx"))
+            {
+                Table table = document.InsertTable(1,1);
+
+                table.SetTableCellMargin(TableCellMarginType.left, 20);
+                table.SetTableCellMargin(TableCellMarginType.right, 40);
+
+                var elements = table.Xml.Descendants(XName.Get("tblCellMar", DocX.w.NamespaceName)).ToList();
+                // should contain only one element named tblCellMar
+                Assert.AreEqual(1, elements.Count);
+                var element = elements.First();
+                // should contain two elements defining the margins
+                Assert.AreEqual(2, element.Elements().Count());
+
+                var left = element.Element(XName.Get("left", DocX.w.NamespaceName));
+                var right = element.Element(XName.Get("right", DocX.w.NamespaceName));
+
+                Assert.IsNotNull(left);
+                Assert.IsNotNull(right);
+
+                Assert.AreEqual("20", left.Attribute(XName.Get("w", DocX.w.NamespaceName)).Value);
+                Assert.AreEqual("dxa", left.Attribute(XName.Get("type", DocX.w.NamespaceName)).Value);
+
+                Assert.AreEqual("40", right.Attribute(XName.Get("w", DocX.w.NamespaceName)).Value);
+                Assert.AreEqual("dxa", right.Attribute(XName.Get("type", DocX.w.NamespaceName)).Value);
+            }
+        }
+
+        [TestMethod]
+        public void SetTableCellMargin_WhenReSetCellMargin_ContainsOneCellMargin()
+        {
+            using (var document = DocX.Create("Set table cell margin.docx"))
+            {
+                Table table = document.InsertTable(1, 1);
+
+                table.SetTableCellMargin(TableCellMarginType.left, 20);
+                // change the table cell margin
+                table.SetTableCellMargin(TableCellMarginType.left, 40);
+
+                var elements = table.Xml.Descendants(XName.Get("tblCellMar", DocX.w.NamespaceName)).ToList();
+                // should contain only one element named tblCellMar
+                Assert.AreEqual(1, elements.Count);
+                var element = elements.First();
+                // should contain two elements defining the margins
+                Assert.AreEqual(1, element.Elements().Count());
+
+                var left = element.Element(XName.Get("left", DocX.w.NamespaceName));
+
+                Assert.IsNotNull(left);
+
+                // check that the last value is taken
+                Assert.AreEqual("40", left.Attribute(XName.Get("w", DocX.w.NamespaceName)).Value);
+                Assert.AreEqual("dxa", left.Attribute(XName.Get("type", DocX.w.NamespaceName)).Value);
+            }
+        }
     }
 }