fix name output for merged documents

examples/MergePdfDocuments.cs

@@ -3,6 +3,7 @@
     using System;
     using System.IO;
     using System.Linq;
+    using PdfPig;
     using PdfPig.Writer;
 
     internal static class MergePdfDocuments
@@ -20,6 +21,11 @@
                 var output = Path.Combine(location, "outputOfMerge.pdf");
                 File.WriteAllBytes(output, resultFileBytes);
                 Console.WriteLine($"File output to: {output}");
+
+                using (var doc = PdfDocument.Open(resultFileBytes))
+                {
+                    Console.WriteLine($"Generated document with {doc.NumberOfPages} pages.");
+                }
             }
             catch (Exception ex)
             {

src/UglyToad.PdfPig/Writer/PdfMerger.cs

@@ -48,6 +48,28 @@
             });
         }
 
+        /// <summary>
+        /// Merge multiple PDF documents together with the pages in the order the file paths are provided.
+        /// </summary>
+        public static byte[] Merge(params string[] filePaths)
+        {
+            var bytes = new List<byte[]>(filePaths.Length);
+
+            for (var i = 0; i < filePaths.Length; i++)
+            {
+                var filePath = filePaths[i];
+
+                if (filePath == null)
+                {
+                    throw new ArgumentNullException(nameof(filePaths), $"Null filepath at index {i}.");
+                }
+
+                bytes.Add(File.ReadAllBytes(filePath));
+            }
+
+            return Merge(bytes);
+        }
+
         /// <summary>
         /// Merge the set of PDF documents.
         /// </summary>

src/UglyToad.PdfPig/Writer/TokenWriter.cs

@@ -3,11 +3,13 @@
     using System;
     using System.Collections.Generic;
     using System.Globalization;
+    using System.Text;
     using System.IO;
     using System.Linq;
     using Core;
     using Graphics.Operations;
     using Tokens;
+    using Util;
 
     /// <summary>
     /// Writes any type of <see cref="IToken"/> to the corresponding PDF document format output.
@@ -56,6 +58,20 @@
 
         private static readonly byte[] Xref = OtherEncodings.StringAsLatin1Bytes("xref");
 
+        private static readonly HashSet<char> DelimiterChars = new HashSet<char>
+        {
+            '(',
+            ')',
+            '<',
+            '>',
+            '[',
+            ']',
+            '{',
+            '}',
+            '/',
+            '%'
+        };
+
         /// <summary>
         /// Writes the given input token to the output stream with the correct PDF format and encoding including whitespace and line breaks as applicable.
         /// </summary>
@@ -276,7 +292,29 @@
 
         private static void WriteName(string name, Stream outputStream)
         {
-            var bytes = OtherEncodings.StringAsLatin1Bytes(name);
+            /*
+             * Beginning with PDF 1.2, any character except null (character code 0) may be
+             * included in a name by writing its 2-digit hexadecimal code, preceded by the number sign character (#).
+             * This is required for delimiter and whitespace characters.
+             * This is recommended for characters whose codes are outside the range 33 (!) to 126 (~).
+             */
+
+            var sb = new StringBuilder();
+
+            foreach (var c in name)
+            {
+                if (c < 33 || c > 126 || DelimiterChars.Contains(c))
+                {
+                    var str = Hex.GetString(new[] { (byte)c });
+                    sb.Append('#').Append(str);
+                }
+                else
+                {
+                    sb.Append(c);
+                }
+            }
+
+            var bytes = OtherEncodings.StringAsLatin1Bytes(sb.ToString());
 
             outputStream.WriteByte(NameStart);
             outputStream.Write(bytes, 0, bytes.Length);