#127 pdf/a-1a compliance

adds struct tree and markinfo dictionaries to support pdf/a-1a compliance.

src/UglyToad.PdfPig.Tests/Writer/PdfDocumentBuilderTests.cs

@@ -522,6 +522,34 @@
             }
         }
 
+        [Fact]
+        public void CanGeneratePdfA1AFile()
+        {
+            var builder = new PdfDocumentBuilder
+            {
+                ArchiveStandard = PdfAStandard.A1A
+            };
+
+            var page = builder.AddPage(PageSize.A4);
+
+            var font = builder.AddTrueTypeFont(TrueTypeTestHelper.GetFileBytes("Roboto-Regular.ttf"));
+
+            page.AddText("Howdy PDF/A-1A!", 10, new PdfPoint(25, 700), font);
+
+            var bytes = builder.Build();
+
+            WriteFile(nameof(CanGeneratePdfA1AFile), bytes);
+
+            using (var pdf = PdfDocument.Open(bytes, ParsingOptions.LenientParsingOff))
+            {
+                Assert.Equal(1, pdf.NumberOfPages);
+
+                Assert.True(pdf.TryGetXmpMetadata(out var xmp));
+
+                Assert.NotNull(xmp.GetXDocument());
+            }
+        }
+
         private static void WriteFile(string name, byte[] bytes)
         {
             try

src/UglyToad.PdfPig.Tokens/NameToken.Constants.cs

@@ -334,6 +334,7 @@
         public static readonly NameToken Mac = new NameToken("Mac");
         public static readonly NameToken MacExpertEncoding = new NameToken("MacExpertEncoding");
         public static readonly NameToken MacRomanEncoding = new NameToken("MacRomanEncoding");
+        public static readonly NameToken Marked = new NameToken("Marked");
         public static readonly NameToken MarkInfo = new NameToken("MarkInfo");
         public static readonly NameToken Mask = new NameToken("Mask");
         public static readonly NameToken Matrix = new NameToken("Matrix");

src/UglyToad.PdfPig/Writer/PdfA1ARuleBuilder.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Collections.Generic;
+using UglyToad.PdfPig.Tokens;
+
+namespace UglyToad.PdfPig.Writer
+{
+    internal static class PdfA1ARuleBuilder
+    {
+        public static void Obey(Dictionary<NameToken, IToken> catalog)
+        {
+            var structTreeRoot = GenerateStructTree();
+
+            catalog[NameToken.StructTreeRoot] = structTreeRoot;
+
+            var markInfoDictionary = new DictionaryToken(new Dictionary<NameToken, IToken>
+            {
+                {NameToken.Marked, BooleanToken.True}
+            });
+
+            catalog[NameToken.MarkInfo] = markInfoDictionary;
+        }
+
+        private static DictionaryToken GenerateStructTree()
+        {
+            var rootDictionary = new Dictionary<NameToken, IToken>
+            {
+                {NameToken.Type, NameToken.StructTreeRoot}
+            };
+
+            var structTreeRoot = new DictionaryToken(rootDictionary);
+
+            return structTreeRoot;
+        }
+    }
+}

src/UglyToad.PdfPig/Writer/PdfA1BRuleBuilder.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using UglyToad.PdfPig.Tokens;
+using UglyToad.PdfPig.Writer.Colors;
+using UglyToad.PdfPig.Writer.Xmp;
+
+namespace UglyToad.PdfPig.Writer
+{
+    internal static class PdfA1BRuleBuilder
+    {
+        public static void Obey(Dictionary<NameToken, IToken> catalog, Func<IToken, ObjectToken> writerFunc,
+            PdfDocumentBuilder.DocumentInformationBuilder documentInformationBuilder,
+            PdfAStandard archiveStandard)
+        {
+            catalog[NameToken.OutputIntents] = OutputIntentsFactory.GetOutputIntentsArray(writerFunc);
+            var xmpStream = XmpWriter.GenerateXmpStream(documentInformationBuilder, 1.7m, archiveStandard);
+            var xmpObj = writerFunc(xmpStream);
+            catalog[NameToken.Metadata] = new IndirectReferenceToken(xmpObj.Number);
+        }
+    }
+}

src/UglyToad.PdfPig/Writer/PdfAStandard.cs

@@ -12,6 +12,10 @@
         /// <summary>
         /// Compliance with PDF/A1-B. Level B (basic) conformance are standards necessary for the reliable reproduction of a document's visual appearance.
         /// </summary>
-        A1B = 1
+        A1B = 1,
+        /// <summary>
+        /// Compliance with PDF/A1-A. Level A (accessible) conformance are PDF/A1-B standards in addition to features intended to improve a document's accessibility. 
+        /// </summary>
+        A1A = 2
     }
 }

src/UglyToad.PdfPig/Writer/PdfDocumentBuilder.cs

@@ -13,8 +13,6 @@ namespace UglyToad.PdfPig.Writer
     using PdfPig.Fonts.Standard14Fonts;
     using PdfPig.Fonts.TrueType.Parser;
     using Tokens;
-    using Colors;
-    using Xmp;
 
     using Util.JetBrains.Annotations;
 
@@ -343,10 +341,16 @@ namespace UglyToad.PdfPig.Writer
 
                 if (ArchiveStandard != PdfAStandard.None)
                 {
-                    catalogDictionary[NameToken.OutputIntents] = OutputIntentsFactory.GetOutputIntentsArray(x => context.WriteObject(memory, x));
+                    Func<IToken, ObjectToken> writerFunc = x => context.WriteObject(memory, x);
-                    var xmpStream = XmpWriter.GenerateXmpStream(DocumentInformation, 1.7m, ArchiveStandard);
+
-                    var xmpObj = context.WriteObject(memory, xmpStream);
+                    PdfA1BRuleBuilder.Obey(catalogDictionary, writerFunc, DocumentInformation, ArchiveStandard);
-                    catalogDictionary[NameToken.Metadata] = new IndirectReferenceToken(xmpObj.Number);
+
+                    switch (ArchiveStandard)
+                    {
+                        case PdfAStandard.A1A:
+                            PdfA1ARuleBuilder.Obey(catalogDictionary);
+                            break;
+                    }
                 }
 
                 var catalog = new DictionaryToken(catalogDictionary);

src/UglyToad.PdfPig/Writer/Xmp/XmpWriter.cs

@@ -135,6 +135,10 @@ namespace UglyToad.PdfPig.Writer.Xmp
                     part = 1;
                     conformance = "B";
                     break;
+                case PdfAStandard.A1A:
+                    part = 1;
+                    conformance = "A";
+                    break;
                 default:
                     throw new ArgumentOutOfRangeException(nameof(standard), standard, null);
             }