#127 add basic pdf/a-1b level compliance to the document builder

adds color profiles/output intents and an xmp metadata stream to the document in order to be compliant with pdf/a-1b (basic). this compliance level is toggled on the builder since it will generate larger files and set to 'off/none' by default. pdf/a documents are also not able to use standard fonts so using a font when the compliance level is not none will throw.

src/UglyToad.PdfPig.Tests/PublicApiScannerTests.cs

@@ -195,6 +195,7 @@
                 "UglyToad.PdfPig.Util.Adler32Checksum",
                 "UglyToad.PdfPig.Util.IWordExtractor",
                 "UglyToad.PdfPig.Util.DefaultWordExtractor",
+                "UglyToad.PdfPig.Writer.PdfAStandard",
                 "UglyToad.PdfPig.Writer.PdfDocumentBuilder",
                 "UglyToad.PdfPig.Writer.PdfMerger",
                 "UglyToad.PdfPig.Writer.PdfPageBuilder",

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

@@ -494,6 +494,34 @@
             }
         }
 
+        [Fact]
+        public void CanGeneratePdfA1BFile()
+        {
+            var builder = new PdfDocumentBuilder
+            {
+                ArchiveStandard = PdfAStandard.A1B
+            };
+
+            var page = builder.AddPage(PageSize.A4);
+
+            var font = builder.AddTrueTypeFont(TrueTypeTestHelper.GetFileBytes("Roboto-Regular.ttf"));
+
+            page.AddText("Howdy!", 12, new PdfPoint(25, 670), font);
+
+            var bytes = builder.Build();
+
+            WriteFile(nameof(CanGeneratePdfA1BFile), 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