make filter provider and filter public and use tryget for image bytes

src/UglyToad.PdfPig.Tests/Integration/SinglePageLibreOfficeImages.cs

@@ -1,6 +1,5 @@
 namespace UglyToad.PdfPig.Tests.Integration
 {
-    using System;
     using System.Linq;
     using Xunit;
 
@@ -74,13 +73,12 @@
                 var page = document.GetPage(1);
                 foreach (var image in page.GetImages())
                 {
-                    try
+                    if (image.TryGetBytes(out var bytes))
                     {
-                        Assert.NotNull(image.Bytes);
+                        Assert.NotNull(bytes);
                     }
-                    catch (NotSupportedException )
+                    else
                     {
-                        // Should allow access to raw bytes.
                         Assert.NotNull(image.RawBytes);
                     }
                 }

src/UglyToad.PdfPig.Tests/PublicApiScannerTests.cs

@@ -85,6 +85,9 @@
                 "UglyToad.PdfPig.CrossReference.CrossReferenceType",
                 "UglyToad.PdfPig.CrossReference.TrailerDictionary",
                 "UglyToad.PdfPig.Exceptions.PdfDocumentEncryptedException",
+                "UglyToad.PdfPig.Filters.DefaultFilterProvider",
+                "UglyToad.PdfPig.Filters.IFilter",
+                "UglyToad.PdfPig.Filters.IFilterProvider",
                 "UglyToad.PdfPig.PdfFonts.DescriptorFontFile",
                 "UglyToad.PdfPig.PdfFonts.FontDescriptor",
                 "UglyToad.PdfPig.PdfFonts.FontDescriptorFlags",
@@ -192,6 +195,7 @@
                 "UglyToad.PdfPig.Outline.Destinations.ExplicitDestinationType",
                 "UglyToad.PdfPig.ParsingOptions",
                 "UglyToad.PdfPig.PdfDocument",
+                "UglyToad.PdfPig.PdfExtensions",
                 "UglyToad.PdfPig.Structure",
                 "UglyToad.PdfPig.Util.Adler32Checksum",
                 "UglyToad.PdfPig.Util.IWordExtractor",

src/UglyToad.PdfPig/Content/IPdfImage.cs

@@ -42,13 +42,6 @@
         /// </summary>
         int BitsPerComponent { get; }
 
-        /// <summary>
-        /// The bytes of the image with any filters decoded.
-        /// If the filter used to encode the bytes is not supported accessing this property will throw, access the <see cref="RawBytes"/>
-        /// instead.
-        /// </summary>
-        IReadOnlyList<byte> Bytes { get; }
-
         /// <summary>
         /// The encoded bytes of the image with all filters still applied.
         /// </summary>
@@ -90,5 +83,11 @@
         /// Whether this image is an <see cref="InlineImage"/> or a <see cref="XObjectImage"/>.
         /// </summary>
         bool IsInlineImage { get; }
+
+        /// <summary>
+        /// Get the decoded bytes of the image if applicable. For JPEG images and some other types the
+        /// <see cref="RawBytes"/> should be used directly.
+        /// </summary>
+        bool TryGetBytes(out IReadOnlyList<byte> bytes);
     }
 }

src/UglyToad.PdfPig/Content/InlineImage.cs

@@ -47,9 +47,6 @@
         /// <inheritdoc />
         public bool Interpolate { get; }
 
-        /// <inheritdoc />
-        public IReadOnlyList<byte> Bytes => bytesFactory.Value;
-
         /// <inheritdoc />
         public IReadOnlyList<byte> RawBytes { get; }
 
@@ -76,7 +73,18 @@
             Interpolate = interpolate;
 
             RawBytes = bytes;
-            bytesFactory = new Lazy<IReadOnlyList<byte>>(() =>
+
+            var supportsFilters = true;
+            foreach (var filter in filters)
+            {
+                if (!filter.IsSupported)
+                {
+                    supportsFilters = false;
+                    break;
+                }
+            }
+
+            bytesFactory = supportsFilters ? new Lazy<IReadOnlyList<byte>>(() =>
             {
                 var b = bytes.ToArray();
                 for (var i = 0; i < filters.Count; i++)
@@ -86,7 +94,21 @@
                 }
 
                 return b;
-            });
+            }) : null;
+        }
+
+        /// <inheritdoc />
+        public bool TryGetBytes(out IReadOnlyList<byte> bytes)
+        {
+            bytes = null;
+            if (bytesFactory == null)
+            {
+                return false;
+            }
+
+            bytes = bytesFactory.Value;
+
+            return true;
         }
 
         /// <inheritdoc />

src/UglyToad.PdfPig/Filters/DefaultFilterProvider.cs

@@ -6,13 +6,20 @@
     using Core;
     using Tokens;
 
-    internal class MemoryFilterProvider : IFilterProvider
+    /// <inheritdoc />
+    /// <summary>
+    /// The default implementation of the <see cref="T:UglyToad.PdfPig.Filters.IFilterProvider" />.
+    /// </summary>
+    public class DefaultFilterProvider : IFilterProvider
     {
         private readonly IReadOnlyDictionary<string, IFilter> filterInstances; 
 
-        public static readonly IFilterProvider Instance = new MemoryFilterProvider();
+        /// <summary>
+        /// The single instance of this provider.
+        /// </summary>
+        public static readonly IFilterProvider Instance = new DefaultFilterProvider();
 
-        private MemoryFilterProvider()
+        private DefaultFilterProvider()
         {
             var ascii85 = new Ascii85Filter();
             var asciiHex = new AsciiHexDecodeFilter();
@@ -45,6 +52,7 @@
             };
         }
 
+        /// <inheritdoc />
         public IReadOnlyList<IFilter> GetFilters(DictionaryToken dictionary)
         {
             if (dictionary == null)
@@ -76,6 +84,7 @@
             }
         }
 
+        /// <inheritdoc />
         public IReadOnlyList<IFilter> GetNamedFilters(IReadOnlyList<NameToken> names)
         {
             if (names == null)
@@ -103,6 +112,7 @@
             return factory;
         }
 
+        /// <inheritdoc />
         public IReadOnlyList<IFilter> GetAllFilters()
         {
             return filterInstances.Values.Distinct().ToList();

src/UglyToad.PdfPig/Filters/IFilter.cs

@@ -4,10 +4,9 @@
     using Tokens;
 
     /// <summary>
-    /// A filter is used in a PDF to encode/decode data either to compress it
+    /// A filter is used in a PDF to encode/decode data either to compress it or derive an ASCII representation of the data.
-    /// or derive an ASCII representation of the data.
     /// </summary>
-    internal interface IFilter
+    public interface IFilter
     {
         /// <summary>
         /// Whether this library can decode information encoded using this filter.

src/UglyToad.PdfPig/Filters/IFilterProvider.cs

@@ -3,12 +3,24 @@
     using System.Collections.Generic;
     using Tokens;
 
-    internal interface IFilterProvider
+    /// <summary>
+    /// Gets filter implementations (<see cref="IFilter"/>) for decoding PDF data.
+    /// </summary>
+    public interface IFilterProvider
     {
+        /// <summary>
+        /// Get the filters specified in this dictionary.
+        /// </summary>
         IReadOnlyList<IFilter> GetFilters(DictionaryToken dictionary);
 
+        /// <summary>
+        /// Gets the filters specified by the filter names.
+        /// </summary>
         IReadOnlyList<IFilter> GetNamedFilters(IReadOnlyList<NameToken> names);
 
+        /// <summary>
+        /// Get all available filters in this library.
+        /// </summary>
         IReadOnlyList<IFilter> GetAllFilters();
     }
 }

src/UglyToad.PdfPig/Parser/PdfDocumentFactory.cs

@@ -83,7 +83,7 @@
         private static PdfDocument OpenDocument(IInputBytes inputBytes, ISeekableTokenScanner scanner, ILog log, bool isLenientParsing, 
             IReadOnlyList<string> passwords, bool clipPaths)
         {
-            var filterProvider = MemoryFilterProvider.Instance;
+            var filterProvider = DefaultFilterProvider.Instance;
 
             CrossReferenceTable crossReferenceTable = null;
 

src/UglyToad.PdfPig/PdfExtensions.cs

@@ -7,7 +7,10 @@
     using Tokenization.Scanner;
     using Tokens;
 
-    internal static class PdfExtensions
+    /// <summary>
+    /// Extensions for PDF types.
+    /// </summary>
+    public static class PdfExtensions
     {
         /// <summary>
         /// Try and get the entry with a given name and type or look-up the object if it's an indirect reference.
@@ -44,7 +47,10 @@
             return typedToken;
         }
         
-        internal static IReadOnlyList<byte> Decode(this StreamToken stream, IFilterProvider filterProvider)
+        /// <summary>
+        /// Get the decoded data from this stream.
+        /// </summary>
+        public static IReadOnlyList<byte> Decode(this StreamToken stream, IFilterProvider filterProvider)
         {
             var filters = filterProvider.GetFilters(stream.StreamDictionary);
 

src/UglyToad.PdfPig/Writer/PdfMerger.cs

@@ -24,7 +24,7 @@
     {
         private static readonly ILog Log = new NoOpLog();
 
-        private static readonly IFilterProvider FilterProvider = MemoryFilterProvider.Instance;
+        private static readonly IFilterProvider FilterProvider = DefaultFilterProvider.Instance;
 
         /// <summary>
         /// Merge two PDF documents together with the pages from <paramref name="file1"/> followed by <paramref name="file2"/>.

src/UglyToad.PdfPig/XObjects/XObjectFactory.cs

@@ -66,7 +66,19 @@
             var interpolate = dictionary.TryGet(NameToken.Interpolate, pdfScanner, out BooleanToken interpolateToken)
                               && interpolateToken.Data;
 
-            var decodedBytes = new Lazy<IReadOnlyList<byte>>(() => xObject.Stream.Decode(filterProvider));
+            var filters = filterProvider.GetFilters(xObject.Stream.StreamDictionary);
+            var supportsFilters = true;
+            foreach (var filter in filters)
+            {
+                if (!filter.IsSupported)
+                {
+                    supportsFilters = false;
+                    break;
+                }
+            }
+
+            var decodedBytes = supportsFilters ? new Lazy<IReadOnlyList<byte>>(() => xObject.Stream.Decode(filterProvider))
+                : null;
 
             var decode = EmptyArray<decimal>.Instance;
 

src/UglyToad.PdfPig/XObjects/XObjectImage.cs

@@ -15,7 +15,8 @@
     /// </summary>
     public class XObjectImage : IPdfImage
     {
-        private readonly Lazy<IReadOnlyList<byte>> bytes;
+        [CanBeNull]
+        private readonly Lazy<IReadOnlyList<byte>> bytesFactory;
 
         /// <inheritdoc />
         public PdfRectangle Bounds { get; }
@@ -62,10 +63,6 @@
 
         /// <inheritdoc />
         public IReadOnlyList<byte> RawBytes { get; }
-
-        /// <inheritdoc />
-        [NotNull]
-        public IReadOnlyList<byte> Bytes => bytes.Value;
         
         /// <summary>
         /// Creates a new <see cref="XObjectImage"/>.
@@ -93,7 +90,21 @@
             Decode = decode;
             ImageDictionary = imageDictionary ?? throw new ArgumentNullException(nameof(imageDictionary));
             RawBytes = rawBytes;
-            this.bytes = bytes ?? throw new ArgumentNullException(nameof(bytes));
+            bytesFactory = bytes;
+        }
+
+        /// <inheritdoc />
+        public bool TryGetBytes(out IReadOnlyList<byte> bytes)
+        {
+            bytes = null;
+            if (bytesFactory == null)
+            {
+                return false;
+            }
+
+            bytes = bytesFactory.Value;
+
+            return true;
         }
 
         /// <inheritdoc />