Refactor PdfFunctionParser to account for indirect reference tokens

src/UglyToad.PdfPig.Tests/Functions/PdfFunctionType0Tests.cs

@@ -4,11 +4,16 @@
     using System.Collections.Generic;
     using System.Linq;
     using UglyToad.PdfPig.Functions;
+    using UglyToad.PdfPig.Tests.Tokens;
     using UglyToad.PdfPig.Tokens;
+    using UglyToad.PdfPig.Util;
     using Xunit;
 
     public class PdfFunctionType0Tests
     {
+        private readonly TestPdfTokenScanner testPdfTokenScanner = new TestPdfTokenScanner();
+        private readonly TestFilterProvider testFilterProvider = new TestFilterProvider();
+
         private static ArrayToken GetArrayToken(params double[] data)
         {
             return new ArrayToken(data.Select(v => new NumericToken((decimal)v)).ToArray());
@@ -33,7 +38,10 @@
 
             StreamToken function = new StreamToken(dictionaryToken, data);
 
-            var function0 = new PdfFunctionType0(function);
+            var func = PdfFunctionParser.Create(function, testPdfTokenScanner, testFilterProvider);
+            Assert.Equal(FunctionTypes.Sampled, func.FunctionType);
+            var function0 = func as PdfFunctionType0;
+
             var result = function0.Eval(new double[] { 0 });
             Assert.Equal(4, result.Length);
             result = function0.Eval(new double[] { 0.5 });
@@ -61,7 +69,10 @@
 
             StreamToken function = new StreamToken(dictionaryToken, data);
 
-            var function0 = new PdfFunctionType0(function);
+            var func = PdfFunctionParser.Create(function, testPdfTokenScanner, testFilterProvider);
+            Assert.Equal(FunctionTypes.Sampled, func.FunctionType);
+            var function0 = func as PdfFunctionType0;
+
             var result = function0.Eval(new double[] { 0.00 });
             Assert.Single(result);
             Assert.Equal(0.0, result[0], 3);
@@ -100,7 +111,10 @@
 
             StreamToken function = new StreamToken(dictionaryToken, data);
 
-            var function0 = new PdfFunctionType0(function);
+            var func = PdfFunctionParser.Create(function, testPdfTokenScanner, testFilterProvider);
+            Assert.Equal(FunctionTypes.Sampled, func.FunctionType);
+            var function0 = func as PdfFunctionType0;
+
             var result = function0.Eval(new double[] { 0.00 });
             Assert.Single(result);
             Assert.Equal(0.0, result[0], 3);
@@ -139,7 +153,10 @@
 
             StreamToken function = new StreamToken(dictionaryToken, data);
 
-            var function0 = new PdfFunctionType0(function);
+            var func = PdfFunctionParser.Create(function, testPdfTokenScanner, testFilterProvider);
+            Assert.Equal(FunctionTypes.Sampled, func.FunctionType);
+            var function0 = func as PdfFunctionType0;
+
             var result = function0.Eval(new double[] { 0, 0 });
             Assert.Equal(3, result.Length);
             Assert.Equal(new double[] { 1, 1, 0 }, result); // yellow
@@ -178,7 +195,9 @@
 
             StreamToken function = new StreamToken(dictionaryToken, data);
 
-            var function0 = new PdfFunctionType0(function);
+            var func = PdfFunctionParser.Create(function, testPdfTokenScanner, testFilterProvider);
+            Assert.Equal(FunctionTypes.Sampled, func.FunctionType);
+            var function0 = func as PdfFunctionType0;
 
             var result = function0.Eval(new double[] { 0 });
             Assert.Equal(3, result.Length);

src/UglyToad.PdfPig.Tests/Functions/PdfFunctionType2Tests.cs

@@ -3,16 +3,18 @@
     using System.Collections.Generic;
     using System.Linq;
     using UglyToad.PdfPig.Functions;
+    using UglyToad.PdfPig.Tests.Tokens;
     using UglyToad.PdfPig.Tokens;
+    using UglyToad.PdfPig.Util;
     using Xunit;
 
     public class PdfFunctionType2Tests
     {
-        private PdfFunctionType2 CreateFunction(double[] domain, double[] range, double[] c0, double[] c1, double n)
+        private static PdfFunctionType2 CreateFunction(double[] domain, double[] range, double[] c0, double[] c1, double n)
         {
             DictionaryToken dictionaryToken = new DictionaryToken(new Dictionary<NameToken, IToken>()
             {
-                { NameToken.FunctionType, new NumericToken(4) },
+                { NameToken.FunctionType, new NumericToken(2) },
                 { NameToken.Domain, new ArrayToken(domain.Select(v => new NumericToken((decimal)v)).ToArray()) },
                 { NameToken.Range, new ArrayToken(range.Select(v => new NumericToken((decimal)v)).ToArray()) },
 
@@ -21,7 +23,9 @@
                 { NameToken.N, new NumericToken((decimal)n) },
             });
 
-            return new PdfFunctionType2(dictionaryToken);
+            var func = PdfFunctionParser.Create(dictionaryToken, new TestPdfTokenScanner(), new TestFilterProvider());
+            Assert.Equal(FunctionTypes.Exponential, func.FunctionType);
+            return func as PdfFunctionType2;
         }
 
         [Fact]

src/UglyToad.PdfPig.Tests/Functions/PdfFunctionType4Tests.cs

@@ -4,12 +4,14 @@
     using System.Linq;
     using System.Text;
     using UglyToad.PdfPig.Functions;
+    using UglyToad.PdfPig.Tests.Tokens;
     using UglyToad.PdfPig.Tokens;
+    using UglyToad.PdfPig.Util;
     using Xunit;
 
     public class PdfFunctionType4Tests
     {
-        private PdfFunctionType4 CreateFunction(string function, double[] domain, double[] range)
+        private static PdfFunctionType4 CreateFunction(string function, double[] domain, double[] range)
         {
             DictionaryToken dictionaryToken = new DictionaryToken(new Dictionary<NameToken, IToken>()
             {
@@ -21,7 +23,10 @@
             var data = Encoding.ASCII.GetBytes(function); // OtherEncodings.Iso88591.GetBytes(function);
             StreamToken stream = new StreamToken(dictionaryToken, data);
 
-            return new PdfFunctionType4(stream);
+            var func = PdfFunctionParser.Create(stream, new TestPdfTokenScanner(), new TestFilterProvider());
+            Assert.Equal(FunctionTypes.PostScript, func.FunctionType);
+
+            return func as PdfFunctionType4;
         }
 
         /// <summary>

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

@@ -20,6 +20,7 @@
 
                 var appearance = annotationStamp.normalAppearanceStream;
                 // TODO - load color space in annotation appearance
+                // TODO - contains function with indirect reference
             }
         }
 

src/UglyToad.PdfPig/Functions/PdfFunction.cs

@@ -1,6 +1,5 @@
 namespace UglyToad.PdfPig.Functions
 {
-    using System;
     using System.Linq;
     using UglyToad.PdfPig.Core;
     using UglyToad.PdfPig.Tokens;
@@ -20,25 +19,27 @@
         /// </summary>
         public StreamToken FunctionStream { get; }
 
-        private ArrayToken domain;
-        private ArrayToken range;
         private int numberOfInputValues = -1;
         private int numberOfOutputValues = -1;
 
         /// <summary>
         /// This class represents a function in a PDF document.
         /// </summary>
-        public PdfFunction(DictionaryToken function)
+        public PdfFunction(DictionaryToken function, ArrayToken domain, ArrayToken range)
         {
             FunctionDictionary = function;
+            DomainValues = domain;
+            RangeValues = range;
         }
 
         /// <summary>
         /// This class represents a function in a PDF document.
         /// </summary>
-        public PdfFunction(StreamToken function)
+        public PdfFunction(StreamToken function, ArrayToken domain, ArrayToken range)
         {
             FunctionStream = function;
+            DomainValues = domain;
+            RangeValues = range;
         }
 
         /// <summary>
@@ -119,7 +120,7 @@
             {
                 if (numberOfInputValues == -1)
                 {
-                    ArrayToken array = GetDomainValues();
+                    ArrayToken array = DomainValues;
                     numberOfInputValues = array.Length / 2;
                 }
                 return numberOfInputValues;
@@ -135,7 +136,7 @@
         /// <returns>The domain range for this component.</returns>
         public PdfRange GetDomainForInput(int n)
         {
-            ArrayToken domainValues = GetDomainValues();
+            ArrayToken domainValues = DomainValues;
             return new PdfRange(domainValues.Data.OfType<NumericToken>().Select(t => t.Double), n);
         }
 
@@ -153,34 +154,13 @@
         /// Returns all ranges for the output values as <see cref="ArrayToken"/>. Required for type 0 and type 4 functions.
         /// </summary>
         /// <returns>the ranges array.</returns>
-        protected virtual ArrayToken RangeValues
+        protected ArrayToken RangeValues { get; }
-        {
-            get
-            {
-                if (range == null)
-                {
-                    GetDictionary().TryGet(NameToken.Range, out range); // Optionnal
-                }
-                return range;
-            }
-        }
 
         /// <summary>
         /// Returns all domains for the input values as <see cref="ArrayToken"/>. Required for all function types.
         /// </summary>
         /// <returns>the domains array.</returns>
-        private ArrayToken GetDomainValues()
+        private ArrayToken DomainValues { get; }
-        {
-            if (domain == null)
-            {
-                if (!GetDictionary().TryGet(NameToken.Domain, out ArrayToken domainToken))
-                {
-                    throw new ArgumentException("Could not retrieve Domain.");
-                }
-                domain = domainToken;
-            }
-            return domain;
-        }
 
         /// <summary>
         /// Clip the given input values to the ranges.

src/UglyToad.PdfPig/Functions/PdfFunctionType0.cs

@@ -2,7 +2,6 @@
 {
     using System;
     using System.Collections;
-    using System.Collections.Generic;
     using System.IO;
     using System.Linq;
     using UglyToad.PdfPig.Core;
@@ -10,26 +9,6 @@
 
     internal sealed class PdfFunctionType0 : PdfFunction
     {
-        /// <summary>
-        /// An array of 2 x m numbers specifying the linear mapping of input values 
-        /// into the domain of the function's sample table. Default value: [ 0 (Size0
-        /// - 1) 0 (Size1 - 1) ...].
-        /// </summary>
-        private ArrayToken encode;
-
-        /// <summary>
-        /// An array of 2 x n numbers specifying the linear mapping of sample values
-        /// into the range appropriate for the function's output values. Default
-        /// value: same as the value of Range.
-        /// </summary>
-        private ArrayToken decode;
-
-        /// <summary>
-        /// An array of m positive integers specifying the number of samples in each
-        /// input dimension of the sample table.
-        /// </summary>
-        private ArrayToken size;
-
         /// <summary>
         /// The samples of the function.
         /// </summary>
@@ -38,15 +17,27 @@
         /// <summary>
         /// Stitching function
         /// </summary>
-        internal PdfFunctionType0(DictionaryToken function) : base(function)
+        internal PdfFunctionType0(DictionaryToken function, ArrayToken domain, ArrayToken range, ArrayToken size, int bitsPerSample, int order, ArrayToken encode, ArrayToken decode)
+            : base(function, domain, range)
         {
+            Size = size;
+            BitsPerSample = bitsPerSample;
+            Order = order;
+            EncodeValues = encode;
+            DecodeValues = decode;
         }
 
         /// <summary>
         /// Stitching function
         /// </summary>
-        internal PdfFunctionType0(StreamToken function) : base(function)
+        internal PdfFunctionType0(StreamToken function, ArrayToken domain, ArrayToken range, ArrayToken size, int bitsPerSample, int order, ArrayToken encode, ArrayToken decode)
+            : base(function, domain, range)
         {
+            Size = size;
+            BitsPerSample = bitsPerSample;
+            Order = order;
+            EncodeValues = encode;
+            DecodeValues = decode;
         }
 
         public override FunctionTypes FunctionType
@@ -59,35 +50,16 @@
 
         /// <summary>
         /// The "Size" entry, which is the number of samples in each input dimension of the sample table.
+        /// <para>An array of m positive integers specifying the number of samples in each input dimension of the sample table.</para>
         /// </summary>
-        public ArrayToken Size
+        public ArrayToken Size { get; }
-        {
-            get
-            {
-                if (size == null && !GetDictionary().TryGet(NameToken.Size, out size))
-                {
-                    throw new ArgumentNullException(NameToken.Size);
-                }
-                return size;
-            }
-        }
 
         /// <summary>
         /// Get the number of bits that the output value will take up.
         /// <para>Valid values are 1,2,4,8,12,16,24,32.</para>
         /// </summary>
         /// <returns>Number of bits for each output value.</returns>
-        public int BitsPerSample
+        public int BitsPerSample { get; }
-        {
-            get
-            {
-                if (!GetDictionary().TryGet<NumericToken>(NameToken.BitsPerSample, out var bps))
-                {
-                    throw new ArgumentNullException(NameToken.BitsPerSample);
-                }
-                return bps.Int;
-            }
-        }
 
         /// <summary>
         /// Get the order of interpolation between samples. Valid values are 1 and 3,
@@ -95,69 +67,21 @@
         /// is 1. See p.170 in PDF spec 1.7.
         /// </summary>
         /// <returns>order of interpolation.</returns>
-        public int Order
+        public int Order { get; }
-        {
-            get
-            {
-                if (!GetDictionary().TryGet<NumericToken>(NameToken.Order, out var order))
-                {
-                    return 1;
-                }
-                return order.Int;
-            }
-        }
 
         /// <summary>
-        /// Returns all encode values as <see cref="ArrayToken"/>.
+        /// An array of 2 x m numbers specifying the linear mapping of input values 
+        /// into the domain of the function's sample table. Default value: [ 0 (Size0
+        /// - 1) 0 (Size1 - 1) ...].
         /// </summary>
-        /// <returns>the encode array. </returns>
+        private ArrayToken EncodeValues { get; }
-        private ArrayToken EncodeValues
-        {
-            get
-            {
-                if (encode == null)
-                {
-                    GetDictionary().TryGet<ArrayToken>(NameToken.Encode, out encode);
-
-                    // the default value is [0 (size[0]-1) 0 (size[1]-1) ...]
-                    if (encode == null)
-                    {
-                        var values = new List<NumericToken>();
-                        ArrayToken sizeValues = Size;
-                        int sizeValuesSize = sizeValues.Length;
-                        for (int i = 0; i < sizeValuesSize; i++)
-                        {
-                            values.Add(new NumericToken(0));
-                            values.Add(new NumericToken((sizeValues[i] as NumericToken).Int - 1L));
-                        }
-                        encode = new ArrayToken(values);
-                    }
-                }
-                return encode;
-            }
-        }
 
         /// <summary>
-        /// Returns all decode values as <see cref="ArrayToken"/>.
+        /// An array of 2 x n numbers specifying the linear mapping of sample values
+        /// into the range appropriate for the function's output values. Default
+        /// value: same as the value of Range.
         /// </summary>
-        /// <returns>the decode array.</returns>
+        private ArrayToken DecodeValues { get; }
-        private ArrayToken DecodeValues
-        {
-            get
-            {
-                if (decode == null)
-                {
-                    GetDictionary().TryGet<ArrayToken>(NameToken.Decode, out decode);
-
-                    // if decode is null, the default values are the range values
-                    if (decode == null)
-                    {
-                        decode = RangeValues;
-                    }
-                }
-                return decode;
-            }
-        }
 
         /// <summary>
         /// Get the encode for the input parameter.

src/UglyToad.PdfPig/Functions/PdfFunctionType2.cs

@@ -1,7 +1,6 @@
 namespace UglyToad.PdfPig.Functions
 {
     using System;
-    using System.Collections.Generic;
     using UglyToad.PdfPig.Tokens;
 
     /// <summary>
@@ -12,80 +11,20 @@
         /// <summary>
         /// Exponential interpolation function
         /// </summary>
-        internal PdfFunctionType2(DictionaryToken function) : base(function)
+        internal PdfFunctionType2(DictionaryToken function, ArrayToken domain, ArrayToken range, ArrayToken c0, ArrayToken c1, double n)
+            : base(function, domain, range)
         {
-            if (GetDictionary().TryGet(NameToken.C0, out ArrayToken array0))
+            C0 = c0;
-            {
+            C1 = c1;
-                C0 = array0;
+            N = n;
-            }
-            else
-            {
-                C0 = new ArrayToken(new List<IToken>());
-            }
-            if (C0.Length == 0)
-            {
-                C0 = new ArrayToken(new List<NumericToken>() { new NumericToken(0) });
         }
 
-            if (GetDictionary().TryGet(NameToken.C1, out ArrayToken array1))
+        internal PdfFunctionType2(StreamToken function, ArrayToken domain, ArrayToken range, ArrayToken c0, ArrayToken c1, double n)
+            : base(function, domain, range)
         {
-                C1 = array1;
+            C0 = c0;
-            }
+            C1 = c1;
-            else
+            N = n;
-            {
-                C1 = new ArrayToken(new List<IToken>());
-            }
-            if (C0.Length == 0)
-            {
-                C1 = new ArrayToken(new List<NumericToken>() { new NumericToken(1) });
-            }
-
-            if (GetDictionary().TryGet(NameToken.N, out NumericToken exp))
-            {
-                N = exp.Double;
-            }
-            else
-            {
-                throw new NotImplementedException();
-            }
-        }
-
-        internal PdfFunctionType2(StreamToken function) : base(function)
-        {
-            if (GetDictionary().TryGet(NameToken.C0, out ArrayToken array0))
-            {
-                C0 = array0;
-            }
-            else
-            {
-                C0 = new ArrayToken(new List<IToken>());
-            }
-            if (C0.Length == 0)
-            {
-                C0 = new ArrayToken(new List<NumericToken>() { new NumericToken(0) });
-            }
-
-            if (GetDictionary().TryGet(NameToken.C1, out ArrayToken array1))
-            {
-                C1 = array1;
-            }
-            else
-            {
-                C1 = new ArrayToken(new List<IToken>());
-            }
-            if (C0.Length == 0)
-            {
-                C1 = new ArrayToken(new List<NumericToken>() { new NumericToken(1) });
-            }
-
-            if (GetDictionary().TryGet(NameToken.N, out NumericToken exp))
-            {
-                N = exp.Double;
-            }
-            else
-            {
-                throw new NotImplementedException();
-            }
         }
 
         public override FunctionTypes FunctionType

src/UglyToad.PdfPig/Functions/PdfFunctionType3.cs

@@ -12,35 +12,38 @@
     /// </summary>
     internal sealed class PdfFunctionType3 : PdfFunction
     {
-        private ArrayToken functions;
+        private readonly double[] boundsValues;
-        private ArrayToken encode;
-        private ArrayToken bounds;
-        private double[] boundsValues;
 
         /// <summary>
         /// Stitching function
         /// </summary>
-        internal PdfFunctionType3(DictionaryToken function, IReadOnlyList<PdfFunction> functionsArray)
+        internal PdfFunctionType3(DictionaryToken function, ArrayToken domain, ArrayToken range, IReadOnlyList<PdfFunction> functionsArray, ArrayToken bounds, ArrayToken encode)
-            : base(function)
+            : base(function, domain, range)
         {
             if (functionsArray == null || functionsArray.Count == 0)
             {
                 throw new ArgumentNullException(nameof(functionsArray));
             }
             this.FunctionsArray = functionsArray;
+            Bounds = bounds;
+            Encode = encode;
+            boundsValues = Bounds.Data.OfType<NumericToken>().Select(t => t.Double).ToArray();
         }
 
         /// <summary>
         /// Stitching function
         /// </summary>
-        internal PdfFunctionType3(StreamToken function, IReadOnlyList<PdfFunction> functionsArray)
+        internal PdfFunctionType3(StreamToken function, ArrayToken domain, ArrayToken range, IReadOnlyList<PdfFunction> functionsArray, ArrayToken bounds, ArrayToken encode)
-            : base(function)
+            : base(function, domain, range)
         {
             if (functionsArray == null || functionsArray.Count == 0)
             {
                 throw new ArgumentNullException(nameof(functionsArray));
             }
             this.FunctionsArray = functionsArray;
+            Bounds = bounds;
+            Encode = encode;
+            boundsValues = Bounds.Data.OfType<NumericToken>().Select(t => t.Double).ToArray();
         }
 
         public override FunctionTypes FunctionType
@@ -71,11 +74,6 @@
             }
             else
             {
-                if (boundsValues == null)
-                {
-                    boundsValues = Bounds.Data.OfType<NumericToken>().Select(t => t.Double).ToArray();
-                }
-
                 int boundsSize = boundsValues.Length;
                 // create a combined array containing the domain and the bounds values
                 // domain.min, bounds[0], bounds[1], ...., bounds[boundsSize-1], domain.max
@@ -108,55 +106,22 @@
             return ClipToRange(functionResult);
         }
 
-        public IReadOnlyList<PdfFunction> FunctionsArray { get; }
-
         /// <summary>
-        /// Returns all functions values as <see cref="ArrayToken"/>.
+        /// Returns all functions values.
         /// </summary>
-        /// <returns>the functions array. </returns>
+        public IReadOnlyList<PdfFunction> FunctionsArray { get; }
-        public ArrayToken Functions
-        {
-            get
-            {
-                if (functions == null && !GetDictionary().TryGet<ArrayToken>(NameToken.Functions, out functions))
-                {
-                    throw new ArgumentNullException(NameToken.Functions);
-                }
-                return functions;
-            }
-        }
 
         /// <summary>
         /// Returns all bounds values as <see cref="ArrayToken"/>.
         /// </summary>
         /// <returns>the bounds array.</returns>
-        public ArrayToken Bounds
+        public ArrayToken Bounds { get; }
-        {
-            get
-            {
-                if (bounds == null && !GetDictionary().TryGet<ArrayToken>(NameToken.Bounds, out bounds))
-                {
-                    throw new ArgumentNullException(NameToken.Bounds);
-                }
-                return bounds;
-            }
-        }
 
         /// <summary>
         /// Returns all encode values as <see cref="ArrayToken"/>.
         /// </summary>
         /// <returns>the encode array.</returns>
-        public ArrayToken Encode
+        public ArrayToken Encode { get; }
-        {
-            get
-            {
-                if (encode == null && !GetDictionary().TryGet<ArrayToken>(NameToken.Encode, out encode))
-                {
-                    throw new ArgumentNullException(NameToken.Encode);
-                }
-                return encode;
-            }
-        }
 
         /// <summary>
         /// Get the encode for the input parameter.

src/UglyToad.PdfPig/Functions/PdfFunctionType4.cs

@@ -17,7 +17,8 @@
         /// <summary>
         /// PostScript calculator function
         /// </summary>
-        internal PdfFunctionType4(StreamToken function) : base(function)
+        internal PdfFunctionType4(StreamToken function, ArrayToken domain, ArrayToken range)
+            : base(function, domain, range)
         {
             byte[] bytes = FunctionStream.Data.ToArray();
             string str = OtherEncodings.Iso88591.GetString(bytes);

src/UglyToad.PdfPig/Util/PdfFunctionParser.cs

@@ -30,6 +30,13 @@
                 throw new ArgumentException(nameof(function));
             }
 
+            if (!functionDictionary.TryGet(NameToken.Domain, scanner, out ArrayToken domain))
+            {
+                throw new ArgumentNullException(NameToken.Domain);
+            }
+
+            functionDictionary.TryGet(NameToken.Range, scanner, out ArrayToken range);
+
             int functionType = (functionDictionary.Data[NameToken.FunctionType] as NumericToken).Int;
 
             switch (functionType)
@@ -39,12 +46,93 @@
                     {
                         throw new NotImplementedException("PdfFunctionType0 not stream");
                     }
-                    return new PdfFunctionType0(functionStream);
+                    return CreatePdfFunctionType0(functionStream, domain, range, scanner);
 
                 case 2:
-                    return new PdfFunctionType2(functionDictionary);
+                    return CreatePdfFunctionType2(functionDictionary, domain, range, scanner);
 
                 case 3:
+                    return CreatePdfFunctionType3(functionDictionary, domain, range, scanner, filterProvider);
+
+                case 4:
+                    if (functionStream == null)
+                    {
+                        throw new NotImplementedException("PdfFunctionType4 not stream");
+                    }
+                    return CreatePdfFunctionType4(functionStream, domain, range, scanner);
+
+                default:
+                    throw new IOException("Error: Unknown function type " + functionType);
+            }
+        }
+
+        private static PdfFunctionType0 CreatePdfFunctionType0(StreamToken functionStream, ArrayToken domain, ArrayToken range, IPdfTokenScanner scanner)
+        {
+            if (range == null)
+            {
+                throw new ArgumentException("Could not retrieve Range in type 0 function.");
+            }
+
+            if (!functionStream.StreamDictionary.TryGet<ArrayToken>(NameToken.Size, scanner, out var size))
+            {
+                throw new ArgumentNullException(NameToken.Size);
+            }
+
+            if (!functionStream.StreamDictionary.TryGet<NumericToken>(NameToken.BitsPerSample, scanner, out var bps))
+            {
+                throw new ArgumentNullException(NameToken.BitsPerSample);
+            }
+
+            int order = 1; // Default value
+            if (functionStream.StreamDictionary.TryGet<NumericToken>(NameToken.Order, scanner, out var orderToken))
+            {
+                order = orderToken.Int;
+            }
+
+            if (!functionStream.StreamDictionary.TryGet<ArrayToken>(NameToken.Encode, scanner, out var encode) || encode == null)
+            {
+                // The default value is [0 (size[0]-1) 0 (size[1]-1) ...]
+                var values = new List<NumericToken>();
+                int sizeValuesSize = size.Length;
+                for (int i = 0; i < sizeValuesSize; i++)
+                {
+                    values.Add(new NumericToken(0));
+                    values.Add(new NumericToken((size[i] as NumericToken).Int - 1L));
+                }
+                encode = new ArrayToken(values);
+            }
+
+            if (!functionStream.StreamDictionary.TryGet<ArrayToken>(NameToken.Decode, scanner, out var decode) || decode == null)
+            {
+                // if decode is null, the default values are the range values
+                decode = range;
+            }
+
+            return new PdfFunctionType0(functionStream, domain, range, size, bps.Int, order, encode, decode);
+        }
+
+        private static PdfFunctionType2 CreatePdfFunctionType2(DictionaryToken functionDictionary, ArrayToken domain, ArrayToken range, IPdfTokenScanner scanner)
+        {
+            if (!functionDictionary.TryGet(NameToken.C0, scanner, out ArrayToken array0) || array0.Length == 0)
+            {
+                array0 = new ArrayToken(new List<NumericToken>() { new NumericToken(0) }); // Default value: [0.0].
+            }
+
+            if (!functionDictionary.TryGet(NameToken.C1, scanner, out ArrayToken array1) || array1.Length == 0)
+            {
+                array1 = new ArrayToken(new List<NumericToken>() { new NumericToken(1) }); // Default value: [1.0].
+            }
+
+            if (!functionDictionary.TryGet(NameToken.N, scanner, out NumericToken exp))
+            {
+                throw new ArgumentNullException(NameToken.N);
+            }
+
+            return new PdfFunctionType2(functionDictionary, domain, range, array0, array1, exp.Double);
+        }
+
+        private static PdfFunctionType3 CreatePdfFunctionType3(DictionaryToken functionDictionary, ArrayToken domain, ArrayToken range, IPdfTokenScanner scanner, ILookupFilterProvider filterProvider)
+        {
             var functions = new List<PdfFunction>();
             if (functionDictionary.TryGet<ArrayToken>(NameToken.Functions, scanner, out var functionsToken))
             {
@@ -64,18 +152,32 @@
                     }
                 }
             }
-                    return new PdfFunctionType3(functionDictionary, functions);
+            else
-
-                case 4:
-                    if (functionStream == null)
             {
-                        throw new NotImplementedException("PdfFunctionType4 not stream");
+                throw new ArgumentNullException(NameToken.Functions);
             }
-                    return new PdfFunctionType4(functionStream);
 
-                default:
+            if (!functionDictionary.TryGet<ArrayToken>(NameToken.Bounds, out var bounds))
-                    throw new IOException("Error: Unknown function type " + functionType);
+            {
-            }
+                throw new ArgumentNullException(NameToken.Bounds);
+            }
+
+            if (!functionDictionary.TryGet<ArrayToken>(NameToken.Encode, out var encode))
+            {
+                throw new ArgumentNullException(NameToken.Encode);
+            }
+
+            return new PdfFunctionType3(functionDictionary, domain, range, functions, bounds, encode);
+        }
+
+        private static PdfFunctionType4 CreatePdfFunctionType4(StreamToken functionStream, ArrayToken domain, ArrayToken range, IPdfTokenScanner scanner)
+        {
+            if (range == null)
+            {
+                throw new ArgumentException("Could not retrieve Range in type 4 function.");
+            }
+
+            return new PdfFunctionType4(functionStream, domain, range);
         }
     }
 }