#24 make some fields public

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

@@ -31,5 +31,15 @@
 
             Assert.Throws<ObjectDisposedException>(action);
         }
+
+        [Fact]
+        public void GetsAllFormFields()
+        {
+            using (var document = PdfDocument.Open(GetFilename(), new ParsingOptions { UseLenientParsing = false }))
+            {
+                var form = document.GetForm();
+                Assert.Equal(16, form.Fields.Count);
+            }
+        }
     }
 }

src/UglyToad.PdfPig.Tests/Parser/PageContentParserTests.cs

@@ -51,8 +51,8 @@
 
                 var text = OtherEncodings.BytesAsLatin1String(stream.ToArray());
 
-                text = text.Replace("\n", " ");
+                text = LineEndingsToWhiteSpace(text);
-                content = content.Replace("\r\n", " ");
+                content = LineEndingsToWhiteSpace(content);
                 content = replacementRegex.Replace(content, " 0$1");
 
                 Assert.Equal(content, text);
@@ -82,8 +82,8 @@ ET";
 
                 var text = OtherEncodings.BytesAsLatin1String(stream.ToArray());
 
-                text = text.Replace("\n", " ").Trim();
+                text = LineEndingsToWhiteSpace(text).Trim();
-                var expected = s.Replace("\r\n", " ");
+                var expected = LineEndingsToWhiteSpace(s);
 
                 Assert.Equal(expected, text);
             }
@@ -152,5 +152,10 @@ ET";
 
             Assert.Equal(EndText.Value, result[3]);
         }
+
+        private static string LineEndingsToWhiteSpace(string str)
+        {
+            return str.Replace("\r\n", " ").Replace('\n', ' ').Replace('\r', ' ');
+        }
     }
 }

src/UglyToad.PdfPig.Tests/PublicApiScannerTests.cs

@@ -24,6 +24,12 @@
 
             var expected = new List<string>
             {
+                "UglyToad.PdfPig.AcroForms.Fields.AcroChoiceFieldFlags",
+                "UglyToad.PdfPig.AcroForms.Fields.AcroChoiceOption",
+                "UglyToad.PdfPig.AcroForms.Fields.AcroComboBoxField",
+                "UglyToad.PdfPig.AcroForms.Fields.AcroFieldBase",
+                "UglyToad.PdfPig.AcroForms.Fields.AcroFieldCommonInformation",
+                "UglyToad.PdfPig.AcroForms.Fields.AcroListBoxField",
                 "UglyToad.PdfPig.Annotations.Annotation",
                 "UglyToad.PdfPig.Annotations.AnnotationBorder",
                 "UglyToad.PdfPig.Annotations.AnnotationFlags",
@@ -143,6 +149,11 @@
             {
                 Assert.True(expected.Contains(publicTypeName), $"Type should not be public: {publicTypeName}.");
             }
+
+            foreach (var expectedPublicType in expected)
+            {
+                Assert.True(publicTypeNames.Contains(expectedPublicType), $"Type should be public: {expectedPublicType}.");
+            }
         }
     }
 }

src/UglyToad.PdfPig/AcroForms/AcroFormFactory.cs

@@ -176,27 +176,7 @@
             }
             else if (fieldType == NameToken.Tx)
             {
-                var textFlags = (AcroTextFieldFlags)fieldFlags;
+                result = GetTextField(fieldDictionary, fieldType, fieldFlags, information);
-
-                var textValue = default(string);
-                if (fieldDictionary.TryGet(NameToken.V, out var textValueToken))
-                {
-                    if (DirectObjectFinder.TryGet(textValueToken, tokenScanner, out StringToken valueStringToken))
-                    {
-                        textValue = valueStringToken.Data;
-                    }
-                    else if (DirectObjectFinder.TryGet(textValueToken, tokenScanner, out HexToken valueHexToken))
-                    {
-                        textValue = valueHexToken.Data;
-                    }
-                    else if (DirectObjectFinder.TryGet(textValueToken, tokenScanner, out StreamToken valueStreamToken))
-                    {
-                        
-                    }
-                }
-
-                var field = new AcroTextField(fieldDictionary, fieldType, textFlags, information, textValue);
-                result = field;
             }
             else if (fieldType == NameToken.Ch)
             {
@@ -215,6 +195,38 @@
             return result;
         }
 
+        private AcroFieldBase GetTextField(DictionaryToken fieldDictionary, NameToken fieldType, uint fieldFlags, AcroFieldCommonInformation information)
+        {
+            var textFlags = (AcroTextFieldFlags)fieldFlags;
+
+            var textValue = default(string);
+            if (fieldDictionary.TryGet(NameToken.V, out var textValueToken))
+            {
+                if (DirectObjectFinder.TryGet(textValueToken, tokenScanner, out StringToken valueStringToken))
+                {
+                    textValue = valueStringToken.Data;
+                }
+                else if (DirectObjectFinder.TryGet(textValueToken, tokenScanner, out HexToken valueHexToken))
+                {
+                    textValue = valueHexToken.Data;
+                }
+                else if (DirectObjectFinder.TryGet(textValueToken, tokenScanner, out StreamToken valueStreamToken))
+                {
+                    textValue = OtherEncodings.BytesAsLatin1String(valueStreamToken.Decode(filterProvider).ToArray());
+                }
+            }
+
+            var maxLength = default(int?);
+            if (fieldDictionary.TryGetOptionalTokenDirect(NameToken.MaxLen, tokenScanner, out NumericToken maxLenToken))
+            {
+                maxLength = maxLenToken.Int;
+            }
+
+            var field = new AcroTextField(fieldDictionary, fieldType, textFlags, information, textValue, maxLength);
+
+            return field;
+        }
+
         private AcroFieldBase GetChoiceField(DictionaryToken fieldDictionary, NameToken fieldType, uint fieldFlags, AcroFieldCommonInformation information)
         {
             var selectedOptions = Array.Empty<string>();

src/UglyToad.PdfPig/AcroForms/Fields/AcroButtonFieldFlags.cs

@@ -0,0 +1,40 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using System;
+
+    /// <summary>
+    /// Flags specifying various characteristics of a button type field in an <see cref="AcroFieldBase"/>.
+    /// </summary>
+    [Flags]
+    internal enum AcroButtonFieldFlags : uint
+    {
+        /// <summary>
+        /// The user may not change the value of the field.
+        /// </summary>
+        ReadOnly = 1 << 0,
+        /// <summary>
+        /// The field must have a value before the form can be submitted.
+        /// </summary>
+        Required = 1 << 1,
+        /// <summary>
+        /// Must not be exported by the submit form action.
+        /// </summary>
+        NoExport = 1 << 2,
+        /// <summary>
+        /// For radio buttons, one radio button must be set at all times.
+        /// </summary>
+        NoToggleToOff = 1 << 14,
+        /// <summary>
+        /// The field is a set of radio buttons.
+        /// </summary>
+        Radio = 1 << 15,
+        /// <summary>
+        /// The field is a push button.
+        /// </summary>
+        PushButton = 1 << 16,
+        /// <summary>
+        /// For radio buttons a group of radio buttons will toggle on/off at the same time based on their initial value.
+        /// </summary>
+        RadiosInUnison = 1 << 25
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroCheckboxField.cs

@@ -0,0 +1,19 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using Tokens;
+
+    internal class AcroCheckboxField : AcroFieldBase
+    {
+        public AcroButtonFieldFlags Flags { get; }
+
+        public NameToken CurrentValue { get; }
+
+        public AcroCheckboxField(DictionaryToken dictionary, string fieldType, AcroButtonFieldFlags fieldFlags,
+            AcroFieldCommonInformation information, NameToken currentValue) :
+            base(dictionary, fieldType, (uint)fieldFlags, information)
+        {
+            Flags = fieldFlags;
+            CurrentValue = currentValue;
+        }
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroChoiceFieldFlags.cs

@@ -0,0 +1,48 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using System;
+
+    /// <summary>
+    /// Flags specifying various characteristics of a choice type field in an <see cref="AcroFieldBase"/>.
+    /// </summary>
+    [Flags]
+    public enum AcroChoiceFieldFlags : uint
+    {
+        /// <summary>
+        /// The user may not change the value of the field.
+        /// </summary>
+        ReadOnly = 1 << 0,
+        /// <summary>
+        /// The field must have a value before the form can be submitted.
+        /// </summary>
+        Required = 1 << 1,
+        /// <summary>
+        /// Must not be exported by the submit form action.
+        /// </summary>
+        NoExport = 1 << 2,
+        /// <summary>
+        /// The field is a combo box.
+        /// </summary>
+        Combo = 1 << 17,
+        /// <summary>
+        /// The combo box includes an editable text box. <see cref="Combo"/> must be set.
+        /// </summary>
+        Edit = 1 << 18,
+        /// <summary>
+        /// The options should be sorted alphabetically, this should be ignored by viewer applications.
+        /// </summary>
+        Sort = 1 << 19,
+        /// <summary>
+        /// The field allows multiple options to be selected.
+        /// </summary>
+        MultiSelect = 1 << 21,
+        /// <summary>
+        /// The text entered in the field is not spell checked. <see cref="Combo"/> and <see cref="Edit"/> must be set.
+        /// </summary>
+        DoNotSpellCheck = 1 << 22,
+        /// <summary>
+        /// Any associated field action is fired when the selection is changed rather than on losing focus.
+        /// </summary>
+        CommitOnSelectionChange = 1 << 26
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroChoiceOption.cs

@@ -0,0 +1,51 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    /// <summary>
+    /// An option in a choice field, either <see cref="AcroComboBoxField"/> or <see cref="AcroListBoxField"/>.
+    /// </summary>
+    public class AcroChoiceOption
+    {
+        /// <summary>
+        /// The index of this option in the array.
+        /// </summary>
+        public int Index { get; }
+
+        /// <summary>
+        /// Whether this option is selected.
+        /// </summary>
+        public bool IsSelected { get; }
+
+        /// <summary>
+        /// The text of the option.
+        /// </summary>
+        public string Name { get; }
+
+        /// <summary>
+        /// The value of the option when the form is exported.
+        /// </summary>
+        public string ExportValue { get; }
+
+        /// <summary>
+        /// Whether the field defined an export value for this option.
+        /// </summary>
+        public bool HasExportValue { get; }
+
+        /// <summary>
+        /// Create a new <see cref="AcroChoiceOption"/>.
+        /// </summary>
+        public AcroChoiceOption(int index, bool isSelected, string name, string exportValue = null)
+        {
+            Index = index;
+            IsSelected = isSelected;
+            Name = name;
+            ExportValue = exportValue;
+            HasExportValue = exportValue != null;
+        }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return $"{Index}: {Name} ({IsSelected}).";
+        }
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroComboBoxField.cs

@@ -0,0 +1,60 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using System;
+    using System.Collections.Generic;
+    using Tokens;
+    using Util.JetBrains.Annotations;
+
+    /// <inheritdoc />
+    /// <summary>
+    /// A combo box consisting of a drop-down list optionally accompanied by an editable text box in which the
+    /// user can type a value other than the predefined choices.
+    /// </summary>
+    public class AcroComboBoxField : AcroFieldBase
+    {
+        /// <summary>
+        /// The flags specifying the behaviour of this field.
+        /// </summary>
+        public AcroChoiceFieldFlags Flags { get; }
+
+        /// <summary>
+        /// The options to be presented to the user.
+        /// </summary>
+        [NotNull]
+        public IReadOnlyList<AcroChoiceOption> Options { get; }
+
+        /// <summary>
+        /// The names of any currently selected options.
+        /// </summary>
+        [NotNull]
+        public IReadOnlyList<string> SelectedOptions { get; }
+
+        /// <summary>
+        /// For multiple select lists with duplicate names gives the indices of the selected options.
+        /// </summary>
+        [CanBeNull]
+        public IReadOnlyList<int> SelectedOptionIndices { get; }
+
+        /// <summary>
+        /// Create a new <see cref="AcroComboBoxField"/>.
+        /// </summary>
+        /// <param name="dictionary">The dictionary for this field.</param>
+        /// <param name="fieldType">The type of this field, must be <see cref="NameToken.Ch"/>.</param>
+        /// <param name="fieldFlags">The flags specifying behaviour for this field.</param>
+        /// <param name="information">Additional information for this field.</param>
+        /// <param name="options">The options in this field.</param>
+        /// <param name="selectedOptionIndices">The indices of the selected options where there are multiple with the same name.</param>
+        /// <param name="selectedOptions">The names of the selected options.</param>
+        public AcroComboBoxField(DictionaryToken dictionary, string fieldType, AcroChoiceFieldFlags fieldFlags,
+            AcroFieldCommonInformation information, IReadOnlyList<AcroChoiceOption> options, 
+            IReadOnlyList<string> selectedOptions, 
+            IReadOnlyList<int> selectedOptionIndices) :
+            base(dictionary, fieldType, (uint)fieldFlags, information)
+        {
+            Flags = fieldFlags;
+            Options = options ?? throw new ArgumentNullException(nameof(options));
+            SelectedOptions = selectedOptions ?? throw new ArgumentNullException(nameof(selectedOptions));
+            SelectedOptionIndices = selectedOptionIndices;
+        }
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroFieldBase.cs

@@ -1,23 +1,24 @@
 namespace UglyToad.PdfPig.AcroForms.Fields
 {
     using System;
-    using System.Collections.Generic;
     using Tokens;
     using Util.JetBrains.Annotations;
 
     /// <summary>
     /// A field in an interactive <see cref="AcroForm"/>.
     /// </summary>
-    internal abstract class AcroFieldBase
+    public abstract class AcroFieldBase
     {
         /// <summary>
         /// The raw PDF dictionary for this field.
         /// </summary>
+        [NotNull]
         public DictionaryToken Dictionary { get; }
 
         /// <summary>
         /// The <see cref="string"/> representing the type of this field.
         /// </summary>
+        [NotNull]
         public string FieldType { get; }
 
         /// <summary>
@@ -25,405 +26,25 @@
         /// </summary>
         public uint FieldFlags { get; }
 
+        /// <summary>
+        /// The optional information common to all types of field.
+        /// </summary>
+        [NotNull]
         public AcroFieldCommonInformation Information { get; }
 
+        /// <summary>
+        /// Create a new <see cref="AcroFieldBase"/>.
+        /// </summary>
+        /// <param name="dictionary">The dictionary for this field.</param>
+        /// <param name="fieldType">The type of this field.</param>
+        /// <param name="fieldFlags">The flags specifying behaviour for this field.</param>
+        /// <param name="information">Additional information for this field.</param>
         protected AcroFieldBase(DictionaryToken dictionary, string fieldType, uint fieldFlags, AcroFieldCommonInformation information)
         {
             Dictionary = dictionary ?? throw new ArgumentNullException(nameof(dictionary));
             FieldType = fieldType ?? throw new ArgumentNullException(nameof(fieldType));
             FieldFlags = fieldFlags;
-            Information = information;
+            Information = information ?? new AcroFieldCommonInformation(null, null, null, null);
         }
     }
-
-    /// <summary>
-    /// A non-leaf field in the form's structure.
-    /// </summary>
-    internal class NonTerminalAcroField : AcroFieldBase
-    {
-        public IReadOnlyList<AcroFieldBase> Children { get; }
-
-        public NonTerminalAcroField(DictionaryToken dictionary, string fieldType, uint fieldFlags, AcroFieldCommonInformation information,
-            IReadOnlyList<AcroFieldBase> children) : 
-            base(dictionary, fieldType, fieldFlags, information)
-        {
-            Children = children ?? throw new ArgumentNullException(nameof(children));
-        }
-    }
-
-    internal class AcroRadioButtonsField : AcroFieldBase
-    {
-        public AcroButtonFieldFlags Flags { get; }
-
-        public AcroRadioButtonsField(DictionaryToken dictionary, string fieldType, AcroButtonFieldFlags fieldFlags, 
-            AcroFieldCommonInformation information) : 
-            base(dictionary, fieldType, (uint)fieldFlags, information)
-        {
-            Flags = fieldFlags;
-        }
-    }
-
-    internal class AcroPushButtonField : AcroFieldBase
-    {
-        public AcroButtonFieldFlags Flags { get; }
-
-        public AcroPushButtonField(DictionaryToken dictionary, string fieldType, AcroButtonFieldFlags fieldFlags, 
-            AcroFieldCommonInformation information) : 
-            base(dictionary, fieldType, (uint)fieldFlags, information)
-        {
-            Flags = fieldFlags;
-        }
-    }
-
-    internal class AcroCheckboxField : AcroFieldBase
-    {
-        public AcroButtonFieldFlags Flags { get; }
-
-        public NameToken CurrentValue { get; }
-
-        public AcroCheckboxField(DictionaryToken dictionary, string fieldType, AcroButtonFieldFlags fieldFlags,
-            AcroFieldCommonInformation information, NameToken currentValue) :
-            base(dictionary, fieldType, (uint)fieldFlags, information)
-        {
-            Flags = fieldFlags;
-            CurrentValue = currentValue;
-        }
-    }
-
-    internal class AcroTextField : AcroFieldBase
-    {
-        public AcroTextFieldFlags Flags { get; }
-
-        public AcroTextField(DictionaryToken dictionary, string fieldType, AcroTextFieldFlags fieldFlags,
-            AcroFieldCommonInformation information, string textValue) : 
-            base(dictionary, fieldType, (uint)fieldFlags, information)
-        {
-            Flags = fieldFlags;
-        }
-    }
-
-    internal class AcroSignatureField : AcroFieldBase
-    {
-        public AcroSignatureField(DictionaryToken dictionary, string fieldType, uint fieldFlags, AcroFieldCommonInformation information) : 
-            base(dictionary, fieldType, fieldFlags, information)
-        {
-        }
-    }
-
-    /// <inheritdoc />
-    /// <summary>
-    /// A scrollable list box field.
-    /// </summary>
-    internal class AcroListBoxField : AcroFieldBase
-    {
-        /// <summary>
-        /// The flags specifying the behaviour of this field.
-        /// </summary>
-        public AcroChoiceFieldFlags Flags { get; }
-
-        /// <summary>
-        /// The options to be presented to the user.
-        /// </summary>
-        [NotNull]
-        public IReadOnlyList<AcroChoiceOption> Options { get; }
-
-        /// <summary>
-        /// The names of any currently selected options.
-        /// </summary>
-        [NotNull]
-        public IReadOnlyList<string> SelectedOptions { get; }
-
-        /// <summary>
-        /// For multiple select lists with duplicate names gives the indices of the selected options.
-        /// </summary>
-        [CanBeNull]
-        public IReadOnlyList<int> SelectedOptionIndices { get; }
-
-        /// <summary>
-        /// For scrollable list boxes gives the index of the first visible option.
-        /// </summary>
-        public int TopIndex { get; }
-
-        /// <summary>
-        /// Whether the field allows multiple selections.
-        /// </summary>
-        public bool SupportsMultiSelect => Flags.Equals(AcroChoiceFieldFlags.MultiSelect);
-
-        /// <summary>
-        /// Create a new <see cref="AcroListBoxField"/>.
-        /// </summary>
-        /// <param name="dictionary">The dictionary for this field.</param>
-        /// <param name="fieldType">The type of this field, must be <see cref="NameToken.Ch"/>.</param>
-        /// <param name="fieldFlags">The flags specifying behaviour for this field.</param>
-        /// <param name="information">Additional information for this field.</param>
-        /// <param name="options">The options in this field.</param>
-        /// <param name="selectedOptionIndices"></param>
-        /// <param name="topIndex">The first visible option index.</param>
-        /// <param name="selectedOptions"></param>
-        public AcroListBoxField(DictionaryToken dictionary, string fieldType, AcroChoiceFieldFlags fieldFlags,
-            AcroFieldCommonInformation information, IReadOnlyList<AcroChoiceOption> options,
-            IReadOnlyList<string> selectedOptions, 
-            IReadOnlyList<int> selectedOptionIndices,
-            int? topIndex) : 
-            base(dictionary, fieldType, (uint)fieldFlags, information)
-        {
-            Flags = fieldFlags;
-            Options = options ?? throw new ArgumentNullException(nameof(options));
-            SelectedOptions = selectedOptions ?? throw new ArgumentNullException(nameof(selectedOptions));
-            SelectedOptionIndices = selectedOptionIndices;
-            TopIndex = topIndex ?? 0;
-        }
-    }
-
-    internal class AcroComboBoxField : AcroFieldBase
-    {
-        /// <summary>
-        /// The flags specifying the behaviour of this field.
-        /// </summary>
-        public AcroChoiceFieldFlags Flags { get; }
-
-        /// <summary>
-        /// The options to be presented to the user.
-        /// </summary>
-        [NotNull]
-        public IReadOnlyList<AcroChoiceOption> Options { get; }
-
-        /// <summary>
-        /// The names of any currently selected options.
-        /// </summary>
-        [NotNull]
-        public IReadOnlyList<string> SelectedOptions { get; }
-
-        /// <summary>
-        /// For multiple select lists with duplicate names gives the indices of the selected options.
-        /// </summary>
-        [CanBeNull]
-        public IReadOnlyList<int> SelectedOptionIndices { get; }
-
-        public AcroComboBoxField(DictionaryToken dictionary, string fieldType, AcroChoiceFieldFlags fieldFlags,
-            AcroFieldCommonInformation information, IReadOnlyList<AcroChoiceOption> options, 
-            IReadOnlyList<string> selectedOptions, 
-            IReadOnlyList<int> selectedOptionIndices) :
-            base(dictionary, fieldType, (uint)fieldFlags, information)
-        {
-            Flags = fieldFlags;
-            Options = options ?? throw new ArgumentNullException(nameof(options));
-            SelectedOptions = selectedOptions ?? throw new ArgumentNullException(nameof(selectedOptions));
-            SelectedOptionIndices = selectedOptionIndices;
-        }
-    }
-
-    /// <summary>
-    /// An option in a choice field, either <see cref="AcroComboBoxField"/> or <see cref="AcroListBoxField"/>.
-    /// </summary>
-    internal class AcroChoiceOption
-    {
-        /// <summary>
-        /// The index of this option in the array.
-        /// </summary>
-        public int Index { get; }
-
-        /// <summary>
-        /// Whether this option is selected.
-        /// </summary>
-        public bool IsSelected { get; }
-
-        /// <summary>
-        /// The text of the option.
-        /// </summary>
-        public string Name { get; }
-
-        /// <summary>
-        /// The value of the option when the form is exported.
-        /// </summary>
-        public string ExportValue { get; }
-
-        /// <summary>
-        /// Create a new <see cref="AcroChoiceOption"/>.
-        /// </summary>
-        public AcroChoiceOption(int index, bool isSelected, string name, string exportValue = null)
-        {
-            Index = index;
-            IsSelected = isSelected;
-            Name = name;
-            ExportValue = exportValue;
-        }
-    }
-
-    /// <summary>
-    /// Information from the field dictionary which is common across all field types.
-    /// </summary>
-    internal class AcroFieldCommonInformation
-    {
-        /// <summary>
-        /// The reference to the field which is the parent of this one, if applicable.
-        /// </summary>
-        public IndirectReference? Parent { get; set; }
-
-        /// <summary>
-        /// The partial field name for this field. The fully qualified field name is the
-        /// period '.' joined name of all parents' partial names and this field's partial name.
-        /// </summary>
-        [CanBeNull]
-        public string PartialName { get; }
-
-        /// <summary>
-        /// The alternate field name to be used instead of the fully qualified field name where
-        /// the field is being identified on the user interface or by screen readers.
-        /// </summary>
-        [CanBeNull]
-        public string AlternateName { get; }
-
-        /// <summary>
-        /// The mapping name used when exporting form field data from the document.
-        /// </summary>
-        [CanBeNull]
-        public string MappingName { get; }
-
-        /// <summary>
-        /// Create a new <see cref="AcroFieldCommonInformation"/>.
-        /// </summary>
-        public AcroFieldCommonInformation(IndirectReference? parent, string partialName, string alternateName, string mappingName)
-        {
-            Parent = parent;
-            PartialName = partialName;
-            AlternateName = alternateName;
-            MappingName = mappingName;
-        }
-
-        /// <inheritdoc />
-        public override string ToString()
-        {
-            return $"Parent: {Parent}. Partial: {PartialName}. Alternate: {AlternateName}. Mapping: {MappingName}.";
-        }
-    }
-
-    /// <summary>
-    /// Flags specifying various characteristics of a button type field in an <see cref="AcroFieldBase"/>.
-    /// </summary>
-    [Flags]
-    internal enum AcroButtonFieldFlags : uint
-    {
-        /// <summary>
-        /// The user may not change the value of the field.
-        /// </summary>
-        ReadOnly = 1 << 0,
-        /// <summary>
-        /// The field must have a value before the form can be submitted.
-        /// </summary>
-        Required = 1 << 1,
-        /// <summary>
-        /// Must not be exported by the submit form action.
-        /// </summary>
-        NoExport = 1 << 2,
-        /// <summary>
-        /// For radio buttons, one radio button must be set at all times.
-        /// </summary>
-        NoToggleToOff = 1 << 14,
-        /// <summary>
-        /// The field is a set of radio buttons.
-        /// </summary>
-        Radio = 1 << 15,
-        /// <summary>
-        /// The field is a push button.
-        /// </summary>
-        PushButton = 1 << 16,
-        /// <summary>
-        /// For radio buttons a group of radio buttons will toggle on/off at the same time based on their initial value.
-        /// </summary>
-        RadiosInUnison = 1 << 25
-    }
-
-    /// <summary>
-    /// Flags specifying various characteristics of a text type field in an <see cref="AcroFieldBase"/>.
-    /// </summary>
-    [Flags]
-    internal enum AcroTextFieldFlags : uint
-    {
-        /// <summary>
-        /// The user may not change the value of the field.
-        /// </summary>
-        ReadOnly = 1 << 0,
-        /// <summary>
-        /// The field must have a value before the form can be submitted.
-        /// </summary>
-        Required = 1 << 1,
-        /// <summary>
-        /// Must not be exported by the submit form action.
-        /// </summary>
-        NoExport = 1 << 2,
-        /// <summary>
-        /// The field can contain multiple lines of text.
-        /// </summary>
-        Multiline = 1 << 12,
-        /// <summary>
-        /// The field is for a password and should not be displayed as text and should not be stored to file.
-        /// </summary>
-        Password = 1 << 13,
-        /// <summary>
-        /// The field represents a file path selection.
-        /// </summary>
-        FileSelect = 1 << 20,
-        /// <summary>
-        /// The text entered is not spell checked.
-        /// </summary>
-        DoNotSpellCheck = 1 << 22,
-        /// <summary>
-        /// The field does not scroll if the text exceeds the bounds of the field.
-        /// </summary>
-        DoNotScroll = 1 << 23,
-        /// <summary>
-        /// For a text field which is not a <see cref="Password"/>, <see cref="Multiline"/> or <see cref="FileSelect"/>
-        /// the field text is evenly spaced by splitting into 'combs' based on the MaxLen entry in the field dictionary.
-        /// </summary>
-        Comb = 1 << 24,
-        /// <summary>
-        /// The value of the field is a rich text string.
-        /// </summary>
-        RichText = 1 << 25
-    }
-
-    /// <summary>
-    /// Flags specifying various characteristics of a choice type field in an <see cref="AcroFieldBase"/>.
-    /// </summary>
-    [Flags]
-    internal enum AcroChoiceFieldFlags : uint
-    {
-        /// <summary>
-        /// The user may not change the value of the field.
-        /// </summary>
-        ReadOnly = 1 << 0,
-        /// <summary>
-        /// The field must have a value before the form can be submitted.
-        /// </summary>
-        Required = 1 << 1,
-        /// <summary>
-        /// Must not be exported by the submit form action.
-        /// </summary>
-        NoExport = 1 << 2,
-        /// <summary>
-        /// The field is a combo box.
-        /// </summary>
-        Combo = 1 << 17,
-        /// <summary>
-        /// The combo box includes an editable text box. <see cref="Combo"/> must be set.
-        /// </summary>
-        Edit = 1 << 18,
-        /// <summary>
-        /// The options should be sorted alphabetically, this should be ignored by viewer applications.
-        /// </summary>
-        Sort = 1 << 19,
-        /// <summary>
-        /// The field allows multiple options to be selected.
-        /// </summary>
-        MultiSelect = 1 << 21,
-        /// <summary>
-        /// The text entered in the field is not spell checked. <see cref="Combo"/> and <see cref="Edit"/> must be set.
-        /// </summary>
-        DoNotSpellCheck = 1 << 22,
-        /// <summary>
-        /// Any associated field action is fired when the selection is changed rather than on losing focus.
-        /// </summary>
-        CommitOnSelectionChange = 1 << 26
-    }
 }

src/UglyToad.PdfPig/AcroForms/Fields/AcroFieldCommonInformation.cs

@@ -0,0 +1,53 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using Util.JetBrains.Annotations;
+
+    /// <summary>
+    /// Information from the field dictionary which is common across all field types.
+    /// All of this information is optional.
+    /// </summary>
+    public class AcroFieldCommonInformation
+    {
+        /// <summary>
+        /// The reference to the field which is the parent of this one, if applicable.
+        /// </summary>
+        public IndirectReference? Parent { get; set; }
+
+        /// <summary>
+        /// The partial field name for this field. The fully qualified field name is the
+        /// period '.' joined name of all parents' partial names and this field's partial name.
+        /// </summary>
+        [CanBeNull]
+        public string PartialName { get; }
+
+        /// <summary>
+        /// The alternate field name to be used instead of the fully qualified field name where
+        /// the field is being identified on the user interface or by screen readers.
+        /// </summary>
+        [CanBeNull]
+        public string AlternateName { get; }
+
+        /// <summary>
+        /// The mapping name used when exporting form field data from the document.
+        /// </summary>
+        [CanBeNull]
+        public string MappingName { get; }
+
+        /// <summary>
+        /// Create a new <see cref="AcroFieldCommonInformation"/>.
+        /// </summary>
+        public AcroFieldCommonInformation(IndirectReference? parent, string partialName, string alternateName, string mappingName)
+        {
+            Parent = parent;
+            PartialName = partialName;
+            AlternateName = alternateName;
+            MappingName = mappingName;
+        }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return $"Parent: {Parent}. Partial: {PartialName}. Alternate: {AlternateName}. Mapping: {MappingName}.";
+        }
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroListBoxField.cs

@@ -0,0 +1,72 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using System;
+    using System.Collections.Generic;
+    using Tokens;
+    using Util.JetBrains.Annotations;
+
+    /// <inheritdoc />
+    /// <summary>
+    /// A scrollable list box field.
+    /// </summary>
+    public class AcroListBoxField : AcroFieldBase
+    {
+        /// <summary>
+        /// The flags specifying the behaviour of this field.
+        /// </summary>
+        public AcroChoiceFieldFlags Flags { get; }
+
+        /// <summary>
+        /// The options to be presented to the user.
+        /// </summary>
+        [NotNull]
+        public IReadOnlyList<AcroChoiceOption> Options { get; }
+
+        /// <summary>
+        /// The names of any currently selected options.
+        /// </summary>
+        [NotNull]
+        public IReadOnlyList<string> SelectedOptions { get; }
+
+        /// <summary>
+        /// For multiple select lists with duplicate names gives the indices of the selected options.
+        /// </summary>
+        [CanBeNull]
+        public IReadOnlyList<int> SelectedOptionIndices { get; }
+
+        /// <summary>
+        /// For scrollable list boxes gives the index of the first visible option.
+        /// </summary>
+        public int TopIndex { get; }
+
+        /// <summary>
+        /// Whether the field allows multiple selections.
+        /// </summary>
+        public bool SupportsMultiSelect => Flags.Equals(AcroChoiceFieldFlags.MultiSelect);
+
+        /// <summary>
+        /// Create a new <see cref="AcroListBoxField"/>.
+        /// </summary>
+        /// <param name="dictionary">The dictionary for this field.</param>
+        /// <param name="fieldType">The type of this field, must be <see cref="NameToken.Ch"/>.</param>
+        /// <param name="fieldFlags">The flags specifying behaviour for this field.</param>
+        /// <param name="information">Additional information for this field.</param>
+        /// <param name="options">The options in this field.</param>
+        /// <param name="selectedOptionIndices">The indices of the selected options where there are multiple with the same name.</param>
+        /// <param name="topIndex">The first visible option index.</param>
+        /// <param name="selectedOptions">The names of the selected options.</param>
+        public AcroListBoxField(DictionaryToken dictionary, string fieldType, AcroChoiceFieldFlags fieldFlags,
+            AcroFieldCommonInformation information, IReadOnlyList<AcroChoiceOption> options,
+            IReadOnlyList<string> selectedOptions, 
+            IReadOnlyList<int> selectedOptionIndices,
+            int? topIndex) : 
+            base(dictionary, fieldType, (uint)fieldFlags, information)
+        {
+            Flags = fieldFlags;
+            Options = options ?? throw new ArgumentNullException(nameof(options));
+            SelectedOptions = selectedOptions ?? throw new ArgumentNullException(nameof(selectedOptions));
+            SelectedOptionIndices = selectedOptionIndices;
+            TopIndex = topIndex ?? 0;
+        }
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroPushButtonField.cs

@@ -0,0 +1,16 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using Tokens;
+
+    internal class AcroPushButtonField : AcroFieldBase
+    {
+        public AcroButtonFieldFlags Flags { get; }
+
+        public AcroPushButtonField(DictionaryToken dictionary, string fieldType, AcroButtonFieldFlags fieldFlags, 
+            AcroFieldCommonInformation information) : 
+            base(dictionary, fieldType, (uint)fieldFlags, information)
+        {
+            Flags = fieldFlags;
+        }
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroRadioButtonsField.cs

@@ -0,0 +1,16 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using Tokens;
+
+    internal class AcroRadioButtonsField : AcroFieldBase
+    {
+        public AcroButtonFieldFlags Flags { get; }
+
+        public AcroRadioButtonsField(DictionaryToken dictionary, string fieldType, AcroButtonFieldFlags fieldFlags, 
+            AcroFieldCommonInformation information) : 
+            base(dictionary, fieldType, (uint)fieldFlags, information)
+        {
+            Flags = fieldFlags;
+        }
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroSignatureField.cs

@@ -0,0 +1,12 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using Tokens;
+
+    internal class AcroSignatureField : AcroFieldBase
+    {
+        public AcroSignatureField(DictionaryToken dictionary, string fieldType, uint fieldFlags, AcroFieldCommonInformation information) : 
+            base(dictionary, fieldType, fieldFlags, information)
+        {
+        }
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroTextField.cs

@@ -0,0 +1,65 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using Tokens;
+
+    /// <inheritdoc />
+    /// <summary>
+    /// A text field is a box or space in which the user can enter text from the keyboard.
+    /// The text may be restricted to a single line or may be permitted to span multiple lines.
+    /// </summary>
+    internal class AcroTextField : AcroFieldBase
+    {
+        /// <summary>
+        /// The flags specifying the behaviour of this field.
+        /// </summary>
+        public AcroTextFieldFlags Flags { get; }
+
+        /// <summary>
+        /// The value of the text in this text field.
+        /// This can be <see langword="null"/> if no value has been set.
+        /// </summary>
+        public string Value { get; }
+
+        /// <summary>
+        /// The optional maximum length of the text field.
+        /// </summary>
+        public int? MaxLength { get; }
+
+        /// <summary>
+        /// Whether the field supports rich text content.
+        /// </summary>
+        public bool IsRichText { get; }
+
+        /// <summary>
+        /// Whether the field allows multiline text.
+        /// </summary>
+        public bool IsMultiline { get;}
+
+        /// <inheritdoc />
+        /// <summary>
+        /// Create a new <see cref="T:UglyToad.PdfPig.AcroForms.Fields.AcroTextField" />.
+        /// </summary>
+        /// <param name="dictionary">The dictionary for this field.</param>
+        /// <param name="fieldType">The type of this field, must be <see cref="F:UglyToad.PdfPig.Tokens.NameToken.Ch" />.</param>
+        /// <param name="fieldFlags">The flags specifying behaviour for this field.</param>
+        /// <param name="information">Additional information for this field.</param>
+        /// <param name="value">The text value.</param>
+        /// <param name="maxLength">The maximum length.</param>
+        public AcroTextField(DictionaryToken dictionary, string fieldType, AcroTextFieldFlags fieldFlags,
+            AcroFieldCommonInformation information, string value, int? maxLength) : 
+            base(dictionary, fieldType, (uint)fieldFlags, information)
+        {
+            Flags = fieldFlags;
+            Value = value;
+            MaxLength = maxLength;
+            IsRichText = Flags.HasFlag(AcroTextFieldFlags.RichText);
+            IsMultiline = Flags.HasFlag(AcroTextFieldFlags.Multiline);
+        }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return Value ?? string.Empty;
+        }
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/AcroTextFieldFlags.cs

@@ -0,0 +1,53 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using System;
+
+    /// <summary>
+    /// Flags specifying various characteristics of a text type field in an <see cref="AcroFieldBase"/>.
+    /// </summary>
+    [Flags]
+    public enum AcroTextFieldFlags : uint
+    {
+        /// <summary>
+        /// The user may not change the value of the field.
+        /// </summary>
+        ReadOnly = 1 << 0,
+        /// <summary>
+        /// The field must have a value before the form can be submitted.
+        /// </summary>
+        Required = 1 << 1,
+        /// <summary>
+        /// Must not be exported by the submit form action.
+        /// </summary>
+        NoExport = 1 << 2,
+        /// <summary>
+        /// The field can contain multiple lines of text.
+        /// </summary>
+        Multiline = 1 << 12,
+        /// <summary>
+        /// The field is for a password and should not be displayed as text and should not be stored to file.
+        /// </summary>
+        Password = 1 << 13,
+        /// <summary>
+        /// The field represents a file path selection.
+        /// </summary>
+        FileSelect = 1 << 20,
+        /// <summary>
+        /// The text entered is not spell checked.
+        /// </summary>
+        DoNotSpellCheck = 1 << 22,
+        /// <summary>
+        /// The field does not scroll if the text exceeds the bounds of the field.
+        /// </summary>
+        DoNotScroll = 1 << 23,
+        /// <summary>
+        /// For a text field which is not a <see cref="Password"/>, <see cref="Multiline"/> or <see cref="FileSelect"/>
+        /// the field text is evenly spaced by splitting into 'combs' based on the MaxLen entry in the field dictionary.
+        /// </summary>
+        Comb = 1 << 24,
+        /// <summary>
+        /// The value of the field is a rich text string.
+        /// </summary>
+        RichText = 1 << 25
+    }
+}

src/UglyToad.PdfPig/AcroForms/Fields/NonTerminalAcroField.cs

@@ -0,0 +1,21 @@
+namespace UglyToad.PdfPig.AcroForms.Fields
+{
+    using System;
+    using System.Collections.Generic;
+    using Tokens;
+
+    /// <summary>
+    /// A non-leaf field in the form's structure.
+    /// </summary>
+    internal class NonTerminalAcroField : AcroFieldBase
+    {
+        public IReadOnlyList<AcroFieldBase> Children { get; }
+
+        public NonTerminalAcroField(DictionaryToken dictionary, string fieldType, uint fieldFlags, AcroFieldCommonInformation information,
+            IReadOnlyList<AcroFieldBase> children) : 
+            base(dictionary, fieldType, fieldFlags, information)
+        {
+            Children = children ?? throw new ArgumentNullException(nameof(children));
+        }
+    }
+}