#24 add more information to the choice fields

src/UglyToad.PdfPig/AcroForms/AcroFormFactory.cs

@@ -2,6 +2,7 @@
 {
     using System;
     using System.Collections.Generic;
+    using System.Linq;
     using Content;
     using Exceptions;
     using Fields;
@@ -199,6 +200,66 @@
             }
             else if (fieldType == NameToken.Ch)
             {
+                result = GetChoiceField(fieldDictionary, fieldType, fieldFlags, information);
+            }
+            else if (fieldType == NameToken.Sig)
+            {
+                var field = new AcroSignatureField(fieldDictionary, fieldType, fieldFlags, information);
+                result = field;
+            }
+            else
+            {
+                throw new PdfDocumentFormatException($"Unexpected type for field in AcroForm: {fieldType}.");
+            }
+
+            return result;
+        }
+
+        private AcroFieldBase GetChoiceField(DictionaryToken fieldDictionary, NameToken fieldType, uint fieldFlags, AcroFieldCommonInformation information)
+        {
+            var selectedOptions = Array.Empty<string>();
+            if (fieldDictionary.TryGet(NameToken.V, out var valueToken))
+            {
+                if (DirectObjectFinder.TryGet(valueToken, tokenScanner, out StringToken valueString))
+                {
+                    selectedOptions = new[] {valueString.Data};
+                }
+                else if (DirectObjectFinder.TryGet(valueToken, tokenScanner, out HexToken valueHex))
+                {
+                    selectedOptions = new[] {valueHex.Data};
+
+                }
+                else if (DirectObjectFinder.TryGet(valueToken, tokenScanner, out ArrayToken valueArray))
+                {
+                    selectedOptions = new string[valueArray.Length];
+                    for (var i = 0; i < valueArray.Length; i++)
+                    {
+                        var valueOptToken = valueArray.Data[i];
+
+                        if (DirectObjectFinder.TryGet(valueOptToken, tokenScanner, out StringToken valueOptString))
+                        {
+                            selectedOptions[i] = valueOptString.Data;
+                        }
+                        else if (DirectObjectFinder.TryGet(valueOptToken, tokenScanner, out HexToken valueOptHex))
+                        {
+                            selectedOptions[i] = valueOptHex.Data;
+                        }
+                    }
+                }
+            }
+
+            var selectedIndices = default(int[]);
+            if (fieldDictionary.TryGetOptionalTokenDirect(NameToken.I, tokenScanner, out ArrayToken indicesArray))
+            {
+                selectedIndices = new int[indicesArray.Length];
+                for (var i = 0; i < indicesArray.Data.Count; i++)
+                {
+                    var token = indicesArray.Data[i];
+                    var numericToken = DirectObjectFinder.Get<NumericToken>(token, tokenScanner);
+                    selectedIndices[i] = numericToken.Int;
+                }
+            }
+
             var options = new List<AcroChoiceOption>();
             if (fieldDictionary.TryGetOptionalTokenDirect(NameToken.Opt, tokenScanner, out ArrayToken optionsArrayToken))
             {
@@ -207,11 +268,15 @@
                     var optionToken = optionsArrayToken.Data[i];
                     if (DirectObjectFinder.TryGet(optionToken, tokenScanner, out StringToken optionStringToken))
                     {
-                            options.Add(new AcroChoiceOption(i, optionStringToken.Data));
+                        var name = optionStringToken.Data;
+                        var isSelected = IsChoiceSelected(selectedOptions, selectedIndices, i, name);
+                        options.Add(new AcroChoiceOption(i, isSelected, optionStringToken.Data));
                     }
                     else if (DirectObjectFinder.TryGet(optionToken, tokenScanner, out HexToken optionHexToken))
                     {
-                            options.Add(new AcroChoiceOption(i, optionHexToken.Data));
+                        var name = optionHexToken.Data;
+                        var isSelected = IsChoiceSelected(selectedOptions, selectedIndices, i, name);
+                        options.Add(new AcroChoiceOption(i, isSelected, optionHexToken.Data));
                     }
                     else if (DirectObjectFinder.TryGet(optionToken, tokenScanner, out ArrayToken optionArrayToken))
                     {
@@ -248,7 +313,8 @@
                             throw new PdfDocumentFormatException($"An option array array element's second value should be the option name string, instead got: {optionArrayToken.Data[1]}.");
                         }
 
-                            options.Add(new AcroChoiceOption(i, name, exportValue));
+                        var isSelected = IsChoiceSelected(selectedOptions, selectedIndices, i, name);
+                        options.Add(new AcroChoiceOption(i, isSelected, name, exportValue));
                     }
                     else
                     {
@@ -261,26 +327,49 @@
             
             if (choiceFlags.HasFlag(AcroChoiceFieldFlags.Combo))
             {
-                    var field = new AcroComboBoxField(fieldDictionary, fieldType, choiceFlags, information);
+                var field = new AcroComboBoxField(fieldDictionary, fieldType, choiceFlags, information, options, selectedOptions, selectedIndices);
-                    result = field;
+                return field;
-                }
-                else
-                {
-                    var field = new AcroListBoxField(fieldDictionary, fieldType, choiceFlags, information, options);
-                    result = field;
-                }
-            }
-            else if (fieldType == NameToken.Sig)
-            {
-                var field = new AcroSignatureField(fieldDictionary, fieldType, fieldFlags, information);
-                result = field;
-            }
-            else
-            {
-                throw new PdfDocumentFormatException($"Unexpected type for field in AcroForm: {fieldType}.");
             }
 
-            return result;
+            var topIndex = default(int?);
+            if (fieldDictionary.TryGetOptionalTokenDirect(NameToken.Ti, tokenScanner, out NumericToken topIndexToken))
+            {
+                topIndex = topIndexToken.Int;
+            }
+
+            return new AcroListBoxField(fieldDictionary, fieldType, choiceFlags, information, options, selectedOptions, selectedIndices, topIndex);
+        }
+
+        private static bool IsChoiceSelected(IReadOnlyList<string> selectedOptionNames, IReadOnlyList<int> selectedOptionIndices, int index, string name)
+        {
+            if (selectedOptionNames.Count == 0)
+            {
+                return false;
+            }
+
+            for (var i = 0; i < selectedOptionNames.Count; i++)
+            {
+                var optionName = selectedOptionNames[i];
+
+                if (optionName != name)
+                {
+                    continue;
+                }
+
+                if (selectedOptionIndices == null)
+                {
+                    return true;
+                }
+
+                if (selectedOptionIndices.Contains(index))
+                {
+                    return true;
+                }
+
+                return false;
+            }
+
+            return false;
         }
     }
 }

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

@@ -110,30 +110,106 @@
         }
     }
 
+    /// <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) : 
+            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) :
+            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;
         }
     }
 
@@ -147,6 +223,11 @@
         /// </summary>
         public int Index { get; }
 
+        /// <summary>
+        /// Whether this option is selected.
+        /// </summary>
+        public bool IsSelected { get; }
+
         /// <summary>
         /// The text of the option.
         /// </summary>
@@ -160,9 +241,10 @@
         /// <summary>
         /// Create a new <see cref="AcroChoiceOption"/>.
         /// </summary>
-        public AcroChoiceOption(int index, string name, string exportValue = null)
+        public AcroChoiceOption(int index, bool isSelected, string name, string exportValue = null)
         {
             Index = index;
+            IsSelected = isSelected;
             Name = name;
             ExportValue = exportValue;
         }