Make all structs readonly when possible

src/UglyToad.PdfPig.Core/IndirectReference.cs

@@ -5,7 +5,7 @@
     /// <summary>
     /// Used to uniquely identify and refer to objects in the PDF file.
     /// </summary>
-    public struct IndirectReference
+    public readonly struct IndirectReference
     {
         /// <summary>
         /// A positive integer object number.

src/UglyToad.PdfPig.Core/PdfLine.cs

@@ -3,14 +3,14 @@
     using System;
 
     /// <summary>
-    /// A line in a PDF file. 
+    /// A line in a PDF file.
     /// </summary>
     /// <remarks>
     /// PDF coordinates are defined with the origin at the lower left (0, 0).
     /// The Y-axis extends vertically upwards and the X-axis horizontally to the right.
     /// Unless otherwise specified on a per-page basis, units in PDF space are equivalent to a typographic point (1/72 inch).
     /// </remarks>
-    public struct PdfLine
+    public readonly struct PdfLine
     {
         /// <summary>
         /// Length of the line.
@@ -71,7 +71,6 @@ public PdfRectangle GetBoundingRectangle()
         /// Returns a value indicating whether this <see cref="PdfLine"/> is equal to a specified <see cref="PdfLine"/> .
         /// </summary>
         /// <param name="obj"></param>
-        /// <returns></returns>
         public override bool Equals(object obj)
         {
             if (obj is PdfLine line)
@@ -84,7 +83,6 @@ public override bool Equals(object obj)
         /// <summary>
         /// Returns the hash code for this <see cref="PdfLine"/>.
         /// </summary>
-        /// <returns></returns>
         public override int GetHashCode()
         {
             return (Point1, Point2).GetHashCode();

src/UglyToad.PdfPig.Core/PdfPoint.cs

@@ -4,14 +4,14 @@
     using System.Globalization;
 
     /// <summary>
-    /// A point in a PDF file. 
+    /// A point in a PDF file.
     /// </summary>
     /// <remarks>
     /// PDF coordinates are defined with the origin at the lower left (0, 0).
     /// The Y-axis extends vertically upwards and the X-axis horizontally to the right.
     /// Unless otherwise specified on a per-page basis, units in PDF space are equivalent to a typographic point (1/72 inch).
     /// </remarks>
-    public struct PdfPoint
+    public readonly struct PdfPoint
     {
         /// <summary>
         /// The origin of the coordinates system.

src/UglyToad.PdfPig.Core/PdfRange.cs

@@ -6,7 +6,7 @@
     /// <summary>
     /// This class will be used to signify a range. a(min) &lt;= a* &lt;= a(max)
     /// </summary>
-    public struct PdfRange
+    public readonly struct PdfRange
     {
         private readonly IReadOnlyList<double> rangeArray;
         private readonly int startingIndex;

src/UglyToad.PdfPig.Core/PdfRectangle.cs

@@ -4,7 +4,7 @@
     using System.Globalization;
 
     /// <summary>
-    /// A rectangle in a PDF file. 
+    /// A rectangle in a PDF file.
     /// </summary>
     /// <remarks>
     /// PDF coordinates are defined with the origin at the lower left (0, 0).
@@ -36,7 +36,7 @@ public struct PdfRectangle
         /// <summary>
         /// Centroid point of the rectangle.
         /// </summary>
-        public PdfPoint Centroid
+        public readonly PdfPoint Centroid
         {
             get
             {
@@ -86,13 +86,7 @@ public double Height
         /// Rotation angle of the rectangle. Counterclockwise, in degrees.
         /// <para>-180 ≤ θ ≤ 180</para>
         /// </summary>
-        public double Rotation
-        {
-            get
-            {
-                return GetT() * 180 / Math.PI;
-            }
-        }
+        public readonly double Rotation => GetT() * 180 / Math.PI;
 
         /// <summary>
         /// Area of the rectangle.
@@ -102,22 +96,22 @@ public double Rotation
         /// <summary>
         /// Left. This value is only valid if the rectangle is not rotated, check <see cref="Rotation"/>.
         /// </summary>
-        public double Left => TopLeft.X < TopRight.X ? TopLeft.X : TopRight.X;
+        public readonly double Left => TopLeft.X < TopRight.X ? TopLeft.X : TopRight.X;
 
         /// <summary>
         /// Top. This value is only valid if the rectangle is not rotated, check <see cref="Rotation"/>.
         /// </summary>
-        public double Top => TopLeft.Y > BottomLeft.Y ? TopLeft.Y : BottomLeft.Y;
+        public readonly double Top => TopLeft.Y > BottomLeft.Y ? TopLeft.Y : BottomLeft.Y;
 
         /// <summary>
         /// Right. This value is only valid if the rectangle is not rotated, check <see cref="Rotation"/>.
         /// </summary>
-        public double Right => BottomRight.X > BottomLeft.X ? BottomRight.X : BottomLeft.X;
+        public readonly double Right => BottomRight.X > BottomLeft.X ? BottomRight.X : BottomLeft.X;
 
         /// <summary>
         /// Bottom. This value is only valid if the rectangle is not rotated, check <see cref="Rotation"/>.
         /// </summary>
-        public double Bottom => BottomRight.Y < TopRight.Y ? BottomRight.Y : TopRight.Y;
+        public readonly double Bottom => BottomRight.Y < TopRight.Y ? BottomRight.Y : TopRight.Y;
 
         /// <summary>
         /// Create a new <see cref="PdfRectangle"/>.
@@ -171,7 +165,7 @@ public PdfRectangle(PdfPoint topLeft, PdfPoint topRight, PdfPoint bottomLeft, Pd
         /// <param name="dx">The distance to move the rectangle in the x direction relative to its current location.</param>
         /// <param name="dy">The distance to move the rectangle in the y direction relative to its current location.</param>
         /// <returns>A new rectangle shifted on the y axis by the given delta value.</returns>
-        public PdfRectangle Translate(double dx, double dy)
+        public readonly PdfRectangle Translate(double dx, double dy)
         {
             return new PdfRectangle(TopLeft.Translate(dx, dy), TopRight.Translate(dx, dy),
                                     BottomLeft.Translate(dx, dy), BottomRight.Translate(dx, dy));
@@ -180,17 +174,15 @@ public PdfRectangle Translate(double dx, double dy)
         /// <summary>
         /// -π ≤ θ ≤ π
         /// </summary>
-        private double GetT()
+        private readonly double GetT()
         {
             if (!BottomRight.Equals(BottomLeft))
             {
                 return Math.Atan2(BottomRight.Y - BottomLeft.Y, BottomRight.X - BottomLeft.X);
             }
-            else
-            {
-                // handle the case where both bottom points are identical
-                return Math.Atan2(TopLeft.Y - BottomLeft.Y, TopLeft.X - BottomLeft.X) - Math.PI / 2;
-            }
+
+            // handle the case where both bottom points are identical
+            return Math.Atan2(TopLeft.Y - BottomLeft.Y, TopLeft.X - BottomLeft.X) - Math.PI / 2;
         }
 
         private void GetWidthHeight()

src/UglyToad.PdfPig.Core/TransformationMatrix.cs

@@ -135,47 +135,47 @@ public static TransformationMatrix GetRotationMatrix(double degreesCounterclockw
                 switch (row)
                 {
                     case 0:
+                    {
+                        switch (col)
                         {
-                            switch (col)
-                            {
-                                case 0:
-                                    return A;
-                                case 1:
-                                    return B;
-                                case 2:
-                                    return row1;
-                                default:
+                            case 0:
+                                return A;
+                            case 1:
+                                return B;
+                            case 2:
+                                return row1;
+                            default:
                                     throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.");
-                            }
                         }
+                    }
                     case 1:
+                    {
+                        switch (col)
                         {
-                            switch (col)
-                            {
-                                case 0:
-                                    return C;
-                                case 1:
-                                    return D;
-                                case 2:
-                                    return row2;
-                                default:
+                            case 0:
+                                return C;
+                            case 1:
+                                return D;
+                            case 2:
+                                return row2;
+                            default:
                                     throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.");
-                            }
                         }
+                    }
                     case 2:
+                    {
+                        switch (col)
                         {
-                            switch (col)
-                            {
-                                case 0:
-                                    return E;
-                                case 1:
-                                    return F;
-                                case 2:
-                                    return row3;
-                                default:
+                            case 0:
+                                return E;
+                            case 1:
+                                return F;
+                            case 2:
+                                return row3;
+                            default:
                                     throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.");
-                            }
                         }
+                    }
                     default:
                         throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.");
                 }
@@ -404,7 +404,7 @@ public TransformationMatrix Multiply(TransformationMatrix matrix)
             var r3 = (E * matrix.row1) + (F * matrix.row2) + (row3 * matrix.row3);
 
             return new TransformationMatrix(a, b, r1,
-                c, d, r2,
+                c, d, r2, 
                 e, f, r3);
         }
 

src/UglyToad.PdfPig.DocumentLayoutAnalysis/PageSegmenter/DocstrumBoundingBoxes.cs

@@ -575,7 +575,7 @@ private static double AngleBL(Word pivot, Word candidate)
         /// <summary>
         /// The bounds for the angle between two words for them to have a certain type of relationship.
         /// </summary>
-        public struct AngleBounds
+        public readonly struct AngleBounds
         {
             /// <summary>
             /// The lower bound in degrees.
@@ -646,7 +646,7 @@ public class DocstrumBoundingBoxesOptions : IPageSegmenterOptions
             public AngleBounds WithinLineBounds { get; set; } = new AngleBounds(-30, 30);
 
             /// <summary>
-            /// Multiplier that gives the maximum euclidian distance between
+            /// Multiplier that gives the maximum euclidean distance between
             /// words for building lines. Maximum distance will be this number times the within-line
             /// distance found by the analysis.
             /// <para>Default value is 3.</para>

src/UglyToad.PdfPig.Fonts/AdobeFontMetrics/AdobeFontMetricsVector.cs

@@ -3,7 +3,7 @@
     /// <summary>
     /// A vector in the Adobe Font Metrics.
     /// </summary>
-    public struct AdobeFontMetricsVector
+    public readonly struct AdobeFontMetricsVector
     {
         /// <summary>
         /// The x component of the vector.

src/UglyToad.PdfPig.Fonts/CompactFontFormat/CharStrings/Type2CharStrings.cs

@@ -196,7 +196,7 @@ public override string ToString()
                 return stringBuilder.ToString();
             }
 
-            public struct CommandIdentifier
+            public readonly struct CommandIdentifier
             {
                 public int CommandIndex { get; }
 

src/UglyToad.PdfPig.Fonts/CompactFontFormat/CompactFontFormatHeader.cs

@@ -3,13 +3,13 @@
     /// <summary>
     /// The header table for the binary data of a Compact Font Format file.
     /// </summary>
-    public struct CompactFontFormatHeader
+    public readonly struct CompactFontFormatHeader
     {
         /// <summary>
         /// The major version of this font format. Starting at 1.
         /// </summary>
         public byte MajorVersion { get; }
-        
+
         /// <summary>
         /// The minor version of this font format. Starting at 0. Indicates extensions to the format which
         /// are undetectable by readers which do not support them.

src/UglyToad.PdfPig.Fonts/CompactFontFormat/CompactFontFormatIndividualFontParser.cs

@@ -397,7 +397,7 @@ public int GetFontDictionaryIndex(int glyphId)
             return 0;
         }
 
-        internal struct Range3
+        internal readonly struct Range3
         {
             public int First { get; }
 
@@ -415,7 +415,4 @@ public override string ToString()
             }
         }
     }
-
-
-
 }

src/UglyToad.PdfPig.Fonts/CompactFontFormat/Dictionaries/CompactFontFormatDictionaryReader.cs

@@ -290,7 +290,7 @@ protected static decimal[] ReadDeltaToArray(List<Operand> operands)
             return results;
         }
 
-        protected struct Operand
+        protected readonly struct Operand
         {
             public int? Int { get; }
 
@@ -309,13 +309,13 @@ public Operand(decimal d)
             }
         }
 
-        protected struct OperandKey
+        protected readonly struct OperandKey
         {
             public byte Byte0 { get; }
 
             public byte? Byte1 { get; }
 
-            public OperandKey(Byte byte0)
+            public OperandKey(byte byte0)
             {
                 Byte0 = byte0;
                 Byte1 = null;

src/UglyToad.PdfPig.Fonts/CompactFontFormat/Dictionaries/CompactFontFormatTopLevelDictionary.cs

@@ -60,7 +60,7 @@ internal class CompactFontFormatTopLevelDictionary
 
         public CidFontOperators CidFontOperators { get; set; } = new CidFontOperators();
 
-        public struct SizeAndOffset
+        public readonly struct SizeAndOffset
         {
             public int Size { get; }
 

src/UglyToad.PdfPig.Fonts/SystemFonts/SystemFontRecord.cs

@@ -2,7 +2,7 @@
 {
     using System;
 
-    internal struct SystemFontRecord
+    internal readonly struct SystemFontRecord
     {
         public string Path { get; }
 

src/UglyToad.PdfPig.Fonts/TrueType/Glyphs/CompositeTransformMatrix3By2.cs

@@ -3,7 +3,7 @@ namespace UglyToad.PdfPig.Fonts.TrueType.Glyphs
 {
     using Core;
 
-    internal struct CompositeTransformMatrix3By2
+    internal readonly struct CompositeTransformMatrix3By2
     {
         private readonly double r0c0;
         private readonly double r0c1;

src/UglyToad.PdfPig.Fonts/TrueType/Glyphs/GlyphPoint.cs

@@ -2,7 +2,7 @@
 {
     using UglyToad.PdfPig.Core;
 
-    internal struct GlyphPoint
+    internal readonly struct GlyphPoint
     {
         public short X { get; }
 

src/UglyToad.PdfPig.Fonts/TrueType/Glyphs/HorizontalMetric.cs

@@ -3,7 +3,7 @@
     /// <summary>
     /// The pair of horizontal metrics for an individual glyph.
     /// </summary>
-    public struct HorizontalMetric
+    public readonly struct HorizontalMetric
     {
         /// <summary>
         /// The advance width.

src/UglyToad.PdfPig.Fonts/TrueType/Parser/NameTableParser.cs

@@ -125,7 +125,7 @@ private static string GetName(int nameId, TrueTypeNameRecord[] names)
             return windows ?? any;
         }
 
-        private struct NameRecordBuilder
+        private readonly struct NameRecordBuilder
         {
             public TrueTypePlatformIdentifier PlatformId { get; }