Improve Code Quality (#831)

* Introduce globals

* Spanify TransformationMatrix.FromArray

* Eliminate allocation in GeometryExtensions.ParametricPerpendicularProjection

* Eliminate allocation in CrossReferenceTablePart.Parse

* Optimize Adam7 (eliminate virtual calls)

* Spanify QuadPointsQuadrilateral.Points to eliminate virtual calls

* Eliminate allocation in PdfRectangle.Normalize

* Format TransformMatrix

* Pass TransformationMatrix  by reference in TransformationMatrix.Multiply

* Seal NoTextTokenWriter

src/UglyToad.PdfPig.Core/Globals.cs

@@ -0,0 +1,2 @@
+global using System;
+global using System.Collections.Generic;

src/UglyToad.PdfPig.Core/TransformationMatrix.cs

@@ -1,9 +1,6 @@
 namespace UglyToad.PdfPig.Core
 {
-    using System;
-    using System.Collections.Generic;
     using System.Diagnostics.Contracts;
-    using System.Linq;
     using static UglyToad.PdfPig.Core.PdfSubpath;
 
     /// <summary>
@@ -138,53 +135,27 @@
                     throw new ArgumentOutOfRangeException(nameof(col), "Cannot access negative columns in a matrix.");
                 }
 
-                switch (row)
-                {
-                    case 0:
-                    {
-                        switch (col)
-                        {
-                            case 0:
-                                return A;
-                            case 1:
-                                return B;
-                            case 2:
-                                return row1;
-                            default:
-                                    throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.");
-                        }
-                    }
-                    case 1:
-                    {
-                        switch (col)
-                        {
-                            case 0:
-                                return C;
-                            case 1:
-                                return D;
-                            case 2:
-                                return row2;
-                            default:
-                                    throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.");
-                        }
-                    }
-                    case 2:
-                    {
-                        switch (col)
-                        {
-                            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.");
-                }
+                return row switch {
+                    0 => col switch {
+                        0 => A,
+                        1 => B,
+                        2 => row1,
+                        _ => throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.")
+                    },
+                    1 => col switch {
+                        0 => C,
+                        1 => D,
+                        2 => row2,
+                        _ => throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.")
+                    },
+                    2 => col switch {
+                        0 => E,
+                        1 => F,
+                        2 => row3,
+                        _ => throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.")
+                    },
+                    _ => throw new ArgumentOutOfRangeException($"Trying to access {row}, {col} which was not in the value array.")
+                };
             }
         }
 
@@ -201,7 +172,7 @@
         /// Create a new <see cref="TransformationMatrix"/>.
         /// </summary>
         /// <param name="value">The 9 values of the matrix.</param>
-        public TransformationMatrix(double[] value) : this(value[0], value[1], value[2], value[3], value[4], value[5], value[6], value[7], value[8])
+        public TransformationMatrix(ReadOnlySpan<double> value) : this(value[0], value[1], value[2], value[3], value[4], value[5], value[6], value[7], value[8])
         {
         }
 
@@ -373,7 +344,7 @@
         /// </summary>
         /// <param name="values">Either all 9 values of the matrix, 6 values in the default PDF order or the 4 values of the top left square.</param>
         /// <returns></returns>
-        public static TransformationMatrix FromArray(double[] values)
+        public static TransformationMatrix FromArray(ReadOnlySpan<double> values)
         {
             if (values.Length == 9)
             {
@@ -394,7 +365,7 @@
                     0, 0, 1);
             }
 
-            throw new ArgumentException("The array must either define all 9 elements of the matrix or all 6 key elements. Instead array was: " + values);
+            throw new ArgumentException("The array must either define all 9 elements of the matrix or all 6 key elements. Instead array was: " + string.Join(", ", values.ToArray()));
         }
 
         /// <summary>
@@ -403,7 +374,7 @@
         /// <param name="matrix">The matrix to multiply</param>
         /// <returns>The resulting matrix.</returns>
         [Pure]
-        public TransformationMatrix Multiply(TransformationMatrix matrix)
+        public TransformationMatrix Multiply(in TransformationMatrix matrix)
         {
             var a = (A * matrix.A) + (B * matrix.C) + (row1 * matrix.E);
             var b = (A * matrix.B) + (B * matrix.D) + (row1 * matrix.F);
@@ -524,17 +495,19 @@
         /// <inheritdoc />
         public override int GetHashCode()
         {
-            var hashCode = 472622392;
-            hashCode = hashCode * -1521134295 + row1.GetHashCode();
-            hashCode = hashCode * -1521134295 + row2.GetHashCode();
-            hashCode = hashCode * -1521134295 + row3.GetHashCode();
-            hashCode = hashCode * -1521134295 + A.GetHashCode();
-            hashCode = hashCode * -1521134295 + B.GetHashCode();
-            hashCode = hashCode * -1521134295 + C.GetHashCode();
-            hashCode = hashCode * -1521134295 + D.GetHashCode();
-            hashCode = hashCode * -1521134295 + E.GetHashCode();
-            hashCode = hashCode * -1521134295 + F.GetHashCode();
-            return hashCode;
+            var hashCode = new HashCode();
+
+            hashCode.Add(row1);
+            hashCode.Add(row2);
+            hashCode.Add(row3);
+            hashCode.Add(A);
+            hashCode.Add(B);
+            hashCode.Add(C);
+            hashCode.Add(D);
+            hashCode.Add(E);
+            hashCode.Add(F);
+
+            return hashCode.ToHashCode();
         }
 
         /// <inheritdoc />

src/UglyToad.PdfPig.DocumentLayoutAnalysis/Globals.cs

@@ -0,0 +1,2 @@
+global using System;
+global using System.Collections.Generic;

src/UglyToad.PdfPig.Fonts/Globals.cs

@@ -0,0 +1,2 @@
+global using System;
+global using System.Collections.Generic;

src/UglyToad.PdfPig.Tokenization/Globals.cs

@@ -0,0 +1,2 @@
+global using System;
+global using System.Collections.Generic;

src/UglyToad.PdfPig.Tokens/Globals.cs

@@ -0,0 +1,2 @@
+global using System;
+global using System.Collections.Generic;

src/UglyToad.PdfPig/Annotations/QuadPointsQuadrilateral.cs

@@ -1,7 +1,5 @@
 namespace UglyToad.PdfPig.Annotations
 {
-    using System;
-    using System.Collections.Generic;
     using Core;
 
     /// <summary>
@@ -10,13 +8,15 @@
     /// </summary>
     public readonly struct QuadPointsQuadrilateral
     {
+        private readonly PdfPoint[] points;
+
         /// <summary>
         /// The 4 points defining this quadrilateral.
         /// The PDF specification defines these as being in anti-clockwise order starting from the lower-left corner, however
         /// Adobe's implementation doesn't obey the specification and points seem to go in the order: top-left, top-right,
         /// bottom-left, bottom-right. See: https://stackoverflow.com/questions/9855814/pdf-spec-vs-acrobat-creation-quadpoints.
         /// </summary>
-        public IReadOnlyList<PdfPoint> Points { get; }
+        public ReadOnlySpan<PdfPoint> Points => points;
 
         /// <summary>
         /// Create a new <see cref="QuadPointsQuadrilateral"/>.
@@ -33,7 +33,7 @@
                 throw new ArgumentException($"Quadpoints quadrilateral should only contain 4 points, instead got {points.Length} points.");
             }
 
-            Points = points;
+            this.points = points;
         }
 
         /// <inheritdoc />

src/UglyToad.PdfPig/Geometry/GeometryExtensions.cs

@@ -1,10 +1,8 @@
 namespace UglyToad.PdfPig.Geometry
 {
-    using Core;
-    using System;
-    using System.Collections.Generic;
     using System.Linq;
     using System.Text;
+    using Core;
     using UglyToad.PdfPig.Geometry.ClipperLibrary;
     using UglyToad.PdfPig.Graphics;
     using static UglyToad.PdfPig.Core.PdfSubpath;
@@ -83,7 +81,7 @@
                 return new PdfRectangle(polygon[0], polygon[1]);
             }
 
-            double[] MBR = new double[8];
+            Span<double> mrb = stackalloc double[8];
 
             double Amin = double.PositiveInfinity;
             int j = 1;
@@ -169,7 +167,7 @@
                     if (A < Amin)
                     {
                         Amin = A;
-                        MBR = [R0X, R0Y, R1X, R1Y, R2X, R2Y, R3X, R3Y];
+                        mrb = [R0X, R0Y, R1X, R1Y, R2X, R2Y, R3X, R3Y];
                     }
                 }
 
@@ -180,10 +178,10 @@
                 if (k == polygon.Count) break;
             }
 
-            return new PdfRectangle(new PdfPoint(MBR[4], MBR[5]),
-                                    new PdfPoint(MBR[6], MBR[7]),
-                                    new PdfPoint(MBR[2], MBR[3]),
-                                    new PdfPoint(MBR[0], MBR[1]));
+            return new PdfRectangle(new PdfPoint(mrb[4], mrb[5]),
+                                    new PdfPoint(mrb[6], mrb[7]),
+                                    new PdfPoint(mrb[2], mrb[3]),
+                                    new PdfPoint(mrb[0], mrb[1]));
         }
 
         /// <summary>
@@ -471,10 +469,19 @@
         /// Gets the axis-aligned rectangle that completely containing the original rectangle, with no rotation.
         /// </summary>
         /// <param name="rectangle"></param>
-        public static PdfRectangle Normalise(this PdfRectangle rectangle)
+        public static PdfRectangle Normalise(this in PdfRectangle rectangle)
         {
-            var points = new[] { rectangle.BottomLeft, rectangle.BottomRight, rectangle.TopLeft, rectangle.TopRight };
-            return new PdfRectangle(points.Min(p => p.X), points.Min(p => p.Y), points.Max(p => p.X), points.Max(p => p.Y));
+            var bottomLeft = rectangle.BottomLeft;
+            var bottomRight = rectangle.BottomRight;
+            var topLeft = rectangle.TopLeft;
+            var topRight = rectangle.TopRight;
+
+            var minX = Math.Min(Math.Min(bottomLeft.X, bottomRight.X), Math.Min(topLeft.X, topRight.X));
+            var minY = Math.Min(Math.Min(bottomLeft.Y, bottomRight.Y), Math.Min(topLeft.Y, topRight.Y));
+            var maxX = Math.Max(Math.Max(bottomLeft.X, bottomRight.X), Math.Max(topLeft.X, topRight.X));
+            var maxY = Math.Max(Math.Max(bottomLeft.Y, bottomRight.Y), Math.Max(topLeft.Y, topRight.Y));
+
+            return new PdfRectangle(minX, minY, maxX, maxY);
         }
 
         /// <summary>

src/UglyToad.PdfPig/Globals.cs

@@ -0,0 +1,2 @@
+global using System;
+global using System.Collections.Generic;

src/UglyToad.PdfPig/Images/Png/Adam7.cs

@@ -1,33 +1,29 @@
 namespace UglyToad.PdfPig.Images.Png
 {
-    using System.Collections.Generic;
-
     internal static class Adam7
     {
         /// <summary>
         /// For a given pass number (1 indexed) the scanline indexes of the lines included in that pass in the 8x8 grid.
         /// </summary>
-        private static readonly IReadOnlyDictionary<int, int[]> PassToScanlineGridIndex = new Dictionary<int, int[]>
-        {
-            { 1, [0] },
-            { 2, [0] },
-            { 3, [4] },
-            { 4, [0, 4] },
-            { 5, [2, 6] },
-            { 6, [0, 2, 4, 6] },
-            { 7, [1, 3, 5, 7] }
-        };
+        private static readonly int[][] PassToScanlineGridIndex = [
+            [0],
+            [0],
+            [4],
+            [0, 4],
+            [2, 6],
+            [0, 2, 4, 6],
+            [1, 3, 5, 7]
+        ];
 
-        private static readonly IReadOnlyDictionary<int, int[]> PassToScanlineColumnIndex = new Dictionary<int, int[]>
-        {
-            { 1, [0] },
-            { 2, [4] },
-            { 3, [0, 4] },
-            { 4, [2, 6] },
-            { 5, [0, 2, 4, 6] },
-            { 6, [1, 3, 5, 7] },
-            { 7, [0, 1, 2, 3, 4, 5, 6, 7] }
-        };
+        private static readonly int[][] PassToScanlineColumnIndex = [
+            [0],
+            [4],
+            [0, 4],
+            [2, 6],
+            [0, 2, 4, 6],
+            [1, 3, 5, 7],
+            [0, 1, 2, 3, 4, 5, 6, 7]
+        ];
 
         /*
          * To go from raw image data to interlaced:
@@ -50,7 +46,7 @@
 
         public static int GetNumberOfScanlinesInPass(ImageHeader header, int pass)
         {
-            var indices = PassToScanlineGridIndex[pass + 1];
+            var indices = PassToScanlineGridIndex[pass];
 
             var mod = header.Height % 8;
 
@@ -75,7 +71,7 @@
 
         public static int GetPixelsPerScanlineInPass(ImageHeader header, int pass)
         {
-            var indices = PassToScanlineColumnIndex[pass + 1];
+            var indices = PassToScanlineColumnIndex[pass];
 
             var mod = header.Width % 8;
 
@@ -100,8 +96,8 @@
 
         public static (int x, int y) GetPixelIndexForScanlineInPass(ImageHeader header, int pass, int scanlineIndex, int indexInScanline)
         {
-            var columnIndices = PassToScanlineColumnIndex[pass + 1];
-            var rows = PassToScanlineGridIndex[pass + 1];
+            var columnIndices = PassToScanlineColumnIndex[pass];
+            var rows = PassToScanlineGridIndex[pass];
 
             var actualRow = scanlineIndex % rows.Length;
             var actualCol = indexInScanline % columnIndices.Length;

src/UglyToad.PdfPig/Parser/Parts/CrossReference/CrossReferenceStreamParser.cs

@@ -1,6 +1,5 @@
 namespace UglyToad.PdfPig.Parser.Parts.CrossReference
 {
-    using System.Collections.Generic;
     using Core;
     using Filters;
     using PdfPig.CrossReference;
@@ -45,7 +44,10 @@
             var objectNumbers = GetObjectNumbers(stream.StreamDictionary);
 
             var lineNumber = 0;
-            var lineBuffer = new byte[fieldSizes.LineLength];
+            Span<byte> lineBuffer = fieldSizes.LineLength <= 64
+                ? stackalloc byte[fieldSizes.LineLength]
+                : new byte[fieldSizes.LineLength];
+
             foreach (var objectNumber in objectNumbers)
             {
                 if (lineNumber >= lineCount)
@@ -84,7 +86,7 @@
         }
 
         private static void ReadNextStreamObject(int type, long objectNumber, CrossReferenceStreamFieldSize fieldSizes,
-            CrossReferenceTablePartBuilder builder, byte[] lineBuffer)
+            CrossReferenceTablePartBuilder builder, ReadOnlySpan<byte> lineBuffer)
         {
             switch (type)
             {

src/UglyToad.PdfPig/Writer/NoTextTokenWriter.cs

@@ -1,13 +1,10 @@
-using System;
-using System.Collections.Generic;
-using System.Diagnostics.CodeAnalysis;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
-using System.Linq;
 using UglyToad.PdfPig.Core;
 using UglyToad.PdfPig.Filters;
-using UglyToad.PdfPig.Graphics.Operations.TextShowing;
-using UglyToad.PdfPig.Graphics.Operations;
 using UglyToad.PdfPig.Graphics;
+using UglyToad.PdfPig.Graphics.Operations;
+using UglyToad.PdfPig.Graphics.Operations.TextShowing;
 using UglyToad.PdfPig.Logging;
 using UglyToad.PdfPig.Parser;
 using UglyToad.PdfPig.Tokens;
@@ -17,7 +14,7 @@ namespace UglyToad.PdfPig.Writer
     /// <summary>
     /// Derived class of <see cref="TokenWriter"/> that does not write <see cref="ShowText"/> or <see cref="ShowTextsWithPositioning"/> operations in streams
     /// </summary>
-    internal class NoTextTokenWriter : TokenWriter
+    internal sealed class NoTextTokenWriter : TokenWriter
     {
         /// <summary>
         /// Set this value prior to processing page to get the right page number in log messages