Make markers common

src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsAdobe.cs → src/ImageSharp/Formats/Jpeg/Common/Decoder/AdobeMarker.cs

@@ -4,12 +4,12 @@
 using System;
 
 // ReSharper disable InconsistentNaming
-namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
+namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
 {
     /// <summary>
     /// Provides information about the Adobe marker segment
     /// </summary>
-    internal struct PdfJsAdobe : IEquatable<PdfJsAdobe>
+    internal struct AdobeMarker : IEquatable<AdobeMarker>
     {
         /// <summary>
         /// The DCT Encode Version
@@ -36,7 +36,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         public byte ColorTransform;
 
         /// <inheritdoc/>
-        public bool Equals(PdfJsAdobe other)
+        public bool Equals(AdobeMarker other)
         {
             return this.DCTEncodeVersion == other.DCTEncodeVersion
                 && this.APP14Flags0 == other.APP14Flags0
@@ -52,21 +52,24 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                 return false;
             }
 
-            return obj is PdfJsAdobe && this.Equals((PdfJsAdobe)obj);
+            return obj is AdobeMarker && this.Equals((AdobeMarker)obj);
         }
 
         /// <inheritdoc/>
         public override int GetHashCode()
         {
-            unchecked
-            {
-                // TODO: Merge and use HashCodeHelpers
-                int hashCode = this.DCTEncodeVersion.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.APP14Flags0.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.APP14Flags1.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.ColorTransform.GetHashCode();
-                return hashCode;
-            }
+            return GetHashCode(this);
+        }
+
+        private static int GetHashCode(AdobeMarker marker)
+        {
+            return HashHelpers.Combine(
+                marker.DCTEncodeVersion.GetHashCode(),
+                HashHelpers.Combine(
+                    marker.APP14Flags0.GetHashCode(),
+                    HashHelpers.Combine(
+                        marker.APP14Flags1.GetHashCode(),
+                        marker.ColorTransform.GetHashCode())));
         }
     }
 }

src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsJFif.cs → src/ImageSharp/Formats/Jpeg/Common/Decoder/JFifMarker.cs

@@ -3,13 +3,13 @@
 
 using System;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
+namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
 {
     /// <summary>
     /// Provides information about the JFIF marker segment
     /// TODO: Thumbnail?
     /// </summary>
-    internal struct PdfJsJFif : IEquatable<PdfJsJFif>
+    internal struct JFifMarker : IEquatable<JFifMarker>
     {
         /// <summary>
         /// The major version
@@ -40,7 +40,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         public short YDensity;
 
         /// <inheritdoc/>
-        public bool Equals(PdfJsJFif other)
+        public bool Equals(JFifMarker other)
         {
             return this.MajorVersion == other.MajorVersion
                 && this.MinorVersion == other.MinorVersion
@@ -57,21 +57,24 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                 return false;
             }
 
-            return obj is PdfJsJFif && this.Equals((PdfJsJFif)obj);
+            return obj is JFifMarker && this.Equals((JFifMarker)obj);
         }
 
         /// <inheritdoc/>
         public override int GetHashCode()
         {
-            unchecked
-            {
-                int hashCode = this.MajorVersion.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.MinorVersion.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.DensityUnits.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.XDensity.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.YDensity.GetHashCode();
-                return hashCode;
-            }
+            return GetHashCode(this);
+        }
+
+        private static int GetHashCode(JFifMarker marker)
+        {
+            return HashHelpers.Combine(
+                marker.MajorVersion.GetHashCode(),
+                HashHelpers.Combine(
+                    marker.MinorVersion.GetHashCode(),
+                    HashHelpers.Combine(
+                        marker.DensityUnits.GetHashCode(),
+                        HashHelpers.Combine(marker.XDensity, marker.YDensity))));
         }
     }
 }

src/ImageSharp/Formats/Jpeg/GolangPort/OrigJpegConstants.cs

@@ -165,6 +165,32 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
             public const byte APP15 = 0xef;
         }
 
+        /// <summary>
+        /// Contains JFIF specific markers
+        /// </summary>
+        public static class JFif
+        {
+            /// <summary>
+            /// Represents J in ASCII
+            /// </summary>
+            public const byte J = 0x4A;
+
+            /// <summary>
+            /// Represents F in ASCII
+            /// </summary>
+            public const byte F = 0x46;
+
+            /// <summary>
+            /// Represents I in ASCII
+            /// </summary>
+            public const byte I = 0x49;
+
+            /// <summary>
+            /// Represents the null "0" marker
+            /// </summary>
+            public const byte Null = 0x0;
+        }
+
         /// <summary>
         /// Describes Adobe specific markers <see href="http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#Adobe"/>
         /// </summary>

src/ImageSharp/Formats/Jpeg/PdfJsPort/PdfJsJpegDecoderCore.cs

@@ -5,6 +5,7 @@ using System;
 using System.IO;
 using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder;
 using SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.MetaData;
@@ -53,12 +54,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// <summary>
         /// Contains information about the JFIF marker
         /// </summary>
-        private PdfJsJFif jFif;
+        private JFifMarker jFif;
 
         /// <summary>
         /// Contains information about the Adobe marker
         /// </summary>
-        private PdfJsAdobe adobe;
+        private AdobeMarker adobe;
 
         /// <summary>
         /// Initializes static members of the <see cref="PdfJsJpegDecoderCore"/> class.
@@ -345,7 +346,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
 
             if (this.NumberOfComponents == 3)
             {
-                if (this.adobe.Equals(default(PdfJsAdobe)) || this.adobe.ColorTransform == PdfJsJpegConstants.Markers.Adobe.ColorTransformYCbCr)
+                if (this.adobe.Equals(default(AdobeMarker)) || this.adobe.ColorTransform == PdfJsJpegConstants.Markers.Adobe.ColorTransformYCbCr)
                 {
                     this.FillYCbCrImage(image);
                 }
@@ -420,7 +421,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
 
             if (isJfif)
             {
-                this.jFif = new PdfJsJFif
+                this.jFif = new JFifMarker
                 {
                     MajorVersion = this.temp[5],
                     MinorVersion = this.temp[6],
@@ -542,7 +543,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
 
             if (isAdobe)
             {
-                this.adobe = new PdfJsAdobe
+                this.adobe = new AdobeMarker
                 {
                     DCTEncodeVersion = (short)((this.temp[5] << 8) | this.temp[6]),
                     APP14Flags0 = (short)((this.temp[7] << 8) | this.temp[8]),