Move pending buffer

src/ImageSharp/Formats/Png/Zlib/Deflater.cs

@@ -50,7 +50,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         /// </summary>
         private int state;
 
-        private DeflaterPendingBuffer pending;
         private DeflaterEngine engine;
         private bool isDisposed;
 
@@ -80,10 +79,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
                 throw new ArgumentOutOfRangeException(nameof(level));
             }
 
-            this.pending = new DeflaterPendingBuffer(memoryAllocator);
-
             // TODO: Possibly provide DeflateStrategy as an option.
-            this.engine = new DeflaterEngine(memoryAllocator, this.pending, DeflateStrategy.Default);
+            this.engine = new DeflaterEngine(memoryAllocator, DeflateStrategy.Default);
 
             this.SetLevel(level);
             this.Reset();
@@ -126,7 +123,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         /// Gets a value indicating whetherthe stream was finished and no more output bytes
         /// are available.
         /// </summary>
-        public bool IsFinished => (this.state == FinishedState) && this.pending.IsFlushed;
+        public bool IsFinished => (this.state == FinishedState) && this.engine.Pending.IsFlushed;
 
         /// <summary>
         /// Gets a value indicating whether the input buffer is empty.
@@ -145,7 +142,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         public void Reset()
         {
             this.state = BusyState;
-            this.pending.Reset();
+            this.engine.Pending.Reset();
             this.engine.Reset();
         }
 
@@ -236,7 +233,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
 
             while (true)
             {
-                int count = this.pending.Flush(output, offset, length);
+                int count = this.engine.Pending.Flush(output, offset, length);
                 offset += count;
                 length -= count;
 
@@ -259,11 +256,11 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
                                 // We have to supply some lookahead.  8 bit lookahead
                                 // is needed by the zlib inflater, and we must fill
                                 // the next byte, so that all bits are flushed.
-                                int neededbits = 8 + ((-this.pending.BitCount) & 7);
+                                int neededbits = 8 + ((-this.engine.Pending.BitCount) & 7);
                                 while (neededbits > 0)
                                 {
                                     // Write a static tree block consisting solely of an EOF:
-                                    this.pending.WriteBits(2, 10);
+                                    this.engine.Pending.WriteBits(2, 10);
                                     neededbits -= 10;
                                 }
                             }
@@ -272,7 +269,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
                             break;
 
                         case FinishingState:
-                            this.pending.AlignToByte();
+                            this.engine.Pending.AlignToByte();
                             this.state = FinishedState;
                             break;
                     }
@@ -296,10 +293,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
                 if (disposing)
                 {
                     this.engine.Dispose();
-                    this.pending.Dispose();
                 }
 
-                this.pending = null;
                 this.engine = null;
                 this.isDisposed = true;
             }

src/ImageSharp/Formats/Png/Zlib/DeflaterEngine.cs

@@ -100,7 +100,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         private int inputEnd;
 
         private readonly DeflateStrategy strategy;
-        private readonly DeflaterPendingBuffer pending;
         private DeflaterHuffman huffman;
         private bool isDisposed;
 
@@ -145,12 +144,11 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         /// Initializes a new instance of the <see cref="DeflaterEngine"/> class.
         /// </summary>
         /// <param name="memoryAllocator">The memory allocator to use for buffer allocations.</param>
-        /// <param name="pending">The pending buffer to use.</param>
         /// <param name="strategy">The deflate strategy to use.</param>
-        public DeflaterEngine(MemoryAllocator memoryAllocator, DeflaterPendingBuffer pending, DeflateStrategy strategy)
+        public DeflaterEngine(MemoryAllocator memoryAllocator, DeflateStrategy strategy)
         {
-            this.pending = pending;
+            this.huffman = new DeflaterHuffman(memoryAllocator);
-            this.huffman = new DeflaterHuffman(pending);
+            this.Pending = this.huffman.Pending;
             this.strategy = strategy;
 
             // Create pinned pointers to the various buffers to allow indexing
@@ -175,6 +173,11 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
             this.blockStart = this.strstart = 1;
         }
 
+        /// <summary>
+        /// Gets the pending buffer to use.
+        /// </summary>
+        public DeflaterPendingBuffer Pending { get; }
+
         /// <summary>
         /// Deflate drives actual compression of data
         /// </summary>
@@ -208,7 +211,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
                         break;
                 }
             }
-            while (this.pending.IsFlushed && progress); // repeat while we have no pending output and progress was made
+            while (this.Pending.IsFlushed && progress); // repeat while we have no pending output and progress was made
             return progress;
         }
 
@@ -834,6 +837,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
             {
                 if (disposing)
                 {
+                    this.huffman.Dispose();
+
                     this.windowBufferHandle.Dispose();
                     this.windowBuffer.Dispose();
 
@@ -844,6 +849,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
                     this.prevBuffer.Dispose();
                 }
 
+                this.huffman = null;
+
                 this.isDisposed = true;
             }
         }

src/ImageSharp/Formats/Png/Zlib/DeflaterHuffman.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using SixLabors.Memory;
 
 namespace SixLabors.ImageSharp.Formats.Png.Zlib
 {
@@ -15,7 +16,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
     ///
     /// author of the original java version : Jochen Hoenicke
     /// </summary>
-    public class DeflaterHuffman
+    public sealed class DeflaterHuffman : IDisposable
     {
         private const int BufferSize = 1 << (DeflaterConstants.DEFAULT_MEM_LEVEL + 6);
 
@@ -60,6 +61,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         private byte[] literalBuffer;
         private int lastLiteral;
         private int extraBits;
+        private bool isDisposed;
 
         static DeflaterHuffman()
         {
@@ -106,10 +108,10 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         /// <summary>
         /// Initializes a new instance of the <see cref="DeflaterHuffman"/> class.
         /// </summary>
-        /// <param name="pending">Pending buffer to use</param>
+        /// <param name="memoryAllocator">The memory allocator to use for buffer allocations.</param>
-        public DeflaterHuffman(DeflaterPendingBuffer pending)
+        public DeflaterHuffman(MemoryAllocator memoryAllocator)
         {
-            this.Pending = pending;
+            this.Pending = new DeflaterPendingBuffer(memoryAllocator);
 
             this.literalTree = new Tree(this, LiteralNumber, 257, 15);
             this.distTree = new Tree(this, DistanceNumber, 1, 15);
@@ -122,7 +124,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         /// <summary>
         /// Gets the pending buffer to use.
         /// </summary>
-        public DeflaterPendingBuffer Pending { get; }
+        public DeflaterPendingBuffer Pending { get; private set; }
 
         /// <summary>
         /// Reset internal state
@@ -351,6 +353,13 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
                             Bit4Reverse[toReverse >> 12]);
         }
 
+        /// <inheritdoc/>
+        public void Dispose()
+        {
+            this.Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
         private static int Lcode(int length)
         {
             if (length == 255)
@@ -380,6 +389,20 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
             return code + distance;
         }
 
+        private void Dispose(bool disposing)
+        {
+            if (!this.isDisposed)
+            {
+                if (disposing)
+                {
+                    this.Pending.Dispose();
+                }
+
+                this.Pending = null;
+                this.isDisposed = true;
+            }
+        }
+
         private class Tree
         {
             private readonly int minNumCodes;