Rent the scanlines

src/ImageSharp/Formats/Png/PngDecoderCore.cs

@@ -6,6 +6,7 @@
 namespace ImageSharp.Formats
 {
     using System;
+    using System.Buffers;
     using System.Collections.Generic;
     using System.IO;
     using System.Linq;
@@ -111,8 +112,7 @@ namespace ImageSharp.Formats
         /// Thrown if the image is larger than the maximum allowable size.
         /// </exception>
         public void Decode<TColor, TPacked>(Image<TColor, TPacked> image, Stream stream)
-            where TColor : struct, IPackedPixel<TPacked>
+            where TColor : struct, IPackedPixel<TPacked> where TPacked : struct
-            where TPacked : struct
         {
             Image<TColor, TPacked> currentImage = image;
             this.currentStream = stream;
@@ -182,8 +182,7 @@ namespace ImageSharp.Formats
         /// <param name="image">The image to read to.</param>
         /// <param name="data">The data containing physical data.</param>
         private void ReadPhysicalChunk<TColor, TPacked>(Image<TColor, TPacked> image, byte[] data)
-            where TColor : struct, IPackedPixel<TPacked>
+            where TColor : struct, IPackedPixel<TPacked> where TPacked : struct
-            where TPacked : struct
         {
             data.ReverseBytes(0, 4);
             data.ReverseBytes(4, 4);
@@ -244,8 +243,7 @@ namespace ImageSharp.Formats
         /// <param name="dataStream">The <see cref="MemoryStream"/> containing data.</param>
         /// <param name="pixels"> The pixel data.</param>
         private void ReadScanlines<TColor, TPacked>(MemoryStream dataStream, PixelAccessor<TColor, TPacked> pixels)
-            where TColor : struct, IPackedPixel<TPacked>
+            where TColor : struct, IPackedPixel<TPacked> where TPacked : struct
-            where TPacked : struct
         {
             this.bytesPerPixel = this.CalculateBytesPerPixel();
             this.bytesPerScanline = this.CalculateScanlineLength() + 1;
@@ -270,13 +268,13 @@ namespace ImageSharp.Formats
         /// <param name="compressedStream">The compressed pixel data stream.</param>
         /// <param name="pixels">The image pixel accessor.</param>
         private void DecodePixelData<TColor, TPacked>(Stream compressedStream, PixelAccessor<TColor, TPacked> pixels)
-            where TColor : struct, IPackedPixel<TPacked>
+            where TColor : struct, IPackedPixel<TPacked> where TPacked : struct
-            where TPacked : struct
         {
-            // TODO: ArrayPool<byte>.Shared.Rent(this.bytesPerScanline)
+            byte[] previousScanline = ArrayPool<byte>.Shared.Rent(this.bytesPerScanline);
-            byte[] previousScanline = new byte[this.bytesPerScanline];
+            byte[] scanline = ArrayPool<byte>.Shared.Rent(this.bytesPerScanline);
-            byte[] scanline = new byte[this.bytesPerScanline];
 
+            try
+            {
                 for (int y = 0; y < this.header.Height; y++)
                 {
                     compressedStream.Read(scanline, 0, this.bytesPerScanline);
@@ -326,6 +324,12 @@ namespace ImageSharp.Formats
                     scanline = temp;
                 }
             }
+            finally
+            {
+                ArrayPool<byte>.Shared.Return(previousScanline);
+                ArrayPool<byte>.Shared.Return(scanline);
+            }
+        }
 
         /// <summary>
         /// Processes the de-filtered scanline filling the image pixel data
@@ -618,10 +622,7 @@ namespace ImageSharp.Formats
         /// <summary>
         /// Calculates the length of the given chunk.
         /// </summary>
-        /// <param name="chunk">he chunk.</param>
+        /// <param name="chunk">The chunk.</param>
-        /// <returns>
-        /// The <see cref="int"/> representing the chunk length.
-        /// </returns>
         /// <exception cref="ImageFormatException">
         /// Thrown if the input stream is not valid.
         /// </exception>