Add parallel options

Former-commit-id: a81f9393544d2c2fac2a4ebe247dc83cc27a3934
Former-commit-id: 098166601a68b3b8d34f5e8206aea51ed02f82aa
Former-commit-id: c5b423b967d17e571d9bc6b1918f7414eddde44e

src/ImageProcessorCore/Bootstrapper.cs

@@ -10,6 +10,7 @@ namespace ImageProcessorCore
     using System.Collections.ObjectModel;
 
     using ImageProcessorCore.Formats;
+    using System.Threading.Tasks;
 
     /// <summary>
     /// Provides initialization code which allows extending the library.
@@ -58,6 +59,11 @@ namespace ImageProcessorCore
         /// </summary>
         public IReadOnlyCollection<IImageFormat> ImageFormats => new ReadOnlyCollection<IImageFormat>(this.imageFormats);
 
+        /// <summary>
+        /// Gets or sets the global parallel options for processing tasks in parallel.
+        /// </summary>
+        public ParallelOptions ParallelOptions { get; set; } = new ParallelOptions { MaxDegreeOfParallelism = Environment.ProcessorCount };
+
         /// <summary>
         /// Adds a new <see cref="IImageFormat"/> to the collection of supported image formats.
         /// </summary>

src/ImageProcessorCore/Image/IImageProcessor.cs

@@ -3,6 +3,8 @@
 // Licensed under the Apache License, Version 2.0.
 // </copyright>
 
+using System.Threading.Tasks;
+
 namespace ImageProcessorCore.Processors
 {
     /// <summary>
@@ -26,6 +28,11 @@ namespace ImageProcessorCore.Processors
         /// </remarks>
         event ProgressEventHandler OnProgress;
 
+        /// <summary>
+        /// Gets or sets the global parallel options for processing tasks in parallel.
+        /// </summary>
+        ParallelOptions ParallelOptions { get; set; }
+
         /// <summary>
         /// Applies the process to the specified portion of the specified <see cref="ImageBase{T, TP}"/>.
         /// </summary>

src/ImageProcessorCore/ImageProcessor.cs

@@ -7,6 +7,7 @@ namespace ImageProcessorCore.Processors
 {
     using System;
     using System.Threading;
+    using System.Threading.Tasks;
 
     /// <summary>
     /// Allows the application of processors to images.
@@ -26,6 +27,9 @@ namespace ImageProcessorCore.Processors
         /// </summary>
         private int totalRows;
 
+        /// <inheritdoc/>
+        public virtual ParallelOptions ParallelOptions { get; set; } = Bootstrapper.Instance.ParallelOptions;
+
         /// <inheritdoc/>
         public void Apply<T, TP>(ImageBase<T, TP> target, ImageBase<T, TP> source, Rectangle sourceRectangle)
             where T : IPackedVector<TP>, new()

src/ImageProcessorCore/Samplers/Processors/ResizeProcessor.cs

@@ -84,6 +84,7 @@ namespace ImageProcessorCore.Processors
                     Parallel.For(
                         startY,
                         endY,
+                        this.ParallelOptions,
                         y =>
                             {
                                 if (targetY <= y && y < targetBottom)
@@ -122,6 +123,7 @@ namespace ImageProcessorCore.Processors
                 Parallel.For(
                     0,
                     sourceHeight,
+                    this.ParallelOptions,
                     y =>
                     {
                         for (int x = startX; x < endX; x++)
@@ -160,6 +162,7 @@ namespace ImageProcessorCore.Processors
                 Parallel.For(
                     startY,
                     endY,
+                    this.ParallelOptions,
                     y =>
                     {
                         if (y >= 0 && y < height)