Do not dispose of source Fix #404

Former-commit-id: 5bcb4977e45de08f9c1c0c15583dc5140356609f
Former-commit-id: 5f21f6f1488a284413427231b76e0ad71eca9240
Former-commit-id: 8a227c50ce892ce7a1189015f3a2bbbb26c6e20d

src/ImageProcessorCore/ImageBase.cs

@@ -41,7 +41,7 @@ namespace ImageProcessorCore
         /// method will not dispose again. This help not to prolong the entity's
         /// life in the Garbage Collector.
         /// </remarks>
-        protected bool IsDisposed;
+        internal bool IsDisposed;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageBase"/> class.

src/ImageProcessorCore/ImageExtensions.cs

@@ -78,9 +78,7 @@ namespace ImageProcessorCore
         /// <returns>The <see cref="Image"/>.</returns>
         public static Image Process(this Image source, Rectangle sourceRectangle, IImageProcessor processor)
         {
-            source = PerformAction(source, true, (sourceImage, targetImage) => processor.Apply(targetImage, sourceImage, sourceRectangle));
-
-            return source;
+            return PerformAction(source, true, (sourceImage, targetImage) => processor.Apply(targetImage, sourceImage, sourceRectangle));
         }
 
         /// <summary>
@@ -94,7 +92,7 @@ namespace ImageProcessorCore
         /// <param name="height">The target image height.</param>
         /// <param name="sampler">The processor to apply to the image.</param>
         /// <returns>The <see cref="Image"/>.</returns>
-        internal static Image Process(this Image source, int width, int height, IImageSampler sampler)
+        public static Image Process(this Image source, int width, int height, IImageSampler sampler)
         {
             return Process(source, width, height, source.Bounds, default(Rectangle), sampler);
         }
@@ -102,8 +100,7 @@ namespace ImageProcessorCore
         /// <summary>
         /// Applies the collection of processors to the image.
         /// <remarks>
-        /// This method does will resize the target image if the source and target
-        /// rectangles are different.
+        /// This method does will resize the target image if the source and target rectangles are different.
         /// </remarks>
         /// </summary>
         /// <param name="source">The source image. Cannot be null.</param>
@@ -120,9 +117,7 @@ namespace ImageProcessorCore
         /// <returns>The <see cref="Image"/>.</returns>
         public static Image Process(this Image source, int width, int height, Rectangle sourceRectangle, Rectangle targetRectangle, IImageSampler sampler)
         {
-            source = PerformAction(source, false, (sourceImage, targetImage) => sampler.Apply(targetImage, sourceImage, width, height, targetRectangle, sourceRectangle));
-
-            return source;
+           return PerformAction(source, false, (sourceImage, targetImage) => sampler.Apply(targetImage, sourceImage, width, height, targetRectangle, sourceRectangle));
         }
 
         /// <summary>
@@ -134,6 +129,11 @@ namespace ImageProcessorCore
         /// <returns>The <see cref="Image"/>.</returns>
         private static Image PerformAction(Image source, bool clone, Action<ImageBase, ImageBase> action)
         {
+            if (source.IsDisposed)
+            {
+                throw new ObjectDisposedException("Image");
+            }
+
             Image transformedImage = clone
                 ? new Image(source)
                 : new Image
@@ -165,9 +165,11 @@ namespace ImageProcessorCore
                 }
             }
 
-            // Clean up.
-            source.Dispose();
-            return transformedImage;
+            // According to http://stackoverflow.com/questions/37921815/idisposable-unmanaged-fields-reference-types-and-assignments/37922955#37922955
+            // There's no need to dispose of the original image as the GC will get around to cleaning it up now there are no references to the original data.
+            // TODO: Investigate how log this is held onto and try to keep that to a minimum.
+            source = transformedImage;
+            return source;
         }
     }
 }

tests/ImageProcessorCore.Tests/Processors/Samplers/SamplerTests.cs

@@ -388,6 +388,42 @@
             }
         }
 
+        [Fact]
+        public void ImageShouldNotDispose()
+        {
+            if (!Directory.Exists("TestOutput/Dispose"))
+            {
+                Directory.CreateDirectory("TestOutput/Dispose");
+            }
+
+            foreach (string file in Files)
+            {
+                using (FileStream stream = File.OpenRead(file))
+                {
+                    Stopwatch watch = Stopwatch.StartNew();
+                    string filename = Path.GetFileName(file);
+
+                    Image image = new Image(stream);
+                    image = image.BackgroundColor(Color.RebeccaPurple);
+                    using (FileStream output = File.OpenWrite($"TestOutput/Dispose/{filename}"))
+                    {
+                        ResizeOptions options = new ResizeOptions()
+                        {
+                            Size = new Size(image.Width - 200, image.Height),
+                            Mode = ResizeMode.Stretch
+                        };
+
+                        image.Resize(options, this.ProgressUpdate)
+                             .Save(output);
+                    }
+
+                    image.Dispose();
+
+                    Trace.WriteLine($"{filename}: {watch.ElapsedMilliseconds}ms");
+                }
+            }
+        }
+
         [Theory]
         [MemberData("RotateFlips")]
         public void ImageShouldRotateFlip(RotateType rotateType, FlipType flipType)