Adding entropy crop to web

TODO: Unit tests

Former-commit-id: 91dffbbaeb62ae184dd3ecc5500db7a1d6b3321b

src/ImageProcessor.Web/Configuration/Resources/processing.config

@@ -7,8 +7,9 @@
     <plugin name="BackgroundColor" type="ImageProcessor.Web.Processors.BackgroundColor, ImageProcessor.Web"/>
     <plugin name="Brightness" type="ImageProcessor.Web.Processors.Brightness, ImageProcessor.Web"/>
     <plugin name="Contrast" type="ImageProcessor.Web.Processors.Contrast, ImageProcessor.Web"/>
-    <plugin name="DetectEdges" type="ImageProcessor.Web.Processors.DetectEdges, ImageProcessor.Web"/>
     <plugin name="Crop" type="ImageProcessor.Web.Processors.Crop, ImageProcessor.Web"/>
+    <plugin name="DetectEdges" type="ImageProcessor.Web.Processors.DetectEdges, ImageProcessor.Web"/>
+    <plugin name="EntropyCrop" type="ImageProcessor.Web.Processors.EntropyCrop, ImageProcessor.Web"/>
     <plugin name="Filter" type="ImageProcessor.Web.Processors.Filter, ImageProcessor.Web"/>
     <plugin name="Flip" type="ImageProcessor.Web.Processors.Flip, ImageProcessor.Web"/>
     <plugin name="Format" type="ImageProcessor.Web.Processors.Format, ImageProcessor.Web"/>   

src/ImageProcessor.Web/Helpers/CommonParameterParserUtility.cs

@@ -35,7 +35,7 @@ namespace ImageProcessor.Web.Helpers
         /// The regular expression to search strings for colors.
         /// </summary>
         private static readonly Regex ColorRegex = BuildColorRegex();
-
+ 
         /// <summary>
         /// The regular expression to search strings for angles.
         /// </summary>

src/ImageProcessor.Web/ImageProcessor.Web.csproj

@@ -47,6 +47,7 @@
   <ItemGroup>
     <Compile Include="Caching\CachedImage.cs" />
     <Compile Include="Processors\DetectEdges.cs" />
+    <Compile Include="Processors\EntropyCrop.cs" />
     <Compile Include="Services\IImageService.cs" />
     <Compile Include="Caching\MemCache.cs" />
     <Compile Include="Caching\DiskCache.cs" />

src/ImageProcessor.Web/Processors/Crop.cs

@@ -86,7 +86,8 @@ namespace ImageProcessor.Web.Processors
 
             foreach (Match match in this.RegexPattern.Matches(queryString))
             {
-                if (match.Success)
+                // Match but ignore entropy
+                if (match.Success && !queryString.ToUpperInvariant().Contains("ENTROPYCROP="))
                 {
                     if (index == 0)
                     {

src/ImageProcessor.Web/Processors/EntropyCrop.cs

@@ -0,0 +1,119 @@
+// --------------------------------------------------------------------------------------------------------------------
+// <copyright file="EntropyCrop.cs" company="James South">
+//   Copyright (c) James South.
+//   Licensed under the Apache License, Version 2.0.
+// </copyright>
+// <summary>
+//   Performs a crop on an image to the area of greatest entropy.
+// </summary>
+// --------------------------------------------------------------------------------------------------------------------
+
+namespace ImageProcessor.Web.Processors
+{
+    using System.Globalization;
+    using System.Text.RegularExpressions;
+
+    using ImageProcessor.Common.Extensions;
+    using ImageProcessor.Processors;
+
+    /// <summary>
+    /// Performs a crop on an image to the area of greatest entropy.
+    /// </summary>
+    public class EntropyCrop : IWebGraphicsProcessor
+    {
+        /// <summary>
+        /// The regular expression to search strings for.
+        /// </summary>
+        private static readonly Regex QueryRegex = new Regex(@"entropycrop=(\d+)[^&]+|entropycrop", RegexOptions.Compiled);
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="EntropyCrop"/> class.
+        /// </summary>
+        public EntropyCrop()
+        {
+            this.Processor = new ImageProcessor.Processors.EntropyCrop();
+        }
+
+        /// <summary>
+        /// Gets the regular expression to search strings for.
+        /// </summary>
+        public Regex RegexPattern
+        {
+            get
+            {
+                return QueryRegex;
+            }
+        }
+
+        /// <summary>
+        /// Gets the order in which this processor is to be used in a chain.
+        /// </summary>
+        public int SortOrder { get; private set; }
+
+        /// <summary>
+        /// Gets the associated graphics processor.
+        /// </summary>
+        public IGraphicsProcessor Processor { get; private set; }
+
+        /// <summary>
+        /// The position in the original string where the first character of the captured substring was found.
+        /// </summary>
+        /// <param name="queryString">The query string to search.</param>
+        /// <returns>
+        /// The zero-based starting position in the original string where the captured substring was found.
+        /// </returns>
+        public int MatchRegexIndex(string queryString)
+        {
+            int index = 0;
+
+            // Set the sort order to max to allow filtering.
+            this.SortOrder = int.MaxValue;
+
+            foreach (Match match in this.RegexPattern.Matches(queryString))
+            {
+                if (match.Success)
+                {
+                    if (index == 0)
+                    {
+                        // Set the index on the first instance only.
+                        this.SortOrder = match.Index;
+                        byte threshold = this.ParseThreshold(match.Value);
+                        this.Processor.DynamicParameter = threshold;
+                    }
+
+                    index += 1;
+                }
+            }
+
+            return this.SortOrder;
+        }
+
+        /// <summary>
+        /// Returns the correct <see cref="T:System.Int32"/> containing the radius for the given string.
+        /// </summary>
+        /// <param name="input">
+        /// The input string containing the value to parse.
+        /// </param>
+        /// <returns>
+        /// The correct <see cref="T:System.Int32"/> containing the radius for the given string.
+        /// </returns>
+        private byte ParseThreshold(string input)
+        {
+            foreach (Match match in QueryRegex.Matches(input))
+            {
+                if (!match.Value.Contains("="))
+                {
+                    continue;
+                }
+
+                // Split on threshold
+                int threshold;
+                int.TryParse(match.Value.Split('=')[1], NumberStyles.Any, CultureInfo.InvariantCulture, out threshold);
+                return threshold.ToByte();
+            }
+
+            // No threshold - matches the EntropyCrop default.
+            return 128;
+        }
+    }
+}

src/TestWebsites/MVC/config/imageprocessor/processing.config

@@ -9,6 +9,7 @@
     <plugin name="Contrast" type="ImageProcessor.Web.Processors.Contrast, ImageProcessor.Web"/>
     <plugin name="Crop" type="ImageProcessor.Web.Processors.Crop, ImageProcessor.Web"/>
     <plugin name="DetectEdges" type="ImageProcessor.Web.Processors.DetectEdges, ImageProcessor.Web"/>
+    <plugin name="EntropyCrop" type="ImageProcessor.Web.Processors.EntropyCrop, ImageProcessor.Web"/>
     <plugin name="Filter" type="ImageProcessor.Web.Processors.Filter, ImageProcessor.Web"/>
     <plugin name="Flip" type="ImageProcessor.Web.Processors.Flip, ImageProcessor.Web"/>
     <plugin name="Format" type="ImageProcessor.Web.Processors.Format, ImageProcessor.Web"/>