mirror of https://github.com/SixLabors/ImageSharp
James South
12 years ago
14 changed files with 338 additions and 36 deletions
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// --------------------------------------------------------------------------------------------------------------------
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// <copyright file="DetectEdges.cs" company="James South">
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// Copyright (c) James South.
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// Licensed under the Apache License, Version 2.0.
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// </copyright>
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// <summary>
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// Produces an image with the detected edges highlighted.
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// </summary>
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// --------------------------------------------------------------------------------------------------------------------
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namespace ImageProcessor.Web.Processors |
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{ |
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using System; |
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using System.Collections.Generic; |
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using System.Linq; |
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using System.Reflection; |
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using System.Text; |
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using System.Text.RegularExpressions; |
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using System.Web.Compilation; |
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using ImageProcessor.Common.Extensions; |
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using ImageProcessor.Imaging.Filters.EdgeDetection; |
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using ImageProcessor.Processors; |
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/// <summary>
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/// Produces an image with the detected edges highlighted.
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/// </summary>
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public class DetectEdges : IWebGraphicsProcessor |
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{ |
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/// <summary>
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/// The regular expression to search strings for.
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/// </summary>
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private static readonly Regex QueryRegex = BuildRegex(); |
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/// <summary>
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/// The regular expression to search strings for the greyscale attribute.
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/// </summary>
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private static readonly Regex GreyscaleRegex = new Regex(@"greyscale=false", RegexOptions.Compiled); |
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/// <summary>
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/// The edge detectors.
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/// </summary>
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private static Dictionary<string, object> detectors; |
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/// <summary>
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/// Initializes a new instance of the <see cref="DetectEdges"/> class.
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/// </summary>
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public DetectEdges() |
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{ |
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this.Processor = new ImageProcessor.Processors.DetectEdges(); |
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} |
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/// <summary>
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/// Gets the regular expression to search strings for.
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/// </summary>
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public Regex RegexPattern |
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{ |
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get |
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{ |
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return QueryRegex; |
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} |
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} |
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/// <summary>
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/// Gets the order in which this processor is to be used in a chain.
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/// </summary>
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public int SortOrder { get; private set; } |
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/// <summary>
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/// Gets the processor.
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/// </summary>
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/// <value>
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/// The processor.
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/// </value>
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public IGraphicsProcessor Processor { get; private set; } |
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/// <summary>
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/// The position in the original string where the first character of the captured substring was found.
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/// </summary>
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/// <param name="queryString">
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/// The query string to search.
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/// </param>
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/// <returns>
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/// The zero-based starting position in the original string where the captured substring was found.
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/// </returns>
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public int MatchRegexIndex(string queryString) |
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{ |
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int index = 0; |
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// Set the sort order to max to allow filtering.
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this.SortOrder = int.MaxValue; |
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// First merge the matches so we can parse .
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StringBuilder stringBuilder = new StringBuilder(); |
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foreach (Match match in this.RegexPattern.Matches(queryString)) |
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{ |
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if (match.Success) |
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{ |
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if (index == 0) |
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{ |
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// Set the index on the first instance only.
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this.SortOrder = match.Index; |
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stringBuilder.Append(queryString); |
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} |
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index += 1; |
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} |
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} |
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if (this.SortOrder < int.MaxValue) |
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{ |
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// Match syntax
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string toParse = stringBuilder.ToString(); |
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IEdgeFilter filter = this.ParseFilter(toParse); |
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bool greyscale = !GreyscaleRegex.IsMatch(toParse); |
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this.Processor.DynamicParameter = new Tuple<IEdgeFilter, bool>(filter, greyscale); |
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} |
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return this.SortOrder; |
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} |
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/// <summary>
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/// Builds a regular expression from the <see cref="IEdgeFilter"/> type, this allows extensibility.
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/// </summary>
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/// <returns>
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/// The <see cref="Regex"/> to match matrix filters.
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/// </returns>
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private static Regex BuildRegex() |
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{ |
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StringBuilder stringBuilder = new StringBuilder(); |
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stringBuilder.Append("detectedges=("); |
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Type type = typeof(IEdgeFilter); |
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// Build a list of native IEdgeFilter instances.
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detectors = BuildManager.GetReferencedAssemblies() |
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.Cast<Assembly>() |
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.SelectMany(s => s.GetLoadableTypes()) |
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.Where(t => type.IsAssignableFrom(t) && t.IsClass && !t.IsAbstract) |
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.ToDictionary(t => t.Name.ToLowerInvariant().Replace("edgefilter", string.Empty), Activator.CreateInstance); |
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stringBuilder.Append(string.Join("|", detectors.Keys.ToList())); |
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stringBuilder.Append(")"); |
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return new Regex(stringBuilder.ToString(), RegexOptions.IgnoreCase); |
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} |
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/// <summary>
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/// Parses the input string to return the correct <see cref="IEdgeFilter"/>.
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/// </summary>
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/// <param name="identifier">
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/// The identifier.
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/// </param>
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/// <returns>
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/// The <see cref="IEdgeFilter"/>.
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/// </returns>
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private IEdgeFilter ParseFilter(string identifier) |
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{ |
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return (IEdgeFilter)detectors[this.RegexPattern.Match(identifier).Value.Split('=')[1]]; |
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} |
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} |
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} |
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