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TODO: Unit tests Former-commit-id: 91dffbbaeb62ae184dd3ecc5500db7a1d6b3321bpull/17/head
James South
12 years ago
6 changed files with 126 additions and 3 deletions
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// --------------------------------------------------------------------------------------------------------------------
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// <copyright file="EntropyCrop.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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// Performs a crop on an image to the area of greatest entropy.
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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.Globalization; |
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using System.Text.RegularExpressions; |
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using ImageProcessor.Common.Extensions; |
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using ImageProcessor.Processors; |
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/// <summary>
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/// Performs a crop on an image to the area of greatest entropy.
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/// </summary>
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public class EntropyCrop : 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 = new Regex(@"entropycrop=(\d+)[^&]+|entropycrop", RegexOptions.Compiled); |
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/// <summary>
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/// Initializes a new instance of the <see cref="EntropyCrop"/> class.
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/// </summary>
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public EntropyCrop() |
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{ |
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this.Processor = new ImageProcessor.Processors.EntropyCrop(); |
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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 associated graphics processor.
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/// </summary>
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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">The query string to search.</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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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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byte threshold = this.ParseThreshold(match.Value); |
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this.Processor.DynamicParameter = threshold; |
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} |
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index += 1; |
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} |
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} |
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return this.SortOrder; |
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} |
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/// <summary>
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/// Returns the correct <see cref="T:System.Int32"/> containing the radius for the given string.
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/// </summary>
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/// <param name="input">
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/// The input string containing the value to parse.
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/// </param>
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/// <returns>
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/// The correct <see cref="T:System.Int32"/> containing the radius for the given string.
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/// </returns>
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private byte ParseThreshold(string input) |
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{ |
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foreach (Match match in QueryRegex.Matches(input)) |
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{ |
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if (!match.Value.Contains("=")) |
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{ |
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continue; |
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} |
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// Split on threshold
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int threshold; |
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int.TryParse(match.Value.Split('=')[1], NumberStyles.Any, CultureInfo.InvariantCulture, out threshold); |
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return threshold.ToByte(); |
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} |
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// No threshold - matches the EntropyCrop default.
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return 128; |
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} |
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} |
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} |
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