ImageSharp/src/ImageProcessor/Processors/Crop.cs

// -----------------------------------------------------------------------
// <copyright file="Crop.cs" company="James South">
// TODO: Update copyright text.
// </copyright>
// -----------------------------------------------------------------------

namespace ImageProcessor.Processors
{
    #region Using
    using System.Collections.Generic;
    using System.Drawing;
    using System.Drawing.Drawing2D;
    using System.Drawing.Imaging;
    using System.Text.RegularExpressions;
    using ImageProcessor.Helpers.Extensions;
    #endregion

    /// <summary>
    /// Crops an image to the given directions.
    /// </summary>
    public class Crop : IGraphicsProcessor
    {
        /// <summary>
        /// The regular expression to search strings for.
        /// http://stackoverflow.com/a/6400969/427899
        /// </summary>
        private static readonly Regex QueryRegex = new Regex(@"crop=\d+-\d+-\d+-\d+", RegexOptions.Compiled);

        #region IGraphicsProcessor Members
        /// <summary>
        /// Gets the name.
        /// </summary>
        public string Name
        {
            get
            {
                return "Crop";
            }
        }

        /// <summary>
        /// Gets the description.
        /// </summary>
        public string Description
        {
            get
            {
                return "Crops an image to the given directions.";
            }
        }

        /// <summary>
        /// Gets the regular expression to search strings for.
        /// </summary>
        public Regex RegexPattern
        {
            get
            {
                return QueryRegex;
            }
        }

        /// <summary>
        /// Gets or sets DynamicParameter.
        /// </summary>
        public dynamic DynamicParameter
        {
            get;
            set;
        }

        /// <summary>
        /// Gets the order in which this processor is to be used in a chain.
        /// </summary>
        public int SortOrder
        {
            get;
            private set;
        }

        /// <summary>
        /// Gets or sets any additional settings required by the processor.
        /// </summary>
        public Dictionary<string, string> Settings
        {
            get;
            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;
                        int[] coordinates = match.Value.ToIntegerArray();

                        int x = coordinates[0];
                        int y = coordinates[1];
                        int width = coordinates[2];
                        int height = coordinates[3];

                        Rectangle rectangle = new Rectangle(x, y, width, height);
                        this.DynamicParameter = rectangle;
                    }

                    index += 1;
                }
            }

            return this.SortOrder;
        }

        /// <summary>
        /// Processes the image.
        /// </summary>
        /// <param name="factory">
        /// The the current instance of the <see cref="T:ImageProcessor.ImageFactory"/> class containing
        /// the image to process.
        /// </param>
        /// <returns>
        /// The processed image from the current instance of the <see cref="T:ImageProcessor.ImageFactory"/> class.
        /// </returns>
        public Image ProcessImage(ImageFactory factory)
        {
            Bitmap newImage = null;
            Image image = factory.Image;
            try
            {
                Rectangle rectangle = this.DynamicParameter;

                int sourceWidth = image.Width;
                int sourceHeight = image.Height;

                if (rectangle.X < sourceWidth && rectangle.Y < sourceHeight)
                {
                    if (rectangle.Width > (sourceWidth - rectangle.X))
                    {
                        rectangle.Width = sourceWidth - rectangle.X;
                    }

                    if (rectangle.Height > (sourceHeight - rectangle.Y))
                    {
                        rectangle.Height = sourceHeight - rectangle.Y;
                    }

                    newImage = new Bitmap(rectangle.Width, rectangle.Height, PixelFormat.Format32bppPArgb) { Tag = image.Tag };

                    using (Graphics graphics = Graphics.FromImage(newImage))
                    {
                        graphics.SmoothingMode = SmoothingMode.AntiAlias;
                        graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
                        graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
                        graphics.CompositingQuality = CompositingQuality.HighQuality;

                        // An unwanted border appears when using InterpolationMode.HighQualityBicubic to resize the image
                        // as the algorithm appears to be pulling averaging detail from surrounding pixels beyond the edge 
                        // of the image. Using the ImageAttributes class to specify that the pixels beyond are simply mirror 
                        // images of the pixels within solves this problem.
                        using (ImageAttributes wrapMode = new ImageAttributes())
                        {
                            wrapMode.SetWrapMode(WrapMode.TileFlipXY);
                            graphics.DrawImage(
                                image,
                                new Rectangle(0, 0, rectangle.Width, rectangle.Height),
                                rectangle.X,
                                rectangle.Y,
                                rectangle.Width,
                                rectangle.Height,
                                GraphicsUnit.Pixel,
                                wrapMode);
                        }

                        // Reassign the image.
                        image.Dispose();
                        image = newImage;
                    }
                }
            }
            catch
            {
                if (newImage != null)
                {
                    newImage.Dispose();
                }
            }

            return image;
        }
        #endregion
    }
}