moved image manager to an interface

MediaBrowser.Server.Implementations/Drawing/ImageProcessor.cs

@@ -0,0 +1,752 @@
+using System.Collections.Generic;
+using System.Drawing;
+using System.Drawing.Drawing2D;
+using System.Drawing.Imaging;
+using System.Globalization;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using MediaBrowser.Common.Extensions;
+using MediaBrowser.Common.IO;
+using MediaBrowser.Controller;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Drawing;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Providers;
+using MediaBrowser.Model.Drawing;
+using System;
+using System.Collections.Concurrent;
+using System.IO;
+using MediaBrowser.Model.Entities;
+using MediaBrowser.Model.Logging;
+
+namespace MediaBrowser.Server.Implementations.Drawing
+{
+    /// <summary>
+    /// Class ImageProcessor
+    /// </summary>
+    public class ImageProcessor : IImageProcessor
+    {
+        /// <summary>
+        /// The us culture
+        /// </summary>
+        protected readonly CultureInfo UsCulture = new CultureInfo("en-US");
+
+        /// <summary>
+        /// The _cached imaged sizes
+        /// </summary>
+        private readonly ConcurrentDictionary<string, ImageSize> _cachedImagedSizes = new ConcurrentDictionary<string, ImageSize>();
+
+        /// <summary>
+        /// Gets the list of currently registered image processors
+        /// Image processors are specialized metadata providers that run after the normal ones
+        /// </summary>
+        /// <value>The image enhancers.</value>
+        public IEnumerable<IImageEnhancer> ImageEnhancers { get; private set; }
+
+        /// <summary>
+        /// The _logger
+        /// </summary>
+        private readonly ILogger _logger;
+        /// <summary>
+        /// The _app paths
+        /// </summary>
+        private readonly IServerApplicationPaths _appPaths;
+
+        private readonly string _imageSizeCachePath;
+        private readonly string _croppedWhitespaceImageCachePath;
+        private readonly string _enhancedImageCachePath;
+        private readonly string _resizedImageCachePath;
+
+        public ImageProcessor(ILogger logger, IServerApplicationPaths appPaths)
+        {
+            _logger = logger;
+            _appPaths = appPaths;
+
+            _imageSizeCachePath = Path.Combine(_appPaths.ImageCachePath, "image-sizes");
+            _croppedWhitespaceImageCachePath = Path.Combine(_appPaths.ImageCachePath, "cropped-images");
+            _enhancedImageCachePath = Path.Combine(_appPaths.ImageCachePath, "enhanced-images");
+            _resizedImageCachePath = Path.Combine(_appPaths.ImageCachePath, "resized-images");
+        }
+
+        public void AddParts(IEnumerable<IImageEnhancer> enhancers)
+        {
+            ImageEnhancers = enhancers.ToArray();
+        }
+
+        public async Task ProcessImage(BaseItem entity, ImageType imageType, int imageIndex, string originalImagePath, bool cropWhitespace, DateTime dateModified, Stream toStream, int? width, int? height, int? maxWidth, int? maxHeight, int? quality, List<IImageEnhancer> enhancers)
+        {
+            if (entity == null)
+            {
+                throw new ArgumentNullException("entity");
+            }
+
+            if (toStream == null)
+            {
+                throw new ArgumentNullException("toStream");
+            }
+
+            if (cropWhitespace)
+            {
+                originalImagePath = await GetWhitespaceCroppedImage(originalImagePath, dateModified).ConfigureAwait(false);
+            }
+
+            // No enhancement - don't cache
+            if (enhancers.Count > 0)
+            {
+                try
+                {
+                    // Enhance if we have enhancers
+                    var ehnancedImagePath = await GetEnhancedImage(originalImagePath, dateModified, entity, imageType, imageIndex, enhancers).ConfigureAwait(false);
+
+                    // If the path changed update dateModified
+                    if (!ehnancedImagePath.Equals(originalImagePath, StringComparison.OrdinalIgnoreCase))
+                    {
+                        dateModified = File.GetLastWriteTimeUtc(ehnancedImagePath);
+                        originalImagePath = ehnancedImagePath;
+                    }
+                }
+                catch (Exception ex)
+                {
+                    _logger.Error("Error enhancing image", ex);
+                }
+            }
+
+            var originalImageSize = GetImageSize(originalImagePath, dateModified);
+
+            // Determine the output size based on incoming parameters
+            var newSize = DrawingUtils.Resize(originalImageSize, width, height, maxWidth, maxHeight);
+
+            if (!quality.HasValue)
+            {
+                quality = 90;
+            }
+
+            var cacheFilePath = GetCacheFilePath(originalImagePath, newSize, quality.Value, dateModified);
+
+            try
+            {
+                using (var fileStream = new FileStream(cacheFilePath, FileMode.Open, FileAccess.Read, FileShare.Read, StreamDefaults.DefaultFileStreamBufferSize, FileOptions.Asynchronous))
+                {
+                    await fileStream.CopyToAsync(toStream).ConfigureAwait(false);
+                    return;
+                }
+            }
+            catch (IOException)
+            {
+                // Cache file doesn't exist or is currently being written ro
+            }
+
+            var semaphore = GetLock(cacheFilePath);
+
+            await semaphore.WaitAsync().ConfigureAwait(false);
+
+            // Check again in case of lock contention
+            if (File.Exists(cacheFilePath))
+            {
+                try
+                {
+                    using (var fileStream = new FileStream(cacheFilePath, FileMode.Open, FileAccess.Read, FileShare.Read, StreamDefaults.DefaultFileStreamBufferSize, FileOptions.Asynchronous))
+                    {
+                        await fileStream.CopyToAsync(toStream).ConfigureAwait(false);
+                        return;
+                    }
+                }
+                finally
+                {
+                    semaphore.Release();
+                }
+            }
+
+            try
+            {
+                using (var fileStream = new FileStream(originalImagePath, FileMode.Open, FileAccess.Read, FileShare.Read, StreamDefaults.DefaultFileStreamBufferSize, true))
+                {
+                    // Copy to memory stream to avoid Image locking file
+                    using (var memoryStream = new MemoryStream())
+                    {
+                        await fileStream.CopyToAsync(memoryStream).ConfigureAwait(false);
+
+                        using (var originalImage = Image.FromStream(memoryStream, true, false))
+                        {
+                            var newWidth = Convert.ToInt32(newSize.Width);
+                            var newHeight = Convert.ToInt32(newSize.Height);
+
+                            // Graphics.FromImage will throw an exception if the PixelFormat is Indexed, so we need to handle that here
+                            using (var thumbnail = !ImageExtensions.IsPixelFormatSupportedByGraphicsObject(originalImage.PixelFormat) ? new Bitmap(originalImage, newWidth, newHeight) : new Bitmap(newWidth, newHeight, originalImage.PixelFormat))
+                            {
+                                // Preserve the original resolution
+                                thumbnail.SetResolution(originalImage.HorizontalResolution, originalImage.VerticalResolution);
+
+                                using (var thumbnailGraph = Graphics.FromImage(thumbnail))
+                                {
+                                    thumbnailGraph.CompositingQuality = CompositingQuality.HighQuality;
+                                    thumbnailGraph.SmoothingMode = SmoothingMode.HighQuality;
+                                    thumbnailGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
+                                    thumbnailGraph.PixelOffsetMode = PixelOffsetMode.HighQuality;
+                                    thumbnailGraph.CompositingMode = CompositingMode.SourceOver;
+
+                                    thumbnailGraph.DrawImage(originalImage, 0, 0, newWidth, newHeight);
+
+                                    var outputFormat = originalImage.RawFormat;
+
+                                    using (var outputMemoryStream = new MemoryStream())
+                                    {
+                                        // Save to the memory stream
+                                        thumbnail.Save(outputFormat, outputMemoryStream, quality.Value);
+
+                                        var bytes = outputMemoryStream.ToArray();
+
+                                        var outputTask = toStream.WriteAsync(bytes, 0, bytes.Length);
+
+                                        // kick off a task to cache the result
+                                        var cacheTask = CacheResizedImage(cacheFilePath, bytes);
+
+                                        await Task.WhenAll(outputTask, cacheTask).ConfigureAwait(false);
+                                    }
+                                }
+                            }
+
+                        }
+                    }
+                }
+            }
+            finally
+            {
+                semaphore.Release();
+            }
+        }
+
+        /// <summary>
+        /// Crops whitespace from an image, caches the result, and returns the cached path
+        /// </summary>
+        /// <param name="originalImagePath">The original image path.</param>
+        /// <param name="dateModified">The date modified.</param>
+        /// <returns>System.String.</returns>
+        private async Task<string> GetWhitespaceCroppedImage(string originalImagePath, DateTime dateModified)
+        {
+            var name = originalImagePath;
+            name += "datemodified=" + dateModified.Ticks;
+
+            var croppedImagePath = GetCachePath(_croppedWhitespaceImageCachePath, name, Path.GetExtension(originalImagePath));
+
+            var semaphore = GetLock(croppedImagePath);
+
+            await semaphore.WaitAsync().ConfigureAwait(false);
+
+            // Check again in case of contention
+            if (File.Exists(croppedImagePath))
+            {
+                semaphore.Release();
+                return croppedImagePath;
+            }
+
+            try
+            {
+                using (var fileStream = new FileStream(originalImagePath, FileMode.Open, FileAccess.Read, FileShare.Read, StreamDefaults.DefaultFileStreamBufferSize, true))
+                {
+                    // Copy to memory stream to avoid Image locking file
+                    using (var memoryStream = new MemoryStream())
+                    {
+                        await fileStream.CopyToAsync(memoryStream).ConfigureAwait(false);
+
+                        using (var originalImage = (Bitmap)Image.FromStream(memoryStream, true, false))
+                        {
+                            var outputFormat = originalImage.RawFormat;
+
+                            using (var croppedImage = originalImage.CropWhitespace())
+                            {
+                                var parentPath = Path.GetDirectoryName(croppedImagePath);
+
+                                if (!Directory.Exists(parentPath))
+                                {
+                                    Directory.CreateDirectory(parentPath);
+                                }
+
+                                using (var outputStream = new FileStream(croppedImagePath, FileMode.Create, FileAccess.Write, FileShare.Read))
+                                {
+                                    croppedImage.Save(outputFormat, outputStream, 100);
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                // We have to have a catch-all here because some of the .net image methods throw a plain old Exception
+                _logger.ErrorException("Error cropping image {0}", ex, originalImagePath);
+
+                return originalImagePath;
+            }
+            finally
+            {
+                semaphore.Release();
+            }
+
+            return croppedImagePath;
+        }
+
+        /// <summary>
+        /// Caches the resized image.
+        /// </summary>
+        /// <param name="cacheFilePath">The cache file path.</param>
+        /// <param name="bytes">The bytes.</param>
+        private async Task CacheResizedImage(string cacheFilePath, byte[] bytes)
+        {
+            var parentPath = Path.GetDirectoryName(cacheFilePath);
+
+            if (!Directory.Exists(parentPath))
+            {
+                Directory.CreateDirectory(parentPath);
+            }
+
+            // Save to the cache location
+            using (var cacheFileStream = new FileStream(cacheFilePath, FileMode.Create, FileAccess.Write, FileShare.Read, StreamDefaults.DefaultFileStreamBufferSize, FileOptions.Asynchronous))
+            {
+                // Save to the filestream
+                await cacheFileStream.WriteAsync(bytes, 0, bytes.Length).ConfigureAwait(false);
+            }
+        }
+
+        /// <summary>
+        /// Gets the cache file path based on a set of parameters
+        /// </summary>
+        /// <param name="originalPath">The path to the original image file</param>
+        /// <param name="outputSize">The size to output the image in</param>
+        /// <param name="quality">Quality level, from 0-100. Currently only applies to JPG. The default value should suffice.</param>
+        /// <param name="dateModified">The last modified date of the image</param>
+        /// <returns>System.String.</returns>
+        private string GetCacheFilePath(string originalPath, ImageSize outputSize, int quality, DateTime dateModified)
+        {
+            var filename = originalPath;
+
+            filename += "width=" + outputSize.Width;
+
+            filename += "height=" + outputSize.Height;
+
+            filename += "quality=" + quality;
+
+            filename += "datemodified=" + dateModified.Ticks;
+
+            return GetCachePath(_resizedImageCachePath, filename, Path.GetExtension(originalPath));
+        }
+
+        /// <summary>
+        /// Gets the size of the image.
+        /// </summary>
+        /// <param name="path">The path.</param>
+        /// <returns>ImageSize.</returns>
+        public ImageSize GetImageSize(string path)
+        {
+            return GetImageSize(path, File.GetLastWriteTimeUtc(path));
+        }
+
+        /// <summary>
+        /// Gets the size of the image.
+        /// </summary>
+        /// <param name="path">The path.</param>
+        /// <param name="imageDateModified">The image date modified.</param>
+        /// <returns>ImageSize.</returns>
+        /// <exception cref="System.ArgumentNullException">path</exception>
+        public ImageSize GetImageSize(string path, DateTime imageDateModified)
+        {
+            if (string.IsNullOrEmpty(path))
+            {
+                throw new ArgumentNullException("path");
+            }
+
+            var name = path + "datemodified=" + imageDateModified.Ticks;
+
+            ImageSize size;
+
+            if (!_cachedImagedSizes.TryGetValue(name, out size))
+            {
+                size = GetImageSizeInternal(name, path);
+
+                _cachedImagedSizes.AddOrUpdate(name, size, (keyName, oldValue) => size);
+            }
+
+            return size;
+        }
+
+        /// <summary>
+        /// Gets the image size internal.
+        /// </summary>
+        /// <param name="cacheKey">The cache key.</param>
+        /// <param name="path">The path.</param>
+        /// <returns>ImageSize.</returns>
+        private ImageSize GetImageSizeInternal(string cacheKey, string path)
+        {
+            // Now check the file system cache
+            var fullCachePath = GetCachePath(_imageSizeCachePath, cacheKey, ".txt");
+
+            try
+            {
+                var result = File.ReadAllText(fullCachePath).Split('|').Select(i => double.Parse(i, UsCulture)).ToArray();
+
+                return new ImageSize { Width = result[0], Height = result[1] };
+            }
+            catch (IOException)
+            {
+                // Cache file doesn't exist or is currently being written to
+            }
+
+            var syncLock = GetObjectLock(fullCachePath);
+
+            lock (syncLock)
+            {
+                try
+                {
+                    var result = File.ReadAllText(fullCachePath)
+                        .Split('|')
+                        .Select(i => double.Parse(i, UsCulture))
+                        .ToArray();
+
+                    return new ImageSize { Width = result[0], Height = result[1] };
+                }
+                catch (FileNotFoundException)
+                {
+                    // Cache file doesn't exist no biggie
+                }
+                catch (DirectoryNotFoundException)
+                {
+                    // Cache file doesn't exist no biggie
+                }
+
+                var size = ImageHeader.GetDimensions(path, _logger);
+
+                var parentPath = Path.GetDirectoryName(fullCachePath);
+
+                if (!Directory.Exists(parentPath))
+                {
+                    Directory.CreateDirectory(parentPath);
+                }
+
+                // Update the file system cache
+                File.WriteAllText(fullCachePath, size.Width.ToString(UsCulture) + @"|" + size.Height.ToString(UsCulture));
+
+                return new ImageSize { Width = size.Width, Height = size.Height };
+            }
+        }
+
+        /// <summary>
+        /// Gets the image cache tag.
+        /// </summary>
+        /// <param name="item">The item.</param>
+        /// <param name="imageType">Type of the image.</param>
+        /// <param name="imagePath">The image path.</param>
+        /// <returns>Guid.</returns>
+        /// <exception cref="System.ArgumentNullException">item</exception>
+        public Guid GetImageCacheTag(BaseItem item, ImageType imageType, string imagePath)
+        {
+            if (item == null)
+            {
+                throw new ArgumentNullException("item");
+            }
+
+            if (string.IsNullOrEmpty(imagePath))
+            {
+                throw new ArgumentNullException("imagePath");
+            }
+
+            var dateModified = item.GetImageDateModified(imagePath);
+
+            var supportedEnhancers = GetSupportedEnhancers(item, imageType).ToList();
+
+            return GetImageCacheTag(item, imageType, imagePath, dateModified, supportedEnhancers);
+        }
+
+        /// <summary>
+        /// Gets the image cache tag.
+        /// </summary>
+        /// <param name="item">The item.</param>
+        /// <param name="imageType">Type of the image.</param>
+        /// <param name="originalImagePath">The original image path.</param>
+        /// <param name="dateModified">The date modified of the original image file.</param>
+        /// <param name="imageEnhancers">The image enhancers.</param>
+        /// <returns>Guid.</returns>
+        /// <exception cref="System.ArgumentNullException">item</exception>
+        public Guid GetImageCacheTag(BaseItem item, ImageType imageType, string originalImagePath, DateTime dateModified, IEnumerable<IImageEnhancer> imageEnhancers)
+        {
+            if (item == null)
+            {
+                throw new ArgumentNullException("item");
+            }
+
+            if (imageEnhancers == null)
+            {
+                throw new ArgumentNullException("imageEnhancers");
+            }
+
+            if (string.IsNullOrEmpty(originalImagePath))
+            {
+                throw new ArgumentNullException("originalImagePath");
+            }
+
+            // Cache name is created with supported enhancers combined with the last config change so we pick up new config changes
+            var cacheKeys = imageEnhancers.Select(i => i.GetConfigurationCacheKey(item, imageType)).ToList();
+            cacheKeys.Add(originalImagePath + dateModified.Ticks);
+
+            return string.Join("|", cacheKeys.ToArray()).GetMD5();
+        }
+
+        /// <summary>
+        /// Gets the enhanced image.
+        /// </summary>
+        /// <param name="originalImagePath">The original image path.</param>
+        /// <param name="dateModified">The date modified.</param>
+        /// <param name="item">The item.</param>
+        /// <param name="imageType">Type of the image.</param>
+        /// <param name="imageIndex">Index of the image.</param>
+        /// <returns>Task{System.String}.</returns>
+        /// <exception cref="System.ArgumentNullException">item</exception>
+        public Task<string> GetEnhancedImage(string originalImagePath, DateTime dateModified, BaseItem item, ImageType imageType, int imageIndex)
+        {
+            if (item == null)
+            {
+                throw new ArgumentNullException("item");
+            }
+
+            var supportedImageEnhancers = ImageEnhancers.Where(i =>
+            {
+                try
+                {
+                    return i.Supports(item, imageType);
+                }
+                catch (Exception ex)
+                {
+                    _logger.ErrorException("Error in image enhancer: {0}", ex, i.GetType().Name);
+
+                    return false;
+                }
+
+            }).ToList();
+
+            return GetEnhancedImage(originalImagePath, dateModified, item, imageType, imageIndex, supportedImageEnhancers);
+        }
+
+        /// <summary>
+        /// Runs an image through the image enhancers, caches the result, and returns the cached path
+        /// </summary>
+        /// <param name="originalImagePath">The original image path.</param>
+        /// <param name="dateModified">The date modified of the original image file.</param>
+        /// <param name="item">The item.</param>
+        /// <param name="imageType">Type of the image.</param>
+        /// <param name="imageIndex">Index of the image.</param>
+        /// <param name="supportedEnhancers">The supported enhancers.</param>
+        /// <returns>System.String.</returns>
+        /// <exception cref="System.ArgumentNullException">originalImagePath</exception>
+        public async Task<string> GetEnhancedImage(string originalImagePath, DateTime dateModified, BaseItem item, ImageType imageType, int imageIndex, List<IImageEnhancer> supportedEnhancers)
+        {
+            if (string.IsNullOrEmpty(originalImagePath))
+            {
+                throw new ArgumentNullException("originalImagePath");
+            }
+
+            if (item == null)
+            {
+                throw new ArgumentNullException("item");
+            }
+
+            var cacheGuid = GetImageCacheTag(item, imageType, originalImagePath, dateModified, supportedEnhancers);
+
+            // All enhanced images are saved as png to allow transparency
+            var enhancedImagePath = GetCachePath(_enhancedImageCachePath, cacheGuid + ".png");
+
+            var semaphore = GetLock(enhancedImagePath);
+
+            await semaphore.WaitAsync().ConfigureAwait(false);
+
+            // Check again in case of contention
+            if (File.Exists(enhancedImagePath))
+            {
+                semaphore.Release();
+                return enhancedImagePath;
+            }
+
+            try
+            {
+                using (var fileStream = new FileStream(originalImagePath, FileMode.Open, FileAccess.Read, FileShare.Read, StreamDefaults.DefaultFileStreamBufferSize, true))
+                {
+                    // Copy to memory stream to avoid Image locking file
+                    using (var memoryStream = new MemoryStream())
+                    {
+                        await fileStream.CopyToAsync(memoryStream).ConfigureAwait(false);
+
+                        using (var originalImage = Image.FromStream(memoryStream, true, false))
+                        {
+                            //Pass the image through registered enhancers
+                            using (var newImage = await ExecuteImageEnhancers(supportedEnhancers, originalImage, item, imageType, imageIndex).ConfigureAwait(false))
+                            {
+                                var parentDirectory = Path.GetDirectoryName(enhancedImagePath);
+
+                                if (!Directory.Exists(parentDirectory))
+                                {
+                                    Directory.CreateDirectory(parentDirectory);
+                                }
+
+                                //And then save it in the cache
+                                using (var outputStream = new FileStream(enhancedImagePath, FileMode.Create, FileAccess.Write, FileShare.Read))
+                                {
+                                    newImage.Save(ImageFormat.Png, outputStream, 100);
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            finally
+            {
+                semaphore.Release();
+            }
+
+            return enhancedImagePath;
+        }
+
+        /// <summary>
+        /// Executes the image enhancers.
+        /// </summary>
+        /// <param name="imageEnhancers">The image enhancers.</param>
+        /// <param name="originalImage">The original image.</param>
+        /// <param name="item">The item.</param>
+        /// <param name="imageType">Type of the image.</param>
+        /// <param name="imageIndex">Index of the image.</param>
+        /// <returns>Task{EnhancedImage}.</returns>
+        private async Task<Image> ExecuteImageEnhancers(IEnumerable<IImageEnhancer> imageEnhancers, Image originalImage, BaseItem item, ImageType imageType, int imageIndex)
+        {
+            var result = originalImage;
+
+            // Run the enhancers sequentially in order of priority
+            foreach (var enhancer in imageEnhancers)
+            {
+                var typeName = enhancer.GetType().Name;
+
+                try
+                {
+                    result = await enhancer.EnhanceImageAsync(item, result, imageType, imageIndex).ConfigureAwait(false);
+                }
+                catch (Exception ex)
+                {
+                    _logger.ErrorException("{0} failed enhancing {1}", ex, typeName, item.Name);
+
+                    throw;
+                }
+            }
+
+            return result;
+        }
+
+        /// <summary>
+        /// The _semaphoreLocks
+        /// </summary>
+        private readonly ConcurrentDictionary<string, object> _locks = new ConcurrentDictionary<string, object>();
+
+        /// <summary>
+        /// Gets the lock.
+        /// </summary>
+        /// <param name="filename">The filename.</param>
+        /// <returns>System.Object.</returns>
+        private object GetObjectLock(string filename)
+        {
+            return _locks.GetOrAdd(filename, key => new object());
+        }
+
+        /// <summary>
+        /// The _semaphoreLocks
+        /// </summary>
+        private readonly ConcurrentDictionary<string, SemaphoreSlim> _semaphoreLocks = new ConcurrentDictionary<string, SemaphoreSlim>();
+
+        /// <summary>
+        /// Gets the lock.
+        /// </summary>
+        /// <param name="filename">The filename.</param>
+        /// <returns>System.Object.</returns>
+        private SemaphoreSlim GetLock(string filename)
+        {
+            return _semaphoreLocks.GetOrAdd(filename, key => new SemaphoreSlim(1, 1));
+        }
+
+        /// <summary>
+        /// Gets the cache path.
+        /// </summary>
+        /// <param name="path">The path.</param>
+        /// <param name="uniqueName">Name of the unique.</param>
+        /// <param name="fileExtension">The file extension.</param>
+        /// <returns>System.String.</returns>
+        /// <exception cref="System.ArgumentNullException">
+        /// path
+        /// or
+        /// uniqueName
+        /// or
+        /// fileExtension
+        /// </exception>
+        public string GetCachePath(string path, string uniqueName, string fileExtension)
+        {
+            if (string.IsNullOrEmpty(path))
+            {
+                throw new ArgumentNullException("path");
+            }
+            if (string.IsNullOrEmpty(uniqueName))
+            {
+                throw new ArgumentNullException("uniqueName");
+            }
+
+            if (string.IsNullOrEmpty(fileExtension))
+            {
+                throw new ArgumentNullException("fileExtension");
+            }
+
+            var filename = uniqueName.GetMD5() + fileExtension;
+
+            return GetCachePath(path, filename);
+        }
+
+        /// <summary>
+        /// Gets the cache path.
+        /// </summary>
+        /// <param name="path">The path.</param>
+        /// <param name="filename">The filename.</param>
+        /// <returns>System.String.</returns>
+        /// <exception cref="System.ArgumentNullException">
+        /// path
+        /// or
+        /// filename
+        /// </exception>
+        public string GetCachePath(string path, string filename)
+        {
+            if (string.IsNullOrEmpty(path))
+            {
+                throw new ArgumentNullException("path");
+            }
+            if (string.IsNullOrEmpty(filename))
+            {
+                throw new ArgumentNullException("filename");
+            }
+
+            var prefix = filename.Substring(0, 1);
+
+            path = Path.Combine(path, prefix);
+
+            return Path.Combine(path, filename);
+        }
+
+        public IEnumerable<IImageEnhancer> GetSupportedEnhancers(BaseItem item, ImageType imageType)
+        {
+            return ImageEnhancers.Where(i =>
+            {
+                try
+                {
+                    return i.Supports(item as BaseItem, imageType);
+                }
+                catch (Exception ex)
+                {
+                    _logger.ErrorException("Error in image enhancer: {0}", ex, i.GetType().Name);
+
+                    return false;
+                }
+
+            }).ToList();
+        }
+    }
+}