/// <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<ImageStream> ExecuteImageEnhancers(IEnumerable<IImageEnhancer> imageEnhancers, ImageStream originalImage, IHasImages 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>
/// 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="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>
/// <param name="cacheGuid">The cache unique identifier.</param>
/// <returns>System.String.</returns>
/// <exception cref="System.ArgumentNullException">originalImagePath</exception>
private async Task<string> GetEnhancedImageInternal(string originalImagePath,
IHasImages item,
ImageType imageType,
int imageIndex,
IEnumerable<IImageEnhancer> supportedEnhancers,
string cacheGuid)
{
if (string.IsNullOrEmpty(originalImagePath))
{
throw new ArgumentNullException("originalImagePath");
}
if (item == null)
{
throw new ArgumentNullException("item");
}
// 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 = _fileSystem.GetFileStream(originalImagePath, FileMode.Open, FileAccess.Read, FileShare.Read, true))
{
// Copy to memory stream to avoid Image locking file
using (var memoryStream = new MemoryStream())
{
await fileStream.CopyToAsync(memoryStream).ConfigureAwait(false);
memoryStream.Position = 0;
var imageStream = new ImageStream
{
Stream = memoryStream,
Format = GetFormat(originalImagePath)
};
//Pass the image through registered enhancers
using (var newImageStream = await ExecuteImageEnhancers(supportedEnhancers, imageStream, item, imageType, imageIndex).ConfigureAwait(false))
{
var parentDirectory = Path.GetDirectoryName(enhancedImagePath);
Directory.CreateDirectory(parentDirectory);
// Save as png
if (newImageStream.Format == Model.Drawing.ImageFormat.Png)
{
//And then save it in the cache
using (var outputStream = _fileSystem.GetFileStream(enhancedImagePath, FileMode.Create, FileAccess.Write, FileShare.Read, false))
{
await newImageStream.Stream.CopyToAsync(outputStream).ConfigureAwait(false);
}
}
else
{
using (var newImage = Image.FromStream(newImageStream.Stream, true, false))
{
//And then save it in the cache
using (var outputStream = _fileSystem.GetFileStream(enhancedImagePath, FileMode.Create, FileAccess.Write, FileShare.Read, false))
{
newImage.Save(System.Drawing.Imaging.ImageFormat.Png, outputStream, 100);
}
}
}
}
}
}
}
finally
{
semaphore.Release();
}
return enhancedImagePath;
}