/// <summary>
/// Encodes an image for storage.
/// </summary>
/// <param name="imageStream">The image to encode.</param>
/// <returns>The encoded image, or null if decoding fails.</returns>
/// <remarks>
/// The image returned is guaranteed to have no side longer than
/// <see cref="F:HospitalAllocation.Providers.Image.Database.DbImageProvider.MaxSideLength"/> pixels.
/// </remarks>
private static SKData EncodeImage(IImageStream imageStream)
{
// Get the image
var imageArray = new byte[imageStream.Length];
var stream = new MemoryStream(imageArray);
imageStream.CopyTo(stream);
var data = SKData.CreateCopy(imageArray);
var image = SKImage.FromEncodedData(data);
// Decode failed
if (image == null)
{
return(null);
}
// Resize the image if required
if (Math.Max(image.Height, image.Width) > MaxSideLength)
{
int resizedHeight;
int resizedWidth;
float scale;
if (image.Height > image.Width)
{
resizedHeight = MaxSideLength;
scale = ((float)resizedHeight / image.Height);
resizedWidth = (int)Math.Round(image.Width * scale);
}
else
{
resizedWidth = MaxSideLength;
scale = ((float)resizedWidth / image.Width);
resizedHeight = (int)Math.Round(image.Height * scale);
}
var surface = SKSurface.Create(new SKImageInfo(resizedWidth, resizedHeight));
var paint = new SKPaint
{
FilterQuality = SKFilterQuality.High
};
surface.Canvas.Scale(scale);
surface.Canvas.DrawImage(image, 0, 0, paint);
surface.Canvas.Flush();
image = surface.Snapshot();
}
// Encode the image
return(image.Encode(SKEncodedImageFormat.Jpeg, JpegQualityLevel));
}
/// <summary>
/// Replace the image at the given index with the given one
/// </summary>
/// <param name="id">Identifier.</param>
/// <param name="newImage">New image.</param>
public void ReplaceImage(int id, IImageStream newImage)
{
FileInfo file = GetImageFileFromIndex(id);
if (file == null || !file.Exists)
{
throw new ArgumentException(String.Format("Image with ID {0} does not exist.", id));
}
using (var stream = file.OpenWrite())
{
newImage.CopyTo(stream);
}
}
public IActionResult RetrieveImage(int id)
{
IImageStream image = _imageProvider.GetImage(id);
if (image == null)
{
return(BadRequest(new ErrorResponse("No such image")));
}
// We need to copy the image to an internal memory stream in order
// to transfer it out with a byte array. This is probably inefficient
// since we copy once to the filesystem to memory and then from
// memory to HTTP - worth refactoring later
var dataStream = new MemoryStream();
image.CopyTo(dataStream);
return(File(dataStream.ToArray(), image.Format.ContentTypeString()));
}
/// <summary>
/// Takes an image from an image stream and saves it to the directory
/// in the conventional format of this image provider
/// </summary>
/// <returns>The image.</returns>
/// <param name="imageData">Image data.</param>
public int CreateImage(IImageStream imageData)
{
// Always assign to a deleted index first if possible
int index = -1;
if (_deletedIndices.Any())
{
index = _deletedIndices.FirstOrDefault();
_deletedIndices.Remove(index);
}
else
{
index = _nextImageIndex;
_nextImageIndex++;
}
using (var stream = FileForNewImage(index, imageData.Format).OpenWrite())
{
imageData.CopyTo(stream);
}
return(index);
}
