/// <summary>
/// Parse request details from relative path
/// </summary>
/// <param name="request"></param>
/// <returns></returns>
private ThumbnailRequest ParseRequest(HttpRequest request)
{
var req = new ThumbnailRequest();
req.RequestedPath = request.Path;
req.ThumbnailSize = ParseSize(request.Query["size"]);
req.SourceImagePath = GetPhysicalPath(request.Path);
req.ThumbnailImagePath = GenerateThumbnailFilePath(request.Path, req.ThumbnailSize);
return(req);
}
/// <summary>
/// Generates thumbnail image, cache and write to output stream
/// </summary>
/// <param name="request"></param>
/// <param name="stream"></param>
/// <returns></returns>
private async Task GenerateThumbnail(ThumbnailRequest request, Stream stream)
{
if (File.Exists(request.SourceImagePath))
{
Image image = Image.FromFile(request.SourceImagePath);
System.Drawing.Image thumbnail =
new Bitmap(request.ThumbnailSize.Value.Width, request.ThumbnailSize.Value.Height);
System.Drawing.Graphics graphic =
System.Drawing.Graphics.FromImage(thumbnail);
graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphic.SmoothingMode = SmoothingMode.HighQuality;
graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphic.CompositingQuality = CompositingQuality.HighQuality;
double ratioX = (double)request.ThumbnailSize.Value.Width / (double)image.Width;
double ratioY = (double)request.ThumbnailSize.Value.Height / (double)image.Height;
double ratio = ratioX < ratioY ? ratioX : ratioY;
int newHeight = Convert.ToInt32(image.Height * ratio);
int newWidth = Convert.ToInt32(image.Width * ratio);
int posX = Convert.ToInt32((request.ThumbnailSize.Value.Width - (image.Width * ratio)) / 2);
int posY = Convert.ToInt32((request.ThumbnailSize.Value.Height - (image.Height * ratio)) / 2);
graphic.Clear(_options.ThumbnailBackground);
graphic.DrawImage(image, posX, posY, newWidth, newHeight);
System.Drawing.Imaging.ImageCodecInfo[] info =
ImageCodecInfo.GetImageEncoders();
EncoderParameters encoderParameters;
encoderParameters = new EncoderParameters(1);
encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality,
_options.ImageQuality);
thumbnail.Save(request.ThumbnailImagePath);
image.Dispose();
using (var fs = new FileStream(request.ThumbnailImagePath, FileMode.Open))
{
await fs.CopyToAsync(stream);
}
}
}