C＃图像压缩-导致图像裁剪

Question

I'm working on compressing our images that are uploaded using a Telerik RadAsyncUpload control.

On the backend I get the uploaded file input stream (Stream class) and pass it to this compression method:

    private byte[] GetCompressedImage(Stream stream, ImageFormat format)
    {
        ImageCodecInfo imgCodec = ImageCodecInfo.GetImageEncoders().First(c => c.FormatID == format.Guid);

        EncoderParameters codecParams = new EncoderParameters(1);
        codecParams.Param[0] = new EncoderParameter(Encoder.Quality, 70L);

        using (Bitmap bitmap = new Bitmap(stream))
        {
            using (var ms = new MemoryStream())
            {
                bitmap.Save(ms, imgCodec, codecParams);
                return ms.ToArray();
            }
        }
    }

I then add the bytes to the a list of bytes that represents each file uploaded (this control allows multiples). We then pass it on to the FTP folder, etc.

I can't for the life of me figure out why it's cropping the image rather than compressing. The bytes are smaller, width and height are the same, and it just doesn't show whatever a portion of the image.

Any ideas?

Answer 1

I finally got it working. I moved the method into where we pass in the list of bytes (aka files uploaded) and passed in an Image object to the method rather than the stream.

    /// <summary>
    /// Compress the image
    /// </summary>
    /// <param name="stream">Image stream</param>
    /// <param name="format">Image format</param>
    /// <returns>Byte array representing the image</returns>
    public static byte[] GetCompressedImage(Image original, ImageFormat format)
    {
        ImageCodecInfo imgCodec = ImageCodecInfo.GetImageEncoders().First(c => c.FormatID == format.Guid);

        EncoderParameters codecParams = new EncoderParameters(1);
        codecParams.Param[0] = new EncoderParameter(Encoder.Quality, 70L);

        using (var bitmap = new Bitmap(original))
        {
            using (var ms = new MemoryStream())
            {
                bitmap.Save(ms, imgCodec, codecParams);
                return ms.ToArray();
            }
        }
    }

Thanks for the suggestions!