using System;

using System.Collections;

using System.Collections.Generic;

using System.Drawing;

using System.IO;

using System.Linq;

using System.Net;

using System.Net.Mime;

using System.Text;

using System.Threading.Tasks;

using System.Management;

​

//http://stackoverflow.com/questions/38693292/c-sharp-image-fromstream-lost-metadata-when-running-in-windows-8-10/38809151#38809151

//V2

//Created: Aug, 12 2016

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Reading Metadata tExt from PNG Loaded from web");

        Console.WriteLine("OS Version: {0}" ,Environment.OSVersion);

        Console.WriteLine("Operating System: {0}", OS.GetWindowsVersion());

​

        MetaDataReader.Test1();

    }

}

​

​

​

   class MetaDataReader

    {

        static MemoryStream myMemoryStream = new MemoryStream();

        public static void Test1()

        {

            var url = "https://raw.githubusercontent.com/moh-hassan/Images/master/kodim03.png";        

            var img = DownLoadImage(url);

            //do whatever processing in image

            //too latter may extract metadata from memoryStream not image.CopyFrom (stream)

            Console.WriteLine("-------------------------------------");

            //here a surprise , the current environment is windows 8

            GetData(img);

            Console.WriteLine("-------------------------------------");

             GetData(myMemoryStream);

        }

​

        public static Image DownLoadImage(string url)

        {

​

            WebRequest request = WebRequest.Create(url);

            Image img = null;

            using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)

            {

                if (response != null)

                {

                    Stream stream = response.GetResponseStream();

                    // Define buffer and buffer size

                    int bufferSize = 1024;

                    byte[] buffer = new byte[bufferSize];

                    int bytesRead;

                    while (stream != null && (bytesRead = stream.Read(buffer, 0, bufferSize)) != 0)

                    {

                        myMemoryStream.Write(buffer, 0, bytesRead);

                    } //

​

                    Console.WriteLine("Loading {0} byte from server", myMemoryStream.Length);

                    img = Image.FromStream(myMemoryStream);

                    stream.CopyTo(myMemoryStream); //fill memoryStream for latter use

                }

                //.......

            }

           byte[] result = (byte[])new ImageConverter().ConvertTo(img, typeof(byte[]));

​

            Console.WriteLine("Have a look to this size compared to original stream from web Response");

            Console.WriteLine("Image stream size : {0}", result.Length);

            return img;

        }

         //this code generate metadata in windows 7  and windows 8 /10

​

        public static Hashtable GetData(Stream stream)

        {

            stream.Position = 0; //fo safety

            Hashtable metadata = new Hashtable();

            //  data = new Hashtable();

​

            byte[] imageBytes;

            //using (MemoryStream stream = new MemoryStream())

            //{

            //    image.Save(stream, image.RawFormat);

            //    imageBytes = new byte[stream.Length];

            //    imageBytes = stream.ToArray();

            //}

            imageBytes = myMemoryStream.ToArray();

            Console.WriteLine("Reading Metadata using stream as a parameter (direct read from stream with no Image object in between, size: {0}", imageBytes.Length);

          //  Console.WriteLine(imageBytes.Length);

​

            if (imageBytes.Length <= 8)

            {

                Console.WriteLine("return ->size =0");

                return null;

            }

​

            // Skipping 8 bytes of PNG header

            int pointer = 8;

​

            while (pointer < imageBytes.Length)

            {

                // read the next chunk

                uint chunkSize = GetChunkSize(imageBytes, pointer);

                pointer += 4;

                string chunkName = GetChunkName(imageBytes, pointer);

                pointer += 4;

​

                // chunk data -----

                if (chunkName.Equals("tEXt"))

                {

                    byte[] data = new byte[chunkSize];

                    Array.Copy(imageBytes, pointer, data, 0, chunkSize);

                    StringBuilder stringBuilder = new StringBuilder();

                    foreach (byte t in data)

                    {

                        stringBuilder.Append((char)t);

                    }

​

                    string[] pair = stringBuilder.ToString().Split(new char[] { '\0' });

                    metadata[pair[0]] = pair[1];

                    Console.WriteLine("Tag Name: {0} | Tag Value: {1}", pair[0], pair[1]);

                }

​

                pointer += (int)chunkSize + 4;

​

                if (pointer > imageBytes.Length)

                    break;

            }

            if (metadata.Count == 0)

                Console.WriteLine("No metadata available");

            return metadata;

        }

       //--------------------------------- original version as is *************************

       //this code generate metadata in windows 7 , but not in windows 8 /10

           public static Hashtable GetData(Image image)

        {

            Console.WriteLine("Reading Metadata using Image object as a parameter  ( stream->image->stream");

            Hashtable metadata = new Hashtable( );

          //  data = new Hashtable();

​

            byte[] imageBytes;

            using (MemoryStream stream = new MemoryStream())

            {

                  image.Save(stream, image.RawFormat);                

                imageBytes = new byte[stream.Length];

                imageBytes = stream.ToArray();

            }

​

            if (imageBytes.Length <= 8)

            {

                return null;

            }

​

            // Skipping 8 bytes of PNG header

            int pointer = 8;

​

            while (pointer < imageBytes.Length)

            {

                // read the next chunk

                uint chunkSize = GetChunkSize(imageBytes, pointer);

                pointer += 4;

                string chunkName = GetChunkName(imageBytes, pointer);

                pointer += 4;

​

                // chunk data -----

                if (chunkName.Equals("tEXt"))

                {

                    byte[] data = new byte[chunkSize];

                    Array.Copy(imageBytes, pointer, data, 0, chunkSize);

                    StringBuilder stringBuilder = new StringBuilder();

                    foreach (byte t in data)

                    {

                        stringBuilder.Append((char)t);

                    }

​

                    string[] pair = stringBuilder.ToString().Split(new char[] { '\0' });

                    metadata[pair[0]] = pair[1];

                    Console.WriteLine(" Tag Name: {0} | Tag Value: {1}",pair[0] ,pair[1]);

                }

​

                pointer += (int)chunkSize + 4;

​

                if (pointer > imageBytes.Length)

                    break;

            }

            if (metadata.Count==0)

                Console.WriteLine("No metadata available");

            return metadata;

        }

​

        private static uint GetChunkSize(byte[] bytes, int pos)

        {

            byte[] quad = new byte[4];

            for (int i = 0; i < 4; i++) { quad[3 - i] = bytes[pos + i]; }

​

            return BitConverter.ToUInt32(quad, 0);

​

        }

​

        private static string GetChunkName(byte[] bytes, int pos)

        {

            StringBuilder builder = new StringBuilder(); for (int i = 0; i < 4; i++) { builder.Append((char)bytes[pos + i]); }

​

            return builder.ToString();

​

        }

    }

​

​

class OS

    {

     private  static   Dictionary<string, string> _osVersions = new Dictionary<string, string>

        {

            {"10.0","Windows 10" },

            {"6.3","Windows 8.1" },

            {"6.2","Windows 8" },

            {"6.1","Windows 7" }

​

        };

​

     public      static string  GetWindowsVersion()

        {

            OperatingSystem os = Environment.OSVersion;

            Version ver = os.Version;

            var key = ver.Major + "." + ver.Minor;

            var name = "Unknown";

            if (_osVersions.ContainsKey(key)) name = _osVersions[key];

            return name;

        }

​

}

​

​