Question

This is my Server side code:

        public void ReceivingData(object sender, EventArgs e)
        {
            while (mysocket.Connected)
            {
                buffer = new byte[accepted.SendBufferSize];
            int bytesRead = accepted.Receive(buffer);
            MemoryStream Data = new MemoryStream(buffer);
            if ( picbox.InvokeRequired)
            {
                picbox.Invoke(new MethodInvoker(delegate { picbox.Image = Image.FromStream(Data); }));
            }
            }
        }

The connection gets established and the file is being received without any issue. However the image gets distorted on Transfer. I do not understand why this is happening. Here is the screenshot:

I remember i had to format the strings which i used to send over sockets using Encoding.ASCII.GetString(StringToFormat). What do i need to do in case of Images?

Answer 1

In your ReceivingData callback you may not receive all the data back in one pop. Some data can be partially received and the rest of it in a subsequent (or multiple) callbacks and it will be your task to re-assemble the original message.

You will need to define a protocol to ensure that you have read all necessary data.
You could for example use base64 to encode the image on the server and decode it on the client. You would need to know how many bytes you should anticipate. This can be done, either by prefixing your response with the total bytes that the client should anticipate or by having a special marker (such as byte value 0x00) to distinguish message boundaries.

Using Base64 will also have the effect of increasing file sizes by 33% since base64 basically encodes every 6bits of the incoming stream to an 8bit readable character. So for every 3 ‘real’ bytes you would like to transfer you will need 4 encoded bytes.