C# string multi-byte c++ , gif binary data convert to png or image

Question

I'm seriously stuck in this problem. this problem caused because i'm weak with C# concept. all i want do is electronic equipment return gif format data. which is binary i believe. so i want convert this data to image.

/// below is just send command to instrument that i want " Returns an image of the display in .gif format "

    my6705B.WriteString("hcop:sdump:data?", true);
    string image_format = my6705B.ReadString();

So i received gif data from instrument, manual said this is " Returns an image of the display in .gif format " ==> I believe this is binary format. below link is what's in side in string image_format. string image_format https://i.sstatic.net/UcYqV.png

my goal is convert this string to image file. (png or jpg whatever) so i convert this string variable to byte array. below is my code after this command ....

        //// this also couldn't work ~~~
        System.Text.UnicodeEncoding encode = new System.Text.UnicodeEncoding();
        byte[] byte_array22 = encode.GetBytes(image_format);
        MemoryStream ms4 = new MemoryStream(byte_array22);
        Image image = Image.FromStream(ms4);     //// error point
        image.Save(@"C:\Users\Administrator\Desktop\imageTest.png");

        //// this also couldn't work ~~~
        byte[] byte_array22 = Encoding.Unicode.GetBytes(image_format);  
        MemoryStream ms4 = new MemoryStream(byte_array22);
        Image image = Image.FromStream(ms4, true, true);     /// always error here,,, 
        image.Save(@"C:\Users\Administrator\Desktop\imageTest.png", System.Drawing.Imaging.ImageFormat.Png);

both code didn't work and error point is same. i commented error point. and anyway string to byte array is work. I'm pain with this problem several days. but my vendor make this code with C++,, this is working . let me share my vendor's code,.this is implemented C++.

    char szReadBuffer[102400]       = {'\0', };
    char szReadBinary[102400]       = {'\0', };

    m_iStatus = viOpenDefaultRM(&m_vDefaultRM);
    m_iStatus = viOpen(m_vDefaultRM, (LPSTR)(LPCTSTR)m_strVISA, VI_NULL, VI_NULL, (ViPSession)&m_iDevHandle); 

    m_iStatus = viSetAttribute(m_iDevHandle, VI_ATTR_TMO_VALUE, 15000);

    m_iStatus = QueryGPIB("HCOPy:SDUMp:DATA?", szReadBuffer, sizeof(szReadBuffer));

    //Store the results in a text file
    CFile file;
    file.Open("PICTURE.GIF", CFile::modeReadWrite | CFile::modeCreate | CFile::typeBinary);
    memcpy(szReadBinary, &szReadBuffer[2], sizeof(szReadBuffer));
    file.Write(szReadBinary, sizeof(szReadBinary));
    file.Close();

i think important point is what they declare. they declare char[] . and adviced me that this C++ code did use String MultiByte ? (just hear from him) i have no exp with C++. and if i follow this c++ code then working.

my goal is implement with C#. so need to follow C++ code.

please advice my problem.

Answer 1

It can be confusing sometimes to port C++ to C# if you're unfamiliar with one or the other (never mind both! :) ). One thing to keep in mind: there's no "byte" type in C++. Instead, binary data is stored in char[] arrays, just like C strings.

On the other hand, C# distinguishes between the two. So when you see a char[] in C++ that's being used to store binary data instead of character data, the C# equivalent is a byte[], not a char[] or System.String as it might be for other C++ usages of char[].

Your "my6705B" object appears to be some kind of abstraction of your hardware device. Presumably in addition to the WriteString() and ReadString() methods, there are methods that can be used to write and read binary data, using a byte[] type instead of characters or strings. Use that instead.

Let's assume the proper method is named "ReadBytes()". Then your code would look like this:

byte[] image_format = my6705B.ReadBytes();
MemoryStream ms4 = new MemoryStream(image_format);
Image image = Image.FromStream(ms4);
image.Save(@"C:\Users\Administrator\Desktop\imageTest.png");

Now, that may or may not be exactly what you need. You haven't provided enough information about the "my6705B" object. Many I/O APIs allow for partial reads of available data, so it's possible you would need to read from the device in a loop until you know (somehow) that you've received all of the available bytes for the image. Or maybe the type you're using for the "my6705B" object handles that all for you. I have no way to know…you'll have to figure that out yourself.

But hopefully the above gets you oriented enough wrt the C++ vs C# issues to get you a little further.