Send an image from Android to an ASP.NET Web Service

Question

I'm developing an Android App that should send an image to my ASP.NET Web Service where the image will be saved as a file. I've seen a couple of ways to do this and I went for this one: convert the image to a byte array -> convert the byte array to a string -> send the string to the web service using KSOAP2 -> receive the String at the Web Service -> convert it to a byte array -> Save it as an image:

IVtest = (ImageView)findViewById(R.id.carticon);
BitmapDrawable drawable = (BitmapDrawable) IVtest.getDrawable();
    Bitmap bitmap = drawable.getBitmap();

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
    byte[] data = baos.toByteArray();
    ImageView image=new ImageView(this);
    image.setImageBitmap(bmp);
    String strBase64 = Base64.encode(data);

Then I send strBase64 to the web service. In the Web Service I have this:

public Image ConvertToImage(byte[] image)
{
    MemoryStream ms = new MemoryStream(image);
    Image returnImage = Image.FromStream(ms);
    return returnImage;
}

[WebMethod]
public String UploadImage(String image, String name)
{
    byte[] image_byte = Encoding.Unicode.GetBytes(image);
    Image convertedImage = ConvertToImage(image_byte);
    try {
        convertedImage.Save(Server.MapPath("generated_image.jpg"),     System.Drawing.Imaging.ImageFormat.Jpeg);
    } catch (Exception e) {
        return e.Message;
    }
    return "Success";
}

I get an error at this line: Image returnImage = Image.FromStream(ms);

This is the error I get:

SoapFault - faultcode: 'soap:Server' faultstring: 'System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.ArgumentException: Parameter is not valid.
   at System.Drawing.Image.FromStream(Stream stream, Boolean useEmbeddedColorManagement, Boolean validateImageData)
   at System.Drawing.Image.FromStream(Stream stream)
   at Service.ConvertToImage(Byte[] image) in e:\FTP\nvm\Service.asmx:line 1366
   at Service.UploadImage(String image, String name) in e:\FTP\nvm\Service.asmx:line 1374
   --- End of inner exception stack trace ---' faultactor: 'null' detail: org.kxml2.kdom.Node@437bf7b0

Thanks

Answer 1

Seems like there is something iffy with your conversion from string to image. Also you are not disposing your stream which will leak memory.

Try this instead:

private Image Base64ToImage(string base64String)
    {
        // Convert Base64 String to byte[]
        byte[] imageBytes = Convert.FromBase64String(base64String);
        using (var ms = new MemoryStream(imageBytes, 0,
                                         imageBytes.Length))
        {
            // Convert byte[] to Image
            ms.Write(imageBytes, 0, imageBytes.Length);
            Image image = Image.FromStream(ms, true);
            return image;
        }
    }