using AE.Net.Mail how to send mail with image inline - api

Question

I using AE.Net.Mail in .net project.
I sent html mail and file attachment by gmail api and it work perfect.
But i dont know way to embed an image in body mail with it?
Somebody help me ?
string To = txtTo.Text;
string Subject = txtEmailSubject.Text;
string Body = hdfEmailContentSend.Value;
string InputAttachmentArr = hdfInputAttachmentArr.Value;
var msg = new AE.Net.Mail.MailMessage();
msg.From = new MailAddress("haunguyen1791990#gmail.com", "=?UTF-8?B?" + EncodeTo64UTF8(User.FullName) + "?=");
msg.ReplyTo.Add(msg.From);
msg.To.Add(new MailAddress(To));
msg.Subject = "=?UTF-8?B?" + EncodeTo64UTF8(Subject) + "?=";
msg.Body = Body;
var result = SendMessage(InputAttachmentArr, msg, "");
private Google.Apis.Gmail.v1.Data.Message SendMessage(string InputAttachmentArr, AE.Net.Mail.MailMessage msg, string ThreadId) {
try {
bool isAttackFile = false;
string boundary = "boundary_" + DateTime.Now.ToString("yyyyMMddHHmmss");
var service = CRMGmailUtils.DefineServiceGet(Server.MapPath(".") + "\\client_secret.json");
//get info file attachment
List<string> lstAttachFile = InputAttachmentArr.Split(',').ToList();
lstAttachFile.RemoveAll(item => item.Length == 0);
foreach (var item in lstAttachFile) {
string filePath = Server.MapPath("~/" + "Upload/gmail/" + item);
var bytes = File.ReadAllBytes(filePath);
AE.Net.Mail.Attachment file = new AE.Net.Mail.Attachment(bytes, GetMimeType(item), item, true);
msg.Attachments.Add(file);
isAttackFile = true;
}
var msgStr = new StringWriter();
//if file attachment not exists, set type mail is html
if (!isAttackFile) {
msg.ContentType = "text/html";
}
msg.Save(msgStr);
string data = msgStr.ToString();
//else i customize body mail with new boundary
if (isAttackFile) {
string beginBody = "Content-Type: multipart/alternative; boundary=" + boundary;
//beginBody += "\n\n--" + boundary;
//beginBody += "\nContent-Type: text/plain; charset=UTF-8";
//beginBody += "\n\n*2*";
beginBody += "\n\n--" + boundary;
beginBody += "\nContent-Type: text/html; charset=UTF-8";
string endBody = "\n\n--" + boundary + "--";
msg.Body += endBody;
string parentBoundary = Regex.Match(data, #"----(.*?)--").Groups[1].Value;
Regex rgx = new Regex("----" + parentBoundary);
data = rgx.Replace(data, "----" + parentBoundary + "\n" + beginBody, 1);
}
string raw = Base64UrlEncode(data.ToString());
var result = new Google.Apis.Gmail.v1.Data.Message();
//case send with reply
if (!string.IsNullOrEmpty(ThreadId)) {
result = service.Users.Messages.Send(new Google.Apis.Gmail.v1.Data.Message { Raw = raw, ThreadId = ThreadId }, "me").Execute();
} else {
//case send new mail
result = service.Users.Messages.Send(new Google.Apis.Gmail.v1.Data.Message { Raw = raw }, "me").Execute();
}
DeleteAttackFile(lstAttachFile);
return result;
} catch (Exception objEx) {
throw objEx;
}
}