Images streaming using Indy client side

[rlebeau]

Any ideas on how to handle client side in C++ builder code not Delphi?

The procedure is exactly the same in C++Builder as it is in Delphi.

If you are using an up-to-date version of Indy, you can use the hoNoReadMultipartMIME flag in the TIdHTTP::HTTPOptions property.

Enable the flag, and then call TIdHTTP::Get() to begin the streaming. When TIdHTTP.Get() exits, check to make sure that the response's ResponseCode is 200 and ContentType is "multipart/x-mixed-replace", and if so then you can manually read the server's pushed updates from the TIdHTTP::IOHandler as needed until disconnected.

You can use TIdMessageDecoderMIME to help you parse the incoming MIME data, for example:

Code:

IdHTTP1->HTTPOptions = IdHTTP1->HTTPOptions << hoNoReadMultipartMIME;
IdHTTP1->Get(_D("http://server/stream"));

if (IdHTTP1->ResponseCode != 200 || !IsHeaderMediaType(IdHTTP1->Response->ContentType, _D("multipart/x-mixed-replace"))) return;

String LBoundary = ExtractHeaderSubItem(IdHTTP1.Request->ContentType, _D("boundary"), QuoteHTTP);
// or: String LBoundary := IdHTTP1->Response->RawHeaders->Params[_D("Content-Type"), _D("boundary")];

String LBoundaryStart = _D("--") + LBoundary;
String LBoundaryEnd = LBoundaryStart + _D("--");

do
{
    String LLine = IdHTTP1->IOHandler->ReadLn();
    if (LLine == LBoundaryStart) break;
    if (LLine == LBoundaryEnd) return;
}
until (true);

TIdTCPStream *Stream = new TIdTCPStream(IdHTTP1);
try
{
    TIdMessageDecoder *LDecoder = new TIdMessageDecoderMIME(NULL);
    try
    {
        bool LMsgEnd = false;
        do
        {
            static_cast<TIdMessageDecoderMIME*>(LDecoder)->MIMEBoundary = LBoundary;
            LDecoder->SourceStream = Stream;
            LDecoder->FreeSourceStream = false;

            LDecoder->ReadHeader();
            switch (LDecoder->PartType())
            {
                case mcptText:
                case mcptAttachment:
                {
                    TMemoryStream *LMStream = new TMemoryStream;
                    try
                    {
                        TIdMessageDecoder *LNewDecoder = LDecoder->ReadBody(LMStream, LMsgEnd);
                        try
                        {
                            // process LMStream as needed...
                        }
                        catch (const Exception &)
                        {
                            delete LNewDecoder;
                            throw;
                        }
                        delete LDecoder;
                        LDecoder = LNewDecoder;
                    }
                    __finally
                    {
                        delete LMStream;
                    }
                    break;
                }

                case mcptIgnore:
                {
                    FreeAndNil(LDecoder);
                    LDecoder = new TIdMessageDecoderMIME(NULL);
                    break;
                }

                case mcptEOF:
                {
                    LMsgEnd = true;
                    break;
                }
            }
        }
        while (LDecoder && !LMsgEnd);
    }
    __finally
    {
        delete LDecoder;
    }
}
__finally
{
    delete Stream;
}