在 C++ 中通过 UDP 发送缓冲图像

Question

我已经从答案帖子here 改编了这段代码，它将图像保存到缓冲区中。现在我想通过 UDP 数据包发送这个缓冲区。我对如何使用感到困惑 套接字中的 sendto() 函数。感谢您提供的任何帮助。

{
    IStream *pStream = NULL;
    LARGE_INTEGER liZero = {};
    ULARGE_INTEGER pos = {};
    STATSTG stg = {};
    ULONG bytesRead=0;
    HRESULT hrRet=S_OK;

    BYTE* buffer = NULL;  // this is your buffer that will hold the jpeg bytes
    DWORD dwBufferSize = 0;  // this is the size of that buffer;


    hrRet = CreateStreamOnHGlobal(NULL, TRUE, &pStream);
    //hrRet = pScreenShot->Save(pStream, &imageCLSID, &encoderParams) == 0 ? S_OK : E_FAIL;
    bitmap.Save(pStream, &clsid, &encoderParameters);
    hrRet = pStream->Seek(liZero, STREAM_SEEK_SET, &pos);
    hrRet = pStream->Stat(&stg, STATFLAG_NONAME);

    // allocate a byte buffer big enough to hold the jpeg stream in memory
    buffer = new BYTE[stg.cbSize.LowPart];
    hrRet = (buffer == NULL) ? E_OUTOFMEMORY : S_OK;
    dwBufferSize = stg.cbSize.LowPart;

    // copy the stream into memory
    hrRet = pStream->Read(buffer, stg.cbSize.LowPart, &bytesRead);

    // now go save "buffer" and "dwBufferSize" off somewhere.  This is the jpeg buffer
    // don't forget to free it when you are done

    // After success or if any of the above calls fail, don't forget to release the stream
    if (pStream)
    {
        pStream->Release();
    }
}

Answer 1

请在下面找到使用sendto()通过UDP发送数据的代码，您只需要添加您的代码 用于读取图像并将其存储在缓冲区中（我已经在下面的代码中提到了添加代码的位置）。请不要在c 中编写此代码，所以在您身边，您需要从c 到c++ 进行一些对话。

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h> 
#include <sys/time.h>

#define REMOTE_SERVER_PORT 1501
#define MAX_MSG 100


int main(int argc, char *argv[]) {

  int sd, rc, i;
  struct sockaddr_in cliAddr, remoteServAddr;
  struct hostent *h;
  FILE* filein;
 long lSize;
 char *buffer;

  /* get server IP address (no check if input is IP address or DNS name */
  h = gethostbyname(argv[1]);
  if(h==NULL) {
    printf("%s: unknown host '%s' \n", argv[0], argv[1]);
    exit(1);
  }

  printf("%s: sending data to '%s' (IP : %s) \n", argv[0], h->h_name,
     inet_ntoa(*(struct in_addr *)h->h_addr_list[0]));

  remoteServAddr.sin_family = h->h_addrtype;
  memcpy((char *) &remoteServAddr.sin_addr.s_addr, 
     h->h_addr_list[0], h->h_length);
  remoteServAddr.sin_port = htons(REMOTE_SERVER_PORT);

  /* socket creation */
  sd = socket(AF_INET,SOCK_DGRAM,0);
  if(sd<0) {
    printf("%s: cannot open socket \n",argv[0]);
    exit(1);
  }

  /* bind any port */
  cliAddr.sin_family = AF_INET;
  cliAddr.sin_addr.s_addr = htonl(INADDR_ANY);
  cliAddr.sin_port = htons(0);

  rc = bind(sd, (struct sockaddr *) &cliAddr, sizeof(cliAddr));
  if(rc<0) {
    printf("%s: cannot bind port\n", argv[0]);
    exit(1);
  }

 //please put Here your code to read image and store it in buffer    


  // send data 

    rc = sendto(sd, buffer, sizeof(buffer)+1, 0, 
        (struct sockaddr *) &remoteServAddr, 
        sizeof(remoteServAddr));

    if(rc<0) {
      printf("%s: cannot send data %d \n",argv[0],i-1);
      close(sd);
      exit(1);
    }

  return 1;

}