使用Winsock的，和的GetDIBits位图SetDiBits转移 [英] Bitmap transfer using Winsock, GetDIBits and SetDiBits

问题描述

我开始在类似于C ++中的遥控应用的东西的工作。我希望一个特定的窗口的屏幕快照中的一个窗口传送到另一台PC并显示它。双方的GetDIBits和SetDIBits函数成功，建立连接，数据发送，但图像不会出现在另一边，只是黑暗。

I started working on something similar to a remote control application in c++. I wish to transfer a particular window's screenshot to another PC and display it in a window. Both GetDIBits and SetDIBits functions succeed, the connection is established, the data is sent, yet the image does not appear on the other side, just blackness.

下面是我送code：

void GetScreenData(BITMAPINFO* bi, BYTE* buf) //gets the bitmap data
{
  HBITMAP hBitmap;
  BITMAP Bitmap;
  RECT r;

  HDC ActiveDC = GetDC(hActive);
  HDC CopyDC = CreateCompatibleDC(ActiveDC);

  GetWindowRect(hActive, &r);

  int scrWidth = r.right-r.left;
  int scrHeight = r.bottom-r.top;

  hBitmap = CreateCompatibleBitmap(ActiveDC, scrWidth, scrHeight);
  SelectObject(CopyDC, hBitmap);

  BitBlt(CopyDC, 0, 0, scrWidth, scrHeight, ActiveDC, 0, 0, SRCCOPY);

  GetObject(hBitmap, sizeof(BITMAP), &Bitmap);

  int cClrBits = Bitmap.bmPlanes*Bitmap.bmBitsPixel;

  memset(bi, 0, sizeof(BITMAPINFO));

  bi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
  bi->bmiHeader.biWidth = Bitmap.bmWidth;
  bi->bmiHeader.biHeight = Bitmap.bmHeight;
  bi->bmiHeader.biPlanes = Bitmap.bmPlanes;
  bi->bmiHeader.biBitCount = Bitmap.bmBitsPixel;

  if(cClrBits<24)
  {
    bi->bmiHeader.biClrUsed = (1<<cClrBits);
  }

  bi->bmiHeader.biCompression = BI_RGB;
  bi->bmiHeader.biSizeImage = ((bi->bmiHeader.biWidth * cClrBits +31) & ~31)/8*bi->bmiHeader.biHeight;

  int i = GetDIBits(CopyDC, hBitmap, 0, scrHeight, buf, bi, DIB_RGB_COLORS);

  printf("GetDIBits returned %i\n", i);

  ReleaseDC(hActive, ActiveDC);
  DeleteDC(CopyDC);
}

DWORD WINAPI SendImage(LPVOID param) //sends the bitmap data
{
  BITMAPINFO bi;
  BYTE* data = new BYTE[256*256*256];
  BYTE* buf = new BYTE[256*256*256];
  BYTE *packetsize1, *packetsize2;
  int biSize = sizeof(BITMAPINFO);
  int i, clocks, oldclocks=0;

  while(true)
  {
    clocks=clock();

    if((clocks-oldclocks)*CLOCKS_PER_SEC<0.1)
    {
      continue;
    }

    oldclocks=clocks;

    if(bConnected)
    {
      GetScreenData(&bi, buf);

      i=0;

      data[i++]=3;
      packetsize1=&data[i++];
      packetsize2=&data[i++];

      memcpy(data+i, &bi, biSize);

      i+=biSize;

      memcpy(data+i, buf, bi.bmiHeader.biSizeImage);

      printf("Sending image...\n");

      i+=bi.bmiHeader.biSizeImage;

      *packetsize1=int(i/256);
      *packetsize2=int(i%256);

      send(s, (char*)data, i, 0);
    }
  }
}

这里是接收方：

void DrawScreen(HDC hdc) //called from windows message WM_PAINT
{
  HGDIOBJ hobj;

  hobj = SelectObject(RemoteDC, hRemoteBitmap);

  BitBlt(hdc, 0, 0, scrWidth, scrHeight, RemoteDC, 0, 0, SRCCOPY);

  SelectObject(hdc, hobj);
}

DWORD WINAPI RecvData(LPVOID param)
{
  BYTE* data = new BYTE[256*256*256];
  int packetsize, num;
  int newWidth, newHeight;
  int recvimgsize=0;

  bool bAwaitingImage = false;

  while(true)
  {
    if(bConnected)
    {
      num=recv(s, (char*)data, 3, 0);

      if(num>0)
      {
        packetsize = data[1]*256+data[2];

        num=recv(s, (char*)(data+3), packetsize-3, 0);
      }

      if(num>0)
      {
        switch(data[0])
        {
          case 2: //received information about window size (image size)
            newWidth = data[3]*256+data[4];
            newHeight = data[5]*256+data[6];

            if(newHeight!=scrHeight || newWidth!=scrWidth)
            {
              scrWidth = newWidth;
              scrHeight = newHeight;

              RECT r;

              GetWindowRect(hwnd, &r);
              SetWindowPos(hwnd, NULL, r.left, r.top, scrWidth, scrHeight, 0);

              HDC ThisDC = GetDC(hwnd);

              DeleteDC(RemoteDC);
              RemoteDC = CreateCompatibleDC(ThisDC);

              DeleteObject(hRemoteBitmap);
              hRemoteBitmap = CreateCompatibleBitmap(ThisDC, scrWidth, scrHeight);

              SelectObject(RemoteDC, hRemoteBitmap);

              ReleaseDC(hwnd, ThisDC);
            }
            break;
          case 3:
          {
            BITMAPINFO bi;
            HBITMAP hBitmap;

            int biSize = sizeof(BITMAPINFO);
            memcpy(&bi, data+3, biSize);
            SetDIBits(RemoteDC, hRemoteBitmap, 0, scrHeight, data+biSize+3, &bi, DIB_RGB_COLORS);

            InvalidateRect(hwnd, NULL, false);

            break;
          }
        }

        continue;
      }

      if(num==0)
      {
        //connection closed
        bConnected=false;
      }else{
        //error
        bConnected=false;
      }
    }
  }
}

在这里psented的code我$ P $是有点长，因为我不知道可能是什么用的。谢谢你在前进。

The code I presented here is a bit long, because I wasn't sure what might be of use. Thank you in advance.

推荐答案

与贴code的问题是，有两个字节唯一的（[数据+1]和[数据+ 2]）分配给总传输数据的长度。两个字节处理多达数据和图像的64K容易点到为止， I 值不检查溢出。

The problem with posted code is that that there were two BYTEs only ([data+1] and [data+2]) allocated for the total transfer data length. Two bytes handle up to 64K of data and images easily go beyond that, i value is not checked for overflows.

要带上code段起死回生，需要有补充位，使他们能够容纳实际长度。也就是说，应该有一个额外的字节或两个，使分组长度24或32位值。

To bring the code snippet back to life, one needs to add bits there so that they could hold real length. That is, there should be an additional byte or two to make packet length 24 or 32 bit value.

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