通过 TCP 发送的图像被翻转

Question

我创建了一个客户端，它通过 TCP 将屏幕截图发送到 server.The 图片已成功发送。但是在接收时图像是颠倒的（我知道这是由结构属性之一的负高度设置的）。我已经在网上搜索了实现方法，但是找不到合适的方法来实现this.So如果有更好的方法，请指正。

这是我发送截图（客户端）的方式：

HDC ScreenDC = GetDC(0);
HDC hMemory = CreateCompatibleDC(ScreenDC);
POINT ScreenSize = { GetDeviceCaps(ScreenDC, HORZRES),GetDeviceCaps(ScreenDC, VERTRES)};

// fill the hbitmap wtih the screenshot
HBITMAP hBitmap = CreateCompatibleBitmap(ScreenDC, ScreenSize.x, ScreenSize.y);
HGDIOBJ hOldBitmap = SelectObject(hMemory, hBitmap);
BITMAPINFO bmpInfo = { 0 };

bmpInfo.bmiHeader.biSize = sizeof(bmpInfo.bmiHeader);
GetDIBits(ScreenDC , hBitmap, 0, 0, NULL, &bmpInfo, DIB_RGB_COLORS); // fill bmpInfo with info about the hBitmap
char * dataBuffer = new char[bmpInfo.bmiHeader.biSizeImage];

// adjust the header for our needs
bmpInfo.bmiHeader.biBitCount = 32;
bmpInfo.bmiHeader.biCompression = BI_RGB;  // no compression -> easier to use
bmpInfo.bmiHeader.biHeight = abs(bmpInfo.bmiHeader.biHeight);
BitBlt(hMemory, 0, 0, ScreenSize.x, ScreenSize.y, ScreenDC, 0, 0, SRCCOPY); // take a screenshot
GetDIBits(ScreenDC, hBitmap, 0, bmpInfo.bmiHeader.biHeight, dataBuffer, &bmpInfo, DIB_RGB_COLORS);  // fill dataBuffer with raw image data

// send first the bmpInfo.bmiHeader struct
// send raw data : dataBuffer
//.....

我确定消息已正确发送和接收，因为我已经实施了用于分隔 packets.This 的协议，这不是问题所在。

这是接收者（服务器）：

// data is the entire sent : structure + dataBuffer

HDC hDc = GetDC(windowHwnd);
HDC tCpyHdc = CreateCompatibleDC(hDc);

BITMAPINFOHEADER bmpHeader = *(BITMAPINFOHEADER*)data;
BITMAP bmp;
bmp.bmType = 0;
bmp.bmWidth = bmpHeader.biWidth;
bmp.bmHeight = abs(bmpHeader.biHeight);
bmp.bmPlanes = bmpHeader.biPlanes;
bmp.bmWidthBytes = bmpHeader.biWidth * 4;
bmp.bmBitsPixel = bmpHeader.biBitCount;
bmp.bmBits = (char*)(data + sizeof(BITMAPINFOHEADER));

HBITMAP hB = CreateBitmapIndirect(&bmp);

HBITMAP oldBmp = (HBITMAP)SelectObject(tCpyHdc, hB);
StretchBlt(hDc, 0, 0, width - 20, height - 40, tCpyHdc, 0, 0, bmp.bmWidth, bmp.bmHeight, SRCCOPY);

图像颠倒了。我该如何解决？

Answer 1

感谢@Igor Tandetnik 我解决了这个问题。这是最终代码：

在客户端我发送 BITMAPINFO 而不是 BITMAPINFOHEADER:

//...
// send first the bmpInfo struct
// send raw data : dataBuffer
//.....

服务器端（我使用 CreateDIBSection 而不是 CreateBitmapIndirect）：

// data is the entire sent : structure + dataBuffer

HDC hDc = GetDC(windowHwnd);
HDC tCpyHdc = CreateCompatibleDC(hDc);

BITMAPINFO bmpInfo = *(BITMAPINFO*)data;
BITMAP bmp;
bmp.bmType = 0;
bmp.bmWidth = bmpInfo.bmiHeader.biWidth;
bmp.bmHeight = -abs(bmpInfo.bmiHeader.biHeight);
bmp.bmPlanes = bmpInfo.bmiHeader.biPlanes;
bmp.bmWidthBytes = bmpInfo.bmiHeader.biWidth * 4;
bmp.bmBitsPixel = bmpInfo.bmiHeader.biBitCount;
bmp.bmBits = (char*)(data + sizeof(BITMAPINFO));

char* dibarr = NULL;
HBITMAP hB = CreateDIBSection(windowData.tCpyHdc, &bmpInfo, DIB_RGB_COLORS, (void**)&dibarr, 0, 0);
memcpy((void*)dibarr, (void*)bmp.bmBits, inf.packetsz - sizeof(BITMAPINFO));

HBITMAP oldBmp = (HBITMAP)SelectObject(tCpyHdc, hB);
StretchBlt(hDc, 0, 0, width - 20, height - 40, tCpyHdc, 0, 0, bmp.bmWidth, bmp.bmHeight, SRCCOPY);

通过 TCP 发送的图像被翻转

Image sent over TCP is flipped

c++

sockets

winapi

gdi

bitblt