BMP FILE DEPUIS HDC EN PUR API (WIN32)

int __stdcall HdcToBmpFile(HDC hdc, char *pszflname)
{
  HDC memdc;
  HANDLE hfl;
  DWORD dwBytes, dwWidth, dwHeight, dwNumColors, dwBPP, ColorSize;
  void *pBits;
  HBITMAP hbmp;
  BITMAPFILEHEADER fileheader;
  BITMAPINFOHEADER infoheader;
  RGBQUAD colors[256];
  BITMAPINFO bmpinfo;
  HGDIOBJ hret;
  dwWidth = GetDeviceCaps(hdc, HORZRES);
  dwHeight = GetDeviceCaps(hdc, VERTRES);
  dwBPP = GetDeviceCaps(hdc, BITSPIXEL);
  if(dwBPP <= 8) dwNumColors = 256;
  else dwNumColors = 0;
  if(!(memdc = CreateCompatibleDC(hdc))) return 0;
  bmpinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
  bmpinfo.bmiHeader.biWidth = dwWidth;
  bmpinfo.bmiHeader.biHeight = dwHeight;
  bmpinfo.bmiHeader.biPlanes = 1;
  bmpinfo.bmiHeader.biBitCount = (WORD) dwBPP;
  bmpinfo.bmiHeader.biCompression = BI_RGB;
  bmpinfo.bmiHeader.biSizeImage = 0;
  bmpinfo.bmiHeader.biXPelsPerMeter = 0;
  bmpinfo.bmiHeader.biYPelsPerMeter = 0;
  bmpinfo.bmiHeader.biClrUsed = dwNumColors;
  bmpinfo.bmiHeader.biClrImportant = dwNumColors;
  hbmp = CreateDIBSection(hdc, &bmpinfo, DIB_PAL_COLORS, &pBits, NULL, 0);
  if(!hbmp) goto errato;
  hret = SelectObject(memdc, hbmp);
  if(!hret || (hret == HGDI_ERROR)) goto errato;
  if(!BitBlt(memdc, 0, 0, dwWidth, dwHeight, hdc, 0, 0, SRCCOPY)) goto errato;
  if(dwNumColors) dwNumColors = GetDIBColorTable(memdc, 0, dwNumColors, colors);
  fileheader.bfType = 0x4D42;
  ColorSize = dwNumColors * sizeof(RGBQUAD);
  fileheader.bfSize = ((dwWidth*dwHeight*dwBPP) >> 3)+ColorSize+sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER);
  fileheader.bfReserved1 = fileheader.bfReserved2 = 0;
  fileheader.bfOffBits = ColorSize+sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER);
  infoheader.biSize = sizeof(BITMAPINFOHEADER);
  infoheader.biWidth = dwWidth;
  infoheader.biHeight = dwHeight;
  infoheader.biPlanes = 1;
  infoheader.biBitCount = (WORD) dwBPP;
  infoheader.biCompression = BI_RGB;
  infoheader.biSizeImage = infoheader.biClrImportant = 0;
  infoheader.biXPelsPerMeter = infoheader.biYPelsPerMeter = 0;
  infoheader.biClrUsed = dwNumColors;
  hfl = CreateFile(pszflname,GENERIC_WRITE,0,0,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,0);
  if(hfl == INVALID_HANDLE_VALUE) {DeleteObject(hbmp); goto errato;}
  WriteFile(hfl, &fileheader, sizeof(BITMAPFILEHEADER), &dwBytes, 0);
  WriteFile(hfl, &infoheader, sizeof(BITMAPINFOHEADER), &dwBytes, 0);
  if(!dwNumColors) WriteFile(hfl, colors, ColorSize, &dwBytes, 0);
  ColorSize = (dwWidth*dwHeight*dwBPP) >> 3;
  WriteFile(hfl, pBits, ColorSize, &dwBytes, 0);
  CloseHandle(hfl);
  DeleteObject(hbmp);
  DeleteDC(memdc);
  return 1;
errato:
  DeleteDC(memdc); return 0;
}