🚀 go-pugleaf

Hello,

I seem to be missing how the DPtoLP function works.  I am using

POINT pt;
    .
    .
    .
  case WM_MOUSEMOVE:

        pt.x = (LONG)LOWORD(lParam);
        pt.y = (LONG)HIWORD(lParam);

        SetMapMode(hDC,MM_ANISOTROPIC);
        SetWindowExtEx(hDC, xwin,ywin,NULL);
        SetViewportExtEx(hDC,width,-height,NULL);

// Mouse moves are stored in pt.x and pt.y in DEVICE COORDINATES??
// Using the DPtoLP function should return their coordinates in LOGICAL
COORDINATES??

        retval = DPtoLP(hDC, &pt, 1);
        reterr = GetLastError();
      .
      .
      .

I find that I get an error in the retval and I retrieve the error using
GetLastError() which is 87.  87 is Invalid Parameter as defined in System
Error Codes on MSDN.

????

Anyone have any ideas on what is causing the error?
Should I expect that the coordinates returned are
    pt.x = pt.x * (xwin / width)
    pt.y = pt.y * (ywin / height)

which are the device coordinates times  the ratio of logical to device
coordinates??


Thanks in advance.

Mike Finch