EMF and GetPath

[Massad]

I have a question regarding Playing back emf files and using the GetPath function after the playback is completed.

What I would like to do is capture the paths that the PlayMetaFile function writes to the screen. However when I run the code below, instead of returning the number of points that were drawn, GetPath returns -1.

According to MSDN, -1 is returned by GetPath when you supply a 3rd parameter to GetPath which is less than the number of points in the path.
However if you pass in a 0 (as in my case), it should return the number of points that the path contains. Below is the code I am using. Does anyone know what I may be doing wrong?

[this code is executed in the OnDraw event handler)

CDerivativesViewDoc* pDoc = (CDerivativesViewDoc*)this->GetDocument();
RECT rcRect;
GetClientRect(&rcRect);
HENHMETAFILE meta_file = pDoc->GetMetaFile();
pDC->BeginPath();
pDC->PlayMetaFile(meta_file,&rcRect);
pDC->EndPath();

//the function below always returns a -1 !!!!!!!
int nPoints = pDC->GetPath(NULL,NULL,0);
if(nPoints > 0)
{
     //do somethign else
}

[olivthill]

I suppose that the problem comes from:

pDC->PlayMetaFile(meta_file,&rcRect);

This line places your metafile into the display context.
Is your metafile put at the same time in your path?

I have not checked with a program, but in my old MS help file, I read that the only functions that can be used to put points in a path are:

AngleArc LineTo Polyline
Arc MoveToEx PolylineTo
ArcTo Pie PolyPolygon
Chord PolyBezier PolyPolyline
CloseFigure PolyBezierTo Rectangle
Ellipse PolyDraw RoundRect
ExtTextOut Polygon TextOut

So maybe a simple test would be to replace PlayMetafile by a LineTo and see if you get a number with GetPath.

[Massad]

I have previously performed the test using LineTo and yes I was able to receive a correct number of points from there.

I had a feeling that EMF may not generate a path but I wasn't sure and thought that since I was getting a -1 from GetPath(), that I was doing something wrong.

Is there another way to retrieve the points from an EMF file?

I know you can Enumerate the records in an EMF but I seem to get extremely large coordinates which are way outside the valid range of my View.

Thanks for your help.