Passing a SAFEARRAY from C# to COM
- by SlavaGu
I use 3rd party COM to find faces in a picture. One of the methods has the following signature, from SDK:
long FindMultipleFaces(
IUnknown* pIDibImage,
VARIANTARG* FacePositionArray
);
Parameters: pIDibImage[in] - The image
to search.
FacePositionArray[out]- The array of
FacePosition2 objects into which face
information is placed. This array is
in a safe array (VARIANT) of type
VT_UNKNOWN. The size of the array
dictates the maximum number of faces
for which to search.
which translates into the following C# method signature (from metadata):
int FindMultipleFaces(object pIDibImage, ref object pIFacePositions);
Being optimistic I call it the following way but get an exception that the memory is corrupt. The exception is thrown only when a face is present in the image.
FacePosition2[] facePositions = new FacePosition2[10];
object positions = facePositions;
int faceCount = FaceLocator.FindMultipleFaces(dibImage, ref positions);
What's the right way to pass SAFEARRAY to unmanaged code?
