[CONNECT C++] AssociativePoint::InitXxx

Question

void AssociativePoint::InitOrigin (AssocPoint& assocPoint, 
 UShort option 
); 
 What values are suitable for option ? Help says See also: DisplayHandler::GetSnapOrigin but why? 
 void AssociativePoint::InitKeypoint ( AssocPoint & assocPoint, 
 UShort vertex, 
 UShort nVertex, 
 UShort numerator, 
 UShort divisor 
 ) 
 vertex and nVertex are reasonably clear, but what are numerator and divisor ? Help has this: The number of units (segments) to be considered between the points at vertex and vertex+1. The values of numerator and divisor are used together as the fraction of the distance between the points at vertex and vertex+1, where the association point will be located. The denominator must be between 1 and 32767 
 Let me put this another way: I have a class 
 struct ChooseShapeTool : public DgnElementSetTool
 
 When user selects a shape element, I want to construct an AssocPoint in the _OnDataButton event. What's a good way to do that?

Robert Hook · Accepted Answer

Unknown said: void AssociativePoint::InitOrigin (AssocPoint& assocPoint, UShort option ); 
 This method is analogous to the MDL C function mdlAssoc_createOrigin and its respective documentation; where the option integer value represents the Justification Point (0-default, or: 1 thru 9-origin points being;: LL, UL, UR, LR, CL, UC, CR, LC, CC) and can be used for element types: cell headers, shared cells, text nodes and text elements. 
 Unknown said: void AssociativePoint::InitKeypoint ( AssocPoint & assocPoint, UShort vertex, UShort nVertex, UShort numerator, UShort divisor ) 
 This method is analogous to the MDL C function mdlAssoc_createKeypoint and its respective documentation.can be used for Linear element types: lines, line strings and shapes . An association point can be placed directly on a specific vertex index (nVertex). Other times it is desired to calculate an association point to a projected (divisor) segment (numerator) between 2 specific vertices (e.g. Create association point between vertex 2 and 3, but projected 2/3 the distance of that segment). Is functionally similar to how MicroStation users set the keypoint snap divisor (ky=3, then snap on a segment project at points 1/3, 2/3, and 3/3 divisor points) 
 Unknown said: When user selects a shape element, I want to construct an AssocPoint in the _OnDataButton event. What's a good way to do that? 
 You will need to call InitKeypoint with your generic vertex/segment parameters as per above, then associate to the (root) element by calling SetRoot; something like: 
 switch (targetElementType)
 {
 case LINE_ELM:
 case LINE_STRING_ELM:
 case SHAPE_ELM:
 { AssociativePoint::InitKeypoint (assocPoint, vertex, nVertex, numerator, divisor); AssociativePoint::SetRoot(assocPoint, targetId, 0, 0); break;
 }

HTH, Bob