All objects which have information to display in details view must override this method.

The two possible queries are:

Query 1

A request for the CLASSFIELDINFO linked the list segment associated with an object. This information is needed just prior to changing the view of a container control to details view.

If pClassFieldInfo is NULL (no subclasses have appended details data), the number of columns of details information for this class and all its superclasses is returned. If pClassFieldInfo is NON-NULL, the number of columns of details informtion is returned and *pClassFieldInfo points to the head of a linked list of CLASSFIELDINFO structures to which a linked list of CLASSFIELDINFO structures describing the details fields of objects of this subclass should be appended.

For example,on input *pClassFieldInfo:

CLASSFIELDINFO_1_grandparent_
CLASSFIELDINFO_2_grandparent
  CLASSFIELDINFO_1_parent

on output, *pClassFieldInfo:

CLASSFIELDINFO_1_grandparent_
CLASSFIELDINFO_2_grandparent
  CLASSFIELDINFO_1_parent
CLASSFIELDINFO_1_self

The correct way to handle this request is to do the following:

• Call the parent method. The parent method returns the number of columns the ancestors have contributed.

• Walk the chain of CLASSFIELDINFO structures to the end and append the chain of CLASSFIELDINFO structures for the current class (using the pNextFieldInfo element).

• If *pClassFieldInfo is zero (indicating no parent columns), assign *pClassFieldInfo = beginning of CLASSFIELDINFO chain for this subclass.

• Return the sum of the details columns of the parent and the current subclass.

Note the following differences between the CLASSFIELDINFO and FIELDINFO structures:

• The offFieldData and ulLenFieldData fields are required so that appropriate offsets for the data can be computed. The application is responsible for providing offFieldData and ulLenFieldData fields.

• The ulReserved field should be left NULL.

• Owner draw, comparison, and sort functions may be specified for the field.

For example, if an object has three fields:

typedef struct _SAMPLE_DETAIL_DATA {
  CDATE   cdate;
  CTIME   ctime;
  PSZ     psz;
}  SAMPLE_DETAIL_DATA;

classfieldinfo[0].offFieldData   = FIELDOFFSET(SAMPLE,cdate);
classfieldinfo[0].ulLenFieldData = FIELDOFFSET(SAMPLE,ctime)
                                       FIELDOFFSET(SAMPLE,cdate);

classfieldinfo[1].offFieldData   = FIELDOFFSET(SAMPLE,ctime);
classfieldinfo[1].ulLenFieldData = FIELDOFFSET(SAMPLE,psz) -
                                       FIELDOFFSET(SAMPLE,ctime);

classfieldinfo[2].offFieldData   = FIELDOFFSET(SAMPLE,psz);
classfieldinfo[2].ulLenFieldData = sizeof(SAMPLE) -
                                       FIELDOFFSET(SAMPLE,psz);

Note that *pClassFieldInfo must be modified to point to the beginning of the CLASSFIELDINFO linked list only if *pClassFieldInfo is 0.

The application must return the sum of the details columns of the parent and itself:

return(n_cols + n_parent_cols);

Note also that the fields MUST be set up sequentially. classfieldinfo[0] must point to data at an offset of 0. classfieldinfo[n] must point to data adjacent, and directly following that described by classfieldinfo[-1].

Query 2

The number of bytes of details data associated with an object. This information is needed prior to allocating memory for a container control insert record.

If pSize is NON-NULL, the override should adjust *pSize by the number of bytes which must be added to the end of a MINIRECORDCORE structure to hold the details information for objects of this class.

Example:

*pSize += bytes_of_details_data;

In the case of the above example,

*pSize += sizeof(SAMPLE_DETAIL_DATA);

Note: All class field pointers returned should be pointers to static data areas.