The
Passport Reader system uses the
gxVariant data type to pass along complex input/output data structures. The
gxVariant
has the following important features:
- Uses run-time type information for automatic data conversion according to user demand.
- Stores id which can be used to identify a data in a complex structure. Most of the Ids are specified in the
PR_VAR_ID
enumeration. - Stores children. The variants can be connected together to form a tree through child-parent relation.
- Uses reference counting to save memory and to form a closed tree.
- Can be a list and can connect list items like the children. The list and list items can have children too.
The most frequently used variant structures are the Document structures which contain the recognized data and the Image structures which in turn contain the images stored in the system. These structures can be accessed from the prDoc
and the prImage
classes.
The following symbols are used to describe the data structure elements in the subsequent pages:
- the List symbol denotes a list which can have list items and children; a list can also be an item of another list;
- the List Item symbol denotes an item of a list;
- the Data symbol denotes a data item or a child data item of an item, a list or a list item.
List symbol
|
List Item symbol
|
Data symbol
|