An interface to be implemented by objects that can determine the
settings of an IIOMetadata object, either by putting
up a GUI to obtain values from a user, or by other means. This
interface merely specifies a generic activate method
that invokes the controller, without regard for how the controller
obtains values (i.e., whether the controller puts up a GUI
or merely computes a set of values is irrelevant to this
interface).
Within the activate method, a controller obtains
initial values by querying the IIOMetadata object's
settings, either using the XML DOM tree or a plug-in specific
interface, modifies values by whatever means, then modifies the
IIOMetadata object's settings, using either the
setFromTree or mergeTree methods, or a
plug-in specific interface. In general, applications may expect
that when the activate method returns
true, the IIOMetadata object is ready for
use in a write operation.
Vendors may choose to provide GUIs for the
IIOMetadata subclasses they define for a particular
plug-in. These can be set up as default controllers in the
corresponding IIOMetadata subclasses.
Alternatively, an algorithmic process such as a database lookup
or the parsing of a command line could be used as a controller, in
which case the activate method would simply look up or
compute the settings, call methods on IIOMetadata to
set its state, and return true. |
