Recognition: Advanced Topics

About Advanced Topics in Recognition

applications to change these system-wide settings. Instead, individual views can
customize their own recognition behavior by using a

recConfig

frame or

recToggle

view to override these inherited values locally.

In practice, most views' recognition behavior is defined by a combination of
inherited and overridden values. For example, because most users tend not to
change the speed at which they write, it's common for views to use inherited values
for the

timeoutCursiveOption

slot, which specifies the relative delay required

to consider a group of input strokes complete. At the same time, individual views
may customize certain recognition settings by overriding values that would
otherwise be inherited from the system's user configuration data. For example, a
view can use a

recConfig

frame to disable the automatic addition of new words

to the user dictionary.

A view based on the

protoRecToggle

system prototype provides another way to

override inherited recognition settings. This view provides a picker that allows the
user to change recognition settings easily. Each view controlled by this picker must
provide a

_recogSettings

slot that the picker sets according to the user's

current choice of recognition settings. The value in the

_recogSettings

slot

overrides values inherited from the system's user configuration data.

Your application supplies only one

_recogSettings

slot for each

recToggle

view it provides. Because views use parent inheritance to find a

_recogSettings

slot, a single

recToggle

view and a single

_recogSettings

slot can control

the recognition behavior of one view or multiple views, depending on the

_recogSettings

slot's position in the view hierarchy. For more information, see

"Creating the _recogSettings Slot" beginning on page 10-20.

You can also provide an optional

RecogSettingsChanged

method in the

_parent

chain of any view controlled by the

recToggle

view. If a

RecogSettingsChanged

method is provided, the

recToggle

view sends this

message to

self

when the user chooses an item in the

recToggle

picker.Your

RecogSettingsChanged

method can perform any application-specific task that

is appropriate; typically, this method reconfigures recognition settings in response
to the change in the

recToggle

view's state.

Finally, any view can provide an optional

recConfig

frame that specifies the

view's recognition behavior at the local level.

Although

recConfig

frames have thus far been presented as simply an alternate

interface to the recognition system, they are actually used internally by the system
to represent the recognition behavior of each view. When the user writes, draws, or
gestures in a view, the system builds a

recConfig

frame that specifies the precise

settings of all the recognizers needed for the view. If you supply a

recConfig

frame for the view, the

recConfig

frame that the system builds is based on the

recConfig

frame you have supplied and any recognition-related user preferences

that may apply.