Recognition: Advanced Topics

Using Advanced Topics in Recognition

Customized Processing of Double Taps

10

To process double taps reliably, your view's

ViewGestureScript

method can

test for the presence of the

aeDoubleTap

gesture. The gesture recognizer

measures time between pen events reliably even when the main NewtonScript
thread is busy.

The recognition system considers a second tap to be part of a double tap when it
occurs within a specified amount of time and distance relative to the first tap.

The second tap must be within 6 pixels of the first to be considered part of a double
tap. Any stroke longer than 6 pixels is not recognized as a tap (or as the second
tap). Measurement of the distance between taps is based on the midpoint of the
start and end points of the stroke.

The amount of time that determines whether a second tap is considered part of a
double tap is specified by the value of the

timeoutCursiveOption

slot in the

system's user configuration data. This value ranges between 15 and 60 ticks, with a
default value of 45 ticks. The user sets the value of this slot by moving the
"Transform my handwriting" slider in the Fine Tuning slip. The Fine Tuning slip is
available from the picker displayed by the Options button in the Handwriting
Recognition preferences slip.

Your

ViewGestureScript

method is called only if the view does not handle the

gesture automatically. Your

ViewGestureScript

method should return the

value

true

to avoid passing the gesture unit to other

ViewGestureScript

methods, such as those supplied by views in the

_parent

chain. If you do want to

pass the gesture unit to other views, your method should return the value

nil

.

Changing User Preferences for Recognition

10

When you must make system-wide changes in recognition behavior, you can set
the values of slots in the system's user configuration data to do so. However, in
most cases it is more appropriate to change the behavior of individual views, rather
than system-wide settings. For information on using

recConfig

frames to specify

the recognition behavior of individual views, see "Using recConfig Frames"
beginning on page 10-8.

Take the following steps to change recognition settings used by all views:

1. Call the

SetUserConfig

function to set the values of one or more slots in the

system's user configuration data. For a complete listing of the recognition-
related slots, see "System-Wide Settings" (page 8-2) in Newton Programmer's
Reference.

2. Call the

ReadCursiveOptions

function to cause the system to use the

new settings.