Recognition

Using the Recognition System

this regard. If necessary, you can provide a

ViewWordScript

or

ViewChangedScript

method that validates the recognizer's output; this method

can be especially useful when working with the printed recognizer.

Accepting Pen Input

9

When setting up any view, you must specify whether it accepts pen input at all. If
you set the

vNothingAllowed

flag (or turn off all recognition-oriented flags), the

view does not accept pen input. If you want the view to accept pen input, you must
set the

vClickable

flag in its

viewFlags

slot. Setting this flag only causes the

view to accept pen taps and send

ViewClickScript

messages; it does not

enable ink handling or send messages to any of the unit-handling methods that
provide recognition behavior.

Setting the

vClickable

flag specifies that the view system is to send the

ViewClickScript

message to the view once for each pen tap that occurs within

the view. Note that this is the case only when

vClickable

is the only flag set for

the view--other flags, such as the

vCustomDictionaries

flag, set the

vClickable

bit in the view's input mask also.

When this flag is set, the system sends additional messages to the view to signal
taps, strokes, gestures, and words. All pen input is signaled by the

ViewClickScript

message, which indicates that the pen contacted the screen

or was lifted from it within the boundaries of the view. If you supply a

ViewClickScript

method, it should return

true

to indicate that the message

was handled, or

nil

to pass the message on to another view. If this message is not

handled by the view and additional recognition flags are set, other messages may
be sent to the view, depending on what was written. These other messages include

ViewStrokeScript

,

ViewGestureScript

, and

ViewWordScript

--in that

order, if all are sent.

Each of the corresponding input-related view methods accept as an argument a unit
object passed to it by the system. The unit contains information about the pen
input. You cannot examine the unit directly from NewtonScript, but you can pass it
to other system-supplied functions that extract information from it such as the
beginning and ending points of the stroke, an array of stroke points, the stroke
bounds, and so on.

Taps and Overlapping Views

9

When views overlap, taps can "fall through" from the top view to the one beneath,
causing unexpected results. For example, when the user taps in an area of the top
view that doesn't handle taps, and the view beneath provides a button in the
vicinity of the tap, the button may be activated unintentionally.