Apple Newton Utilities Betriebsanweisung PDF herunterladen (Seite 366)

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CHAPTER 9

Recognition

9-24 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.

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