Apple Newton Utilities Guide de l'utilisateur télécharger pdf (Page 345)

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CHAPTER 9

Recognition

About the Recognition System 9-3

Classifying Strokes 9

Recognition is an iterative process that compares raw input strokes with various

system-deﬁned models to identify the best matches for further processing. When

the user writes or draws in an edit view or paragraph view that accepts user input,

the system

■ notiﬁes the view that a pen event occurred within its boundaries.

■ provides user feedback, in the form of electronic ink drawn on the screen as the

pen moves across its surface.

■ attempts to group strokes meaningfully according to temporal and spatial data.

A view that accepts pen input is notiﬁed of pen events within its boundaries by

ViewClickScript messages that are sent when the pen contacts the screen

and when it is lifted from the screen. Views based on the

clEditView and

clParagraphView classes handle these events automatically; other views may

not, depending on the type of view in which the pen event occurred. Your view can

supply an optional

ViewClickScript method to take application-speciﬁc action

in response to these events as necessary.

The electronic ink displayed as the pen moves across the screen is called raw ink.

Raw ink is drawn in the same place on the screen as the original input strokes.

Views based on the

clParagraphView view class can be conﬁgured to replace

the raw ink with another representation of the input strokes called ink text. Ink text

is a version of the original strokes that has been scaled for display and formatted

into paragraphs: spaces between groups of strokes are made uniform and groups of

strokes are wrapped to the margins of the screen. The size to which ink text is

scaled is speciﬁed by the user from the Text Editing Settings user preference slip.

This user preference slip and others that affect recognition behavior are discussed

in “User Preferences for Recognition” beginning on page 9-14.

The recognition system encapsulates raw input strokes in an object called a stroke

unit. Stroke units cannot be examined directly from NewtonScript; however, you

can pass them to functions that construct useful objects from them or perform

recognition using the stroke data they contain.

Views conﬁgured to image input as ink text display a scaled representation of the

original input strokes without performing any further processing; that is, they

circumvent the remainder of the recognition process described here.

When stroke units are made available to a view that performs recognition, all of

the recognizers enabled for the view compete equally to classify the input. Each

recognizer compares the input to a system-deﬁned model; if there is a match,

the recognizer involved claims the stroke unit as its own.

Once a stroke unit is claimed by one of the recognizers, it is not returned to the

other recognizers for additional classiﬁcation; however, recognizers may combine

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Apple Newton Utilities Guide de l'utilisateur Page 345

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