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.TH SCRIBBLE 2

.SH NAME

scribblealloc,

recognize \- character recognition

.SH SYNOPSIS

.PP

.EX

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#include <u.h>

#include <libc.h>

#include <draw.h>

#include <scribble.h>

Scribble	*scribblealloc(void);

Rune		recognize(Scribble *);

.EE

.SH DESCRIPTION

.PP

The scribble library implements simple character recognition.

All characters are drawn using a single stroke of the pen (mouse button 1)

as on a palmtop computer.

A reference card is in

.BR /sys/src/libscribble/quickref.gif .

.PP

The library is not really intended for standalone use.  Its primary

use is by the scribble graphical control (see

.IR control (2)).

.PP

.B Scribblealloc

allocates and returns an appropriately initialized

.B Scribble

structure:

.IP

.EX

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#define	CS_LETTERS			0

#define	CS_DIGITS			1

#define	CS_PUNCTUATION	2

struct Scribble {

	/* private state */

	Point			*pt;

	int			ppasize;

	Stroke	   ps;

	Graffiti		*graf;

	int			capsLock;

	int			puncShift;

	int			tmpShift;

	int			ctrlShift;

	int			curCharSet;

};

.EE

.PP

This structure encodes the points making up the stroke

to be recognized, as well as the \f2character group\fP in which

the stroke should be searched.

.PP

There are three such groups:

.IR letters ,

.IR digits ,

and

.IR punctuation .

The current group is encoded in the

.B curCharSet

field of the

.B Scribble

structure.

Special strokes are recognized to switch between groups.

In addition, the charater recognized is influenced by

.I mode

parameters and modifies them.

These are identified by the

.BR capsLock ,

.BR puncShift ,

.BR tmpShift ,

and

.B ctrlShift

fields of the

.B Scribble

structure.

When

.B puncShift

is non-zero, the character is recognized in the punctuation

character set.

Similarly,

when the character recognized is printable and

.B ctrlShift

is set, the associated control character is returned as if the

control key were depressed,

and when the character is a letter and

.B capsLock

or

.B tmpShift

is set, the upper-case version is returned.

The

.B puncShift

and

.B tmpShift

flags are turned off

once a character has been recognized; the others are left set.

.PP

The character to be recognized is encoded as an array of pen_points in the

.B ps

field.

To allow easy drawing of the stroke as it is drawn,

the

.I pt

and

.I ppasize

fields are available to the application code for storing an array

of points for a call to

.B poly

(see

.IR draw (2)).

.PP

.I Recognize

recognizes the character provided in the

.B ps

field of the

.B Scribble

structure; it

returns the rune or zero if nothing was recognized.

.SH FILES

.B /sys/src/libscribble/quickref.gif

serves as a quick reference card.

.PP

.B /sys/lib/scribble/classifiers

contains the stroke definitions.

.SH SOURCE

.B /sys/src/libscribble

.PP

This library is adapted from software reproduced by permission:

.PP

.B Graffiti.c

is based on the file

.B Scribble.c

copyrighted

by Keith Packard:

.IP

Copyright © 1999 Keith Packard

.PP

Permission to use, copy, modify, distribute, and sell this software and its

documentation for any purpose is hereby granted without fee, provided that

the above copyright notice appear in all copies and that both that

copyright notice and this permission notice appear in supporting

documentation, and that the name of Keith Packard not be used in

advertising or publicity pertaining to distribution of the software without

specific, written prior permission.  Keith Packard makes no

representations about the suitability of this software for any purpose.  It

is provided "as is" without express or implied warranty.

.PP

Portions of the software Copyright © 1994 by Sun Microsystems Computer Company.

.PP

Portions of the software Copyright © 2000 by Compaq Computer Corporation.

.SH SEE ALSO

.B Keyboard

and

.B prompter

in

.IR bitsyload (1),

.IR draw (2),

.IR control (2)