SCRIBBLE(2) SCRIBBLE(2)
NAME
scribblealloc, recognize - character recognition
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <draw.h>
#include <scribble.h>
Scribble *scribblealloc(void);
Rune recognize(Scribble *);
DESCRIPTION
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.
The library is not really intended for standalone use. Its
primary use is by the scribble graphical control (see
control(2)).
Scribblealloc allocates and returns an appropriately ini-
tialized Scribble structure:
#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;
};
This structure encodes the points making up the stroke to be
recognized, as well as the character group in which the
stroke should be searched.
There are three such groups: letters, digits, and
punctuation. The current group is encoded in the curCharSet
field of the Scribble structure. Special strokes are recog-
nized to switch between groups. In addition, the charater
recognized is influenced by mode parameters and modifies
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them. These are identified by the capsLock, puncShift,
tmpShift, and ctrlShift fields of the Scribble structure.
When puncShift is non-zero, the character is recognized in
the punctuation character set. Similarly, when the charac-
ter recognized is printable and ctrlShift is set, the asso-
ciated control character is returned as if the control key
were depressed, and when the character is a letter and
capsLock or tmpShift is set, the upper-case version is
returned. The puncShift and tmpShift flags are turned off
once a character has been recognized; the others are left
set.
The character to be recognized is encoded as an array of
pen_points in the ps field. To allow easy drawing of the
stroke as it is drawn, the pt and ppasize fields are avail-
able to the application code for storing an array of points
for a call to poly (see draw(2)).
Recognize recognizes the character provided in the ps field
of the Scribble structure; it returns the rune or zero if
nothing was recognized.
FILES
/sys/lib/scribble/classifiers contains the stroke defini-
tions.
SOURCE
/sys/src/libscribble
This library is adapted from software reproduced by permis-
sion:
Graffiti.c is based on the file Scribble.c copyrighted by
Keith Packard:
Copyright © 1999 Keith Packard
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 docu-
mentation, 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" with-
out express or implied warranty.
Portions of the software Copyright © 1994 by Sun Microsys-
tems Computer Company.
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SCRIBBLE(2) SCRIBBLE(2)
Portions of the software Copyright © 2000 by Compaq Computer
Corporation.
SEE ALSO
Keyboard and prompter in bitsyload(1), draw(2), control(2)
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