HGKeeper

libgstroke - a GNOME stroke interface library

See the file COPYING for distribution information.

This file contains the stroke recognition algorithm.

#include "config.h"

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#include <stdlib.h>

#include <stdio.h>

#include <math.h>

#include <glib.h>

#include <gtk/gtk.h>

#include "gstroke.h"

#include "gstroke-internal.h"

void

_gstroke_init (struct gstroke_metrics *metrics)

{

if (metrics->pointList != NULL) {

g_slist_free_full(metrics->pointList, g_free);

metrics->pointList = NULL;

metrics->point_count = 0;

}

/* figure out which bin the point falls in */

static gint

_gstroke_bin (p_point point_p, gint bound_x_1, gint bound_x_2,

gint bound_y_1, gint bound_y_2)

{

gint bin_num = 1;

if (point_p->x > bound_x_1) bin_num += 1;

if (point_p->x > bound_x_2) bin_num += 1;

if (point_p->y > bound_y_1) bin_num += 3;

if (point_p->y > bound_y_2) bin_num += 3;

return bin_num;

}

gint

_gstroke_trans (gchar *sequence, struct gstroke_metrics *metrics)

{

GSList *crt_elem;

/* number of bins recorded in the stroke */

guint sequence_count = 0;

/* points-->sequence translation scratch variables */

gint prev_bin = 0;

gint current_bin = 0;

gint bin_count = 0;

/* flag indicating the start of a stroke - always count it in the sequence */

gint first_bin = TRUE;

/* bin boundary and size variables */

gint delta_x, delta_y;

gint bound_x_1, bound_x_2;

gint bound_y_1, bound_y_2;

/* determine size of grid */

delta_x = metrics->max_x - metrics->min_x;

delta_y = metrics->max_y - metrics->min_y;

/* calculate bin boundary positions */

bound_x_1 = metrics->min_x + (delta_x / 3);

bound_x_2 = metrics->min_x + 2 * (delta_x / 3);

bound_y_1 = metrics->min_y + (delta_y / 3);

bound_y_2 = metrics->min_y + 2 * (delta_y / 3);

if (delta_x > GSTROKE_SCALE_RATIO * delta_y) {

bound_y_1 = (metrics->max_y + metrics->min_y - delta_x) / 2 + (delta_x / 3);

bound_y_2 = (metrics->max_y + metrics->min_y - delta_x) / 2 + 2 * (delta_x / 3);

} else if (delta_y > GSTROKE_SCALE_RATIO * delta_x) {

bound_x_1 = (metrics->max_x + metrics->min_x - delta_y) / 2 + (delta_y / 3);

bound_x_2 = (metrics->max_x + metrics->min_x - delta_y) / 2 + 2 * (delta_y / 3);

}

#if 0

printf ("DEBUG:: point count: %d\n", metrics->point_count);

printf ("DEBUG:: metrics->min_x: %d\n", metrics->min_x);

printf ("DEBUG:: metrics->max_x: %d\n", metrics->max_x);

printf ("DEBUG:: metrics->min_y: %d\n", metrics->min_y);

printf ("DEBUG:: metrics->max_y: %d\n", metrics->max_y);

printf ("DEBUG:: delta_x: %d\n", delta_x);

printf ("DEBUG:: delta_y: %d\n", delta_y);

printf ("DEBUG:: bound_x_1: %d\n", bound_x_1);

printf ("DEBUG:: bound_x_2: %d\n", bound_x_2);

printf ("DEBUG:: bound_y_1: %d\n", bound_y_1);

printf ("DEBUG:: bound_y_2: %d\n", bound_y_2);

#endif

build string by placing points in bins, collapsing bins and

discarding those with too few points... */

crt_elem = metrics->pointList;

while (crt_elem != NULL)

{

/* figure out which bin the point falls in */

/*printf ("X = %d Y = %d\n", ((p_point)crt_elem->data)->x,

((p_point)crt_elem->data)->y); */

current_bin = _gstroke_bin ((p_point)crt_elem->data, bound_x_1,

bound_x_2, bound_y_1, bound_y_2);

/* if this is the first point, consider it the previous bin, too. */

if (prev_bin == 0)

prev_bin = current_bin;

/*printf ("DEBUG:: current bin: %d x=%d y = %d\n", current_bin,

((p_point)crt_elem->data)->x,

((p_point)crt_elem->data)->y); */

if (prev_bin == current_bin)

bin_count++;

else {

/* we are moving to a new bin -- consider adding to the sequence */

if ((bin_count > (metrics->point_count * GSTROKE_BIN_COUNT_PERCENT))

|| (first_bin == TRUE)) {

gchar val = '0' + prev_bin;

printf ("%c", val);fflush (stdout);

g_string_append (&sequence, &val);

first_bin = FALSE;

sequence[sequence_count++] = '0' + prev_bin;

/* printf ("DEBUG:: adding sequence: %d\n", prev_bin); */

}

/* restart counting points in the new bin */

bin_count=0;

prev_bin = current_bin;

}

/* move to next point, freeing current point from list */

g_free(crt_elem->data);

crt_elem = g_slist_next(crt_elem);

}

metrics->pointList = NULL;

/* add the last run of points to the sequence */

sequence[sequence_count++] = '0' + current_bin;

/* printf ("DEBUG:: adding final sequence: %d\n", current_bin); */

_gstroke_init (metrics);

{

/* FIXME: get rid of this block

gchar val = '0' + current_bin;

printf ("%c\n", val);fflush (stdout);

g_string_append (&sequence, '\0');

sequence[sequence_count] = '\0';

}

return TRUE;

}

/* my plan is to make a stroke training program where you can enter all of

the variations of slop that map to a canonical set of strokes. When the

application calls gstroke_canonical, it gets one of the recognized strokes,

or "", if it's not a recognized variation. I will probably use a hash

table. Right now, it just passes the values through to gstroke_trans */

gint

_gstroke_canonical (gchar *sequence, struct gstroke_metrics *metrics)

{

return _gstroke_trans (sequence, metrics);

}

void

_gstroke_record (gint x, gint y, struct gstroke_metrics *metrics)

{

p_point new_point_p;

gint delx, dely;

float ix, iy;

g_return_if_fail( metrics != NULL );

#if 0

printf ("%d:%d ", x, y); fflush (stdout);

#endif

if (metrics->point_count < GSTROKE_MAX_POINTS) {

if (metrics->pointList == NULL) {

/* first point in list - initialize metrics */

metrics->min_x = 10000;

metrics->min_y = 10000;

metrics->max_x = -1;

metrics->max_y = -1;

new_point_p = g_new0(struct s_point, 1);

metrics->pointList = g_slist_prepend(metrics->pointList, new_point_p);

metrics->point_count = 0;

} else {

p_point last_point = (p_point)g_slist_last(metrics->pointList)->data;

/* interpolate between last and current point */

delx = x - last_point->x;

dely = y - last_point->y;

if (abs(delx) > abs(dely)) { /* step by the greatest delta direction */

iy = last_point->y;

/* go from the last point to the current, whatever direction it may be */

for (ix = last_point->x; (delx > 0) ? (ix < x) : (ix > x); ix += (delx > 0) ? 1 : -1) {

/* step the other axis by the correct increment */

iy += fabs(((float) dely / (float) delx)) * (float) ((dely < 0) ? -1.0 : 1.0);

/* add the interpolated point */

new_point_p = g_new0(struct s_point, 1);

new_point_p->x = ix;

new_point_p->y = iy;

metrics->pointList = g_slist_append (metrics->pointList, new_point_p);

/* update metrics */

if (((gint) ix) < metrics->min_x) metrics->min_x = (gint) ix;

if (((gint) ix) > metrics->max_x) metrics->max_x = (gint) ix;

if (((gint) iy) < metrics->min_y) metrics->min_y = (gint) iy;

if (((gint) iy) > metrics->max_y) metrics->max_y = (gint) iy;

metrics->point_count++;

}

} else { /* same thing, but for dely larger than delx case... */

p_point last_point = (p_point)g_slist_last(metrics->pointList)->data;

ix = last_point->x;

/* go from the last point to the current, whatever direction it may be

for (iy = last_point->y; (dely > 0) ? (iy < y) : (iy > y); iy += (dely > 0) ? 1 : -1) {

/* step the other axis by the correct increment */

ix += fabs(((float) delx / (float) dely)) * (float) ((delx < 0) ? -1.0 : 1.0);

/* add the interpolated point */

new_point_p = g_new0(struct s_point, 1);

new_point_p->y = iy;

new_point_p->x = ix;

metrics->pointList = g_slist_append(metrics->pointList, new_point_p);

/* update metrics */

if (((gint) ix) < metrics->min_x) metrics->min_x = (gint) ix;

if (((gint) ix) > metrics->max_x) metrics->max_x = (gint) ix;

if (((gint) iy) < metrics->min_y) metrics->min_y = (gint) iy;

if (((gint) iy) > metrics->max_y) metrics->max_y = (gint) iy;

metrics->point_count++;

}

/* add the sampled point */

new_point_p = g_new0(struct s_point, 1);

metrics->pointList = g_slist_append(metrics->pointList, new_point_p);

}

/* record the sampled point values */

new_point_p->x = x;

new_point_p->y = y;

#if 0

{

GSList *crt = metrics->pointList;

printf ("Record ");

while (crt != NULL)

{

printf ("(%d,%d)", ((p_point)crt->data)->x, ((p_point)crt->data)->y);

crt = g_slist_next (crt);

}

printf ("\n");

}

#endif

}

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