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touchpad: add hysteresis smoothing for input coordinates

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Same algorithm as in evdev-touchpad.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
This commit is contained in:
Peter Hutterer 2014-02-06 18:57:10 +10:00
parent 37a04e0b0d
commit e75a0430be
1 changed files with 63 additions and 0 deletions
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63
src/evdev-mt-touchpad.c
View file

@ -23,10 +23,12 @@
#include "config.h"
#include <assert.h>
#include <math.h>
#include <stdbool.h>
#include "evdev.h"
#define DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR 700.0
#define TOUCHPAD_HISTORY_LENGTH 4
#define tp_for_each_touch(_tp, _t) \
@ -56,6 +58,11 @@ struct tp_touch {
unsigned int index;
unsigned int count;
} history;
struct {
int32_t center_x;
int32_t center_y;
} hysteresis;
};
struct tp_dispatch {
@ -66,8 +73,27 @@ struct tp_dispatch {
unsigned int ntouches; /* number of slots */
struct tp_touch *touches; /* len == ntouches */
struct {
int32_t margin_x;
int32_t margin_y;
} hysteresis;
};
static inline int
tp_hysteresis(int in, int center, int margin)
{
int diff = in - center;
if (abs(diff) <= margin)
return center;
if (diff > margin)
return center + diff - margin;
else if (diff < -margin)
return center + diff + margin;
return center + diff;
}
static inline struct tp_motion *
tp_motion_history_offset(struct tp_touch *t, int offset)
{
@ -91,6 +117,30 @@ tp_motion_history_push(struct tp_touch *t)
t->history.index = motion_index;
}
static inline void
tp_motion_hysteresis(struct tp_dispatch *tp,
struct tp_touch *t)
{
int x = t->x,
y = t->y;
if (t->history.count == 0) {
t->hysteresis.center_x = t->x;
t->hysteresis.center_y = t->y;
} else {
x = tp_hysteresis(x,
t->hysteresis.center_x,
tp->hysteresis.margin_x);
y = tp_hysteresis(y,
t->hysteresis.center_y,
tp->hysteresis.margin_y);
t->hysteresis.center_x = x;
t->hysteresis.center_y = y;
t->x = x;
t->y = y;
}
}
static inline void
tp_motion_history_reset(struct tp_touch *t)
{
@ -210,6 +260,7 @@ tp_process_state(struct tp_dispatch *tp, uint32_t time)
if (!t->dirty)
continue;
tp_motion_hysteresis(tp, t);
tp_motion_history_push(t);
}
}
@ -311,12 +362,24 @@ static int
tp_init(struct tp_dispatch *tp,
struct evdev_device *device)
{
int width, height;
double diagonal;
tp->base.interface = &tp_interface;
tp->device = device;
if (tp_init_slots(tp, device) != 0)
return -1;
width = abs(device->abs.max_x - device->abs.min_x);
height = abs(device->abs.max_y - device->abs.min_y);
diagonal = sqrt(width*width + height*height);
tp->hysteresis.margin_x =
diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;
tp->hysteresis.margin_y =
diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;
return 0;
}