Same algorithm as in evdev-touchpad.
Signed-off-by: Peter Hutterer <peter.hutte...@who-t.net>
---
src/evdev-mt-touchpad.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 63 insertions(+)
diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
index 856d54f..f625814 100644
--- a/src/evdev-mt-touchpad.c
+++ b/src/evdev-mt-touchpad.c
@@ -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)
{
@@ -92,6 +118,30 @@ tp_motion_history_push(struct tp_touch *t)
}
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)
{
t->history.count = 0;
@@ -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;
}
--
1.8.4.2
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