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touchscreen: Improved kinetic scrolling in lists

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Kinetic scrolling now accelerates when repeatedly swiping over
the screen, so you can scroll through large lists easily without
using the scrollbar. Press & hold to slow down and stop.

Menu items can no longer be selected during a kinetic scroll
event, to reduce the chance of accidental selections.

Change-Id: I05b7d5fe6681a9edf53096b1fa265442fb31bf33
This commit is contained in:
Aidan MacDonald 2022-11-25 14:13:29 +00:00 • committed by Solomon Peachy
parent 842492d77b
commit 0ca22b9a71
1 changed files with 66 additions and 17 deletions
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83
apps/gui/bitmap/list.c
View file

@ -543,12 +543,22 @@ static int swipe_scroll(struct gui_synclist *gui_list, int delta)
/* these could possibly be configurable */
/* the lower the smoother */
#define RELOAD_INTERVAL (HZ/25)
/* the higher the earler the list stops */
#define DECELERATION (1000*RELOAD_INTERVAL/HZ)
/* deceleration factors: new velocity = P * old velocity * - K */
#define DECEL_P (RELOAD_INTERVAL * 1) / (2 * HZ)
#define DECEL_K (RELOAD_INTERVAL * 2 * LCD_HEIGHT / HZ)
/* fast deceleration when the screen is pressed */
#define FINGER_DECEL_P (RELOAD_INTERVAL * 2) / (1 * HZ)
#define FINGER_DECEL_K (RELOAD_INTERVAL * (LCD_HEIGHT * 4) / HZ)
/* finger deceleration does not kick in until the touch duration exceeds this */
#define FINGER_DECEL_GRACE (HZ/4)
/* fraction used to multiply gesture velocity before accumulating it */
#define VELOCITY_RESIST 3 / 4
struct kinetic_cb_data {
struct gui_synclist *list;
int velocity;
int subpixel_accum;
long finger_tick;
};
struct kinetic {
@ -563,7 +573,11 @@ static struct gesture_vel list_gvel;
static void kinetic_stop_scrolling(struct kinetic *k, struct gui_synclist *list)
{
if (k->cb_data.list == list)
{
k->cb_data.subpixel_accum = 0;
k->cb_data.velocity = 0;
timeout_cancel(&k->tmo);
}
}
/* helper for gui/list.c to cancel scrolling if a normal button event comes */
@ -586,7 +600,11 @@ static int kinetic_callback(struct timeout *tmo)
return 0;
/* ds = v*dt */
int pixel_diff = data->velocity * RELOAD_INTERVAL / HZ;
data->subpixel_accum += 100 * data->velocity * RELOAD_INTERVAL / HZ;
int pixel_diff = data->subpixel_accum / 100;
data->subpixel_accum %= 100;
int action = swipe_scroll(list, pixel_diff);
if (action == ACTION_REDRAW)
{
@ -594,14 +612,33 @@ static int kinetic_callback(struct timeout *tmo)
button_queue_post(BUTTON_REDRAW, 0);
}
/* apply deceleration */
int old_sign = SIGN(data->velocity);
data->velocity -= SIGN(data->velocity) * DECELERATION;
if (SIGN(data->velocity) != old_sign)
/* calculate and apply deceleration */
int sign = SIGN(data->velocity);
int absvel = abs(data->velocity);
int decel;
if (data->finger_tick != 0 &&
!TIME_BEFORE(current_tick, data->finger_tick + FINGER_DECEL_GRACE))
{
decel = data->velocity * FINGER_DECEL_P + sign * FINGER_DECEL_K;
}
else
{
decel = data->velocity * DECEL_P + sign * DECEL_K;
}
/*
* Ensure velocity is smoothly reduced to zero to avoid jerkiness.
*/
if (absvel < 3)
data->velocity = 0;
else if (absvel < sign*decel)
data->velocity = data->velocity / 3;
else
data->velocity -= decel;
/* stop scrolling if we didn't move, it means we hit the end */
if (list->y_pos == list->scroll_base_y)
if (list->y_pos == list->scroll_base_y && pixel_diff != 0)
data->velocity = 0;
else
/* update base y since our scroll distance doesn't accumulate. */
@ -625,7 +662,7 @@ static bool kinetic_start_scrolling(struct kinetic *k, struct gui_synclist *list
return false;
k->cb_data.list = list;
k->cb_data.velocity = yvel;
k->cb_data.velocity += yvel * VELOCITY_RESIST;
list->scroll_mode = SCROLL_KINETIC;
list->scroll_base_y = list->y_pos;
@ -728,6 +765,11 @@ unsigned gui_synclist_do_touchscreen(struct gui_synclist *list)
int action = ACTION_NONE;
int click_loc;
if (action_gesture_is_pressed())
kinetic.cb_data.finger_tick = gevent.start_tick;
else
kinetic.cb_data.finger_tick = 0;
switch (gevent.id)
{
case GESTURE_NONE:
@ -737,7 +779,15 @@ unsigned gui_synclist_do_touchscreen(struct gui_synclist *list)
case GESTURE_TAP:
case GESTURE_LONG_PRESS:
_gui_synclist_stop_kinetic_scrolling(list);
/* In kinetic mode taps and presses only decelerate scrolling.
* User needs to wait until scrolling stops to select an item. */
if (list->scroll_mode == SCROLL_KINETIC)
{
if (gevent.id != GESTURE_NONE)
gesture_vel_reset(&list_gvel);
break;
}
click_loc = get_click_location(list, gevent.x, gevent.y);
if (click_loc & LIST)
{
@ -789,9 +839,7 @@ unsigned gui_synclist_do_touchscreen(struct gui_synclist *list)
break;
case GESTURE_DRAGSTART:
_gui_synclist_stop_kinetic_scrolling(list);
gesture_vel_reset(&list_gvel);
list->scroll_base_y = list->y_pos;
/* fallthrough */
case GESTURE_DRAG:
@ -799,7 +847,9 @@ unsigned gui_synclist_do_touchscreen(struct gui_synclist *list)
if (list->scroll_mode == SCROLL_NONE)
{
list->scroll_base_y = list->y_pos;
click_loc = get_click_location(list, gevent.ox, gevent.oy);
if (click_loc & SCROLLBAR)
list->scroll_mode = SCROLL_BAR;
else if (click_loc & LIST)
@ -810,15 +860,14 @@ unsigned gui_synclist_do_touchscreen(struct gui_synclist *list)
action = scrollbar_scroll(list, gevent.y);
else if (list->scroll_mode == SCROLL_SWIPE)
action = swipe_scroll(list, gevent.y - gevent.oy);
break;
case GESTURE_RELEASE:
if (list->scroll_mode != SCROLL_SWIPE ||
!kinetic_start_scrolling(&kinetic, list))
{
if (list->scroll_mode == SCROLL_BAR)
list->scroll_mode = SCROLL_NONE;
else if(!kinetic_start_scrolling(&kinetic, list) &&
list->scroll_mode != SCROLL_KINETIC)
list->scroll_mode = SCROLL_NONE;
}
action_gesture_reset();
action = ACTION_REDRAW;