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evdev: Add touchscreen mouse emulation and pressure support (thanks, …
…Zach!).

This also solves reports of this log message:

"INFO: The key you just pressed is not recognized by SDL. To help get this
fixed, please report this to the SDL forums/mailing list
<https://discourse.libsdl.org/> EVDEV KeyCode 330"

(EVDEV KeyCode 330 is BTN_TOUCH.)

Fixes Bugzilla #4147.
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icculus committed Jan 15, 2019
1 parent dc26345 commit 2755a505a344e8356ae05ad735847b1c609659e7
Showing 1 changed file with 85 additions and 5 deletions.
@@ -55,6 +55,7 @@
#define ABS_MT_POSITION_X 0x35
#define ABS_MT_POSITION_Y 0x36
#define ABS_MT_TRACKING_ID 0x39
#define ABS_MT_PRESSURE 0x3a
#endif

typedef struct SDL_evdevlist_item
@@ -74,6 +75,7 @@ typedef struct SDL_evdevlist_item

int min_x, max_x, range_x;
int min_y, max_y, range_y;
int min_pressure, max_pressure, range_pressure;

int max_slots;
int current_slot;
@@ -85,8 +87,10 @@ typedef struct SDL_evdevlist_item
EVDEV_TOUCH_SLOTDELTA_MOVE
} delta;
int tracking_id;
int x, y;
int x, y, pressure;
} * slots;

int pointerFingerID;
} * touchscreen_data;

struct SDL_evdevlist_item *next;
@@ -229,7 +233,8 @@ SDL_EVDEV_Poll(void)
SDL_Scancode scan_code;
int mouse_button;
SDL_Mouse *mouse;
float norm_x, norm_y;
float norm_x, norm_y, norm_pressure;
int abs_x, abs_y;

if (!_this) {
return;
@@ -264,6 +269,16 @@ SDL_EVDEV_Poll(void)
break;
}

/* BTH_TOUCH event value 1 indicates there is contact with
a touchscreen or trackpad (earlist finger's current
position is sent in EV_ABS ABS_X/ABS_Y, switching to
next finger after earlist is released) however using it
for virtual mouse SDL_TOUCH_MOUSEID would differ from
other SDL backends which require a new finger touch. */
if (item->is_touchscreen && events[i].code == BTN_TOUCH) {
break;
}

/* Probably keyboard */
scan_code = SDL_EVDEV_translate_keycode(events[i].code);
if (scan_code != SDL_SCANCODE_UNKNOWN) {
@@ -308,6 +323,14 @@ SDL_EVDEV_Poll(void)
item->touchscreen_data->slots[item->touchscreen_data->current_slot].delta = EVDEV_TOUCH_SLOTDELTA_MOVE;
}
break;
case ABS_MT_PRESSURE:
if (!item->is_touchscreen) /* FIXME: temp hack */
break;
item->touchscreen_data->slots[item->touchscreen_data->current_slot].pressure = events[i].value;
if (item->touchscreen_data->slots[item->touchscreen_data->current_slot].delta == EVDEV_TOUCH_SLOTDELTA_NONE) {
item->touchscreen_data->slots[item->touchscreen_data->current_slot].delta = EVDEV_TOUCH_SLOTDELTA_MOVE;
}
break;
case ABS_X:
if (item->is_touchscreen) /* FIXME: temp hack */
break;
@@ -352,18 +375,45 @@ SDL_EVDEV_Poll(void)
norm_y = (float)(item->touchscreen_data->slots[j].y - item->touchscreen_data->min_y) /
(float)item->touchscreen_data->range_y;

if (item->touchscreen_data->range_pressure > 0) {
norm_pressure = (float)(item->touchscreen_data->slots[j].pressure - item->touchscreen_data->min_pressure) /
(float)item->touchscreen_data->range_pressure;
} else {
/* This touchscreen does not support pressure */
norm_pressure = 1.0f;
}

abs_x = item->touchscreen_data->slots[j].x;
abs_y = item->touchscreen_data->slots[j].y;

switch(item->touchscreen_data->slots[j].delta) {
case EVDEV_TOUCH_SLOTDELTA_DOWN:
SDL_SendTouch(item->fd, item->touchscreen_data->slots[j].tracking_id, SDL_TRUE, norm_x, norm_y, 1.0f);
if (item->touchscreen_data->pointerFingerID == -1) {
SDL_SendMouseMotion(mouse->focus, SDL_TOUCH_MOUSEID, 0, abs_x, abs_y);

SDL_SendMouseButton(mouse->focus, SDL_TOUCH_MOUSEID, SDL_PRESSED, SDL_BUTTON_LEFT);
item->touchscreen_data->pointerFingerID = item->touchscreen_data->slots[j].tracking_id;
}

SDL_SendTouch(item->fd, item->touchscreen_data->slots[j].tracking_id, SDL_TRUE, norm_x, norm_y, norm_pressure);
item->touchscreen_data->slots[j].delta = EVDEV_TOUCH_SLOTDELTA_NONE;
break;
case EVDEV_TOUCH_SLOTDELTA_UP:
SDL_SendTouch(item->fd, item->touchscreen_data->slots[j].tracking_id, SDL_FALSE, norm_x, norm_y, 1.0f);
if (item->touchscreen_data->pointerFingerID == item->touchscreen_data->slots[j].tracking_id) {
SDL_SendMouseButton(mouse->focus, SDL_TOUCH_MOUSEID, SDL_RELEASED, SDL_BUTTON_LEFT);
item->touchscreen_data->pointerFingerID = -1;
}

SDL_SendTouch(item->fd, item->touchscreen_data->slots[j].tracking_id, SDL_FALSE, norm_x, norm_y, norm_pressure);
item->touchscreen_data->slots[j].tracking_id = -1;
item->touchscreen_data->slots[j].delta = EVDEV_TOUCH_SLOTDELTA_NONE;
break;
case EVDEV_TOUCH_SLOTDELTA_MOVE:
SDL_SendTouchMotion(item->fd, item->touchscreen_data->slots[j].tracking_id, norm_x, norm_y, 1.0f);
if (item->touchscreen_data->pointerFingerID == item->touchscreen_data->slots[j].tracking_id) {
SDL_SendMouseMotion(mouse->focus, SDL_TOUCH_MOUSEID, 0, abs_x, abs_y);
}

SDL_SendTouchMotion(item->fd, item->touchscreen_data->slots[j].tracking_id, norm_x, norm_y, norm_pressure);
item->touchscreen_data->slots[j].delta = EVDEV_TOUCH_SLOTDELTA_NONE;
break;
default:
@@ -453,6 +503,16 @@ SDL_EVDEV_init_touchscreen(SDL_evdevlist_item* item)
item->touchscreen_data->max_y = abs_info.maximum;
item->touchscreen_data->range_y = abs_info.maximum - abs_info.minimum;

ret = ioctl(item->fd, EVIOCGABS(ABS_MT_PRESSURE), &abs_info);
if (ret < 0) {
SDL_free(item->touchscreen_data->name);
SDL_free(item->touchscreen_data);
return SDL_SetError("Failed to get evdev touchscreen limits");
}
item->touchscreen_data->min_pressure = abs_info.minimum;
item->touchscreen_data->max_pressure = abs_info.maximum;
item->touchscreen_data->range_pressure = abs_info.maximum - abs_info.minimum;

ret = ioctl(item->fd, EVIOCGABS(ABS_MT_SLOT), &abs_info);
if (ret < 0) {
SDL_free(item->touchscreen_data->name);
@@ -474,6 +534,8 @@ SDL_EVDEV_init_touchscreen(SDL_evdevlist_item* item)
item->touchscreen_data->slots[i].tracking_id = -1;
}

item->touchscreen_data->pointerFingerID = -1;

ret = SDL_AddTouch(item->fd, /* I guess our fd is unique enough */
SDL_TOUCH_DEVICE_DIRECT,
item->touchscreen_data->name);
@@ -594,6 +656,24 @@ SDL_EVDEV_sync_device(SDL_evdevlist_item *item)
}
}

*mt_req_code = ABS_MT_PRESSURE;
ret = ioctl(item->fd, EVIOCGMTSLOTS(mt_req_size), mt_req_code);
if (ret < 0) {
SDL_free(mt_req_code);
return;
}
for(i = 0; i < item->touchscreen_data->max_slots; i++) {
if (item->touchscreen_data->slots[i].tracking_id >= 0 &&
item->touchscreen_data->slots[i].pressure != mt_req_values[i]) {
item->touchscreen_data->slots[i].pressure = mt_req_values[i];
if (item->touchscreen_data->slots[i].delta ==
EVDEV_TOUCH_SLOTDELTA_NONE) {
item->touchscreen_data->slots[i].delta =
EVDEV_TOUCH_SLOTDELTA_MOVE;
}
}
}

ret = ioctl(item->fd, EVIOCGABS(ABS_MT_SLOT), &abs_info);
if (ret < 0) {
SDL_free(mt_req_code);

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