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Emulate tablet-class pen capabilities for osu!lazer input #6

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Emulate tablet-class pen capabilities for osu!lazer input #6

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107f9fe
Emulate tablet-class pen capabilities for osu!lazer input
sciboy12 Apr 17, 2026
e22e884
Mirror BTN_TOUCH state from source device events
sciboy12 Apr 17, 2026
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63 changes: 48 additions & 15 deletions abs-c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -133,9 +133,13 @@ int init_uinput(int tmin_x, int tmax_x, int tmin_y, int tmax_y) {

if (ioctl(fd, UI_SET_EVBIT, EV_KEY) < 0 ||
ioctl(fd, UI_SET_KEYBIT, BTN_LEFT) < 0 ||
ioctl(fd, UI_SET_KEYBIT, BTN_TOUCH) < 0 ||
ioctl(fd, UI_SET_KEYBIT, BTN_TOOL_PEN) < 0 ||
ioctl(fd, UI_SET_EVBIT, EV_ABS) < 0 ||
ioctl(fd, UI_SET_ABSBIT, ABS_X) < 0 ||
ioctl(fd, UI_SET_ABSBIT, ABS_Y) < 0 ||
ioctl(fd, UI_SET_ABSBIT, ABS_PRESSURE) < 0 ||
ioctl(fd, UI_SET_PROPBIT, INPUT_PROP_DIRECT) < 0 ||
ioctl(fd, UI_SET_EVBIT, EV_SYN) < 0) {
perror("ioctl uinput setup");
close(fd);
Expand All @@ -152,6 +156,8 @@ int init_uinput(int tmin_x, int tmax_x, int tmin_y, int tmax_y) {
uidev.absmax[ABS_X] = tmax_x;
uidev.absmin[ABS_Y] = tmin_y;
uidev.absmax[ABS_Y] = tmax_y;
uidev.absmin[ABS_PRESSURE] = 0;
uidev.absmax[ABS_PRESSURE] = 8191;

ssize_t wrote = write(fd, &uidev, sizeof(uidev));
if (wrote != (ssize_t)sizeof(uidev)) {
Expand All @@ -167,6 +173,20 @@ int init_uinput(int tmin_x, int tmax_x, int tmin_y, int tmax_y) {
return fd;
}

static inline bool emit_pen_tool_state(void) {
struct input_event ev[2] = {
{ .type = EV_KEY, .code = BTN_TOOL_PEN, .value = 1 },
{ .type = EV_SYN, .code = SYN_REPORT, .value = 0 }
};

ssize_t wrote = write(tab_fd, ev, sizeof(ev));
if (wrote != (ssize_t)sizeof(ev)) {
perror("write BTN_TOOL_PEN");
return false;
}
return true;
}

static inline int test_bit(int bit, const unsigned long *array) {
return (array[bit / (8 * sizeof(unsigned long))] >> (bit % (8 * sizeof(unsigned long)))) & 1;
}
Expand Down Expand Up @@ -438,7 +458,10 @@ int main(int argc, char *argv[]) {


int x = 0, y = 0;
int x_old = -1, y_old = -1;
int pressure = 0;
bool is_down = false;
bool got_x = false;
bool got_y = false;
bool active;

if (config.enable_tosu == true) {
Expand Down Expand Up @@ -468,6 +491,10 @@ int main(int argc, char *argv[]) {
set_grab(fd, &grabbed, active);

if (active == true) {
if (!emit_pen_tool_state()) {
break;
}

if (poll(&pfd, 1, -1) <= 0)
continue;
if (pfd.revents & (POLLERR | POLLHUP | POLLNVAL)) {
Expand All @@ -485,39 +512,45 @@ int main(int argc, char *argv[]) {
if (rd != sizeof(ev))
continue;

bool x_dirty = false;
bool y_dirty = false;

if (ev.type == EV_ABS) {
if (ev.code == ABS_X && ev.value != x_old) {
if (ev.code == ABS_X) {
x = ev.value;
x_dirty = true;
got_x = true;
}
else if (ev.code == ABS_Y && ev.value != y_old) {
else if (ev.code == ABS_Y) {
y = ev.value;
y_dirty = true;
got_y = true;
}

if (x_dirty || y_dirty) {
if (!emit_abs_delta(x, y, x_dirty, y_dirty)) {
}
else if (ev.type == EV_SYN && ev.code == SYN_REPORT) {
if (got_x && got_y) {
if (!emit_abs_delta(x, y, true, true)) {
Comment on lines +527 to +528

@chatgpt-codex-connector chatgpt-codex-connector Bot Apr 17, 2026

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P1 Badge Emit movement when either axis changes per frame

Many evdev tablets emit only the axis that changed before SYN_REPORT (e.g., pure horizontal movement can be ABS_X only). The new if (got_x && got_y) condition drops those frames, so single-axis motion is not forwarded until the other axis changes, which makes the cursor stall or jump and is a functional regression from the previous x_dirty || y_dirty behavior.

Useful? React with 👍 / 👎.

break;
}
x_old = x;
y_old = y;
got_x = false;
got_y = false;
}
}

if (config.enable_buttons &&
ev.type == EV_KEY &&
ev.code == BTN_LEFT) {
is_down = (ev.value != 0);
if (is_down) {
pressure = 8191;
} else {
pressure = 0;
}
(void)pressure;

struct input_event btn[2] = {
struct input_event btn[3] = {
{ .type = EV_KEY, .code = BTN_LEFT, .value = ev.value },
{ .type = EV_KEY, .code = BTN_TOUCH, .value = is_down ? 1 : 0 },
{ .type = EV_SYN, .code = SYN_REPORT, .value = 0 }
};
ssize_t bw = write(tab_fd, btn, sizeof(btn));
if (bw != (ssize_t)sizeof(btn)) {
perror("write BTN_LEFT");
perror("write BTN_LEFT/BTN_TOUCH");
break;
}
}
Expand Down