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Elan V4 Palm Rejection #66

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Elan V4 Palm Rejection #66

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74e0f51
Very rough first draft palm reject
averycblack Oct 30, 2025
7ca35bb
Make width check more permissive
averycblack Nov 10, 2025
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41 changes: 27 additions & 14 deletions VoodooPS2Trackpad/VoodooPS2Elan.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1941,12 +1941,12 @@ void ApplePS2Elan::processPacketHeadV4() {
pres = (packet[1] & 0xf0) | ((packet[4] & 0xf0) >> 4);
traces = (packet[0] & 0xf0) >> 4;

INTERRUPT_LOG("VoodooPS2Elan: pres: %d, traces: %d, width: %d\n", pres, traces, etd.width);
INTERRUPT_LOG("VoodooPS2Elan: pres: %d, traces: %d, width: %d)\n", pres, traces, traces * info.width / info.x_res);

virtualFinger[id].button = (packet[0] & 0x3);
virtualFinger[id].prev = virtualFinger[id].now;
virtualFinger[id].pressure = pres;
virtualFinger[id].width = traces;
virtualFinger[id].width = traces * info.width / info.x_res;

virtualFinger[id].now.x = x;
virtualFinger[id].now.y = y;
Expand Down Expand Up @@ -1997,7 +1997,11 @@ void ApplePS2Elan::processPacketMotionV4() {
sendTouchData();
}

MT2FingerType ApplePS2Elan::GetBestFingerType(int i) {
MT2FingerType ApplePS2Elan::GetBestFingerType(int i, uint8_t width, uint8_t pressure) {
if (width > 25 || pressure >= 80) {
return kMT2FingerTypePalm;
}

switch (i) {
case 0: return kMT2FingerTypeIndexFinger;
case 1: return kMT2FingerTypeMiddleFinger;
Expand All @@ -2019,30 +2023,32 @@ void ApplePS2Elan::sendTouchData() {

// Ignore input for specified time after keyboard/trackpoint usage
if (timestamp_ns - keytime < maxaftertyping) {
return;
// return;
}

static_assert(VOODOO_INPUT_MAX_TRANSDUCERS >= ETP_MAX_FINGERS, "Trackpad supports too many fingers");

int transducers_count = 0;
for (int i = 0; i < ETP_MAX_FINGERS; i++) {
const auto &state = virtualFinger[i];
if (!state.touch) {
continue;
}
// if (!state.touch) {
// continue;
// }

auto &transducer = inputEvent.transducers[transducers_count];
auto &transducer = inputEvent.transducers[i];

transducer.currentCoordinates = state.now;
transducer.previousCoordinates = state.prev;
transducer.timestamp = timestamp;

transducer.isValid = true;
transducer.isPhysicalButtonDown = info.is_buttonpad && state.button;
transducer.isTransducerActive = true;
transducer.isTransducerActive = state.touch;

transducer.secondaryId = i;
transducer.fingerType = GetBestFingerType(transducers_count);
if (transducer.fingerType != kMT2FingerTypePalm) {
transducer.fingerType = GetBestFingerType(i, state.width, state.pressure);
}
transducer.type = FINGER;

// it looks like Elan PS2 pressure and width is very inaccurate
Expand All @@ -2058,7 +2064,8 @@ void ApplePS2Elan::sendTouchData() {
transducer.currentCoordinates.width = 10;
}

transducers_count++;
if (transducer.isTransducerActive)
transducers_count++;
}

// set the thumb to improve 4F pinch and spread gesture and cross-screen dragging
Expand All @@ -2069,11 +2076,16 @@ void ApplePS2Elan::sendTouchData() {
int newThumbIndex = 0;
int currentThumbIndex = 0;
for (int i = 0; i < transducers_count; i++) {
if (inputEvent.transducers[i].currentCoordinates.y > maxY) {
auto &transducer = inputEvent.transducers[i];
if (!transducer.isTransducerActive || transducer.fingerType == kMT2FingerTypePalm) {
continue;
}

if (transducer.currentCoordinates.y > maxY) {
maxY = inputEvent.transducers[i].currentCoordinates.y;
newThumbIndex = i;
}
if (inputEvent.transducers[i].fingerType == kMT2FingerTypeThumb) {
if (transducer.fingerType == kMT2FingerTypeThumb) {
currentThumbIndex = i;
}
}
Expand All @@ -2085,9 +2097,10 @@ void ApplePS2Elan::sendTouchData() {
inputEvent.transducers[i].isValid = false;
inputEvent.transducers[i].isPhysicalButtonDown = false;
inputEvent.transducers[i].isTransducerActive = false;
inputEvent.transducers[i].fingerType = kMT2FingerTypeUndefined;
}

inputEvent.contact_count = transducers_count;
inputEvent.contact_count = ETP_MAX_FINGERS;
inputEvent.timestamp = timestamp;

if (voodooInputInstance) {
Expand Down
2 changes: 1 addition & 1 deletion VoodooPS2Trackpad/VoodooPS2Elan.h
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Original file line number Diff line number Diff line change
Expand Up @@ -324,7 +324,7 @@ class EXPORT ApplePS2Elan : public IOService {
void resetMouse();
void setTouchPadEnable(bool enable);

static MT2FingerType GetBestFingerType(int i);
static MT2FingerType GetBestFingerType(int i, uint8_t width, uint8_t pressure);

template<int I>
int ps2_command(UInt8* params, unsigned int command);
Expand Down