path: root/src/haptic_button_generator_filter_interpreter.cc

// Copyright 2021 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "include/haptic_button_generator_filter_interpreter.h"

#include <math.h>

#include "include/gestures.h"
#include "include/interpreter.h"
#include "include/logging.h"
#include "include/tracer.h"
#include "include/util.h"

namespace gestures {

HapticButtonGeneratorFilterInterpreter::HapticButtonGeneratorFilterInterpreter(
    PropRegistry* prop_reg, Interpreter* next, Tracer* tracer)
    : FilterInterpreter(nullptr, next, tracer, false),
      release_suppress_factor_(1.0),
      active_gesture_(false),
      active_gesture_timeout_(0.1),
      active_gesture_deadline_(NO_DEADLINE),
      button_down_(false),
      dynamic_down_threshold_(0.0),
      dynamic_up_threshold_(0.0),
      sensitivity_(prop_reg, "Haptic Button Sensitivity", 3),
      use_custom_thresholds_(prop_reg,
                             "Use Custom Haptic Button Force Thresholds",
                             false),
      custom_down_threshold_(prop_reg,
                             "Custom Haptic Button Force Threshold Down",
                             150.0),
      custom_up_threshold_(prop_reg,
                            "Custom Haptic Button Force Threshold Up",
                            130.0),
      enabled_(prop_reg, "Enable Haptic Button Generation", false),
      force_scale_(prop_reg, "Force Calibration Slope", 1.0),
      force_translate_(prop_reg, "Force Calibration Offset", 0.0),
      complete_release_suppress_speed_(
          prop_reg, "Haptic Complete Release Suppression Speed", 200.0),
      use_dynamic_thresholds_(prop_reg, "Use Dynamic Haptic Thresholds", false),
      dynamic_down_ratio_(prop_reg, "Dynamic Haptic Down Ratio", 1.2),
      dynamic_up_ratio_(prop_reg, "Dynamic Haptic Up Ratio", 0.5),
      max_dynamic_up_force_(prop_reg, "Max Dynamic Haptic Up Force", 350.0) {
  InitName();
}

void HapticButtonGeneratorFilterInterpreter::Initialize(
    const HardwareProperties* hwprops,
    Metrics* metrics,
    MetricsProperties* mprops,
    GestureConsumer* consumer) {
  is_haptic_pad_ = hwprops->is_haptic_pad;
  FilterInterpreter::Initialize(hwprops, nullptr, mprops, consumer);
}

void HapticButtonGeneratorFilterInterpreter::SyncInterpretImpl(
    HardwareState& hwstate, stime_t* timeout) {
  HandleHardwareState(hwstate);
  stime_t next_timeout = NO_DEADLINE;
  next_->SyncInterpret(hwstate, &next_timeout);
  UpdatePalmState(hwstate);
  *timeout = SetNextDeadlineAndReturnTimeoutVal(
      hwstate.timestamp, active_gesture_deadline_, next_timeout);
}

void HapticButtonGeneratorFilterInterpreter::HandleHardwareState(
    HardwareState& hwstate) {
  if (!enabled_.val_ || !is_haptic_pad_)
    return;

  // Ignore the button state generated by the haptic touchpad.
  hwstate.buttons_down = 0;

  // Determine force thresholds.
  double down_threshold;
  double up_threshold;
  if (use_custom_thresholds_.val_) {
    down_threshold = custom_down_threshold_.val_;
    up_threshold = custom_up_threshold_.val_;
  }
  else {
    down_threshold = down_thresholds_[sensitivity_.val_ - 1];
    up_threshold = up_thresholds_[sensitivity_.val_ - 1];
  }

  if (use_dynamic_thresholds_.val_) {
    up_threshold = fmax(up_threshold, dynamic_up_threshold_);
    down_threshold = fmax(down_threshold, dynamic_down_threshold_);
  }

  up_threshold *= release_suppress_factor_;

  // Determine maximum force on touchpad in grams
  double force = 0.0;
  for (short i = 0; i < hwstate.finger_cnt; i++) {
    const FingerState& fs = hwstate.fingers[i];
    if (!SetContainsValue(palms_, fs.tracking_id)) {
      force = fmax(force, fs.pressure);
    }
  }
  force *= force_scale_.val_;
  force += force_translate_.val_;

  // Set the button state
  bool prev_button_down = button_down_;
  if (button_down_) {
    if (force < up_threshold)
      button_down_ = false;
    else
      hwstate.buttons_down = GESTURES_BUTTON_LEFT;
  } else if (force > down_threshold && !active_gesture_) {
    button_down_ = true;
    hwstate.buttons_down = GESTURES_BUTTON_LEFT;
  }

  // When the user presses very hard, we want to increase the force threshold
  // for releasing the button. We scale the release threshold as a ratio of the
  // max force applied while the button is down.
  if (prev_button_down) {
    if (button_down_) {
      dynamic_up_threshold_ = fmax(dynamic_up_threshold_,
                                   force * dynamic_up_ratio_.val_);
      dynamic_up_threshold_ = fmin(dynamic_up_threshold_,
                                   max_dynamic_up_force_.val_);
    } else {
      dynamic_up_threshold_ = 0.0;
    }
  }

  // Because we dynamically increase the up_threshold when a user presses very
  // hard, we also need to increase the down_threshold for the next click.
  // However, if the user continues to decrease force after the button release,
  // event, we will keep scaling down the dynamic_down_threshold.
  if (prev_button_down) {
    if (!button_down_) {
      dynamic_down_threshold_ = force * dynamic_down_ratio_.val_;
    }
  } else {
    if (button_down_) {
      dynamic_down_threshold_ = 0.0;
    } else {
      dynamic_down_threshold_ = fmin(dynamic_down_threshold_,
                                     force * dynamic_down_ratio_.val_);
    }
  }
  release_suppress_factor_ = 1.0;
}

void HapticButtonGeneratorFilterInterpreter::UpdatePalmState(
    const HardwareState& hwstate) {
  RemoveMissingIdsFromSet(&palms_, hwstate);
  for (short i = 0; i < hwstate.finger_cnt; i++) {
    const FingerState& fs = hwstate.fingers[i];
    if (fs.flags & GESTURES_FINGER_LARGE_PALM) {
      palms_.insert(fs.tracking_id);
    }
  }
}


void HapticButtonGeneratorFilterInterpreter::HandleTimerImpl(
    stime_t now, stime_t *timeout) {
  stime_t next_timeout;
  if (ShouldCallNextTimer(active_gesture_deadline_)) {
    next_timeout = NO_DEADLINE;
    next_->HandleTimer(now, &next_timeout);
  } else {
    if (active_gesture_deadline_ > now) {
      Err("Spurious callback. now: %f, active gesture deadline: %f",
          now, active_gesture_deadline_);
      return;
    }
    // If enough time has passed without an active gesture event assume that we
    // missed the gesture ending event, to prevent a state where the button is
    // stuck down.
    active_gesture_ = false;
    active_gesture_deadline_ = NO_DEADLINE;
    next_timeout = next_timer_deadline_ == NO_DEADLINE ||
                   next_timer_deadline_ <= now
                      ? NO_DEADLINE
                      : next_timer_deadline_ - now;
  }
  *timeout = SetNextDeadlineAndReturnTimeoutVal(now,
                                                active_gesture_deadline_,
                                                next_timeout);
}

void HapticButtonGeneratorFilterInterpreter::ConsumeGesture(
    const Gesture& gesture) {
  if (!enabled_.val_ || !is_haptic_pad_) {
    ProduceGesture(gesture);
    return;
  }

  // Determine if there is an active non-click multi-finger gesture.
  switch (gesture.type) {
    case kGestureTypeScroll:
    case kGestureTypeSwipe:
    case kGestureTypeFourFingerSwipe:
      active_gesture_ = true;
      break;
    case kGestureTypeFling:
    case kGestureTypeSwipeLift:
    case kGestureTypeFourFingerSwipeLift:
      active_gesture_ = false;
      break;
    case kGestureTypePinch:
      active_gesture_ = (gesture.details.pinch.zoom_state != GESTURES_ZOOM_END);
      break;
    default:
      break;
  }
  if (active_gesture_) {
    active_gesture_deadline_ = gesture.end_time + active_gesture_timeout_;
  }

  // When dragging while clicking, users often reduce the force applied, causing
  // accidental release. So we calculate a scaling factor to reduce the "up"
  // threshold which starts at 1.0 (normal threshold) for stationary fingers,
  // and goes down to 0.0 at the complete_release_suppress_speed_.
  if (gesture.type == kGestureTypeMove) {
    float distance_sq = gesture.details.move.dx * gesture.details.move.dx +
        gesture.details.move.dy * gesture.details.move.dy;
    stime_t time_delta = gesture.end_time - gesture.start_time;
    float complete_suppress_dist =
        complete_release_suppress_speed_.val_ * time_delta;
    float complete_suppress_dist_sq =
        complete_suppress_dist * complete_suppress_dist;

    release_suppress_factor_ =
        time_delta <= 0.0 ? 1.0 : 1.0 - distance_sq / complete_suppress_dist_sq;

    // Always allow release at very low force, to prevent a stuck button when
    // the user lifts their finger while moving quickly.
    release_suppress_factor_ = fmax(release_suppress_factor_, 0.1);
  }

  ProduceGesture(gesture);
}

}  // namespace gestures