single_frame_tap_filter.cc

// Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "touch_noise_filter/single_frame_tap_filter.h"

#include <base/basictypes.h>

#include <cstddef>
#include <cstdio>

namespace touch_noise_filter {

namespace {
double kMaxTapDuration = 0.1;
}  // namespace {}

void SingleFrameTapFilter::FilterFinger(Finger* finger) {
  Finger* prev_finger = &prev_fingers_[finger->slot_];
  Log("got finger at %f in slot %d", finger->timestamp_,
    finger->slot_);

  bool arrived = prev_finger->tracking_id_ == -1 && finger->tracking_id_ > 0;
  bool departing = prev_finger->tracking_id_ >= 0 && finger->tracking_id_ == -1;
  if ((prev_arrived_ & (1ULL << finger->slot_)) && departing &&
      (finger->timestamp_ - prev_finger->timestamp_ < kMaxTapDuration)) {
    finger->cancelled_ = true;
    TouchNoiseFilterLog("CANCEL AT %f, %d\n",
                        finger->timestamp_, finger->slot_);
  }
  
  // Store previous info
  *prev_finger = *finger;
  if (arrived)
    prev_arrived_ |= 1ULL << finger->slot_;
  else
    prev_arrived_ &= ~(1ULL << finger->slot_);
}

}  // namespace touch_noise_filter