ui/events/ozone/evdev/touch_filter/single_position_touch_noise_filter.h

// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_EVENTS_OZONE_EVDEV_TOUCH_FILTER_SINGLE_POSITION_TOUCH_NOISE_FILTER_H_
#define UI_EVENTS_OZONE_EVDEV_TOUCH_FILTER_SINGLE_POSITION_TOUCH_NOISE_FILTER_H_

#include <stddef.h>

#include "base/macros.h"
#include "base/time/time.h"
#include "ui/events/ozone/evdev/touch_filter/touch_filter.h"

namespace ui {

class SinglePositionTouchNoiseFilter : public TouchFilter {
 public:
  SinglePositionTouchNoiseFilter();
  ~SinglePositionTouchNoiseFilter() override {}

  // TouchFilter:
  void Filter(const std::vector<InProgressTouchEvdev>& touches,
              base::TimeTicks time,
              std::bitset<kNumTouchEvdevSlots>* slots_with_noise) override;

 private:
  struct TrackedTouch {
    TrackedTouch();
    ~TrackedTouch();

    bool valid;
    size_t slot;
    int x;
    int y;
    base::TimeTicks begin;
    base::TimeTicks end;

    // The age of the oldest touch at the same location as this TrackedTouch.
    // Logged to UMA when we stop tracking the TrackedTouch.
    base::TimeDelta same_location_touch_age;
  };

  void StopTrackingTouch(size_t index);
  void TrackTouch(const InProgressTouchEvdev& touch,
                  base::TimeTicks time);

  // A mapping of slot to tracked touch index in |tracked_touches_|.
  size_t tracked_slots_[kNumTouchEvdevSlots];

  // A circular buffer of tracked touches
  // [|tracked_touches_start_|, |tracked_touches_end_|).
  static const int kNumTrackedTouches = 100;
  TrackedTouch tracked_touches_[kNumTrackedTouches];

  size_t tracked_touches_start_;
  size_t tracked_touches_end_;
};

}  // namespace ui

#endif  // UI_EVENTS_OZONE_EVDEV_TOUCH_FILTER_SINGLE_POSITION_TOUCH_NOISE_FILTER_H_