Port Chromium OS touch noise filtering to Chromium

ui/events/ozone/evdev/touch_noise/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_NOISE_SINGLE_POSITION_TOUCH_NOISE_FILTER_H_
+#define UI_EVENTS_OZONE_EVDEV_TOUCH_NOISE_SINGLE_POSITION_TOUCH_NOISE_FILTER_H_
+
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "ui/events/ozone/evdev/touch_noise/touch_noise_filter.h"
+
+namespace ui {
+
+class SinglePositionTouchNoiseFilter : public TouchNoiseFilter {
+ public:
+  SinglePositionTouchNoiseFilter();
+  ~SinglePositionTouchNoiseFilter() override {}
+
+  // TouchNoiseFilter:
+  void Filter(const std::vector<InProgressTouchEvdev>& touches,
+              base::TimeDelta time,
+              std::bitset<kNumTouchEvdevSlots>* slots_with_noise) override;
+
+ private:
+  struct TrackedTouch {
+    TrackedTouch();
+    ~TrackedTouch();
+
+    bool valid;
+    size_t slot;
+    int x;
+    int y;
+    base::TimeDelta begin;
+    base::TimeDelta end;
+  };
+
+  void StopTrackingTouch(size_t index);
+  void TrackTouch(const InProgressTouchEvdev& touch,
+                  base::TimeDelta 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_NOISE_SINGLE_POSITION_TOUCH_NOISE_FILTER_H_