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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifndef mozilla_layers_OvershootDetector_h_
#define mozilla_layers_OvershootDetector_h_
#include "mozilla/gfx/Types.h" // for Side
#include "mozilla/Maybe.h"
#include "mozilla/TimeStamp.h"
namespace mozilla {
class ScrollWheelInput;
namespace layers {
/*
* Handles detection and telemetry reporting of overshoot events, which are
* situations where the user changes scrolling direction shortly after a
* previous scroll in the other direction, indicating that the user likely
* scrolled too far and had to backtrack.
*
* Currently this data collection is focused on forms of input that trigger
* animated rather than instant scrolling. That includes ScrollWheelInput
*/
class OvershootDetector {
public:
OvershootDetector() = default;
// Updates the internal state machine with a new incoming scrollwheel input.
void Update(const ScrollWheelInput& aInput);
private:
TimeStamp mLastTimeStamp;
Maybe<mozilla::Side> mLastDirection;
};
} // namespace layers
} // namespace mozilla
#endif // mozilla_layers_OvershootDetector_h_