chromium/content/browser/renderer_host/input/mouse_wheel_phase_handler.h

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_RENDERER_HOST_INPUT_MOUSE_WHEEL_PHASE_HANDLER_H_
#define CONTENT_BROWSER_RENDERER_HOST_INPUT_MOUSE_WHEEL_PHASE_HANDLER_H_

#include "base/memory/raw_ptr.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "content/browser/renderer_host/render_widget_host_delegate.h"
#include "third_party/blink/public/common/input/web_mouse_wheel_event.h"
#include "third_party/blink/public/mojom/input/input_event_result.mojom-shared.h"

namespace content {
class RenderWidgetHostViewBase;

// The duration after which a synthetic wheel with zero deltas and
// phase = |kPhaseEnded| will be sent after the last wheel event.
constexpr base::TimeDelta kDefaultMouseWheelLatchingTransaction = …;

// Maximum allowed difference between coordinates of two mouse wheel events in
// the same scroll sequence.
const double kWheelLatchingSlopRegion = …;

// On ChromeOS wheel events don't have phase information; However, whenever the
// user puts down their fingers on touchpad a GFC is received and at the end of
// touchpad scrolling when the user lifts their fingers a GFS is received. This
// enum tracks the current state of the touchpad scrolling by listening to GFC
// and GFS events.
enum TouchpadScrollPhaseState { … };

enum class FirstScrollUpdateAckState { … };

// The MouseWheelPhaseHandler is responsible for adding the proper phase to
// wheel events. Phase information is necessary for wheel scrolling since it
// shows the start and end of a scrolling sequence.
class MouseWheelPhaseHandler { … };

}  // namespace content

#endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_MOUSE_WHEEL_PHASE_HANDLER_H_