chromium/ui/events/blink/fling_booster.cc

// 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.

#include "ui/events/blink/fling_booster.h"

#include "base/trace_event/trace_event.h"

WebGestureEvent;
WebInputEvent;

namespace {
// Minimum fling velocity required for the active fling and new fling for the
// two to accumulate.
const double kMinBoostFlingSpeedSquare = …;

// Minimum velocity for the active touch scroll to preserve (boost) an active
// fling for which cancellation has been deferred.
const double kMinBoostTouchScrollSpeedSquare = …;

// Timeout window after which the active fling will be cancelled if no animation
// ticks, scrolls or flings of sufficient velocity relative to the current fling
// are received. The default value on Android native views is 40ms, but we use a
// slightly increased value to accomodate small IPC message delays.
constexpr base::TimeDelta kFlingBoostTimeoutDelay = …;
}  // namespace

namespace ui {

gfx::Vector2dF FlingBooster::GetVelocityForFlingStart(
    const blink::WebGestureEvent& fling_start) { … }

void FlingBooster::ObserveGestureEvent(const WebGestureEvent& gesture_event) { … }

void FlingBooster::ObserveProgressFling(
    const gfx::Vector2dF& current_velocity) { … }

bool FlingBooster::ShouldBoostFling(const WebGestureEvent& fling_start_event) { … }

void FlingBooster::Reset() { … }

}  // namespace ui