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// 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 THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_MAIN_THREAD_USER_MODEL_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_MAIN_THREAD_USER_MODEL_H_
#include "base/macros.h"
#include "base/trace_event/trace_event.h"
#include "base/trace_event/traced_value.h"
#include "third_party/blink/public/common/input/web_input_event.h"
#include "third_party/blink/public/platform/scheduler/web_thread_scheduler.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/perfetto/include/perfetto/tracing/traced_value_forward.h"
namespace blink {
namespace scheduler {
class PLATFORM_EXPORT UserModel {
USING_FAST_MALLOC(UserModel);
public:
UserModel();
// Tells us that the system started processing an input event. Must be paired
// with a call to DidFinishProcessingInputEvent.
void DidStartProcessingInputEvent(WebInputEvent::Type type,
const base::TimeTicks now);
// Tells us that the system finished processing an input event.
void DidFinishProcessingInputEvent(const base::TimeTicks now);
// Returns the estimated amount of time left in the current user gesture, to a
// maximum of |kGestureEstimationLimitMillis|. After that time has elapased
// this function should be called again.
base::TimeDelta TimeLeftInUserGesture(base::TimeTicks now) const;
// Tries to guess if a user gesture is expected soon. Currently this is
// very simple, but one day I hope to do something more sophisticated here.
// The prediction may change after |prediction_valid_duration| has elapsed.
bool IsGestureExpectedSoon(const base::TimeTicks now,
base::TimeDelta* prediction_valid_duration);
// Returns true if a gesture has been in progress for less than the median
// gesture duration. The prediction may change after
// |prediction_valid_duration| has elapsed.
bool IsGestureExpectedToContinue(
const base::TimeTicks now,
base::TimeDelta* prediction_valid_duration) const;
void WriteIntoTracedValue(perfetto::TracedValue context) const;
// The time we should stay in a priority-escalated mode after an input event.
static const int kGestureEstimationLimitMillis = 100;
// This is based on two weeks of Android usage data.
static const int kMedianGestureDurationMillis = 300;
// We consider further gesture start events to be likely if the user has
// interacted with the device in the past two seconds.
// Based on Android usage data, 2000ms between gestures is the 75th percentile
// with 700ms being the 50th.
static const int kExpectSubsequentGestureMillis = 2000;
// Clears input signals.
void Reset(base::TimeTicks now);
private:
bool IsGestureExpectedSoonImpl(
const base::TimeTicks now,
base::TimeDelta* prediction_valid_duration) const;
int pending_input_event_count_;
base::TimeTicks last_input_signal_time_;
base::TimeTicks last_gesture_start_time_;
base::TimeTicks last_continuous_gesture_time_; // Doesn't include Taps.
base::TimeTicks last_gesture_expected_start_time_;
base::TimeTicks last_reset_time_;
bool is_gesture_active_; // This typically means the user's finger is down.
bool is_gesture_expected_;
DISALLOW_COPY_AND_ASSIGN(UserModel);
};
} // namespace scheduler
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_MAIN_THREAD_USER_MODEL_H_
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