1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_BASE_PREDICTION_KALMAN_PREDICTOR_H_
#define UI_BASE_PREDICTION_KALMAN_PREDICTOR_H_
#include <deque>
#include <vector>
#include "base/component_export.h"
#include "ui/base/prediction/input_predictor.h"
#include "ui/base/prediction/kalman_filter.h"
namespace ui {
// Class to perform kalman filter prediction inherited from InputPredictor.
// This predictor uses kalman filters to predict the current status of the
// motion. Then it predict the future points using <current_position,
// predicted_velocity, predicted_acceleration>. Each kalman_filter will only
// be used to predict one dimension (x, y).
class COMPONENT_EXPORT(UI_BASE_PREDICTION) KalmanPredictor
: public InputPredictor {
public:
// Heuristic option enables changing the influence of acceleration based on
// change of direction. Direction cut off enables discarding the prediction if
// the predicted direction is opposite from the current direction.
enum PredictionOptions {
kNone = 0x0,
kHeuristicsEnabled = 0x1,
kDirectionCutOffEnabled = 0x2
};
explicit KalmanPredictor(unsigned int prediction_options);
KalmanPredictor(const KalmanPredictor&) = delete;
KalmanPredictor& operator=(const KalmanPredictor&) = delete;
~KalmanPredictor() override;
const char* GetName() const override;
// Reset the predictor to initial state.
void Reset() override;
// Store current input in queue.
void Update(const InputData& cur_input) override;
// Return if there is enough data in the queue to generate prediction.
bool HasPrediction() const override;
// Generate the prediction based on stored points and given time_stamp.
// Return false if no prediction available.
std::unique_ptr<InputData> GeneratePrediction(
base::TimeTicks predict_time,
base::TimeDelta frame_interval) override;
// Return the filtered value of time intervals.
base::TimeDelta TimeInterval() const override;
private:
// The following functions get the predicted values from kalman filters.
gfx::Vector2dF PredictPosition() const;
gfx::Vector2dF PredictVelocity() const;
gfx::Vector2dF PredictAcceleration() const;
// Predictor for each axis.
KalmanFilter x_predictor_;
KalmanFilter y_predictor_;
// Filter to smooth time intervals.
KalmanFilter time_filter_;
// Most recent input data.
std::deque<InputData> last_points_;
// Maximum time interval between first and last events in last points queue.
static constexpr base::TimeDelta kMaxTimeInQueue = base::Milliseconds(40);
// Flags to determine the enabled prediction options.
const unsigned int prediction_options_;
};
} // namespace ui
#endif // UI_BASE_PREDICTION_KALMAN_PREDICTOR_H_
|
