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
|
// 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_INPUT_PREDICTOR_H_
#define UI_BASE_PREDICTION_INPUT_PREDICTOR_H_
#include <memory>
#include "base/component_export.h"
#include "base/time/time.h"
#include "ui/gfx/geometry/point_f.h"
namespace ui {
// This class expects a sequence of inputs with their coordinates and timestamps
// and models the input path. It then can predict the coordinates at any given
// time.
class COMPONENT_EXPORT(UI_BASE_PREDICTION) InputPredictor {
public:
virtual ~InputPredictor() = default;
struct InputData {
gfx::PointF pos;
base::TimeTicks time_stamp;
InputData() {
pos = gfx::PointF();
time_stamp = base::TimeTicks();
}
InputData(const gfx::PointF& event_pos, const base::TimeTicks& event_time) {
pos = event_pos;
time_stamp = event_time;
}
};
// Returns the name of the predictor.
virtual const char* GetName() const = 0;
// Reset should be called each time when a new line start.
virtual void Reset() = 0;
// Update the predictor with new input points.
virtual void Update(const InputData& new_input) = 0;
// Return true if the predictor is able to predict points.
virtual bool HasPrediction() const = 0;
// Generate the prediction based on current points.
// It can use a latency based on the vsync refresh rate: `frame_interval`.
// TODO(crbug.com/40154523): Remove the `frame_interval` arg if the expriment
// concludes that a frame-dependent latency isn't better.
virtual std::unique_ptr<InputData> GeneratePrediction(
base::TimeTicks predict_time,
base::TimeDelta frame_interval = base::Seconds(0)) = 0;
// Returns the maximum of prediction available for resampling
// before having side effects (jitter, wrong orientation, etc..)
const base::TimeDelta MaxResampleTime() const { return kMaxResampleTime; }
// Returns the maximum prediction time available for the predictor
// before having side effects (jitter, wrong orientation, etc..)
const base::TimeDelta MaxPredictionTime() const { return kMaxPredictionTime; }
// Return the time interval based on current points.
virtual base::TimeDelta TimeInterval() const = 0;
protected:
static constexpr base::TimeDelta kMaxTimeDelta = base::Milliseconds(20);
// Default time interval between events.
static constexpr base::TimeDelta kTimeInterval = base::Milliseconds(8);
// Minimum time interval between events.
static constexpr base::TimeDelta kMinTimeInterval = base::Milliseconds(2.5);
// Maximum amount of prediction when resampling.
static constexpr base::TimeDelta kMaxResampleTime = base::Milliseconds(20);
// Maximum time delta for prediction.
static constexpr base::TimeDelta kMaxPredictionTime = base::Milliseconds(25);
};
} // namespace ui
#endif // UI_BASE_PREDICTION_INPUT_PREDICTOR_H_
|
