File: input_event_prediction.cc

package info (click to toggle)
chromium 138.0.7204.183-1
  • links: PTS, VCS
  • area: main
  • in suites: trixie
  • size: 6,071,908 kB
  • sloc: cpp: 34,937,088; ansic: 7,176,967; javascript: 4,110,704; python: 1,419,953; asm: 946,768; xml: 739,971; pascal: 187,324; sh: 89,623; perl: 88,663; objc: 79,944; sql: 50,304; cs: 41,786; fortran: 24,137; makefile: 21,806; php: 13,980; tcl: 13,166; yacc: 8,925; ruby: 7,485; awk: 3,720; lisp: 3,096; lex: 1,327; ada: 727; jsp: 228; sed: 36
file content (260 lines) | stat: -rw-r--r-- 9,926 bytes parent folder | download | duplicates (9)
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
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
// 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.

#include "third_party/blink/renderer/platform/widget/input/input_event_prediction.h"

#include "base/feature_list.h"
#include "base/metrics/field_trial_params.h"
#include "base/metrics/histogram_functions.h"
#include "third_party/blink/public/common/features.h"

namespace blink {

namespace {

const WebPointerProperties* ToWebPointerProperties(const WebInputEvent* event) {
  if (WebInputEvent::IsMouseEventType(event->GetType()))
    return static_cast<const WebMouseEvent*>(event);
  if (WebInputEvent::IsPointerEventType(event->GetType()))
    return static_cast<const WebPointerEvent*>(event);
  return nullptr;
}
WebPointerProperties* ToWebPointerProperties(WebInputEvent* event) {
  if (WebInputEvent::IsMouseEventType(event->GetType()))
    return static_cast<WebMouseEvent*>(event);
  if (WebInputEvent::IsPointerEventType(event->GetType()))
    return static_cast<WebPointerEvent*>(event);
  return nullptr;
}

}  // namespace

InputEventPrediction::InputEventPrediction(bool enable_resampling)
    : enable_resampling_(enable_resampling) {
  // When resampling is enabled, set predictor type by resampling flag params;
  // otherwise, get predictor type parameters from kInputPredictorTypeChoice
  // flag.
  std::string predictor_name =
      enable_resampling_
          ? GetFieldTrialParamValueByFeature(
                blink::features::kResamplingInputEvents, "predictor")
          : GetFieldTrialParamValueByFeature(
                blink::features::kInputPredictorTypeChoice, "predictor");

  if (predictor_name.empty()) {
    selected_predictor_type_ =
        input_prediction::PredictorType::kScrollPredictorTypeKalman;
  } else {
    selected_predictor_type_ =
        PredictorFactory::GetPredictorTypeFromName(predictor_name);
  }

  mouse_predictor_ = CreatePredictor();
}

InputEventPrediction::~InputEventPrediction() {}

void InputEventPrediction::HandleEvents(
    blink::WebCoalescedInputEvent& coalesced_event,
    base::TimeTicks frame_time) {
  switch (coalesced_event.Event().GetType()) {
    case WebInputEvent::Type::kMouseMove:
    case WebInputEvent::Type::kTouchMove:
    case WebInputEvent::Type::kPointerMove: {
      size_t coalesced_size = coalesced_event.CoalescedEventSize();
      for (size_t i = 0; i < coalesced_size; i++)
        UpdatePrediction(coalesced_event.CoalescedEvent(i));

      if (enable_resampling_)
        ApplyResampling(frame_time, coalesced_event.EventPointer());

      AddPredictedEvents(coalesced_event);
      break;
    }
    case WebInputEvent::Type::kTouchScrollStarted:
    case WebInputEvent::Type::kPointerCausedUaAction:
      pointer_id_predictor_map_.clear();
      break;
    default:
      ResetPredictor(coalesced_event.Event());
  }
}

std::unique_ptr<ui::InputPredictor> InputEventPrediction::CreatePredictor()
    const {
  return PredictorFactory::GetPredictor(selected_predictor_type_);
}

void InputEventPrediction::UpdatePrediction(const WebInputEvent& event) {
  if (WebInputEvent::IsTouchEventType(event.GetType())) {
    DCHECK(event.GetType() == WebInputEvent::Type::kTouchMove);
    const WebTouchEvent& touch_event = static_cast<const WebTouchEvent&>(event);
    for (unsigned i = 0; i < touch_event.touches_length; ++i) {
      if (touch_event.touches[i].state ==
          blink::WebTouchPoint::State::kStateMoved) {
        UpdateSinglePointer(touch_event.touches[i], touch_event.TimeStamp());
      }
    }
  } else {
    DCHECK(event.GetType() == WebInputEvent::Type::kMouseMove ||
           event.GetType() == WebInputEvent::Type::kPointerMove);
    UpdateSinglePointer(*ToWebPointerProperties(&event), event.TimeStamp());
  }
  last_event_timestamp_ = event.TimeStamp();
}

void InputEventPrediction::ApplyResampling(base::TimeTicks frame_time,
                                           WebInputEvent* event) {
  base::TimeDelta prediction_delta = frame_time - event->TimeStamp();
  base::TimeTicks predict_time;

  if (event->GetType() == WebInputEvent::Type::kTouchMove) {
    WebTouchEvent* touch_event = static_cast<WebTouchEvent*>(event);
    for (unsigned i = 0; i < touch_event->touches_length; ++i) {
      if (touch_event->touches[i].state ==
          blink::WebTouchPoint::State::kStateMoved) {
        if (auto* predictor = GetPredictor(touch_event->touches[i])) {
          // When resampling, we don't want to predict too far away because the
          // result will likely be inaccurate in that case. We then cut off the
          // prediction to the MaxResampleTime for the predictor.
          prediction_delta =
              std::min(prediction_delta, predictor->MaxResampleTime());
          predict_time = event->TimeStamp() + prediction_delta;

          if (GetPointerPrediction(predict_time, &touch_event->touches[i]))
            event->SetTimeStamp(predict_time);
        }
      }
    }
  } else {
    WebPointerProperties* pointer_event = ToWebPointerProperties(event);
    if (auto* predictor = GetPredictor(*pointer_event)) {
      // Cutoff prediction if delta > MaxResampleTime
      prediction_delta =
          std::min(prediction_delta, predictor->MaxResampleTime());
      predict_time = event->TimeStamp() + prediction_delta;

      if (GetPointerPrediction(predict_time, pointer_event))
        event->SetTimeStamp(predict_time);
    }
  }
}

void InputEventPrediction::ResetPredictor(const WebInputEvent& event) {
  if (WebInputEvent::IsTouchEventType(event.GetType())) {
    const WebTouchEvent& touch_event = static_cast<const WebTouchEvent&>(event);
    for (unsigned i = 0; i < touch_event.touches_length; ++i) {
      if (touch_event.touches[i].state !=
              blink::WebTouchPoint::State::kStateMoved &&
          touch_event.touches[i].state !=
              blink::WebTouchPoint::State::kStateStationary)
        pointer_id_predictor_map_.erase(touch_event.touches[i].id);
    }
  } else if (WebInputEvent::IsMouseEventType(event.GetType())) {
    ResetSinglePredictor(static_cast<const WebMouseEvent&>(event));
  } else if (WebInputEvent::IsPointerEventType(event.GetType())) {
    ResetSinglePredictor(static_cast<const WebPointerEvent&>(event));
  }
}

void InputEventPrediction::AddPredictedEvents(
    blink::WebCoalescedInputEvent& coalesced_event) {
  base::TimeTicks predict_time = last_event_timestamp_;
  base::TimeTicks max_prediction_timestamp =
      last_event_timestamp_ + mouse_predictor_->MaxPredictionTime();
  bool success = true;
  while (success) {
    std::unique_ptr<WebInputEvent> predicted_event =
        coalesced_event.Event().Clone();
    success = false;
    if (predicted_event->GetType() == WebInputEvent::Type::kTouchMove) {
      WebTouchEvent& touch_event =
          static_cast<WebTouchEvent&>(*predicted_event);
      // Average all touch intervals
      base::TimeDelta touch_time_interval;
      for (unsigned i = 0; i < touch_event.touches_length; ++i) {
        touch_time_interval +=
            GetPredictionTimeInterval(touch_event.touches[i]);
      }
      predict_time += touch_time_interval / touch_event.touches_length;
      if (predict_time <= max_prediction_timestamp) {
        for (unsigned i = 0; i < touch_event.touches_length; ++i) {
          if (touch_event.touches[i].state ==
              blink::WebTouchPoint::State::kStateMoved) {
            success =
                GetPointerPrediction(predict_time, &touch_event.touches[i]);
          }
        }
      }
    } else {
      WebPointerProperties* pointer_event =
          ToWebPointerProperties(predicted_event.get());
      predict_time += GetPredictionTimeInterval(*pointer_event);
      success = predict_time <= max_prediction_timestamp &&
                GetPointerPrediction(predict_time, pointer_event);
    }
    if (success) {
      predicted_event->SetTimeStamp(predict_time);
      coalesced_event.AddPredictedEvent(*predicted_event);
    }
  }
}

ui::InputPredictor* InputEventPrediction::GetPredictor(
    const WebPointerProperties& event) const {
  if (event.pointer_type == WebPointerProperties::PointerType::kMouse)
    return mouse_predictor_.get();

  auto predictor = pointer_id_predictor_map_.find(event.id);
  if (predictor != pointer_id_predictor_map_.end())
    return predictor->second.get();

  return nullptr;
}

base::TimeDelta InputEventPrediction::GetPredictionTimeInterval(
    const WebPointerProperties& event) const {
  if (auto* predictor = GetPredictor(event))
    return predictor->TimeInterval();
  return mouse_predictor_->TimeInterval();
}

void InputEventPrediction::UpdateSinglePointer(
    const WebPointerProperties& event,
    base::TimeTicks event_time) {
  ui::InputPredictor::InputData data = {event.PositionInWidget(), event_time};
  if (auto* predictor = GetPredictor(event)) {
    predictor->Update(data);
  } else {
    // Create new predictor.
    auto pair = std::make_pair(event.id, CreatePredictor());
    pointer_id_predictor_map_.insert(std::move(pair));
    pointer_id_predictor_map_[event.id]->Update(data);
  }
}

bool InputEventPrediction::GetPointerPrediction(base::TimeTicks predict_time,
                                                WebPointerProperties* event) {
  // Reset mouse predictor if pointer type is touch or stylus
  if (event->pointer_type != WebPointerProperties::PointerType::kMouse)
    mouse_predictor_->Reset();

  if (auto* predictor = GetPredictor(*event)) {
    if (auto predict_result = predictor->GeneratePrediction(predict_time)) {
      event->SetPositionInWidget(predict_result->pos);
      return true;
    }
  }
  return false;
}

void InputEventPrediction::ResetSinglePredictor(
    const WebPointerProperties& event) {
  if (event.pointer_type == WebPointerProperties::PointerType::kMouse)
    mouse_predictor_->Reset();
  else
    pointer_id_predictor_map_.erase(event.id);
}

}  // namespace blink