1 files changed, 160 insertions, 0 deletions
diff --git a/chromium/content/renderer/input/input_event_prediction.cc b/chromium/content/renderer/input/input_event_prediction.cc
new file mode 100644
index 00000000000..89636c9736d
--- /dev/null
+++ b/chromium/content/renderer/input/input_event_prediction.cc
@@ -0,0 +1,160 @@
+// Copyright 2018 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.
+
+#include "content/renderer/input/input_event_prediction.h"
+
+#include "base/feature_list.h"
+#include "content/public/common/content_features.h"
+#include "ui/events/blink/prediction/empty_predictor.h"
+
+using blink::WebInputEvent;
+using blink::WebMouseEvent;
+using blink::WebPointerEvent;
+using blink::WebPointerProperties;
+using blink::WebTouchEvent;
+
+namespace content {
+
+namespace {
+
+std::unique_ptr<ui::InputPredictor> SetUpPredictor() {
+  return std::make_unique<ui::EmptyPredictor>();
+}
+
+}  // namespace
+
+InputEventPrediction::InputEventPrediction() {
+  mouse_predictor_ = SetUpPredictor();
+}
+
+InputEventPrediction::~InputEventPrediction() {}
+
+void InputEventPrediction::HandleEvents(
+    const blink::WebCoalescedInputEvent& coalesced_event,
+    base::TimeTicks frame_time,
+    blink::WebInputEvent* event) {
+  switch (event->GetType()) {
+    case WebInputEvent::kMouseMove:
+    case WebInputEvent::kTouchMove:
+    case WebInputEvent::kPointerMove: {
+      size_t coalesced_size = coalesced_event.CoalescedEventSize();
+      for (size_t i = 0; i < coalesced_size; i++)
+        UpdatePrediction(coalesced_event.CoalescedEvent(i));
+
+      ApplyResampling(frame_time, event);
+      break;
+    }
+    case WebInputEvent::kTouchScrollStarted:
+    case WebInputEvent::kPointerCausedUaAction:
+      pointer_id_predictor_map_.clear();
+      break;
+    default:
+      ResetPredictor(*event);
+  }
+}
+
+void InputEventPrediction::UpdatePrediction(const WebInputEvent& event) {
+  if (WebInputEvent::IsTouchEventType(event.GetType())) {
+    DCHECK(event.GetType() == WebInputEvent::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::kStateMoved) {
+        UpdateSinglePointer(touch_event.touches[i], touch_event.TimeStamp());
+      }
+    }
+  } else if (WebInputEvent::IsMouseEventType(event.GetType())) {
+    DCHECK(event.GetType() == WebInputEvent::kMouseMove);
+    UpdateSinglePointer(static_cast<const WebMouseEvent&>(event),
+                        event.TimeStamp());
+  } else if (WebInputEvent::IsPointerEventType(event.GetType())) {
+    DCHECK(event.GetType() == WebInputEvent::kPointerMove);
+    UpdateSinglePointer(static_cast<const WebPointerEvent&>(event),
+                        event.TimeStamp());
+  }
+}
+
+void InputEventPrediction::ApplyResampling(base::TimeTicks frame_time,
+                                           WebInputEvent* event) {
+  if (event->GetType() == WebInputEvent::kTouchMove) {
+    WebTouchEvent* touch_event = static_cast<WebTouchEvent*>(event);
+    for (unsigned i = 0; i < touch_event->touches_length; ++i) {
+      if (ResampleSinglePointer(frame_time, &touch_event->touches[i]))
+        event->SetTimeStamp(frame_time);
+    }
+  } else if (event->GetType() == WebInputEvent::kMouseMove) {
+    if (ResampleSinglePointer(frame_time, static_cast<WebMouseEvent*>(event)))
+      event->SetTimeStamp(frame_time);
+  } else if (event->GetType() == WebInputEvent::kPointerMove) {
+    if (ResampleSinglePointer(frame_time, static_cast<WebPointerEvent*>(event)))
+      event->SetTimeStamp(frame_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::kStateMoved &&
+          touch_event.touches[i].state !=
+              blink::WebTouchPoint::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::UpdateSinglePointer(
+    const WebPointerProperties& event,
+    base::TimeTicks event_time) {
+  ui::InputPredictor::InputData data = {event.PositionInWidget().x,
+                                        event.PositionInWidget().y, event_time};
+  if (event.pointer_type == WebPointerProperties::PointerType::kMouse)
+    mouse_predictor_->Update(data);
+  else {
+    auto predictor = pointer_id_predictor_map_.find(event.id);
+    if (predictor != pointer_id_predictor_map_.end()) {
+      predictor->second->Update(data);
+    } else {
+      pointer_id_predictor_map_.insert({event.id, SetUpPredictor()});
+      pointer_id_predictor_map_[event.id]->Update(data);
+    }
+  }
+}
+
+bool InputEventPrediction::ResampleSinglePointer(base::TimeTicks frame_time,
+                                                 WebPointerProperties* event) {
+  ui::InputPredictor::InputData predict_result;
+  if (event->pointer_type == WebPointerProperties::PointerType::kMouse) {
+    if (mouse_predictor_->HasPrediction() &&
+        mouse_predictor_->GeneratePrediction(frame_time, &predict_result)) {
+      event->SetPositionInWidget(predict_result.pos_x, predict_result.pos_y);
+      return true;
+    }
+  } else {
+    // Reset mouse predictor if pointer type is touch or stylus
+    mouse_predictor_->Reset();
+
+    auto predictor = pointer_id_predictor_map_.find(event->id);
+    if (predictor != pointer_id_predictor_map_.end() &&
+        predictor->second->HasPrediction() &&
+        predictor->second->GeneratePrediction(frame_time, &predict_result)) {
+      event->SetPositionInWidget(predict_result.pos_x, predict_result.pos_y);
+      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 content