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// 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 THIRD_PARTY_BLINK_RENDERER_PLATFORM_WIDGET_INPUT_INPUT_EVENT_PREDICTION_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_WIDGET_INPUT_INPUT_EVENT_PREDICTION_H_
#include <unordered_map>
#include "base/gtest_prod_util.h"
#include "base/time/time.h"
#include "third_party/blink/public/common/input/pointer_id.h"
#include "third_party/blink/public/common/input/web_coalesced_input_event.h"
#include "third_party/blink/renderer/platform/allow_discouraged_type.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/widget/input/prediction/predictor_factory.h"
#include "ui/base/prediction/input_predictor.h"
namespace blink {
// Handle resampling of WebMouseEvent, WebTouchEvent and WebPointerEvent.
// This class stores prediction of all active pointers.
class PLATFORM_EXPORT InputEventPrediction {
public:
// enable_resampling is true when kResamplingInputEvents is enabled.
explicit InputEventPrediction(bool enable_resampling);
InputEventPrediction(const InputEventPrediction&) = delete;
InputEventPrediction& operator=(const InputEventPrediction&) = delete;
~InputEventPrediction();
// Handle Resampling/Prediction of WebInputEvents. This function is mainly
// doing three things:
// 1. Maintain/Updates predictor using current CoalescedEvents vector.
// 2. When enable_resampling is true, change coalesced_event->EventPointer()'s
// coordinates to the position at frame time.
// 3. Generates 3 predicted events when prediction is available, add the
// PredictedEvent to coalesced_event.
void HandleEvents(blink::WebCoalescedInputEvent& coalesced_event,
base::TimeTicks frame_time);
// Initialize predictor for different pointer.
std::unique_ptr<ui::InputPredictor> CreatePredictor() const;
private:
friend class InputEventPredictionTest;
FRIEND_TEST_ALL_PREFIXES(InputEventPredictionTest, PredictorType);
FRIEND_TEST_ALL_PREFIXES(InputEventPredictionTest, ResamplingDisabled);
FRIEND_TEST_ALL_PREFIXES(InputEventPredictionTest,
NoResampleWhenExceedMaxResampleTime);
// The following functions are for handling multiple TouchPoints in a
// WebTouchEvent. They should be more neat when WebTouchEvent is elimated.
// Cast events from WebInputEvent to WebPointerProperties. Call
// UpdateSinglePointer for each pointer.
void UpdatePrediction(const WebInputEvent& event);
// Cast events from WebInputEvent to WebPointerProperties. Call
// ResamplingSinglePointer for each pointer.
void ApplyResampling(base::TimeTicks frame_time, WebInputEvent* event);
// Reset predictor for each pointer in WebInputEvent by ResetSinglePredictor.
void ResetPredictor(const WebInputEvent& event);
// Add predicted events to WebCoalescedInputEvent if prediction is available.
void AddPredictedEvents(blink::WebCoalescedInputEvent& coalesced_event);
// Get time interval of a pointer. Default to mouse predictor if there is no
// predictor for pointer.
base::TimeDelta GetPredictionTimeInterval(
const WebPointerProperties& event) const;
// Returns a pointer to the predictor for given WebPointerProperties.
ui::InputPredictor* GetPredictor(const WebPointerProperties& event) const;
// Get single predictor based on event id and type, and update the predictor
// with new events coords.
void UpdateSinglePointer(const WebPointerProperties& event,
base::TimeTicks time);
// Get prediction result of a single predictor based on the predict_time,
// and apply predicted result to the event. Return false if no prediction
// available.
bool GetPointerPrediction(base::TimeTicks predict_time,
WebPointerProperties* event);
// Get single predictor based on event id and type. For mouse, reset the
// predictor, for other pointer type, remove it from mapping.
void ResetSinglePredictor(const WebPointerProperties& event);
std::unordered_map<PointerId, std::unique_ptr<ui::InputPredictor>>
pointer_id_predictor_map_
ALLOW_DISCOURAGED_TYPE("TODO(crbug.com/1404327)");
std::unique_ptr<ui::InputPredictor> mouse_predictor_;
// Store the field trial parameter used for choosing different types of
// predictor.
input_prediction::PredictorType selected_predictor_type_;
bool enable_resampling_ = false;
// Records the timestamp for last event added to predictor.
base::TimeTicks last_event_timestamp_;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_WIDGET_INPUT_INPUT_EVENT_PREDICTION_H_
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