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/*
* Copyright (C) 2022 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <cstdint>
#include <memory>
#include <mutex>
#include <optional>
#include <string>
#include <unordered_map>
#include <android-base/result.h>
#include <android-base/thread_annotations.h>
#include <android/sysprop/InputProperties.sysprop.h>
#include <input/Input.h>
#include <input/MotionPredictorMetricsManager.h>
#include <input/TfLiteMotionPredictor.h>
#include <utils/Timers.h> // for nsecs_t
namespace android {
static inline bool isMotionPredictionEnabled() {
return sysprop::InputProperties::enable_motion_prediction().value_or(true);
}
/**
* Given a set of MotionEvents for the current gesture, predict the motion. The returned MotionEvent
* contains a set of samples in the future.
*
* The typical usage is like this:
*
* MotionPredictor predictor(offset = MY_OFFSET);
* predictor.record(DOWN_MOTION_EVENT);
* predictor.record(MOVE_MOTION_EVENT);
* prediction = predictor.predict(futureTime);
*
* The resulting motion event will have eventTime <= (futureTime + MY_OFFSET). It might contain
* historical data, which are additional samples from the latest recorded MotionEvent's eventTime
* to the futureTime + MY_OFFSET.
*
* The offset is used to provide additional flexibility to the caller, in case the default present
* time (typically provided by the choreographer) does not account for some delays, or to simply
* reduce the aggressiveness of the prediction. Offset can be positive or negative.
*/
class MotionPredictor {
public:
using ReportAtomFunction = MotionPredictorMetricsManager::ReportAtomFunction;
/**
* Parameters:
* predictionTimestampOffsetNanos: additional, constant shift to apply to the target
* prediction time. The prediction will target the time t=(prediction time +
* predictionTimestampOffsetNanos).
*
* checkEnableMotionPrediction: the function to check whether the prediction should run. Used to
* provide an additional way of turning prediction on and off. Can be toggled at runtime.
*
* reportAtomFunction: the function that will be called to report prediction metrics. If
* omitted, the implementation will choose a default metrics reporting mechanism.
*/
MotionPredictor(nsecs_t predictionTimestampOffsetNanos,
std::function<bool()> checkEnableMotionPrediction = isMotionPredictionEnabled,
ReportAtomFunction reportAtomFunction = {});
/**
* Record the actual motion received by the view. This event will be used for calculating the
* predictions.
*
* @return empty result if the event was processed correctly, error if the event is not
* consistent with the previously recorded events.
*/
android::base::Result<void> record(const MotionEvent& event);
std::unique_ptr<MotionEvent> predict(nsecs_t timestamp);
bool isPredictionAvailable(int32_t deviceId, int32_t source);
private:
const nsecs_t mPredictionTimestampOffsetNanos;
const std::function<bool()> mCheckMotionPredictionEnabled;
std::unique_ptr<TfLiteMotionPredictorModel> mModel;
std::unique_ptr<TfLiteMotionPredictorBuffers> mBuffers;
std::optional<MotionEvent> mLastEvent;
std::optional<MotionPredictorMetricsManager> mMetricsManager;
const ReportAtomFunction mReportAtomFunction;
};
} // namespace android
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