Add native MotionPredictor (39147cee) · Commits · e / os / platform_frameworks_native

include/input/MotionPredictor.h

0 → 100644

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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 <android-base/thread_annotations.h>
		#include <android/sysprop/InputProperties.sysprop.h>
		#include <input/Input.h>

		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, up to "presentation time + offset".
		*
		* The typical usage is like this:
		*
		* MotionPredictor predictor(offset = MY_OFFSET);
		* predictor.setExpectedPresentationTimeNanos(NEXT_PRESENT_TIME);
		* predictor.record(DOWN_MOTION_EVENT);
		* predictor.record(MOVE_MOTION_EVENT);
		* prediction = predictor.predict();
		*
		* The presentation time should be set some time before calling .predict(). It could be set before
		* or after the recorded motion events. Must be done on every frame.
		*
		* The resulting motion event will have eventTime <= (NEXT_PRESENT_TIME + MY_OFFSET). It might
		* contain historical data, which are additional samples from the latest recorded MotionEvent's
		* eventTime to the NEXT_PRESENT_TIME + 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 both positive and negative.
		*/
		class MotionPredictor {
		public:
		/**
		* Parameters:
		* predictionTimestampOffsetNanos: additional, constant shift to apply to the target
		* presentation time. The prediction will target the time t=(presentationTime +
		* predictionTimestampOffsetNanos).
		*
		* checkEnableMotionPredition: 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.
		*/
		MotionPredictor(nsecs_t predictionTimestampOffsetNanos,
		std::function<bool()> checkEnableMotionPrediction = isMotionPredictionEnabled);
		void record(const MotionEvent& event);
		std::vector<std::unique_ptr<MotionEvent>> predict();
		bool isPredictionAvailable(int32_t deviceId, int32_t source);
		void setExpectedPresentationTimeNanos(int64_t expectedPresentationTimeNanos);

		private:
		std::mutex mLock;
		int64_t mExpectedPresentationTimeNanos GUARDED_BY(mLock) = 0;
		int64_t getExpectedPresentationTimeNanos();
		std::vector<MotionEvent> mEvents;
		const nsecs_t mPredictionTimestampOffsetNanos;
		const std::function<bool()> mCheckMotionPredictionEnabled;
		};

		} // namespace android

libs/input/Android.bp

+3 −1

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		@@ -50,6 +50,7 @@ cc_library {
		"Keyboard.cpp",
		"KeyCharacterMap.cpp",
		"KeyLayoutMap.cpp",
		"MotionPredictor.cpp",
		"PrintTools.cpp",
		"PropertyMap.cpp",
		"TouchVideoFrame.cpp",
		@@ -63,8 +64,9 @@ cc_library {

		shared_libs: [
		"libbase",
		"liblog",
		"libcutils",
		"liblog",
		"libPlatformProperties",
		"libvintf",
		],

libs/input/MotionPredictor.cpp

0 → 100644

+156 −0

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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.
		*/

		#define LOG_TAG "MotionPredictor"

		#include <input/MotionPredictor.h>

		/**
		* Log debug messages about predictions.
		* Enable this via "adb shell setprop log.tag.MotionPredictor DEBUG"
		*/
		static bool isDebug() {
		return __android_log_is_loggable(ANDROID_LOG_DEBUG, LOG_TAG, ANDROID_LOG_INFO);
		}

		namespace android {

		// --- MotionPredictor ---

		MotionPredictor::MotionPredictor(nsecs_t predictionTimestampOffsetNanos,
		std::function<bool()> checkMotionPredictionEnabled)
		: mPredictionTimestampOffsetNanos(predictionTimestampOffsetNanos),
		mCheckMotionPredictionEnabled(std::move(checkMotionPredictionEnabled)) {}

		void MotionPredictor::record(const MotionEvent& event) {
		mEvents.push_back({});
		mEvents.back().copyFrom(&event, /keepHistory=/true);
		if (mEvents.size() > 2) {
		// Just need 2 samples in order to extrapolate
		mEvents.erase(mEvents.begin());
		}
		}

		/**
		* This is an example implementation that should be replaced with the actual prediction.
		* The returned MotionEvent should be similar to the incoming MotionEvent, except for the
		* fields that are predicted:
		*
		* 1) event.getEventTime
		* 2) event.getPointerCoords
		*
		* The returned event should not contain any of the real, existing data. It should only
		* contain the predicted samples.
		*/
		std::vector<std::unique_ptr<MotionEvent>> MotionPredictor::predict() {
		if (mEvents.size() < 2) {
		return {};
		}

		const MotionEvent& event = mEvents.back();
		if (!isPredictionAvailable(event.getDeviceId(), event.getSource())) {
		return {};
		}

		std::unique_ptr<MotionEvent> prediction = std::make_unique<MotionEvent>();
		std::vector<PointerCoords> futureCoords;
		const int64_t futureTime = getExpectedPresentationTimeNanos() + mPredictionTimestampOffsetNanos;
		const nsecs_t currentTime = event.getEventTime();
		const MotionEvent& previous = mEvents.rbegin()[1];
		const nsecs_t oldTime = previous.getEventTime();
		if (currentTime == oldTime) {
		// This can happen if it's an ACTION_POINTER_DOWN event, for example.
		return {}; // prevent division by zero.
		}

		for (size_t i = 0; i < event.getPointerCount(); i++) {
		const int32_t pointerId = event.getPointerId(i);
		PointerCoords coords;
		coords.clear();

		ssize_t index = previous.findPointerIndex(pointerId);
		if (index >= 0) {
		// We have old data for this pointer. Compute the prediction.
		const float oldX = previous.getRawX(index);
		const float oldY = previous.getRawY(index);
		const float currentX = event.getRawX(i);
		const float currentY = event.getRawY(i);

		// Let's do a linear interpolation while waiting for a real model
		const float scale =
		static_cast<float>(futureTime - currentTime) / (currentTime - oldTime);
		const float futureX = currentX + (currentX - oldX) * scale;
		const float futureY = currentY + (currentY - oldY) * scale;

		coords.setAxisValue(AMOTION_EVENT_AXIS_X, futureX);
		coords.setAxisValue(AMOTION_EVENT_AXIS_Y, futureY);
		}

		futureCoords.push_back(coords);
		}

		ALOGD_IF(isDebug(), "Prediction is %.1f ms away from the event",
		(futureTime - event.getEventTime()) * 1E-6);
		/**
		* The process of adding samples is different for the first and subsequent samples:
		* 1. Add the first sample via 'initialize' as below
		* 2. Add subsequent samples via 'addSample'
		*/
		prediction->initialize(event.getId(), event.getDeviceId(), event.getSource(),
		event.getDisplayId(), event.getHmac(), event.getAction(),
		event.getActionButton(), event.getFlags(), event.getEdgeFlags(),
		event.getMetaState(), event.getButtonState(), event.getClassification(),
		event.getTransform(), event.getXPrecision(), event.getYPrecision(),
		event.getRawXCursorPosition(), event.getRawYCursorPosition(),
		event.getRawTransform(), event.getDownTime(), futureTime,
		event.getPointerCount(), event.getPointerProperties(),
		futureCoords.data());

		// To add more predicted samples, use 'addSample':
		prediction->addSample(futureTime + 1, futureCoords.data());

		std::vector<std::unique_ptr<MotionEvent>> out;
		out.push_back(std::move(prediction));
		return out;
		}

		bool MotionPredictor::isPredictionAvailable(int32_t /deviceId/, int32_t source) {
		// Global flag override
		if (!mCheckMotionPredictionEnabled()) {
		ALOGD_IF(isDebug(), "Prediction not available due to flag override");
		return false;
		}

		// Prediction is only supported for stylus sources.
		if (!isFromSource(source, AINPUT_SOURCE_STYLUS)) {
		ALOGD_IF(isDebug(), "Prediction not available for non-stylus source: %s",
		inputEventSourceToString(source).c_str());
		return false;
		}
		return true;
		}

		int64_t MotionPredictor::getExpectedPresentationTimeNanos() {
		std::scoped_lock lock(mLock);
		return mExpectedPresentationTimeNanos;
		}

		void MotionPredictor::setExpectedPresentationTimeNanos(int64_t expectedPresentationTimeNanos) {
		std::scoped_lock lock(mLock);
		mExpectedPresentationTimeNanos = expectedPresentationTimeNanos;
		}

		} // namespace android

libs/input/tests/Android.bp

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		@@ -17,6 +17,7 @@ cc_test {
		"InputDevice_test.cpp",
		"InputEvent_test.cpp",
		"InputPublisherAndConsumer_test.cpp",
		"MotionPredictor_test.cpp",
		"TouchResampling_test.cpp",
		"TouchVideoFrame_test.cpp",
		"VelocityTracker_test.cpp",
		@@ -37,6 +38,7 @@ cc_test {
		"libbinder",
		"libcutils",
		"liblog",
		"libPlatformProperties",
		"libutils",
		"libvintf",
		],

libs/input/tests/MotionPredictor_test.cpp

0 → 100644

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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.
		*/

		#include <gtest/gtest.h>
		#include <gui/constants.h>
		#include <input/Input.h>
		#include <input/MotionPredictor.h>

		namespace android {

		constexpr int32_t DOWN = AMOTION_EVENT_ACTION_DOWN;
		constexpr int32_t MOVE = AMOTION_EVENT_ACTION_MOVE;

		static MotionEvent getMotionEvent(int32_t action, float x, float y, nsecs_t eventTime) {
		MotionEvent event;
		constexpr size_t pointerCount = 1;
		std::vector<PointerProperties> pointerProperties;
		std::vector<PointerCoords> pointerCoords;
		for (size_t i = 0; i < pointerCount; i++) {
		PointerProperties properties;
		properties.clear();
		properties.id = i;
		pointerProperties.push_back(properties);
		PointerCoords coords;
		coords.clear();
		coords.setAxisValue(AMOTION_EVENT_AXIS_X, x);
		coords.setAxisValue(AMOTION_EVENT_AXIS_Y, y);
		pointerCoords.push_back(coords);
		}

		ui::Transform identityTransform;
		event.initialize(InputEvent::nextId(), /deviceId=/0, AINPUT_SOURCE_STYLUS,
		ADISPLAY_ID_DEFAULT, {0}, action, /actionButton=/0, /flags=/0,
		AMOTION_EVENT_EDGE_FLAG_NONE, AMETA_NONE, /buttonState=/0,
		MotionClassification::NONE, identityTransform, /xPrecision=/0.1,
		/yPrecision=/0.2, /xCursorPosition=/280, /yCursorPosition=/540,
		identityTransform, /downTime=/100, eventTime, pointerCount,
		pointerProperties.data(), pointerCoords.data());
		return event;
		}

		/**
		* A linear motion should be predicted to be linear in the future
		*/
		TEST(MotionPredictorTest, LinearPrediction) {
		MotionPredictor predictor(/predictionTimestampOffsetNanos=/0,
		[]() { return true /enable prediction/; });

		predictor.record(getMotionEvent(DOWN, 0, 1, 0));
		predictor.record(getMotionEvent(MOVE, 1, 3, 10));
		predictor.record(getMotionEvent(MOVE, 2, 5, 20));
		predictor.record(getMotionEvent(MOVE, 3, 7, 30));
		predictor.setExpectedPresentationTimeNanos(40);
		std::vector<std::unique_ptr<MotionEvent>> predicted = predictor.predict();
		ASSERT_EQ(1u, predicted.size());
		ASSERT_EQ(predicted[0]->getX(0), 4);
		ASSERT_EQ(predicted[0]->getY(0), 9);
		}

		/**
		* A still motion should be predicted to remain still
		*/
		TEST(MotionPredictorTest, StationaryPrediction) {
		MotionPredictor predictor(/predictionTimestampOffsetNanos=/0,
		[]() { return true /enable prediction/; });

		predictor.record(getMotionEvent(DOWN, 0, 1, 0));
		predictor.record(getMotionEvent(MOVE, 0, 1, 10));
		predictor.record(getMotionEvent(MOVE, 0, 1, 20));
		predictor.record(getMotionEvent(MOVE, 0, 1, 30));
		predictor.setExpectedPresentationTimeNanos(40);
		std::vector<std::unique_ptr<MotionEvent>> predicted = predictor.predict();
		ASSERT_EQ(1u, predicted.size());
		ASSERT_EQ(predicted[0]->getX(0), 0);
		ASSERT_EQ(predicted[0]->getY(0), 1);
		}

		TEST(MotionPredictorTest, IsPredictionAvailable) {
		MotionPredictor predictor(/predictionTimestampOffsetNanos=/0,
		[]() { return true /enable prediction/; });
		ASSERT_TRUE(predictor.isPredictionAvailable(/deviceId=/1, AINPUT_SOURCE_STYLUS));
		ASSERT_FALSE(predictor.isPredictionAvailable(/deviceId=/1, AINPUT_SOURCE_TOUCHSCREEN));
		}

		TEST(MotionPredictorTest, Offset) {
		MotionPredictor predictor(/predictionTimestampOffsetNanos=/1,
		[]() { return true /enable prediction/; });
		predictor.setExpectedPresentationTimeNanos(40);
		predictor.record(getMotionEvent(DOWN, 0, 1, 30));
		predictor.record(getMotionEvent(MOVE, 0, 1, 35));
		std::vector<std::unique_ptr<MotionEvent>> predicted = predictor.predict();
		ASSERT_EQ(1u, predicted.size());
		ASSERT_GE(predicted[0]->getEventTime(), 41);
		}

		TEST(MotionPredictionTest, FlagDisablesPrediction) {
		MotionPredictor predictor(/predictionTimestampOffsetNanos=/0,
		[]() { return false /disable prediction/; });
		predictor.setExpectedPresentationTimeNanos(40);
		predictor.record(getMotionEvent(DOWN, 0, 1, 30));
		predictor.record(getMotionEvent(MOVE, 0, 1, 35));
		std::vector<std::unique_ptr<MotionEvent>> predicted = predictor.predict();
		ASSERT_EQ(0u, predicted.size());
		ASSERT_FALSE(predictor.isPredictionAvailable(/deviceId=/1, AINPUT_SOURCE_STYLUS));
		ASSERT_FALSE(predictor.isPredictionAvailable(/deviceId=/1, AINPUT_SOURCE_TOUCHSCREEN));
		}

		} // namespace android