| /* |
| * Copyright (C) 2012 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. |
| */ |
| |
| #ifndef _LIBINPUT_VELOCITY_TRACKER_H |
| #define _LIBINPUT_VELOCITY_TRACKER_H |
| |
| #include <input/Input.h> |
| #include <utils/Timers.h> |
| #include <utils/BitSet.h> |
| |
| namespace android { |
| |
| class VelocityTrackerStrategy; |
| |
| /* |
| * Calculates the velocity of pointer movements over time. |
| */ |
| class VelocityTracker { |
| public: |
| struct Position { |
| float x, y; |
| }; |
| |
| struct Estimator { |
| static const size_t MAX_DEGREE = 4; |
| |
| // Estimator time base. |
| nsecs_t time; |
| |
| // Polynomial coefficients describing motion in X and Y. |
| float xCoeff[MAX_DEGREE + 1], yCoeff[MAX_DEGREE + 1]; |
| |
| // Polynomial degree (number of coefficients), or zero if no information is |
| // available. |
| uint32_t degree; |
| |
| // Confidence (coefficient of determination), between 0 (no fit) and 1 (perfect fit). |
| float confidence; |
| |
| inline void clear() { |
| time = 0; |
| degree = 0; |
| confidence = 0; |
| for (size_t i = 0; i <= MAX_DEGREE; i++) { |
| xCoeff[i] = 0; |
| yCoeff[i] = 0; |
| } |
| } |
| }; |
| |
| // Creates a velocity tracker using the specified strategy. |
| // If strategy is NULL, uses the default strategy for the platform. |
| VelocityTracker(const char* strategy = nullptr); |
| |
| ~VelocityTracker(); |
| |
| // Resets the velocity tracker state. |
| void clear(); |
| |
| // Resets the velocity tracker state for specific pointers. |
| // Call this method when some pointers have changed and may be reusing |
| // an id that was assigned to a different pointer earlier. |
| void clearPointers(BitSet32 idBits); |
| |
| // Adds movement information for a set of pointers. |
| // The idBits bitfield specifies the pointer ids of the pointers whose positions |
| // are included in the movement. |
| // The positions array contains position information for each pointer in order by |
| // increasing id. Its size should be equal to the number of one bits in idBits. |
| void addMovement(nsecs_t eventTime, BitSet32 idBits, const Position* positions); |
| |
| // Adds movement information for all pointers in a MotionEvent, including historical samples. |
| void addMovement(const MotionEvent* event); |
| |
| // Gets the velocity of the specified pointer id in position units per second. |
| // Returns false and sets the velocity components to zero if there is |
| // insufficient movement information for the pointer. |
| bool getVelocity(uint32_t id, float* outVx, float* outVy) const; |
| |
| // Gets an estimator for the recent movements of the specified pointer id. |
| // Returns false and clears the estimator if there is no information available |
| // about the pointer. |
| bool getEstimator(uint32_t id, Estimator* outEstimator) const; |
| |
| // Gets the active pointer id, or -1 if none. |
| inline int32_t getActivePointerId() const { return mActivePointerId; } |
| |
| // Gets a bitset containing all pointer ids from the most recent movement. |
| inline BitSet32 getCurrentPointerIdBits() const { return mCurrentPointerIdBits; } |
| |
| private: |
| static const char* DEFAULT_STRATEGY; |
| |
| nsecs_t mLastEventTime; |
| BitSet32 mCurrentPointerIdBits; |
| int32_t mActivePointerId; |
| VelocityTrackerStrategy* mStrategy; |
| |
| bool configureStrategy(const char* strategy); |
| |
| static VelocityTrackerStrategy* createStrategy(const char* strategy); |
| }; |
| |
| |
| /* |
| * Implements a particular velocity tracker algorithm. |
| */ |
| class VelocityTrackerStrategy { |
| protected: |
| VelocityTrackerStrategy() { } |
| |
| public: |
| virtual ~VelocityTrackerStrategy() { } |
| |
| virtual void clear() = 0; |
| virtual void clearPointers(BitSet32 idBits) = 0; |
| virtual void addMovement(nsecs_t eventTime, BitSet32 idBits, |
| const VelocityTracker::Position* positions) = 0; |
| virtual bool getEstimator(uint32_t id, VelocityTracker::Estimator* outEstimator) const = 0; |
| }; |
| |
| |
| /* |
| * Velocity tracker algorithm based on least-squares linear regression. |
| */ |
| class LeastSquaresVelocityTrackerStrategy : public VelocityTrackerStrategy { |
| public: |
| enum Weighting { |
| // No weights applied. All data points are equally reliable. |
| WEIGHTING_NONE, |
| |
| // Weight by time delta. Data points clustered together are weighted less. |
| WEIGHTING_DELTA, |
| |
| // Weight such that points within a certain horizon are weighed more than those |
| // outside of that horizon. |
| WEIGHTING_CENTRAL, |
| |
| // Weight such that points older than a certain amount are weighed less. |
| WEIGHTING_RECENT, |
| }; |
| |
| // Degree must be no greater than Estimator::MAX_DEGREE. |
| LeastSquaresVelocityTrackerStrategy(uint32_t degree, Weighting weighting = WEIGHTING_NONE); |
| virtual ~LeastSquaresVelocityTrackerStrategy(); |
| |
| virtual void clear(); |
| virtual void clearPointers(BitSet32 idBits); |
| virtual void addMovement(nsecs_t eventTime, BitSet32 idBits, |
| const VelocityTracker::Position* positions); |
| virtual bool getEstimator(uint32_t id, VelocityTracker::Estimator* outEstimator) const; |
| |
| private: |
| // Sample horizon. |
| // We don't use too much history by default since we want to react to quick |
| // changes in direction. |
| static const nsecs_t HORIZON = 100 * 1000000; // 100 ms |
| |
| // Number of samples to keep. |
| static const uint32_t HISTORY_SIZE = 20; |
| |
| struct Movement { |
| nsecs_t eventTime; |
| BitSet32 idBits; |
| VelocityTracker::Position positions[MAX_POINTERS]; |
| |
| inline const VelocityTracker::Position& getPosition(uint32_t id) const { |
| return positions[idBits.getIndexOfBit(id)]; |
| } |
| }; |
| |
| float chooseWeight(uint32_t index) const; |
| |
| const uint32_t mDegree; |
| const Weighting mWeighting; |
| uint32_t mIndex; |
| Movement mMovements[HISTORY_SIZE]; |
| }; |
| |
| |
| /* |
| * Velocity tracker algorithm that uses an IIR filter. |
| */ |
| class IntegratingVelocityTrackerStrategy : public VelocityTrackerStrategy { |
| public: |
| // Degree must be 1 or 2. |
| IntegratingVelocityTrackerStrategy(uint32_t degree); |
| ~IntegratingVelocityTrackerStrategy(); |
| |
| virtual void clear(); |
| virtual void clearPointers(BitSet32 idBits); |
| virtual void addMovement(nsecs_t eventTime, BitSet32 idBits, |
| const VelocityTracker::Position* positions); |
| virtual bool getEstimator(uint32_t id, VelocityTracker::Estimator* outEstimator) const; |
| |
| private: |
| // Current state estimate for a particular pointer. |
| struct State { |
| nsecs_t updateTime; |
| uint32_t degree; |
| |
| float xpos, xvel, xaccel; |
| float ypos, yvel, yaccel; |
| }; |
| |
| const uint32_t mDegree; |
| BitSet32 mPointerIdBits; |
| State mPointerState[MAX_POINTER_ID + 1]; |
| |
| void initState(State& state, nsecs_t eventTime, float xpos, float ypos) const; |
| void updateState(State& state, nsecs_t eventTime, float xpos, float ypos) const; |
| void populateEstimator(const State& state, VelocityTracker::Estimator* outEstimator) const; |
| }; |
| |
| |
| /* |
| * Velocity tracker strategy used prior to ICS. |
| */ |
| class LegacyVelocityTrackerStrategy : public VelocityTrackerStrategy { |
| public: |
| LegacyVelocityTrackerStrategy(); |
| virtual ~LegacyVelocityTrackerStrategy(); |
| |
| virtual void clear(); |
| virtual void clearPointers(BitSet32 idBits); |
| virtual void addMovement(nsecs_t eventTime, BitSet32 idBits, |
| const VelocityTracker::Position* positions); |
| virtual bool getEstimator(uint32_t id, VelocityTracker::Estimator* outEstimator) const; |
| |
| private: |
| // Oldest sample to consider when calculating the velocity. |
| static const nsecs_t HORIZON = 200 * 1000000; // 100 ms |
| |
| // Number of samples to keep. |
| static const uint32_t HISTORY_SIZE = 20; |
| |
| // The minimum duration between samples when estimating velocity. |
| static const nsecs_t MIN_DURATION = 10 * 1000000; // 10 ms |
| |
| struct Movement { |
| nsecs_t eventTime; |
| BitSet32 idBits; |
| VelocityTracker::Position positions[MAX_POINTERS]; |
| |
| inline const VelocityTracker::Position& getPosition(uint32_t id) const { |
| return positions[idBits.getIndexOfBit(id)]; |
| } |
| }; |
| |
| uint32_t mIndex; |
| Movement mMovements[HISTORY_SIZE]; |
| }; |
| |
| class ImpulseVelocityTrackerStrategy : public VelocityTrackerStrategy { |
| public: |
| ImpulseVelocityTrackerStrategy(); |
| virtual ~ImpulseVelocityTrackerStrategy(); |
| |
| virtual void clear(); |
| virtual void clearPointers(BitSet32 idBits); |
| virtual void addMovement(nsecs_t eventTime, BitSet32 idBits, |
| const VelocityTracker::Position* positions); |
| virtual bool getEstimator(uint32_t id, VelocityTracker::Estimator* outEstimator) const; |
| |
| private: |
| // Sample horizon. |
| // We don't use too much history by default since we want to react to quick |
| // changes in direction. |
| static constexpr nsecs_t HORIZON = 100 * 1000000; // 100 ms |
| |
| // Number of samples to keep. |
| static constexpr size_t HISTORY_SIZE = 20; |
| |
| struct Movement { |
| nsecs_t eventTime; |
| BitSet32 idBits; |
| VelocityTracker::Position positions[MAX_POINTERS]; |
| |
| inline const VelocityTracker::Position& getPosition(uint32_t id) const { |
| return positions[idBits.getIndexOfBit(id)]; |
| } |
| }; |
| |
| size_t mIndex; |
| Movement mMovements[HISTORY_SIZE]; |
| }; |
| |
| } // namespace android |
| |
| #endif // _LIBINPUT_VELOCITY_TRACKER_H |