include/ui/InputReader.h

/*
 * Copyright (C) 2010 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 _UI_INPUT_READER_H
#define _UI_INPUT_READER_H

#include <ui/EventHub.h>
#include <ui/Input.h>
#include <ui/InputDispatcher.h>
#include <utils/KeyedVector.h>
#include <utils/threads.h>
#include <utils/Timers.h>
#include <utils/RefBase.h>
#include <utils/String8.h>
#include <utils/BitSet.h>

#include <stddef.h>
#include <unistd.h>

namespace android {

class InputDevice;
class InputMapper;

/* Describes a virtual key. */
struct VirtualKeyDefinition {
    int32_t scanCode;

    // configured position data, specified in display coords
    int32_t centerX;
    int32_t centerY;
    int32_t width;
    int32_t height;
};


/* Specifies input device calibration settings. */
class InputDeviceCalibration {
public:
    InputDeviceCalibration();

    void clear();
    void addProperty(const String8& key, const String8& value);

    bool tryGetProperty(const String8& key, String8& outValue) const;
    bool tryGetProperty(const String8& key, int32_t& outValue) const;
    bool tryGetProperty(const String8& key, float& outValue) const;

private:
    KeyedVector<String8, String8> mProperties;
};


/*
 * Input reader policy interface.
 *
 * The input reader policy is used by the input reader to interact with the Window Manager
 * and other system components.
 *
 * The actual implementation is partially supported by callbacks into the DVM
 * via JNI.  This interface is also mocked in the unit tests.
 */
class InputReaderPolicyInterface : public virtual RefBase {
protected:
    InputReaderPolicyInterface() { }
    virtual ~InputReaderPolicyInterface() { }

public:
    /* Display orientations. */
    enum {
        ROTATION_0 = 0,
        ROTATION_90 = 1,
        ROTATION_180 = 2,
        ROTATION_270 = 3
    };

    /* Actions returned by interceptXXX methods. */
    enum {
        // The input dispatcher should do nothing and discard the input unless other
        // flags are set.
        ACTION_NONE = 0,

        // The input dispatcher should dispatch the input to the application.
        ACTION_DISPATCH = 0x00000001,
    };

    /* Gets information about the display with the specified id.
     * Returns true if the display info is available, false otherwise.
     */
    virtual bool getDisplayInfo(int32_t displayId,
            int32_t* width, int32_t* height, int32_t* orientation) = 0;

    /* Provides feedback for a virtual key down.
     */
    virtual void virtualKeyDownFeedback() = 0;

    /* Intercepts a key event.
     * The policy can use this method as an opportunity to perform power management functions
     * and early event preprocessing such as updating policy flags.
     *
     * Returns a policy action constant such as ACTION_DISPATCH.
     */
    virtual int32_t interceptKey(nsecs_t when, int32_t deviceId,
            bool down, int32_t keyCode, int32_t scanCode, uint32_t& policyFlags) = 0;

    /* Intercepts a switch event.
     * The policy can use this method as an opportunity to perform power management functions
     * and early event preprocessing such as updating policy flags.
     *
     * Switches are not dispatched to applications so this method should
     * usually return ACTION_NONE.
     */
    virtual int32_t interceptSwitch(nsecs_t when, int32_t switchCode, int32_t switchValue,
            uint32_t& policyFlags) = 0;

    /* Intercepts a generic touch, trackball or other event.
     * The policy can use this method as an opportunity to perform power management functions
     * and early event preprocessing such as updating policy flags.
     *
     * Returns a policy action constant such as ACTION_DISPATCH.
     */
    virtual int32_t interceptGeneric(nsecs_t when, uint32_t& policyFlags) = 0;

    /* Determines whether to turn on some hacks we have to improve the touch interaction with a
     * certain device whose screen currently is not all that good.
     */
    virtual bool filterTouchEvents() = 0;

    /* Determines whether to turn on some hacks to improve touch interaction with another device
     * where touch coordinate data can get corrupted.
     */
    virtual bool filterJumpyTouchEvents() = 0;

    /* Gets the configured virtual key definitions for an input device. */
    virtual void getVirtualKeyDefinitions(const String8& deviceName,
            Vector<VirtualKeyDefinition>& outVirtualKeyDefinitions) = 0;

    /* Gets the calibration for an input device. */
    virtual void getInputDeviceCalibration(const String8& deviceName,
            InputDeviceCalibration& outCalibration) = 0;

    /* Gets the excluded device names for the platform. */
    virtual void getExcludedDeviceNames(Vector<String8>& outExcludedDeviceNames) = 0;
};


/* Processes raw input events and sends cooked event data to an input dispatcher. */
class InputReaderInterface : public virtual RefBase {
protected:
    InputReaderInterface() { }
    virtual ~InputReaderInterface() { }

public:
    /* Dumps the state of the input reader.
     *
     * This method may be called on any thread (usually by the input manager). */
    virtual void dump(String8& dump) = 0;

    /* Runs a single iteration of the processing loop.
     * Nominally reads and processes one incoming message from the EventHub.
     *
     * This method should be called on the input reader thread.
     */
    virtual void loopOnce() = 0;

    /* Gets the current input device configuration.
     *
     * This method may be called on any thread (usually by the input manager).
     */
    virtual void getInputConfiguration(InputConfiguration* outConfiguration) = 0;

    /* Gets information about the specified input device.
     * Returns OK if the device information was obtained or NAME_NOT_FOUND if there
     * was no such device.
     *
     * This method may be called on any thread (usually by the input manager).
     */
    virtual status_t getInputDeviceInfo(int32_t deviceId, InputDeviceInfo* outDeviceInfo) = 0;

    /* Gets the list of all registered device ids. */
    virtual void getInputDeviceIds(Vector<int32_t>& outDeviceIds) = 0;

    /* Query current input state. */
    virtual int32_t getScanCodeState(int32_t deviceId, uint32_t sourceMask,
            int32_t scanCode) = 0;
    virtual int32_t getKeyCodeState(int32_t deviceId, uint32_t sourceMask,
            int32_t keyCode) = 0;
    virtual int32_t getSwitchState(int32_t deviceId, uint32_t sourceMask,
            int32_t sw) = 0;

    /* Determine whether physical keys exist for the given framework-domain key codes. */
    virtual bool hasKeys(int32_t deviceId, uint32_t sourceMask,
            size_t numCodes, const int32_t* keyCodes, uint8_t* outFlags) = 0;
};


/* Internal interface used by individual input devices to access global input device state
 * and parameters maintained by the input reader.
 */
class InputReaderContext {
protected:
    InputReaderContext() { }
    virtual ~InputReaderContext() { }

public:
    virtual void updateGlobalMetaState() = 0;
    virtual int32_t getGlobalMetaState() = 0;

    virtual InputReaderPolicyInterface* getPolicy() = 0;
    virtual InputDispatcherInterface* getDispatcher() = 0;
    virtual EventHubInterface* getEventHub() = 0;
};


/* The input reader reads raw event data from the event hub and processes it into input events
 * that it sends to the input dispatcher.  Some functions of the input reader, such as early
 * event filtering in low power states, are controlled by a separate policy object.
 *
 * IMPORTANT INVARIANT:
 *     Because the policy and dispatcher can potentially block or cause re-entrance into
 *     the input reader, the input reader never calls into other components while holding
 *     an exclusive internal lock whenever re-entrance can happen.
 */
class InputReader : public InputReaderInterface, private InputReaderContext {
public:
    InputReader(const sp<EventHubInterface>& eventHub,
            const sp<InputReaderPolicyInterface>& policy,
            const sp<InputDispatcherInterface>& dispatcher);
    virtual ~InputReader();

    virtual void dump(String8& dump);

    virtual void loopOnce();

    virtual void getInputConfiguration(InputConfiguration* outConfiguration);

    virtual status_t getInputDeviceInfo(int32_t deviceId, InputDeviceInfo* outDeviceInfo);
    virtual void getInputDeviceIds(Vector<int32_t>& outDeviceIds);

    virtual int32_t getScanCodeState(int32_t deviceId, uint32_t sourceMask,
            int32_t scanCode);
    virtual int32_t getKeyCodeState(int32_t deviceId, uint32_t sourceMask,
            int32_t keyCode);
    virtual int32_t getSwitchState(int32_t deviceId, uint32_t sourceMask,
            int32_t sw);

    virtual bool hasKeys(int32_t deviceId, uint32_t sourceMask,
            size_t numCodes, const int32_t* keyCodes, uint8_t* outFlags);

private:
    sp<EventHubInterface> mEventHub;
    sp<InputReaderPolicyInterface> mPolicy;
    sp<InputDispatcherInterface> mDispatcher;

    virtual InputReaderPolicyInterface* getPolicy() { return mPolicy.get(); }
    virtual InputDispatcherInterface* getDispatcher() { return mDispatcher.get(); }
    virtual EventHubInterface* getEventHub() { return mEventHub.get(); }

    // This reader/writer lock guards the list of input devices.
    // The writer lock must be held whenever the list of input devices is modified
    //   and then promptly released.
    // The reader lock must be held whenever the list of input devices is traversed or an
    //   input device in the list is accessed.
    // This lock only protects the registry and prevents inadvertent deletion of device objects
    // that are in use.  Individual devices are responsible for guarding their own internal state
    // as needed for concurrent operation.
    RWLock mDeviceRegistryLock;
    KeyedVector<int32_t, InputDevice*> mDevices;

    // low-level input event decoding and device management
    void process(const RawEvent* rawEvent);

    void addDevice(nsecs_t when, int32_t deviceId);
    void removeDevice(nsecs_t when, int32_t deviceId);
    InputDevice* createDevice(int32_t deviceId, const String8& name, uint32_t classes);
    void configureExcludedDevices();

    void consumeEvent(const RawEvent* rawEvent);

    void handleConfigurationChanged(nsecs_t when);

    // state management for all devices
    Mutex mStateLock;

    int32_t mGlobalMetaState;
    virtual void updateGlobalMetaState();
    virtual int32_t getGlobalMetaState();

    InputConfiguration mInputConfiguration;
    void updateInputConfiguration();

    // state queries
    typedef int32_t (InputDevice::*GetStateFunc)(uint32_t sourceMask, int32_t code);
    int32_t getState(int32_t deviceId, uint32_t sourceMask, int32_t code,
            GetStateFunc getStateFunc);
    bool markSupportedKeyCodes(int32_t deviceId, uint32_t sourceMask, size_t numCodes,
            const int32_t* keyCodes, uint8_t* outFlags);

    // dump state
    void dumpDeviceInfo(String8& dump);
};


/* Reads raw events from the event hub and processes them, endlessly. */
class InputReaderThread : public Thread {
public:
    InputReaderThread(const sp<InputReaderInterface>& reader);
    virtual ~InputReaderThread();

private:
    sp<InputReaderInterface> mReader;

    virtual bool threadLoop();
};


/* Represents the state of a single input device. */
class InputDevice {
public:
    InputDevice(InputReaderContext* context, int32_t id, const String8& name);
    ~InputDevice();

    inline InputReaderContext* getContext() { return mContext; }
    inline int32_t getId() { return mId; }
    inline const String8& getName() { return mName; }
    inline uint32_t getSources() { return mSources; }

    inline bool isIgnored() { return mMappers.isEmpty(); }

    void addMapper(InputMapper* mapper);
    void configure();
    void reset();
    void process(const RawEvent* rawEvent);

    void getDeviceInfo(InputDeviceInfo* outDeviceInfo);
    int32_t getKeyCodeState(uint32_t sourceMask, int32_t keyCode);
    int32_t getScanCodeState(uint32_t sourceMask, int32_t scanCode);
    int32_t getSwitchState(uint32_t sourceMask, int32_t switchCode);
    bool markSupportedKeyCodes(uint32_t sourceMask, size_t numCodes,
            const int32_t* keyCodes, uint8_t* outFlags);

    int32_t getMetaState();

    inline const InputDeviceCalibration& getCalibration() {
        return mCalibration;
    }

private:
    InputReaderContext* mContext;
    int32_t mId;

    Vector<InputMapper*> mMappers;

    String8 mName;
    uint32_t mSources;

    typedef int32_t (InputMapper::*GetStateFunc)(uint32_t sourceMask, int32_t code);
    int32_t getState(uint32_t sourceMask, int32_t code, GetStateFunc getStateFunc);

    InputDeviceCalibration mCalibration;
};


/* An input mapper transforms raw input events into cooked event data.
 * A single input device can have multiple associated input mappers in order to interpret
 * different classes of events.
 */
class InputMapper {
public:
    InputMapper(InputDevice* device);
    virtual ~InputMapper();

    inline InputDevice* getDevice() { return mDevice; }
    inline int32_t getDeviceId() { return mDevice->getId(); }
    inline const String8 getDeviceName() { return mDevice->getName(); }
    inline InputReaderContext* getContext() { return mContext; }
    inline InputReaderPolicyInterface* getPolicy() { return mContext->getPolicy(); }
    inline InputDispatcherInterface* getDispatcher() { return mContext->getDispatcher(); }
    inline EventHubInterface* getEventHub() { return mContext->getEventHub(); }

    virtual uint32_t getSources() = 0;
    virtual void populateDeviceInfo(InputDeviceInfo* deviceInfo);
    virtual void configure();
    virtual void reset();
    virtual void process(const RawEvent* rawEvent) = 0;

    virtual int32_t getKeyCodeState(uint32_t sourceMask, int32_t keyCode);
    virtual int32_t getScanCodeState(uint32_t sourceMask, int32_t scanCode);
    virtual int32_t getSwitchState(uint32_t sourceMask, int32_t switchCode);
    virtual bool markSupportedKeyCodes(uint32_t sourceMask, size_t numCodes,
            const int32_t* keyCodes, uint8_t* outFlags);

    virtual int32_t getMetaState();

protected:
    InputDevice* mDevice;
    InputReaderContext* mContext;

    bool applyStandardPolicyActions(nsecs_t when, int32_t policyActions);
};


class SwitchInputMapper : public InputMapper {
public:
    SwitchInputMapper(InputDevice* device);
    virtual ~SwitchInputMapper();

    virtual uint32_t getSources();
    virtual void process(const RawEvent* rawEvent);

    virtual int32_t getSwitchState(uint32_t sourceMask, int32_t switchCode);

private:
    void processSwitch(nsecs_t when, int32_t switchCode, int32_t switchValue);
};


class KeyboardInputMapper : public InputMapper {
public:
    KeyboardInputMapper(InputDevice* device, int32_t associatedDisplayId, uint32_t sources,
            int32_t keyboardType);
    virtual ~KeyboardInputMapper();

    virtual uint32_t getSources();
    virtual void populateDeviceInfo(InputDeviceInfo* deviceInfo);
    virtual void reset();
    virtual void process(const RawEvent* rawEvent);

    virtual int32_t getKeyCodeState(uint32_t sourceMask, int32_t keyCode);
    virtual int32_t getScanCodeState(uint32_t sourceMask, int32_t scanCode);
    virtual bool markSupportedKeyCodes(uint32_t sourceMask, size_t numCodes,
            const int32_t* keyCodes, uint8_t* outFlags);

    virtual int32_t getMetaState();

private:
    Mutex mLock;

    struct KeyDown {
        int32_t keyCode;
        int32_t scanCode;
    };

    int32_t mAssociatedDisplayId;
    uint32_t mSources;
    int32_t mKeyboardType;

    struct LockedState {
        Vector<KeyDown> keyDowns; // keys that are down
        int32_t metaState;
        nsecs_t downTime; // time of most recent key down
    } mLocked;

    void initializeLocked();

    bool isKeyboardOrGamepadKey(int32_t scanCode);

    void processKey(nsecs_t when, bool down, int32_t keyCode, int32_t scanCode,
            uint32_t policyFlags);
    void applyPolicyAndDispatch(nsecs_t when, uint32_t policyFlags,
            bool down, int32_t keyCode, int32_t scanCode, int32_t metaState, nsecs_t downTime);

    ssize_t findKeyDownLocked(int32_t scanCode);
};


class TrackballInputMapper : public InputMapper {
public:
    TrackballInputMapper(InputDevice* device, int32_t associatedDisplayId);
    virtual ~TrackballInputMapper();

    virtual uint32_t getSources();
    virtual void populateDeviceInfo(InputDeviceInfo* deviceInfo);
    virtual void reset();
    virtual void process(const RawEvent* rawEvent);

    virtual int32_t getScanCodeState(uint32_t sourceMask, int32_t scanCode);

private:
    // Amount that trackball needs to move in order to generate a key event.
    static const int32_t TRACKBALL_MOVEMENT_THRESHOLD = 6;

    Mutex mLock;

    int32_t mAssociatedDisplayId;

    struct Accumulator {
        enum {
            FIELD_BTN_MOUSE = 1,
            FIELD_REL_X = 2,
            FIELD_REL_Y = 4
        };

        uint32_t fields;

        bool btnMouse;
        int32_t relX;
        int32_t relY;

        inline void clear() {
            fields = 0;
        }
    } mAccumulator;

    float mXScale;
    float mYScale;
    float mXPrecision;
    float mYPrecision;

    struct LockedState {
        bool down;
        nsecs_t downTime;
    } mLocked;

    void initializeLocked();

    void sync(nsecs_t when);
    void applyPolicyAndDispatch(nsecs_t when, int32_t motionEventAction,
            PointerCoords* pointerCoords, nsecs_t downTime);
};


class TouchInputMapper : public InputMapper {
public:
    TouchInputMapper(InputDevice* device, int32_t associatedDisplayId);
    virtual ~TouchInputMapper();

    virtual uint32_t getSources();
    virtual void populateDeviceInfo(InputDeviceInfo* deviceInfo);
    virtual void configure();
    virtual void reset();

    virtual int32_t getKeyCodeState(uint32_t sourceMask, int32_t keyCode);
    virtual int32_t getScanCodeState(uint32_t sourceMask, int32_t scanCode);
    virtual bool markSupportedKeyCodes(uint32_t sourceMask, size_t numCodes,
            const int32_t* keyCodes, uint8_t* outFlags);

protected:
    Mutex mLock;

    struct VirtualKey {
        int32_t keyCode;
        int32_t scanCode;
        uint32_t flags;

        // computed hit box, specified in touch screen coords based on known display size
        int32_t hitLeft;
        int32_t hitTop;
        int32_t hitRight;
        int32_t hitBottom;

        inline bool isHit(int32_t x, int32_t y) const {
            return x >= hitLeft && x <= hitRight && y >= hitTop && y <= hitBottom;
        }
    };

    // Raw data for a single pointer.
    struct PointerData {
        uint32_t id;
        int32_t x;
        int32_t y;
        int32_t pressure;
        int32_t touchMajor;
        int32_t touchMinor;
        int32_t toolMajor;
        int32_t toolMinor;
        int32_t orientation;
    };

    // Raw data for a collection of pointers including a pointer id mapping table.
    struct TouchData {
        uint32_t pointerCount;
        PointerData pointers[MAX_POINTERS];
        BitSet32 idBits;
        uint32_t idToIndex[MAX_POINTER_ID + 1];

        void copyFrom(const TouchData& other) {
            pointerCount = other.pointerCount;
            idBits = other.idBits;

            for (uint32_t i = 0; i < pointerCount; i++) {
                pointers[i] = other.pointers[i];

                int id = pointers[i].id;
                idToIndex[id] = other.idToIndex[id];
            }
        }

        inline void clear() {
            pointerCount = 0;
            idBits.clear();
        }
    };

    int32_t mAssociatedDisplayId;

    // Immutable configuration parameters.
    struct Parameters {
        bool useBadTouchFilter;
        bool useJumpyTouchFilter;
        bool useAveragingTouchFilter;
    } mParameters;

    // Immutable calibration parameters in parsed form.
    struct Calibration {
        // Touch Area
        enum TouchAreaCalibration {
            TOUCH_AREA_CALIBRATION_DEFAULT,
            TOUCH_AREA_CALIBRATION_NONE,
            TOUCH_AREA_CALIBRATION_GEOMETRIC,
            TOUCH_AREA_CALIBRATION_PRESSURE,
        };

        TouchAreaCalibration touchAreaCalibration;

        // Tool Area
        enum ToolAreaCalibration {
            TOOL_AREA_CALIBRATION_DEFAULT,
            TOOL_AREA_CALIBRATION_NONE,
            TOOL_AREA_CALIBRATION_GEOMETRIC,
            TOOL_AREA_CALIBRATION_LINEAR,
        };

        ToolAreaCalibration toolAreaCalibration;
        bool haveToolAreaLinearScale;
        float toolAreaLinearScale;
        bool haveToolAreaLinearBias;
        float toolAreaLinearBias;
        bool haveToolAreaIsSummed;
        int32_t toolAreaIsSummed;

        // Pressure
        enum PressureCalibration {
            PRESSURE_CALIBRATION_DEFAULT,
            PRESSURE_CALIBRATION_NONE,
            PRESSURE_CALIBRATION_PHYSICAL,
            PRESSURE_CALIBRATION_AMPLITUDE,
        };
        enum PressureSource {
            PRESSURE_SOURCE_DEFAULT,
            PRESSURE_SOURCE_PRESSURE,
            PRESSURE_SOURCE_TOUCH,
        };

        PressureCalibration pressureCalibration;
        PressureSource pressureSource;
        bool havePressureScale;
        float pressureScale;

        // Size
        enum SizeCalibration {
            SIZE_CALIBRATION_DEFAULT,
            SIZE_CALIBRATION_NONE,
            SIZE_CALIBRATION_NORMALIZED,
        };

        SizeCalibration sizeCalibration;

        // Orientation
        enum OrientationCalibration {
            ORIENTATION_CALIBRATION_DEFAULT,
            ORIENTATION_CALIBRATION_NONE,
            ORIENTATION_CALIBRATION_INTERPOLATED,
        };

        OrientationCalibration orientationCalibration;
    } mCalibration;

    // Raw axis information from the driver.
    struct RawAxes {
        RawAbsoluteAxisInfo x;
        RawAbsoluteAxisInfo y;
        RawAbsoluteAxisInfo pressure;
        RawAbsoluteAxisInfo touchMajor;
        RawAbsoluteAxisInfo touchMinor;
        RawAbsoluteAxisInfo toolMajor;
        RawAbsoluteAxisInfo toolMinor;
        RawAbsoluteAxisInfo orientation;
    } mRawAxes;

    // Current and previous touch sample data.
    TouchData mCurrentTouch;
    TouchData mLastTouch;

    // The time the primary pointer last went down.
    nsecs_t mDownTime;

    struct LockedState {
        Vector<VirtualKey> virtualKeys;

        // The surface orientation and width and height set by configureSurfaceLocked().
        int32_t surfaceOrientation;
        int32_t surfaceWidth, surfaceHeight;

        // Translation and scaling factors, orientation-independent.
        int32_t xOrigin;
        float xScale;
        float xPrecision;

        int32_t yOrigin;
        float yScale;
        float yPrecision;

        float geometricScale;

        float toolAreaLinearScale;
        float toolAreaLinearBias;

        float pressureScale;

        float sizeScale;

        float orientationScale;

        // Oriented motion ranges for input device info.
        struct OrientedRanges {
            InputDeviceInfo::MotionRange x;
            InputDeviceInfo::MotionRange y;

            bool havePressure;
            InputDeviceInfo::MotionRange pressure;

            bool haveSize;
            InputDeviceInfo::MotionRange size;

            bool haveTouchArea;
            InputDeviceInfo::MotionRange touchMajor;
            InputDeviceInfo::MotionRange touchMinor;

            bool haveToolArea;
            InputDeviceInfo::MotionRange toolMajor;
            InputDeviceInfo::MotionRange toolMinor;

            bool haveOrientation;
            InputDeviceInfo::MotionRange orientation;
        } orientedRanges;

        // Oriented dimensions and precision.
        float orientedSurfaceWidth, orientedSurfaceHeight;
        float orientedXPrecision, orientedYPrecision;

        struct CurrentVirtualKeyState {
            bool down;
            nsecs_t downTime;
            int32_t keyCode;
            int32_t scanCode;
        } currentVirtualKey;
    } mLocked;

    virtual void configureParameters();
    virtual void logParameters();
    virtual void configureRawAxes();
    virtual void logRawAxes();
    virtual bool configureSurfaceLocked();
    virtual void logMotionRangesLocked();
    virtual void configureVirtualKeysLocked();
    virtual void parseCalibration();
    virtual void resolveCalibration();
    virtual void logCalibration();

    enum TouchResult {
        // Dispatch the touch normally.
        DISPATCH_TOUCH,
        // Do not dispatch the touch, but keep tracking the current stroke.
        SKIP_TOUCH,
        // Do not dispatch the touch, and drop all information associated with the current stoke
        // so the next movement will appear as a new down.
        DROP_STROKE
    };

    void syncTouch(nsecs_t when, bool havePointerIds);

private:
    /* Maximum number of historical samples to average. */
    static const uint32_t AVERAGING_HISTORY_SIZE = 5;

    /* Slop distance for jumpy pointer detection.
     * The vertical range of the screen divided by this is our epsilon value. */
    static const uint32_t JUMPY_EPSILON_DIVISOR = 212;

    /* Number of jumpy points to drop for touchscreens that need it. */
    static const uint32_t JUMPY_TRANSITION_DROPS = 3;
    static const uint32_t JUMPY_DROP_LIMIT = 3;

    /* Maximum squared distance for averaging.
     * If moving farther than this, turn of averaging to avoid lag in response. */
    static const uint64_t AVERAGING_DISTANCE_LIMIT = 75 * 75;

    struct AveragingTouchFilterState {
        // Individual history tracks are stored by pointer id
        uint32_t historyStart[MAX_POINTERS];
        uint32_t historyEnd[MAX_POINTERS];
        struct {
            struct {
                int32_t x;
                int32_t y;
                int32_t pressure;
            } pointers[MAX_POINTERS];
        } historyData[AVERAGING_HISTORY_SIZE];
    } mAveragingTouchFilter;

    struct JumpyTouchFilterState {
        uint32_t jumpyPointsDropped;
    } mJumpyTouchFilter;

    struct PointerDistanceHeapElement {
        uint32_t currentPointerIndex : 8;
        uint32_t lastPointerIndex : 8;
        uint64_t distance : 48; // squared distance
    };

    void initializeLocked();

    TouchResult consumeOffScreenTouches(nsecs_t when, uint32_t policyFlags);
    void dispatchTouches(nsecs_t when, uint32_t policyFlags);
    void dispatchTouch(nsecs_t when, uint32_t policyFlags, TouchData* touch,
            BitSet32 idBits, uint32_t changedId, uint32_t pointerCount,
            int32_t motionEventAction);

    void applyPolicyAndDispatchVirtualKey(nsecs_t when, uint32_t policyFlags,
            int32_t keyEventAction, int32_t keyEventFlags,
            int32_t keyCode, int32_t scanCode, nsecs_t downTime);

    bool isPointInsideSurfaceLocked(int32_t x, int32_t y);
    const VirtualKey* findVirtualKeyHitLocked(int32_t x, int32_t y);

    bool applyBadTouchFilter();
    bool applyJumpyTouchFilter();
    void applyAveragingTouchFilter();
    void calculatePointerIds();
};


class SingleTouchInputMapper : public TouchInputMapper {
public:
    SingleTouchInputMapper(InputDevice* device, int32_t associatedDisplayId);
    virtual ~SingleTouchInputMapper();

    virtual void reset();
    virtual void process(const RawEvent* rawEvent);

protected:
    virtual void configureRawAxes();

private:
    struct Accumulator {
        enum {
            FIELD_BTN_TOUCH = 1,
            FIELD_ABS_X = 2,
            FIELD_ABS_Y = 4,
            FIELD_ABS_PRESSURE = 8,
            FIELD_ABS_TOOL_WIDTH = 16
        };

        uint32_t fields;

        bool btnTouch;
        int32_t absX;
        int32_t absY;
        int32_t absPressure;
        int32_t absToolWidth;

        inline void clear() {
            fields = 0;
        }
    } mAccumulator;

    bool mDown;
    int32_t mX;
    int32_t mY;
    int32_t mPressure;
    int32_t mToolWidth;

    void initialize();

    void sync(nsecs_t when);
};


class MultiTouchInputMapper : public TouchInputMapper {
public:
    MultiTouchInputMapper(InputDevice* device, int32_t associatedDisplayId);
    virtual ~MultiTouchInputMapper();

    virtual void reset();
    virtual void process(const RawEvent* rawEvent);

protected:
    virtual void configureRawAxes();

private:
    struct Accumulator {
        enum {
            FIELD_ABS_MT_POSITION_X = 1,
            FIELD_ABS_MT_POSITION_Y = 2,
            FIELD_ABS_MT_TOUCH_MAJOR = 4,
            FIELD_ABS_MT_TOUCH_MINOR = 8,
            FIELD_ABS_MT_WIDTH_MAJOR = 16,
            FIELD_ABS_MT_WIDTH_MINOR = 32,
            FIELD_ABS_MT_ORIENTATION = 64,
            FIELD_ABS_MT_TRACKING_ID = 128,
            FIELD_ABS_MT_PRESSURE = 256,
        };

        uint32_t pointerCount;
        struct Pointer {
            uint32_t fields;

            int32_t absMTPositionX;
            int32_t absMTPositionY;
            int32_t absMTTouchMajor;
            int32_t absMTTouchMinor;
            int32_t absMTWidthMajor;
            int32_t absMTWidthMinor;
            int32_t absMTOrientation;
            int32_t absMTTrackingId;
            int32_t absMTPressure;

            inline void clear() {
                fields = 0;
            }
        } pointers[MAX_POINTERS + 1]; // + 1 to remove the need for extra range checks

        inline void clear() {
            pointerCount = 0;
            pointers[0].clear();
        }
    } mAccumulator;

    void initialize();

    void sync(nsecs_t when);
};

} // namespace android

#endif // _UI_INPUT_READER_H