/* * 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_TRANSPORT_H #define _UI_INPUT_TRANSPORT_H /** * Native input transport. * * Uses anonymous shared memory as a whiteboard for sending input events from an * InputPublisher to an InputConsumer and ensuring appropriate synchronization. * One interesting feature is that published events can be updated in place as long as they * have not yet been consumed. * * The InputPublisher and InputConsumer only take care of transferring event data * over an InputChannel and sending synchronization signals. The InputDispatcher and InputQueue * build on these abstractions to add multiplexing and queueing. */ #include #include #include #include #include #include namespace android { /* * An input channel consists of a shared memory buffer and a pair of pipes * used to send input messages from an InputPublisher to an InputConsumer * across processes. Each channel has a descriptive name for debugging purposes. * * Each endpoint has its own InputChannel object that specifies its own file descriptors. * * The input channel is closed when all references to it are released. */ class InputChannel : public RefBase { protected: virtual ~InputChannel(); public: InputChannel(const String8& name, int32_t ashmemFd, int32_t receivePipeFd, int32_t sendPipeFd); /* Creates a pair of input channels and their underlying shared memory buffers * and pipes. * * Returns OK on success. */ static status_t openInputChannelPair(const String8& name, sp& outServerChannel, sp& outClientChannel); inline String8 getName() const { return mName; } inline int32_t getAshmemFd() const { return mAshmemFd; } inline int32_t getReceivePipeFd() const { return mReceivePipeFd; } inline int32_t getSendPipeFd() const { return mSendPipeFd; } /* Sends a signal to the other endpoint. * * Returns OK on success. * Returns DEAD_OBJECT if the channel's peer has been closed. * Other errors probably indicate that the channel is broken. */ status_t sendSignal(char signal); /* Receives a signal send by the other endpoint. * (Should only call this after poll() indicates that the receivePipeFd has available input.) * * Returns OK on success. * Returns WOULD_BLOCK if there is no signal present. * Returns DEAD_OBJECT if the channel's peer has been closed. * Other errors probably indicate that the channel is broken. */ status_t receiveSignal(char* outSignal); private: String8 mName; int32_t mAshmemFd; int32_t mReceivePipeFd; int32_t mSendPipeFd; }; /* * Private intermediate representation of input events as messages written into an * ashmem buffer. */ struct InputMessage { /* Semaphore count is set to 1 when the message is published. * It becomes 0 transiently while the publisher updates the message. * It becomes 0 permanently when the consumer consumes the message. */ sem_t semaphore; /* Initialized to false by the publisher. * Set to true by the consumer when it consumes the message. */ bool consumed; int32_t type; struct SampleData { nsecs_t eventTime; PointerCoords coords[0]; // variable length }; int32_t deviceId; int32_t nature; union { struct { int32_t action; int32_t flags; int32_t keyCode; int32_t scanCode; int32_t metaState; int32_t repeatCount; nsecs_t downTime; nsecs_t eventTime; } key; struct { int32_t action; int32_t metaState; int32_t edgeFlags; nsecs_t downTime; float xOffset; float yOffset; float xPrecision; float yPrecision; size_t pointerCount; int32_t pointerIds[MAX_POINTERS]; size_t sampleCount; SampleData sampleData[0]; // variable length } motion; }; /* Gets the number of bytes to add to step to the next SampleData object in a motion * event message for a given number of pointers. */ static inline size_t sampleDataStride(size_t pointerCount) { return sizeof(InputMessage::SampleData) + pointerCount * sizeof(PointerCoords); } /* Adds the SampleData stride to the given pointer. */ static inline SampleData* sampleDataPtrIncrement(SampleData* ptr, size_t stride) { return reinterpret_cast(reinterpret_cast(ptr) + stride); } }; /* * Publishes input events to an anonymous shared memory buffer. * Uses atomic operations to coordinate shared access with a single concurrent consumer. */ class InputPublisher { public: /* Creates a publisher associated with an input channel. */ explicit InputPublisher(const sp& channel); /* Destroys the publisher and releases its input channel. */ ~InputPublisher(); /* Gets the underlying input channel. */ inline sp getChannel() { return mChannel; } /* Prepares the publisher for use. Must be called before it is used. * Returns OK on success. * * This method implicitly calls reset(). */ status_t initialize(); /* Resets the publisher to its initial state and unpins its ashmem buffer. * Returns OK on success. * * Should be called after an event has been consumed to release resources used by the * publisher until the next event is ready to be published. */ status_t reset(); /* Publishes a key event to the ashmem buffer. * * Returns OK on success. * Returns INVALID_OPERATION if the publisher has not been reset. */ status_t publishKeyEvent( int32_t deviceId, int32_t nature, int32_t action, int32_t flags, int32_t keyCode, int32_t scanCode, int32_t metaState, int32_t repeatCount, nsecs_t downTime, nsecs_t eventTime); /* Publishes a motion event to the ashmem buffer. * * Returns OK on success. * Returns INVALID_OPERATION if the publisher has not been reset. * Returns BAD_VALUE if pointerCount is less than 1 or greater than MAX_POINTERS. */ status_t publishMotionEvent( int32_t deviceId, int32_t nature, int32_t action, int32_t edgeFlags, int32_t metaState, float xOffset, float yOffset, float xPrecision, float yPrecision, nsecs_t downTime, nsecs_t eventTime, size_t pointerCount, const int32_t* pointerIds, const PointerCoords* pointerCoords); /* Appends a motion sample to a motion event unless already consumed. * * Returns OK on success. * Returns INVALID_OPERATION if the current event is not a MOTION_EVENT_ACTION_MOVE event. * Returns FAILED_TRANSACTION if the current event has already been consumed. * Returns NO_MEMORY if the buffer is full and no additional samples can be added. */ status_t appendMotionSample( nsecs_t eventTime, const PointerCoords* pointerCoords); /* Sends a dispatch signal to the consumer to inform it that a new message is available. * * Returns OK on success. * Errors probably indicate that the channel is broken. */ status_t sendDispatchSignal(); /* Receives the finished signal from the consumer in reply to the original dispatch signal. * * Returns OK on success. * Returns WOULD_BLOCK if there is no signal present. * Other errors probably indicate that the channel is broken. */ status_t receiveFinishedSignal(); private: sp mChannel; size_t mAshmemSize; InputMessage* mSharedMessage; bool mPinned; bool mSemaphoreInitialized; bool mWasDispatched; size_t mMotionEventPointerCount; InputMessage::SampleData* mMotionEventSampleDataTail; size_t mMotionEventSampleDataStride; status_t publishInputEvent( int32_t type, int32_t deviceId, int32_t nature); }; /* * Consumes input events from an anonymous shared memory buffer. * Uses atomic operations to coordinate shared access with a single concurrent publisher. */ class InputConsumer { public: /* Creates a consumer associated with an input channel. */ explicit InputConsumer(const sp& channel); /* Destroys the consumer and releases its input channel. */ ~InputConsumer(); /* Gets the underlying input channel. */ inline sp getChannel() { return mChannel; } /* Prepares the consumer for use. Must be called before it is used. */ status_t initialize(); /* Consumes the input event in the buffer and copies its contents into * an InputEvent object created using the specified factory. * This operation will block if the publisher is updating the event. * * Returns OK on success. * Returns INVALID_OPERATION if there is no currently published event. * Returns NO_MEMORY if the event could not be created. */ status_t consume(InputEventFactoryInterface* factory, InputEvent** outEvent); /* Sends a finished signal to the publisher to inform it that the current message is * finished processing. * * Returns OK on success. * Errors probably indicate that the channel is broken. */ status_t sendFinishedSignal(); /* Receives the dispatched signal from the publisher. * * Returns OK on success. * Returns WOULD_BLOCK if there is no signal present. * Other errors probably indicate that the channel is broken. */ status_t receiveDispatchSignal(); private: sp mChannel; size_t mAshmemSize; InputMessage* mSharedMessage; void populateKeyEvent(KeyEvent* keyEvent) const; void populateMotionEvent(MotionEvent* motionEvent) const; }; } // namespace android #endif // _UI_INPUT_TRANSPORT_H