/*
* 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 <semaphore.h>
#include <ui/Input.h>
#include <utils/Errors.h>
#include <utils/Timers.h>
#include <utils/RefBase.h>
#include <utils/String8.h>
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<InputChannel>& outServerChannel, sp<InputChannel>& 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 source;
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 flags;
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<InputMessage::SampleData*>(reinterpret_cast<char*>(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<InputChannel>& channel);
/* Destroys the publisher and releases its input channel. */
~InputPublisher();
/* Gets the underlying input channel. */
inline sp<InputChannel> 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 source,
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 source,
int32_t action,
int32_t flags,
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 AMOTION_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<InputChannel> 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 source);
};
/*
* 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<InputChannel>& channel);
/* Destroys the consumer and releases its input channel. */
~InputConsumer();
/* Gets the underlying input channel. */
inline sp<InputChannel> 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<InputChannel> mChannel;
size_t mAshmemSize;
InputMessage* mSharedMessage;
void populateKeyEvent(KeyEvent* keyEvent) const;
void populateMotionEvent(MotionEvent* motionEvent) const;
};
} // namespace android
#endif // _UI_INPUT_TRANSPORT_H