Current Symbian^3 public API header files (from PDK 3.0.h)
This is the epoc32/include tree with the "platform" subtrees removed, and
all but a selected few mbg and rsg files removed.
/*
* Copyright (c) 2008 Nokia Corporation and/or its subsidiary(-ies).
* All rights reserved.
* This component and the accompanying materials are made available
* under the terms of "Eclipse Public License v1.0"
* which accompanies this distribution, and is available
* at the URL "http://www.eclipse.org/legal/epl-v10.html".
*
* Initial Contributors:
* Nokia Corporation - initial contribution.
*
* Contributors:
*
* Description: Sensor channel class definition
*
*/
#ifndef SENSRVCHANNEL_H
#define SENSRVCHANNEL_H
#include <e32base.h>
#include <sensrvtypes.h>
#include <sensrvchannelconditionset.h>
#include <sensrvchannelinfo.h>
class MSensrvPropertyListener;
class MSensrvDataListener;
class MSensrvChannelConditionListener;
class CSensrvChannelCondition;
class CSensrvChannelListener;
/**
* The CSensrvChannel class provides an API that allows clients to open, control, configure,
* receive data and receive notifications from a sensor channel.
*
* When instantiating CSensrvChannel an instance of TSensrvChannelInfo returned by
* CSensrvChannelFinder::FindChannelsL() must be used. This ensures that internal data used
* in identifying the chosen channel is passed back to Sensor Services in its entirety
* therefore ensuring correct operation. Not using the instance returned by
* CSensrvChannelFinder::FindChannelsL() will result in undefined behaviour.
*
* On instantiation of this class a session connection to the Sensor Server is made. The Sensor
* server is a transient server and is started, if not already running, when a session connection
* is made. The sensor server is shutdown when a device-configured timeout period expires after
* the last session connection has been dropped. The Sensor Server will not shutdown if there is
* a session connection to it.
*
* The instance of TSensrvChannelInfo returned by CSensrvChannelFinder::FindChannelsL()
* contains a channel Id which is only valid for the lifetime of the sensor server. If a client
* requires that this id remains unchanged then the client must ensure that an instance of either
* CSensrvChannelFinder or CSensrvChannel remains instantiated. This keeps a session connection with
* the server open which prevents the sensor server from shutting down.
*
* After creating an instance of this class a client would typically:
* 1. Check the configuration of the channel using GetPropertyL() or GetAllPropertuies().
* 2. Change the configuration where necessary using SetPropertiesL()
* 3. If SetPropertiesL() failed, because of higher priority clients of this same channel or higher
* priority clients of impacted channels on the same sensor, listen for notifications indicating
* when it is able to set properties using SetPropertyListenerl().
* 4. Listen for property changes using SetPropertyListenerl(). This notifies the client of property
* changes made by other clients of this same channel.
* 5. Listen for data and retrieve data on the channel using StartDataListeningL() and GetData().
* 6. Set trigger conditions for a 1 off notification when the condition is met using AddConditionL()
* and SetConditionListeningL().
*
* Its possible that there may be more than 1 client using the same sensor channel on the device. Each
* of these clients will have created their own instance of CSensrvChannel and can attempt to configure
* the sensor using the SetPropertyL() operation. To manage any contention between clients wishing to
* change the configuration of the sensor a concept of Client Priorities is employed. This means that a
* device creator assigns a pre-determined priority to a client. If a client has not been assigned a
* priority then it is assumed it has the lowest priority.
*
* When the SetPropertyL() operation is called the sensor server checks to see if the client has the
* highest Client Priority of all clients using that channel or using an impacted channel on the same
* sensor. If it has the property is set and all other clients of the channel are notified of the property
* change. If it has not the SetPropertyL() operation fails with KErrAccessDenied. If clients have
* the same priority then property setting is done on a first come first served basis.
*
* If a client is unable to set a property because of higher priority clients then the client should
* implement the MSensrvPropertyListener::SetPropertySuccessIndicationChanged() callback so that they can
* be notified when they are able to set properties.
*
* All client applications should be designed in such a way so that they are able to handle the situation
* where they are unable to configure a channel using the SetPropertyL() operation.
*
* For example:
* Should application features be disabled or should the application shutdown in such conditions?
* Should features be disabled under certain channel configurations?
*
* This object is closed when deleted either by a call to operator delete or by the cleanup stack. No special
* cleanup code is necessary to close the object before deletion.
*
* @see CSensrvChannelFinder
* @lib sensrvclient.lib
* @since S60 5.0
*/
NONSHARABLE_CLASS( CSensrvChannel ): public CBase
{
public:
/**
* Two-phased constructor.
*
* The Sensor Server uses aChannelInfo to identify the channel in the server that the returned object
* represents.
*
* @since S60 5.0
* @param aChannelInfo The information that determines which channel object is created. This must
* be an object returned by CSensrvChannelFinder::FindChannelsL().
* @return Pointer to created CSensorChannel object
* @leave KErrNoMemory
* @leave One of the system-wide error codes
*/
IMPORT_C static CSensrvChannel* NewL
( const TSensrvChannelInfo& aChannelInfo );
/**
* Two-phased constructor.
*
* The Sensor Server uses aChannelInfo to identify the channel in the server that the returned object
* represents.
*
* @since S60 5.0
* @param aChannelInfo The information that determines which channel object is created. This must
* be an object returned by CSensrvChannelFinder::FindChannelsL().
* @return Pointer to created CSensorChannel object that is placed on the cleanup stack.
* @leave KErrNoMemory
* @leave One of the system-wide error codes
*/
IMPORT_C static CSensrvChannel* NewLC
( const TSensrvChannelInfo& aChannelInfo );
public:
/**
* Initializes and opens the channel. After the channel is opened, the client can set and get channel
* properties, add channel conditions and listen for sensor data.
*
* @since S60 5.0
* @leave KErrAlreadyExists if channel is already open
* @leave One of the system-wide error codes
*/
virtual void OpenChannelL() = 0;
/**
* Closes the channel.
*
* This object is closed when deleted either by a call to operator delete or by the cleanup stack. No special
* cleanup code is necessary to close the object before deletion.
*
* @since S60 5.0
* @return KErrNone if channel closing is successful, or one of the system-wide error codes
*/
virtual TInt CloseChannel() = 0;
/**
* Retrieves a channel information object related to this channel.
*
* @since S60 5.0
* @return Reference to the channel information object
*/
virtual const TSensrvChannelInfo& GetChannelInfo() const = 0;
/**
* Starts channel data listening on the channel.
*
* To use this operation clients must provide an object that inherits from MSensrvDataListener.
*
* When new data is available to be read, the client is notified by the
* MSensrvDataListener::DataReceived() callback. On receiving this notificaton the client should
* retrieve the data using the GetData() operation.
*
* Note that if a client is listening for both data and conditions on the channel then the lower
* desired count and buffering period provided in either start listening operation arguments will be
* used for both listeners. When either listener is stopped neither the desired count nor the
* buffering period shall be changed.
*
* For the best performance, always use the highest desired count and maximum count as the use case
* allows. This will reduce the overhead caused by a high volume of IPC context switches. However,
* be aware that higher counts need to reserve more memory.
*
* @since S60 5.0
* @param aDataListener Data listener for the channel. Must be valid until data listening is stopped.
* @param aDesiredCount Desired receiving buffer size defined as a count of the channel data objects.
* The maximum value is determined by sensor server internal channel buffer size, and minimum
* value is one. Any value outside these limits is interpreted as maximum possible value.
* The actual count of channel data objects received may be smaller than aDesiredCount, if a
* non-zero buffering period has been specified.
* The actual count of channel data objects received may larger, if aMaximumCount is bigger
* than aDesiredCount.
* If the sensor supplies data sporadically, and the clients requires every data object then
* aDesiredCount should be set to one to ensure that no data objects are missed.
* @param aMaximumCount Maximum receiving buffer size defined as a count of the channel data object.
* The Maximum value is determined by sensor server internal channel buffer size, and minimum
* value is aDesiredCount. Any value outside these limits is interpreted as maximum possible
* value.
* It is recommended that whenever aDesiredCount needs to be low and sensor has relatively high
* data rate, aMaximumCount is set to significantly higher than aDesiredCount to reduce IPC
* context switches and data loss.
* @param aBufferingPeriod Specifies the maximum time in milliseconds that sensor server waits before
* notifying the client that new data is available. It is possible that no new data is will be
* available when the client is notified.
* Zero timeout means that only desired and maximum counts are used in getting data.
* Using a buffering period results in lot of unnecessary IPC context switches if a sensor
* channel supplies data sporadically. It is therefore recommended that a buffering period is
* used only when it is absolutely vital to have data at specific intervals and using a low
* desired count is otherwise too expensive performance-wise.
* @leave KErrArgument if aDataListener is NULL, or if a negative argument is supplied
* @leave KErrNotFound if the channel is not open
* @leave KErrAlreadyExists if data listening has already started on the channel
* @leave One of the system-wide error codes
*/
virtual void StartDataListeningL( MSensrvDataListener* aDataListener,
const TInt aDesiredCount,
const TInt aMaximumCount,
const TInt aBufferingPeriod ) = 0;
/**
* Stop channel data listening.
*
* @since S60 5.0
* @return KErrNone if stopping successful or one of the system-wide error codes
*/
virtual TInt StopDataListening() = 0;
/**
* Get data items when the client is notified by the MSensrvDataListener::DataReceived() callback
* that new data is ready to be retrieved. The callback also indicates the number of data items
* contained in aData.
*
* Example:
*
* How to retrieve data using TPckg
*
* @code
* void DataReceived(CSensrvChannel& aChannel, TInt aCount, TInt aDataLost )
* {
* if(aChannel.GetChannelInfo().iChannelType == KSensrvChannelTypeIdAccelerometerXYZAxisData)
* {
* TSensrvAccelerometerAxisData XYZData;
* TPckg<TSensrvAccelerometerAxisData> XYZPackage( XYZData );
* aChannel.GetData( XYZPackage );
* }
* }
* @endcode
*
* @since S60 5.0
* @param aData Reference to descriptor that contains the data. Typically this is a package buffer
* defined for data type of this channel. See channel specific data headers for details of
* the package types and data supported by a channel.
* @return KErrNotFound if data buffer is empty, KErrOverflow if aData is wrong size for data
* item, or one of the system-wide error codes
*/
virtual TInt GetData( TDes8& aData ) = 0;
/**
* Sets a property value for this channel. To manage any contention between multiple clients wishing
* to change the configuration of the sensor a concept of Client Priorities is employed. See class
* description for further information.
*
* The sensor plugin may police setting of properties by verifying that the client making the request
* has the necessary capabilities. If the client does not then it will return with KErrAccessDenied.
* @since S60 5.0
* @param aProperty Identifies the property that is to be set and its new value. Only the Property Id,
* Item Index and Property Value should be filled in. All other fields in TSensrvProperty are
* ignored.
* @return KErrNotFound if channel is not open or if the property does not exist, KErrAccessDenied
* if there are other clients for this channel or impacted channel on the same sensor with a
* higher Client Priority, KErrAccessDenied if the client does not have the required
* capabilities or one of the system-wide error codes
*/
virtual TInt SetProperty( const TSensrvProperty& aProperty ) = 0;
/**
* Gets a channel property value for this channel.
*
* @since S60 5.0
* @param aPropertyId Id of the property that is to be retrieved
* @param aItemIndex The Item Index of the property to be retrieved. This is mapped to a specific item
* in channel data structure. See channel specific data headers.
* @param aProperty Reference for a property object where property data is to be copied
* @leave KErrNotFound if channel is not open
* @leave KErrNotFound if property does not exist
* @leave KErrArgument if a negative argument is supplied
* @leave One of the system-wide error codes
* */
virtual void GetPropertyL( const TSensrvPropertyId aPropertyId,
const TInt aItemIndex,
TSensrvProperty& aProperty ) = 0;
/**
* Get a channel property value for this channel
*
* @since S60 5.0
* @param aPropertyId Id of the property that is to be retrieved
* @param aItemIndex Item Index of the property to be retrieved. This is mapped to a specific item
* in channel data structure. See channel specific data headers.
* @param aArrayIndex Array index of the property to be retrieved when the property is part of a
* property array.
* @param aProperty Reference for a property object where property data is to be copied
* @leave KErrNotFound if channel is not open
* @leave KErrNotFound if property does not exist
* @leave KErrArgument if a negative argument is supplied
* @leave One of the system-wide error codes
*/
virtual void GetPropertyL( const TSensrvPropertyId aPropertyId,
const TInt aItemIndex,
const TInt aArrayIndex,
TSensrvProperty& aProperty ) = 0;
/**
* Get all properties for this channel
*
* @since S60 5.0
* @param aChannelPropertyList Reference for a property list where all property data is to be
* copied. Any existing data in the list will be lost.
* @leave KErrNotFound if channel is not open
* @leave One of the system-wide error codes
*/
virtual void GetAllPropertiesL
( RSensrvPropertyList& aChannelPropertyList ) = 0;
/**
* Get all channel properties having the supplied Property Id. This is used when the property
* is an array property.
*
* @since S60 5.0
* @param aPropertyId Id of the property to be retrieved
* @param aChannelPropertyList Reference for a property list where all property data is to be
* copied. Any existing data in the list will be lost.
* @leave KErrNotFound if channel is not open
* @leave KErrNotFound if property does not exist
* @leave One of the system-wide error codes
*/
virtual void GetAllPropertiesL
( const TSensrvPropertyId aPropertyId,
RSensrvPropertyList& aChannelPropertyList ) = 0;
/**
* Start property listening on this channel.
*
* To use this operation clients must provide an object that inherits from MSensrvPropertyListener.
*
* The client can use the property listener to get notifications when properties are changed and
* to get a notification when the client is able/unable to set properties because of higher priority
* clients have opened/closed the same sensor channel.
*
* If the client itself changes a property value, no notification is received for that property by
* the client. If another client changes a property on this channel or another channel that impacts
* this channel a notification will be received by the client.
*
* Some sensors support a number of channels with each channel having some common properties.
* Therefore changing a common property may result in notifications on a number of other channels
* supported by the sensor.
*
* @since S60 5.0
* @param aChannelPropertyListener Pointer to channel property listener callback instance. The
* channel property listener must be valid until the CSensrvChannel object is destroyed or
* listening has been stopped. Listening can be stopped using a NULL parameter.
* @leave KErrAlreadyExists if channel property listener has already been set
* @leave KErrNotFound if channel is not open
* @leave One of the system-wide error codes
*/
virtual void SetPropertyListenerL
( MSensrvPropertyListener* aChannelPropertyListener ) = 0;
/**
* Add a channel ConditionSet to the channel.
*
* Channel ConditionSet's are used for channel condition listening and at least 1 ConditionSet must
* be added before listening can begin.
*
* When the conditions defined by the ConditionSet is met the client will be notified by the
* MSensrvChannelConditionListener::ConditionMet() callback and listening for this ConditionSet will
* cease. If a client wishes to listen for this ConditionSet again it must be added again.
*
* The client continues to own the ConditionSet object after a call to this function and must ensure
* that it is destroyed when no longer required.
*
* The client must ensure that the ConditionSet object is valid until it is no longer needed by the
* Sensor Server. This is either after the condition set has been removed by the client using
* RemoveConditionL() or the client has been notified that the condition has been met.
*
* @since S60 5.0
* @param aChannelConditionSet The channel condition set to be added.
* @leave KErrNotFound if channel is not open
* @leave KErrNotSupported if a channel does not support conditions.
* @leave One of the system-wide error codes
* @see CSensrvChannel::StartConditionListeningL()
*/
virtual void AddConditionL( CSensrvChannelConditionSet& aChannelConditionSet ) = 0;
/**
* Remove a channel ConditionSet from the channel.
*
* The same reference used to to add the Condition Set in AddConditionL(), must also be used to
* remove it.
*
* The removed channel ConditionSet is no longer used for channel condition listening.
*
* The client continues to own the ConditionSet object after a call to this function and must ensure
* that it is destroyed when no longer required.
*
* @since S60 5.0
* @param aChannelConditionSet The channel condition set to be removed.
* @leave KErrNotFound if channel is not open
* @leave One of the system-wide error codes
*/
virtual void RemoveConditionL
( CSensrvChannelConditionSet& aChannelConditionSet ) = 0;
/**
* Start channel condition listening.
*
* To use this operation clients must provide an object that inherits from MSensrvChannelConditionListener.
*
* If the conditions of an added ConditionSet is met the MSensrvChannelConditionListener::ConditionMet()
* callback function will be called and listening for this ConditionSet will cease. If a client wishes
* to listen for the same ConditionSet again it must be added again.
*
* Note that if a client is listening for both data and conditions on the channel then the lower
* desired count and buffering period provided in either start listening operation arguments will be
* used for both listeners. When either listener is stopped neither the desired count nor the
* buffering period shall be changed.
*
* @since S60 5.0
* @param aChannelConditionListener Condition listener for the channel. Must be valid until data
* listening is stopped.
* @param aObjectCount Listening buffer size defined as a count of the channel data objects. When the
* desired object count is reached each ConditionSet is evaluated in turn. The maximum value is
* determined by sensor server internal channel buffer size, and minimum value is one. Any value
* outside these limits is interpreted as maximum possible value.
* @param aBufferingPeriod Specifies the maximum time in milliseconds that sensor server waits before
* evaluating new data.
* Zero timeout means that the sensor server only evaluates new data when the object count has been
* reached.
* @leave KErrArgument if aChannelConditionListener is NULL, or if a negative argument is supplied
* @leave KErrNotFound if the channel is not open
* @leave KErrAlreadyExists if condition listening has already started on the channel
* @leave One of the system-wide error codes
*/
virtual void StartConditionListeningL
( MSensrvChannelConditionListener* aChannelConditionListener,
const TInt aObjectCount,
const TInt aBufferingPeriod ) = 0;
/**
* Stop channel condition listening.
*
* All remaining unmet ConditionSet's are removed and channel condition listening is stopped.
*
* If the same ConditionSet's need to be used when condition listening has been restarted then they must be
* re-added.
*
* @since S60 5.0
* @return KErrNone if condition listening is successfully stopped or one of the system-wide error codes
*/
virtual TInt StopConditionListening() = 0;
public:
/**
* Default constructor.
*/
CSensrvChannel();
};
#endif //SENSRVCHANNEL_H
// End of File