diff -r 666f914201fb -r 2fe1408b6811 epoc32/include/sensrvchannel.h --- a/epoc32/include/sensrvchannel.h Tue Nov 24 13:55:44 2009 +0000 +++ b/epoc32/include/sensrvchannel.h Tue Mar 16 16:12:26 2010 +0000 @@ -1,1 +1,472 @@ -sensrvchannel.h +/* +* 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 the License "Symbian Foundation License v1.0" to Symbian Foundation members and "Symbian Foundation End User License Agreement v1.0" to non-members +* which accompanies this distribution, and is available +* at the URL "http://www.symbianfoundation.org/legal/licencesv10.html". +* +* Initial Contributors: +* Nokia Corporation - initial contribution. +* +* Contributors: +* +* Description: Sensor channel class definition +* +*/ + + +#ifndef SENSRVCHANNEL_H +#define SENSRVCHANNEL_H + +#include +#include +#include +#include + + +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 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