Class CMMFController

class CMMFController : public CBase;

Description

Base class for controller plugins.

A controller plugin for the multimedia framework must derive from this class and implement all the pure virtual functions.

Controller plugins control the flow of multimedia data from one or more sources to one or more sinks. For example, an audio controller plugin might take data from a file source and output it to a speaker sink, or take data from a microphone source and save it to a file sink. A controller plugin typically supports one or more multimedia formats, for example WAV or MPEG4.

Derivation

• CBase - Base class for all classes to be instantiated on the heap

• CMMFController - Base class for controller plugins

Members

Defined in CMMFController:
AddCustomCommandParserL(), AddDataSinkL(), AddDataSourceL(), CMMFController(), CustomCommand(), DoSendEventToClient(), DurationL(), GetMetaDataEntryL(), GetNumberOfMetaDataEntriesL(), HandleRequestL(), MMFObjectContainerL(), PauseL(), PauseL(), PlayL(), PlayL(), PositionL(), PrimeL(), PrimeL(), RemoveDataSinkL(), RemoveDataSourceL(), ResetL(), SetPositionL(), SetPrioritySettings(), StopL(), StopL(), ~CMMFController()

Inherited from CBase:
Delete(), Extension_(), operator new()

virtual IMPORT_C ~CMMFController();

Description

Default destructor.

protected: inline CMMFController();

Description

Constructor.

virtual IMPORT_C void HandleRequestL(TMMFMessage &aMessage);

Description

Handles a message from the client.

Decodes the message and calls one of the private DoXxx methods to unpackaged the parameters.

Parameters

TMMFMessage &aMessage The message to be handled.

protected: virtual void AddDataSourceL(MDataSource &aDataSource)=0;

Description

Add a data source to the controller plugin.

NOTE: The data source is owned by the controller framework, NOT by the controller plugin. Under no circumstances should the controller plugin delete the data source.

Parameters

MDataSource &aDataSource A reference to the data source to be added. The controller plugin may call aDataSource.DataSourceType() to find out exactly what type of source it is.

Leave codes

KErrNotSupported If the controller plugin does not support the data source, it should leave with this.

protected: virtual void AddDataSinkL(MDataSink &aDataSink)=0;

Description

Adds a data sink to the controller plugin.

NOTE: The data sink is owned by the controller framework, NOT by the controller plugin. Under no circumstances should the controller plugin delete the data sink.

Parameters

MDataSink &aDataSink A reference to the data sink to be added. The controller plugin may call aDatasink.DatasinkType() to find out exactly what type of sink it is.

Leave codes

KErrNotSupported If the controller plugin does not support the data sink, it should leave with this.

protected: virtual void RemoveDataSourceL(MDataSource &aDataSource)=0;

Description

Removes a data source from the controller plugin.

Note: The data source is owned by the controller framework, NOT by the controller plugin. Under no circumstances should the controller plugin delete the data source.

Parameters

MDataSource &aDataSource A reference to the data source to be removed.

Leave codes

KErrNotSupported The controller plugin may leave during this method. If the controller plugin does not support the removal of data sources, it should leave with KErrNotSupported. If the controller plugin leaves, the data source will not be destroyed by the controller framework. If it does not leave, the data source will be destroyed.

protected: virtual void RemoveDataSinkL(MDataSink &aDataSink)=0;

Description

Removes a data sink from the controller plugin.

Note: The data sink is owned by the controller framework, NOT by the controller plugin. Under no circumstances should the controller plugin delete the data sink.

Parameters

MDataSink &aDataSink A reference to the data sink to be removed.

Leave codes

KErrNotSupported The controller plugin may leave during this method. If the controller plugin does not support the removal of data sinks, it should leave with KErrNotSupported. If the controller plugin leaves, the data sink will not be destroyed by the controller framework. If it does not leave, the data sink will be destroyed.

protected: virtual void ResetL()=0;

Description

Resets the controller plugin.

The controller should revert back to its newly constructed state. If the Reset is successful (i.e. it doesn't leave), the controller framework will delete all objects added to the MMFObjectManager including any sources and sinks.

Leave codes

KErrNotSupported If the controller plugin does not support being reset, it should leave with KErrNotSupported.

protected: virtual void PrimeL()=0;

Description

Primes the controller plugin.

The controller must prepare to start playing, by initialising its sources, sinks and buffers. This moves the controller from the STOPPED to the PRIMED state.

protected: virtual IMPORT_C void PrimeL(TMMFMessage &aMessage);

Description

A partner to the PrimeL() method that is overridable to allow Asynchronous completion in the controller whilst maintaining a Synchronous client API.

The default implementation of this is to call PrimeL() and complete the message with KErrNone.

Parameters

TMMFMessage &aMessage

protected: virtual void PlayL()=0;

Description

Commences playback.

The controller must now begin transferring data from its source(s) to its sink(s). This moves the controller from the PRIMED to the PLAYING state.

Note: This method must return once playing has commenced, and not wait until playing is complete.

protected: virtual IMPORT_C void PlayL(TMMFMessage &aMessage);

Description

A partner to the PlayL() method that is overridable to allow Asynchronous completion in the controller whilst maintaining a Synchronous client API.

The default implementation of this is to call PlayL() and complete the message with KErrNone.

Parameters

TMMFMessage &aMessage

protected: virtual void PauseL()=0;

Description

Pauses the controller plugin.

The controller must now cease transferring data from its source(s) to its sink(s). This moves the controller from the PLAYING back to the PRIMED state.

A subsequent call to Play() will cause the controller plugin to resume playback from the point it was paused (unless there has been a call to SetPosition() in the meantime.

protected: virtual IMPORT_C void PauseL(TMMFMessage &aMessage);

Description

A partner to the PauseL() method that is overridable to allow Asynchronous completion in the controller whilst maintaining a Synchronous client API.

The default implementation of this is to call PauseL() and complete the message with KErrNone.

Parameters

TMMFMessage &aMessage

protected: virtual void StopL()=0;

Description

Stops the controller plugin.

The controller must now undo anything that occurred during the call to Prime(). This moves the controller from the PRIMED back to the STOPPED state.

protected: virtual IMPORT_C void StopL(TMMFMessage &aMessage);

Description

A partner to the StopL() method that is overridable to allow Asynchronous completion in the controller whilst maintaining a Synchronous client API.

The default implementation of this is to call StopL() and complete the message with KErrNone.

Parameters

TMMFMessage &aMessage

protected: virtual TTimeIntervalMicroSeconds PositionL() const=0;

Description

Gets the current position.

The controller plugin should calculate the current position in microseconds.

Return value

TTimeIntervalMicroSeconds The current position in microseconds.

protected: virtual void SetPositionL(const TTimeIntervalMicroSeconds &aPosition)=0;

Description

Sets the current position.

The controller plugin should reposition itself to the position provided.

Parameters

const TTimeIntervalMicroSeconds &aPosition The desired position in microseconds.

protected: virtual TTimeIntervalMicroSeconds DurationL() const=0;

Description

Gets the duration of the clip.

The controller plugin should calculate the clip duration in microseconds.

Return value

TTimeIntervalMicroSeconds The clips duration in microseconds.

Capability:

MultimediaDD

A process requesting or using this method that has MultimediaDD capability will always have precedence over a process that does not have MultimediaDD.

protected: virtual void SetPrioritySettings(const TMMFPrioritySettings &aPrioritySettings)=0;

Description

Sets the priority settings.

The new priority settings must be applied to any resource being used by the controller plugin that requires priority settings (for example the sound device).

Parameters

const TMMFPrioritySettings &aPrioritySettings The new priority settings

protected: inline virtual void CustomCommand(TMMFMessage &aMessage);

Description

Handles a custom command.

Custom commands allow a controller plugin to define its own API. If the controller framework does not understand a message from the client, it is assumed this is a custom command for the plugin and passed into this interface.

The more common custom commands can be handled by Custom Command Parsers on behalf of the controller plugin. This allows the controller plugin to implement a concrete interface (defined by mixin classes) rather than having to decode the command itself. For more information, see CMMFCustomCommandParserBase.

The controller plugin must always complete the message passed into this method, even if it does not support the interface required by the message.

Parameters

TMMFMessage &aMessage The message to be handled by the controller plugin.

See also:

• CMMFCustomCommandParserBase

protected: virtual void GetNumberOfMetaDataEntriesL(TInt &aNumberOfEntries)=0;

Description

RetrieveS the number of meta data entries in the clip.

Parameters

TInt &aNumberOfEntries The controller plugin must set this to the number of meta data entries in the clip.

protected: virtual CMMFMetaDataEntry *GetMetaDataEntryL(TInt aIndex)=0;

Description

Retrieves a meta data entry from the clip.

Parameters

TInt aIndex The index of the meta data entry to retrieve.

Return value

CMMFMetaDataEntry * A pointer to a newly created CMMFMetaDataEntry object containing the meta information. The controller framework will take ownership of the object when this method returns.

protected: IMPORT_C TInt DoSendEventToClient(const TMMFEvent &aEvent);

Description

Sends an event to the client.

The controller plugin can use this method to send an event to the client.

Parameters

const TMMFEvent &aEvent The event to be sent to the client.

Return value

TInt One of the system-wide error codes.

protected: IMPORT_C CMMFObjectContainer &MMFObjectContainerL();

Description

Gets a reference to the multimedia framework object container.

The controller plugin may add CMMFObject-derived objects to the container to allow them to receive messages directly from the client.

Return value

CMMFObjectContainer & A reference to the MMFObjectContainer.

protected: IMPORT_C void AddCustomCommandParserL(CMMFCustomCommandParserBase &aParser);

Description

Adds a custom command parser to the controller framework.

If the controller framework receives a request it does not understand, it will search through its list of custom command parsers before passing the request on to the controller plugin as a custom command.

By using the custom command parsers, the controller plugin can implement a concrete API rather than having to decode the common custom commands itself.

Parameters

CMMFCustomCommandParserBase &aParser The parser to be added to the controller framework. The controller framework takes ownership of the parser if the call does not leave.