Composer Plug-in ECom interface definition. Composer plug-in implementation needs to inherit this class and implement the pure virtual methods which exist in this interface.

Example:

class CMyVideoComposerPlugin: public CComposerPlugin { protected: void SetObservers() ; void RemoveObservers() ;

// Because CComposerPlugin inherits MMdEObjectObserver void HandleObjectNotification(CMdESession& aSession, TObserverNotificationType aType, const RArray<TItemId> & aObjectIdArray);

private: // Active object which does the actual binary writing // so that this interface and its observers remain responsive CMyVideoComposerAO* iVideoComposerAO; }

void SetObservers() { // We want to listen to changes in Video metadata objects // and setup an observer for this CMdENamespaceDef& defaultNamespace = iSession->GetDefaultNamespaceDefL(); CMdEObjectDef& videoDef = defaultNamespace.GetObjectDefL( MdeConstants::Video::KVideoObject ); CMdELogicCondition* condition = CMdELogicCondition::NewL( ELogicConditionOperatorAnd ); condition->AddObjectConditionL( videoDef );

// iSession is reference to CMdESession which is always set in CComposerPlugin::SetSession() iSession->AddObjectObserverL( *this, condition, ENotifyModify, &defaultNamespace ); }

void RemoveObservers() { iSession->RemoveObjectObserverL( *this ) }

void CComposerImagePlugin::HandleObjectNotification(CMdESession& aSession, TObserverNotificationType aType, const RArray<TItemId> & aObjectIdArray) { // We give ID-array of changed Video objects to our active object // which adds then to a its internal queue and processes them one-by-one // with different RunL-calls so that we don't stuck the thread by composing // for example 1000 binary files in a row. iVideoComposerAO->AddToQueue( aObjectIdArray ); }