/*

* Copyright (c) 2008-2009 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:    Generic fetch context to retrieve attributes

*

*/

#ifndef C_GLXATTRIBUTECONTEXT_H

#define C_GLXATTRIBUTECONTEXT_H

#include <e32std.h>

#include "mglxfetchcontext.h"

#include "glxmedialistiterator.h"	// for TGlxSequentialIterator

// Forward declarations

class MGlxMediaList;

class TMPXAttribute;

class T_CGlxAttributeContext; // For E-unit only

/**

 *  CGlxAttributeContext

 *

 *  Fetch context to retrieve thumbnails

 *

 *  @lib glxmedialists.lib

 */

class CGlxAttributeContext : public CBase, public MGlxFetchContext

	{

public:

	/**

	 * Constructor

	 * @param aIterator Iterator that determines the order of attribute 

	 *  	  retrieval and for which items attributes are and are not retrieved

	 */

	IMPORT_C CGlxAttributeContext(MGlxMediaListIterator* aIterator);

	IMPORT_C ~CGlxAttributeContext();

	/**

	 * Adds an attribute to be retrieved for all items

	 * @param aAttribute The attribute to be retrieved

	 */

	IMPORT_C void AddAttributeL(const TMPXAttribute& aAttribute);

	/**

	 * Removes an attribute from the "retrieval instructions"

	 * @param aAttribute The attribute to be removed 

	 */

	IMPORT_C void RemoveAttribute(const TMPXAttribute& aAttribute);

	/**

	 * Returns the count of the attributes to be retrieved

	 * @return the count of the attribtues to be retrieved

	 */

	IMPORT_C TInt AttributeCount();

	/**

	 * Sets granularity of the item index array returned from AttributeRequestL

	 */

	IMPORT_C void SetGranularity(TUint aGranularity);

public: // From MGlxFetchContext

    /// See @ref MGlxFetchContext::AttributeRequestL

    TInt AttributeRequestL(const MGlxMediaList* aList, RArray<TInt>& aItemIndices, 

    	RArray<TMPXAttribute>& aAttributes, CMPXAttributeSpecs*& aDetailedSpecs) const;

    /// See @ref MGlxFetchContext::AllAttributesL

    void AllAttributesL(const MGlxMediaList* aList, TInt aListIndex, 

    	RArray<TMPXAttribute>& aAttributes) const;

    /// See @ref MGlxFetchContext::RequestCountL

    TInt RequestCountL(const MGlxMediaList* aList) const;

private:

	/**

	 * Determine attributes to request for an item

	 * @param aIndexInList item index in media list

	 * @param aList media list

	 * @param aAttributes requested attributes

	 * @return ETrue if attributes to be requested, otherwise EFalse

	 */

	TBool AddItemAttributesL(TInt aIndexInList, const MGlxMediaList* aList, RArray<TMPXAttribute>& aAttributes, 

	                         TInt& aError, TBool aFirstItem) const;

	/**

	 * Append attribute to array, no duplicates

	 * @param aAttributes requested attributes

	 * @param aAttribute attribute to be added

	 */

	void AddItemAttributeL(RArray<TMPXAttribute>& aAttributes, const TMPXAttribute& aAttribute) const;

private:

	/** Attributes to be requested for all items */

	RArray<TMPXAttribute> iAttributes;

	/**

	 * Iterator for traversing the list

	 */

	MGlxMediaListIterator* iIterator;	

	/** 

	 * Granularity of the item index array returned from AttributeRequestL

	 */

	TUint iGranularity;

	/** Tester class */

	friend class T_CGlxAttributeContext;

	};

/**

 *  CGlxDefaultAttributeContext

 *

 *  Fetch context to retrieve MPX attributes starting from focus outward

 *

 *  @lib glxmedialists.lib

 */

class CGlxDefaultAttributeContext : public CGlxAttributeContext

	{

public:

	IMPORT_C static CGlxDefaultAttributeContext* NewL();

	IMPORT_C ~CGlxDefaultAttributeContext();

	/**

	 * Set the range offsets. These determine the outer limits

	 * of attributes to be retrieved, compared to current focus in

	 * the list

	 * If ranges not defined, retrieves the attributes for focused item only

	 */

    IMPORT_C void SetRangeOffsets(TInt aFrontOffset, TInt aRearOffset);

private:

	CGlxDefaultAttributeContext();

private:

	TGlxFromFocusOutwardIterator iFromFocusIterator;	

	};

#endif // C_GLXATTRIBUTECONTEXT_H