photosgallery/viewframework/medialists/inc/glxcache.h
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     1 /*
       
     2 * Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies). 
       
     3 * All rights reserved.
       
     4 * This component and the accompanying materials are made available
       
     5 * under the terms of "Eclipse Public License v1.0"
       
     6 * which accompanies this distribution, and is available
       
     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".
       
     8 *
       
     9 * Initial Contributors:
       
    10 * Nokia Corporation - initial contribution.
       
    11 *
       
    12 * Contributors:
       
    13 *
       
    14 * Description:    Cache implementation for media items sharing the same Id space
       
    15 *
       
    16 */
       
    17 
       
    18 
       
    19 
       
    20 
       
    21 #ifndef C_GLXCACHE_H
       
    22 #define C_GLXCACHE_H
       
    23 
       
    24 #include <e32base.h>
       
    25 
       
    26 #include "glxmediaid.h"
       
    27 
       
    28 // Forward declarations
       
    29 class CMPXMedia;
       
    30 class CGlxMedia;
       
    31 class T_CacheTestHelpers;
       
    32 class TMPXAttribute;
       
    33 class CGlxCacheManager;
       
    34 
       
    35 /**
       
    36  *  CGlxCache
       
    37  *
       
    38  *  Individual cache of media items sharing the same Id space
       
    39  */
       
    40 NONSHARABLE_CLASS( CGlxCache ) : public CBase
       
    41 	{
       
    42 public:
       
    43     /**
       
    44      * Constructor
       
    45      * @param aIdSpaceId The id of the id address space of this cache 
       
    46 	 * @param aCacheManager Instance of cachemanager to cleanup the media
       
    47      */
       
    48     CGlxCache( const TGlxIdSpaceId& aIdSpaceId, CGlxCacheManager* aCacheManager );
       
    49     
       
    50     /**
       
    51      * Destructor
       
    52      */
       
    53     ~CGlxCache();
       
    54 
       
    55     /**
       
    56      * Returns the Id space covered by this cache
       
    57      * @return The Id space covered by this cache    
       
    58      */
       
    59     TGlxIdSpaceId IdSpaceId() const;    
       
    60 
       
    61     /**
       
    62      * Notify the cache that attributes have changed on media item(s)
       
    63      * @param aMedia The updated media item or array of updated media items
       
    64      */
       
    65     void MediaUpdatedL( const CMPXMedia& aMedia );
       
    66 
       
    67     /**
       
    68      * Update media item
       
    69      *
       
    70      * @param aMedia The updated media item
       
    71      */
       
    72     void UpdateMediaL( const CMPXMedia& aMedia );
       
    73 
       
    74     /**
       
    75      * Cleanup the media of the given media id: broadcast this to all observers
       
    76 	 * @param aMediaId The media id of the item
       
    77      */ 
       
    78     void CleanupMedia(const TGlxMediaId& aMediaId);
       
    79 
       
    80     /**
       
    81      * Handles modifications of item in cache
       
    82      *
       
    83      * @param aId Media item id
       
    84      * @param aAttributes Attributes that have been modified
       
    85      */
       
    86     void HandleItemModified( const TGlxMediaId& aId, const RArray<TMPXAttribute>& aAttributes );
       
    87 
       
    88     /**
       
    89      * Access to the items stored in the cache: return the item matching the given media Id
       
    90      * @param aId The media Id
       
    91      * @return The media item, or NULL if not found
       
    92      */
       
    93     CGlxMedia* Media( const TGlxMediaId& aId ) const;
       
    94 
       
    95     /**
       
    96      * Access to the items stored in the cache: return the item matching the given media Id.
       
    97      * If not found, a new item is created
       
    98      * @param aId The media Id
       
    99      * @return The media item
       
   100      */
       
   101     CGlxMedia* FindItemForceCreateL( const TGlxMediaId& aId );
       
   102     
       
   103     /**
       
   104      * Number of items in cache
       
   105      * @return Number of items in cache
       
   106      */
       
   107     TInt Count();
       
   108     
       
   109     /**
       
   110      * Cached item by index
       
   111      * @param aIndex index of the item
       
   112      * @return Cached item
       
   113      */
       
   114     CGlxMedia& Media( TInt aIndex );
       
   115     
       
   116     /**
       
   117      * Delete an item at index from the cache.
       
   118      * @param aIndex Index of the item to delete
       
   119      */
       
   120     void Delete( TInt aIndex );
       
   121     
       
   122     /**
       
   123      * Reserve space for a number of users, for all items in the cache
       
   124      *
       
   125      * @param aCount The number of users to reserve space for
       
   126      */
       
   127     void ReserveUsersL( TInt aCount );
       
   128     
       
   129     /**
       
   130 	 * Finds the media index present in cache
       
   131 	 * @returns the index of media
       
   132 	 */    
       
   133     TInt FindMediaIndexInCache(TGlxMediaId aMediaId);
       
   134 
       
   135 private:
       
   136     /**
       
   137      * Copy the new and modified attributes from aSource to aTarget
       
   138      * @param aTarget The target media item
       
   139      * @param aSource The source media item
       
   140      * @param aNewAttributes The new and modified attributes
       
   141      */
       
   142     void CopyNewAndModifiedL( CGlxMedia& aTarget, const CMPXMedia& aSource, 
       
   143         RArray<TMPXAttribute>& aNewAttributes );
       
   144 
       
   145     /**
       
   146      * Function for TLinearOrder() for comparing two CGlxMedias 
       
   147      * Used from ordering the iItemPool by id
       
   148      * @param aItem1 The first item to compare
       
   149      * @param aItem2 The second item to compare
       
   150      * @return -1 if aItem1 < aItem2; 1 if aItem1 > aItem2; 0 if aItem1 == aItem2
       
   151      */
       
   152     static TInt MediaItemOrderById( const CGlxMedia& aItem1, const CGlxMedia& aItem2 );
       
   153     
       
   154     /**
       
   155      * Function for comparing a TGlxMediaId with a CGlxMedia 
       
   156      * Used from ordering iItemPool by media id
       
   157      * @param aMediaId The media id to compare against aItem2
       
   158      * @param aItem2 The second item to compare
       
   159      * @return -1 if aMediaId < aItem2.Id(); 1 if aMediaId > aItem2.Id(); 0 if aMediaId == aItem2.Id()
       
   160      */
       
   161     static TInt MediaItemOrderByKey( const TGlxMediaId* aMediaId, const CGlxMedia& aItem2 );
       
   162 
       
   163     /**
       
   164      * Create and add an item to the item pool
       
   165      * @param aId Id for the new item
       
   166      * @return Pointer to the created item
       
   167      */
       
   168     CGlxMedia* CreateItemL( const TGlxMediaId& aId );
       
   169     
       
   170 private:
       
   171     /// Id space that this cache covers
       
   172     TGlxIdSpaceId iIdSpaceId;
       
   173     
       
   174     /// Pool of media items. Owned
       
   175     RPointerArray<CGlxMedia> iItemPool; 
       
   176     
       
   177     ///Instance of cacheManager to cleanup cache
       
   178     CGlxCacheManager* iCacheManager;
       
   179 
       
   180     friend class T_CacheTestHelpers;
       
   181     };
       
   182 
       
   183 #endif // C_GLXCACHE_H