1 /*

     2 * Copyright (c) 2002-2008 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:  Defines an internal class CAknsAppSkinInstanceCacheEntry which

    15 *                encapsulates a single skin instance cache entry.

    16 *

    17 */

    18 

    19 

    20 #ifndef AKNSASICACHEENTRY_H

    21 #define AKNSASICACHEENTRY_H

    22 

    23 //  INCLUDES

    24 #include <AknsItemData.h>

    25 

    26 // CLASS DECLARATION

    27 

    28 /**

    29 * Item data cache entry used by CAknsAppSkinInstance.

    30 * CAknsAppSkinInstanceCacheEntry encapsulates single cache item. It provides

    31 * explicit reference counting, but the caller is responsible of calling

    32 * appropriate methods and also destructing the cache entry when it is no longer

    33 * referenced.

    34 *

    35 * This is an internal class that contains no exported functions.

    36 * The class is not intended for derivation outside the library.

    37 *

    38 * @since 2.0

    39 *

    40 * @internal

    41 */

    42 NONSHARABLE_CLASS(CAknsAppSkinInstanceCacheEntry) : public CBase

    43     {

    44     public: // Construction and destruction

    45 

    46         /**

    47         * C++ constructor.

    48         *

    49         * @param aID Item ID of the new cache item.

    50         *

    51         * @param aData Pointer to item data. Ownership is transferred to

    52         *   CAknsAppSkinInstanceCacheEntry instance. @c NULL value is valid.

    53         *

    54         * @internal

    55         */

    56         CAknsAppSkinInstanceCacheEntry( const TAknsItemID& aID,

    57             CAknsItemData* aData );

    58 

    59         /**

    60         * Two-phased constructor.

    61         *

    62         * @param aID Item ID of the new cache item.

    63         *

    64         * @param aData Pointer to item data. Ownership is transferred to

    65         *   CAknsAppSkinInstanceCacheEntry instance. @c NULL value is valid.

    66         *

    67         * @return Newly constructed CAknsAppSkinInstanceCacheEntry object.

    68         *

    69         * @par Exceptions:

    70         *   If construction fails, leaves with an error code.

    71         *

    72         * @internal

    73         */

    74         static CAknsAppSkinInstanceCacheEntry* NewL(

    75             const TAknsItemID& aID, CAknsItemData* aData );

    76 

    77         /**

    78         * Destructor.

    79         * Deletes iData member.

    80         *

    81         * @internal

    82         */

    83         virtual ~CAknsAppSkinInstanceCacheEntry();

    84 

    85     public: // New functions

    86 

    87         /**

    88         * Returns the item ID of this cache entry.

    89         *

    90         * @return Item ID.

    91         *

    92         * @internal

    93         */

    94         inline TAknsItemID ID() const;

    95 

    96         /**

    97         * Returns item data associated with this cache entry.

    98         *

    99         * @return Pointer to item data. CAknsAppSkinInstanceCacheEntry still

   100         *   owns the item data object and controls its lifetime.

   101         *

   102         * @internal

   103         */

   104         inline CAknsItemData* Data();

   105 

   106         /**

   107         * Destroys the old item data (if any) and sets a new one.

   108         *

   109         * @param aData New item data to be associated with this cache entry.

   110         *   Ownership of item data is transferred to

   111         *   CAknsAppSkinInstanceCacheEntry instance.

   112         *

   113         * @internal

   114         */

   115         inline void DestroyAndSetData( CAknsItemData* aData );

   116 

   117         /**

   118         * Increases reference counter by one.

   119         *

   120         * @internal

   121         */

   122         void IncreaseRefCount();

   123 

   124         /**

   125         * Decreases reference counter by one.

   126         * Caller is resposible of deleting the cache item when reference count

   127         * drops to zero. This can be checked by calling

   128         * CAknsAppSkinInstanceCacheEntry::IsReferenced().

   129         *

   130         * @par Exceptions:

   131         *   While this function may not leave and does not delete object, it

   132         *   may panic if reference count becomes negative.

   133         *

   134         * @internal

   135         */

   136         void DecreaseRefCount();

   137 

   138         /**

   139         * Tells whether the cache item is referenced.

   140         *

   141         * @return ETrue if reference count is positive, EFalse otherwise.

   142         *

   143         * @internal

   144         */

   145         TBool IsReferenced() const;

   146 

   147         /**

   148         * Determines the order of two CAknsAppSkinInstanceCacheEntry objects.

   149         * Order is determined based on the item ID of the object, as described

   150         * in TAknsItemID::LinearOrder().

   151         *

   152         * @param aFirst First object to be compared.

   153         *

   154         * @param aSecond Second object to be compared.

   155         *

   156         * @return 0 if the two objects are equal, negative value if the first

   157         *   object is less than the second and positive value if the first

   158         *   object is greater than the second.

   159         *

   160         * @internal

   161         */

   162         static TInt LinearOrder(

   163             const CAknsAppSkinInstanceCacheEntry& aFirst,

   164             const CAknsAppSkinInstanceCacheEntry& aSecond );

   165 

   166     private: // Data members

   167 

   168         TAknsItemID iID;        //!< Item ID.

   169         TInt iRefCount;         //!< Reference counter.

   170         CAknsItemData* iData;   //!< Pointer to item data.

   171 

   172     };

   173 

   174 // INLINED MEMBERS

   175 #include "AknsASICacheEntry.inl"

   176 

   177 #endif      // AKNSASICACHEENTRY_H

   178 

   179 // End of File