williamr@2: /*
williamr@2: * Copyright (c) 2002 Nokia Corporation and/or its subsidiary(-ies).
williamr@2: * All rights reserved.
williamr@2: * This component and the accompanying materials are made available
williamr@4: * under the terms of "Eclipse Public License v1.0"
williamr@2: * which accompanies this distribution, and is available
williamr@4: * at the URL "http://www.eclipse.org/legal/epl-v10.html".
williamr@2: *
williamr@2: * Initial Contributors:
williamr@2: * Nokia Corporation - initial contribution.
williamr@2: *
williamr@2: * Contributors:
williamr@2: *
williamr@2: * Description:  Defines a public interface class MAknsDataContext.
williamr@2: *
williamr@2: */
williamr@2: 
williamr@2: 
williamr@2: #ifndef AKNSDATACONTEXT_H
williamr@2: #define AKNSDATACONTEXT_H
williamr@2: 
williamr@2: //  INCLUDES
williamr@2: #include <AknsConstants.h>
williamr@2: #include <AknsItemID.h>
williamr@2: #include <coemop.h>
williamr@2: 
williamr@2: // CLASS DECLARATION
williamr@2: 
williamr@2: /**
williamr@2: * Interface that provides context sensitive control over data allocation.
williamr@2: * MAknsDataContext can be used to indicate need for specific skin items
williamr@2: * and thus to ensure that they are allocated before first use.
williamr@2: *
williamr@2: * This is a public class with exported functions.
williamr@2: * The class is not usually intended for user derivation - concrete classes
williamr@2: * implementing the interface are provided by the library.
williamr@2: * See @c AknsUtils::CreateDataContextForContainerL() for further 
williamr@2: * details.
williamr@2: *
williamr@2: * @lib AknSkins.lib
williamr@2: *
williamr@2: * @since 2.0
williamr@2: */
williamr@2: class MAknsDataContext 
williamr@2:     {
williamr@2:     public: // Type UID
williamr@2:         /**         
williamr@2:         * Type ID declaration.
williamr@2:         * Type ID is used to make it possible to retrieve data context
williamr@2:         * through @c MObjectProvider::MopSupplyObject interface.
williamr@2:         */
williamr@2:         DECLARE_TYPE_ID(0x10005a28)
williamr@2: 
williamr@2:     public:  // Constructors and destructor    
williamr@2: 
williamr@2:         /**
williamr@2:         * Destructor.
williamr@2:         * Destructor is only provided to enable deletion using base class
williamr@2:         * pointer. Caller should never delete context retrieved using
williamr@2:         * @c MObjectProvider interface.
williamr@2:         */
williamr@2:         inline virtual ~MAknsDataContext() {}
williamr@2:         
williamr@2:     public: // New functions
williamr@2: 
williamr@2:         /**
williamr@2:         * Reserves and allocates specified item.
williamr@2:         * Instructs the data context that the specified item will be used
williamr@2:         * by caller and should be allocated and cached by skin instance.
williamr@2:         * Any control using cached skin items should reserve them, preferably
williamr@2:         * in @c ConstructL(), by calling this method.
williamr@2:         * Note that reservation does not guarantee that the item will be
williamr@2:         * available in cache - it's only a tentative request for allocation.
williamr@2:         *
williamr@2:         * @since 2.0
williamr@2:         *
williamr@2:         * @param aID Item ID of the item to be reserved.
williamr@2:         *
williamr@2:         * @par Exceptions:
williamr@2:         *   If item data allocation fails, function leaves with error code.
williamr@2:         */
williamr@2:         virtual void ReserveItemL( const TAknsItemID& aID ) =0;
williamr@2: 
williamr@2: 		/**
williamr@2:         * Indicates that specified item will no longer be used.
williamr@2:         * Instructs the data context that the specified item will not
williamr@2:         * be used by caller anymore. Exact behavior (e.g. whether cached
williamr@2:         * instance is deallocated) depends on the cache policy of data
williamr@2:         * context and skin instance. Controls should not usually call this
williamr@2:         * method, but instead allow data context (in most cases implemented
williamr@2:         * by a container) go out of scope. 
williamr@2:         *
williamr@2:         * @since 2.0
williamr@2:         * 
williamr@2:         * @param aID Item ID of the item to be released.
williamr@2:         */
williamr@2:         virtual void ReleaseItem( const TAknsItemID& aID ) =0;
williamr@2: 
williamr@2:     protected: // Reserved virtual functions
williamr@2: 
williamr@2:         /**
williamr@2:         * Reserved for future use.
williamr@2:         *
williamr@2:         * @since 2.0
williamr@2:         */
williamr@2:         virtual TInt Reserved1();
williamr@2: 
williamr@2:         /**
williamr@2:         * Reserved for future use.
williamr@2:         *
williamr@2:         * @since 2.0
williamr@2:         */
williamr@2:         virtual TInt Reserved2();
williamr@2: 
williamr@2:     public: // New functions
williamr@2: 
williamr@2:         /**
williamr@2:         * Returns type UID pointer that can be used in MopSupplyObject.
williamr@2:         *
williamr@2:         * @since 2.0
williamr@2:         *
williamr@2:         * @param aId Type UID, should be the same that was given as aId
williamr@2:         *   parameter of MopSupplyObject.
williamr@2:         *
williamr@2:         * @param aContext Pointer to an MAknsDataContext instance.
williamr@2:         *
williamr@2:         * @return Type UID pointer containing aContext, or @c NULL type UID
williamr@2:         *   pointer if given type UID does not match MAknsDataContext or
williamr@2:         *   aContext is @c NULL.
williamr@2:         */
williamr@2:         IMPORT_C static TTypeUid::Ptr SupplyMopObject( TTypeUid aId, 
williamr@2:             MAknsDataContext* aContext );
williamr@2: 
williamr@2:     };
williamr@2: 
williamr@2: #endif // AKNSDATACONTEXT_H
williamr@2:             
williamr@2: // End of File