/*

* Copyright (c) 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:

* Helper system for handling Out-Of-Memory cases.

*

*/

#ifndef XNOOMSYSHANDLER_H

#define XNOOMSYSHANDLER_H

// System includes

#include <e32base.h>

// Forward declarations

// Macros

// Bytes to kilobytes

#define B2KB(val_in_bytes) (TInt)( val_in_bytes / 1024 )

// Kilobytes to bytes 

#define KB2B(val_in_kbytes) (TInt)( val_in_kbytes * 1024 )

#define WIDGET_MIN_MEM  CXnOomSysHandler::EMem1MB

#define VIEW_MIN_MEM    CXnOomSysHandler::EMem4MB

/**

 *  Class helper for handling (and preventing) out-of-memory failures

 *

 *  This Class has only some static method. 

 *  E.g. for showing error popup window or for checking of available memory on

 *  the heap. etc.

 *

 *  @ingroup group_xnlayoutengine

 *  @lib xn3layoutengine.lib

 *  @since S60 5.0

 */

NONSHARABLE_CLASS( CXnOomSysHandler ) : public CBase

    {

public:     // data types

    /**

     * Enumeration of predefined values of memory amount for possible use 

     */

    enum TMemPredefinedValues

        {

#ifdef _DEBUG

        EMemOutOfRangeTest = 209715200,

#endif

        EMinNotDef = 0,

        EMem1kB = 1024,

        EMem2kB = 2048,

        EMem4kB = 4096,

        EMem8kB = 8192,

        EMem16kB = 16384,

        EMem32kB = 32768,

        EMem64kB = 65536,

        EMem128kB = 131072,

        EMem256kB = 262144,

        EMem512kB = 524288,

        EMem1MB = 1024000,

        EMem2MB = 2048000,

        EMem3MB = 3072000,

        EMem4MB = 4096000

        };

public: // Construction / destruction.

    /**

     * Two-phased constructor.

     */

    static CXnOomSysHandler* NewL();

    /**

     * Destructor.

     */

    virtual ~CXnOomSysHandler();

public: // methods.

    /**

     * Checks if required amount of free memory is available on heap.

     * 

     * @param aAmount required amount of free memory (in Bytes - use some 

     * value from TMemPredefinedValues enumeration for your comfort)

     * @return ETrue if required memory is available on heap, otherwise EFalse

     */

    static TBool HeapAvailable( TInt aAmount = EMinNotDef );

    /**

     * Handle potential OOM failure.

     */

    void HandlePotentialOomL();

private: // Constructors.

    /**

     * Symbian 2nd phase constructor.

     */

    void ConstructL();   

    /**

     * C++ constructor.

     */

    CXnOomSysHandler();

private:     // functions

    /**

     * Check whether OOM dialog can be shown.

     * Prevents OOM dialogs popping up more often than

     * defined in KMinInterval (defined in .cpp).

     */

    TBool AllowDialog();

private:    // Data.    

    /**

     * OOM dialog message.

     * 

     * Allocated early because memory might not

     * be available when HandlePotentialOomL is called.

    */

    HBufC* iMsg;    

    /**

     * Stored time stamp representing when dialog was last shown.

    */

    TInt64 iPreviousDialogPopupTime;

    };

#endif // XNOOMSYSHANDLER_H