hxcache2.h

著名的 helix realplayer 基于手机 symbian 系统的 播放器全套源代码

     *	Purpose:
     *
     *	    Changes the capacity of the cache object (in bytes). It is used to
     *      increase or decrease the capacity after the cache object has been
     *      created and it's capacity set usinf Init(). This method can
     *      be called any number of times. If new capacity is less than old capacity,
     *      the oldest data are discarded.
     *
     */

    STDMETHOD(ChangeCapacity)      (THIS_
			            UINT32  /*IN*/	newByteCount) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::GetUnusedCapacity
     *
     *	Purpose:
     *
     *	    Obtain the unused capacity in bytes of the cache object.
     */

    STDMETHOD_(UINT32, GetUnusedCapacity)	(THIS) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::AddBlock
     *
     *	Purpose:
     *
     *	    Adds a block of data to the cache. 
     *      NOTE: !!! The data should be added in a linear fashion. To be precise,
     *      the starting offset of the currently being added block should be
     *      exactly one more than the ending offset of the most previously 
     *      added block.
     *      Returns HXR_OK for success and HXR_OUTOFMEMORY if the cache can't
     *      accomodate the block (since it has a fixed capacity).
     *      
     */

    STDMETHOD(AddBlock)	(THIS_
			 IHXBuffer*		/*IN*/	pBlock) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::VerifyBlock
     *
     *	Purpose:
     *
     *	    Verify that a block of data is in the cache.
     */

    STDMETHOD(VerifyBlock)	(THIS_
				 UINT32		/*IN*/	ulBlockOffset,
				 UINT32		/*IN*/	ulBlockLength) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::ReadBlock
     *
     *	Purpose:
     *
     *	    Read a block out of the cache. Returns HXR_OK if it can supply
     *      *all* data. It returns HXR_FAIL if, at some point in the past,
     *      it had the data but has since discarded (a part of whole of) it.
     *      It returns HXR_INCOMPLETE in all other cases, viz
     *       
     *          (1) Only part of the data is present but no part of the data
     *              was discarded in the past.
     *          (2) No part of the requested data is present but is expected
     *              to be recieved in the future.
     *
     *      To understand it clearly, visulaize yourself storing the data of a
     *      remote file as it arrives to you. As you keep storing more and more
     *      data, then the cache keeps discarding some of the old data. Now, this
     *      discarded data can never be got back by cache. Hence when the user
     *      request contains some data which has already been discarded, then 
     *      the cache replies back with HXR_FAIL otherwise it is HXR_INCOMPLETE
     *      or HXR_OK depending on whether on how much of data it can supply *now*.
     *
     */

    STDMETHOD(ReadBlock)	(THIS_
				 UINT32		/*IN*/	ulBlockOffset,
				 UINT32		/*IN*/	ulBlockLength) PURE;

    /************************************************************************
     *	Method:
     *	    IHXCacheObject::Flush
     *
     *	Purpose:
     *
     *	    Releases all data buffers cached in the object. The object now
     *      gets to a same state as it was when newly created. After flushing,
     *	    the object can be used for writing/reading as before.
     */

    STDMETHOD(Flush)	(THIS) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::IsFull
     *
     *	Purpose:
     *
     *	    Is UnusedCapacity = 0?
     */

    STDMETHOD_(BOOL, IsFull)	(THIS) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::IsEmpty
     *
     *	Purpose:
     *
     *	    Is UnusedCapacity = TotalCapacity?
     */

    STDMETHOD_(BOOL, IsEmpty)	(THIS) PURE;

}; // IHXCacheObject


/****************************************************************************
 * 
 *  Interface:
 * 
 *	IHXCacheObjectResponse
 * 
 *  Purpose:
 * 
 *	Response interface for IHXCacheObject operations
 * 
 *  IID_IHXCacheObjectResponse:
 * 
 *	{00002E11-0901-11d1-8B06-00A024406D59}
 * 
 */
DEFINE_GUID(IID_IHXCacheObjectResponse, 0x00002E11, 0x901, 0x11d1, 0x8b, 0x6,
		0x0, 0xa0, 0x24, 0x40, 0x6d, 0x59);

#undef  INTERFACE
#define INTERFACE   IHXCacheObjectResponse

DECLARE_INTERFACE_(IHXCacheObjectResponse, IUnknown)
{
    /*
     *	IUnknown methods
     */
    STDMETHOD(QueryInterface)	(THIS_
				REFIID riid,
				void** ppvObj) PURE;

    STDMETHOD_(ULONG32,AddRef)	(THIS) PURE;

    STDMETHOD_(ULONG32,Release)	(THIS) PURE;

    /*
     *	IHXCacheObjectResponse methods
     */

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObjectResponse::InitDone
     *
     *	Purpose:
     *
     *	    Notification that IHXCacheObject::Init call has completed.
     */

    STDMETHOD(InitDone)		(THIS_
				 HX_RESULT	/*IN*/	status) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObjectResponse::ChangeCapacityDone
     *
     *	Purpose:
     *
     *	    Notification that IHXCacheObject::ChangeCapacity call has completed.
     */

    STDMETHOD(ChangeCapacityDone)		(THIS_
				                HX_RESULT	/*IN*/	status) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObjectResponse::AddBlockDone
     *
     *	Purpose:
     *
     *	    Notification that IHXCacheObject::AddBlock operation has completed.
     */

    STDMETHOD(AddBlockDone)	(THIS_
				HX_RESULT	/*IN*/	status) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObjectResponse::VerifyBlockDone
     *
     *	Purpose:
     *
     *	    Notification that IHXCacheObject::VerifyBlock operation has
     *	    completed.
     */

    STDMETHOD(VerifyBlockDone)	(THIS_
				BOOL		/*IN*/	bExist) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObjectResponse::ReadBlockDone
     *
     *	Purpose:
     *
     *	    Notification that IHXCacheObject::ReadBlock operation has
     *	    completed.
     */

    STDMETHOD(ReadBlockDone)	(THIS_
				HX_RESULT	/*IN*/	status,
				IHXBuffer*	/*IN*/	pBuffer) PURE;

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObjectResponse::FlushDone
     *
     *	Purpose:
     *
     *	    Notification that IHXCacheObject::Flush operation has completed.
     */

    STDMETHOD(FlushDone)	(THIS_
				HX_RESULT	/*IN*/	status) PURE;


}; // IHXCacheObjectResponse



#endif  /* _HXCACHE2_H_ */