100 lines
3.4 KiB
C++
100 lines
3.4 KiB
C++
/**********************************************************************/
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/** Microsoft Windows/NT **/
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/** Copyright(c) Microsoft Corp., 1991 **/
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/**********************************************************************/
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/*
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uibuffer.hxx
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BUFFER class declaration
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FILE HISTORY:
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rustanl 03-Aug-1990 Created
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beng 30-Apr-1991 Uses lmui.hxx
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*/
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#ifndef _UIBUFFER_HXX_
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#define _UIBUFFER_HXX_
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#include "base.hxx"
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/*************************************************************************
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NAME: BUFFER (buf)
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SYNOPSIS: A resizable object which lives in the application heap.
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Upon construction, the buffer takes a requested size in
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bytes; it allocates storage sufficient to hold that size.
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The client can later change this size with Resize, Trim,
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and FillOut. QuerySize returns the current size of
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the buffer; QueryPtr returns a pointer to its storage.
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Note that a buffer may have size 0, in which case it
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keeps no allocated storage. Hence the largest available
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buffer on OS/2 is 2^16-1 bytes.
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INTERFACE: BUFFER() - Constructor, naming initial size in bytes
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QuerySize() - return size in bytes
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QueryPtr() - return pointer to data buffer
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Resize() - resize the object to the given number
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of bytes. Returns 0 if the resize was
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successful; otherwise returns the OS
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errorcode.
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Trim() - force block to occupy no more storage
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than the client has requested.
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FillOut() - give client access to any additional
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storage occupied by the block.
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PARENT: BASE
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HISTORY:
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RustanL 3 Aug 90 Created
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DavidHov 5 Mar 91 Merged with BUFFER.HXX to supplant same
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beng 19-Jun-1991 Inherit from BASE; UINT sizes
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beng 15-Jul-1991 Resize returns APIERR instead of BOOL
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beng 19-Mar-1992 Remove OS/2 support
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**************************************************************************/
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DLL_CLASS BUFFER: public BASE
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{
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private:
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HANDLE _hMem; // Local/GlobalAlloc results
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BYTE * _pb; // pointer to storage
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UINT _cb; // size of storage, as requested by client
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inline VOID VerifyState() const;
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UINT QueryActualSize();
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APIERR GetNewStorage( UINT cbRequested );
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APIERR ReallocStorage( UINT cbNewlyRequested );
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public:
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BUFFER( UINT cbRequested = 0 );
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~BUFFER();
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BYTE * QueryPtr() const;
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UINT QuerySize() const;
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APIERR Resize( UINT cbNewReqestedSize );
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// The following two methods deal with the difference between the
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// actual memory size and the requested size. These methods are
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// intended to be used when optimization is key.
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// Trim reallocates the buffer so that the actual space allocated is
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// minimally more than the size requested, whereas FillOut changes
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// (without actually reallocating) the requested size to the actual size.
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//
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VOID Trim();
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VOID FillOut();
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};
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#endif // _UIBUFFER_HXX_
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