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       1             : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
       2             : /*
       3             :  * This file is part of the LibreOffice project.
       4             :  *
       5             :  * This Source Code Form is subject to the terms of the Mozilla Public
       6             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       7             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
       8             :  *
       9             :  * This file incorporates work covered by the following license notice:
      10             :  *
      11             :  *   Licensed to the Apache Software Foundation (ASF) under one or more
      12             :  *   contributor license agreements. See the NOTICE file distributed
      13             :  *   with this work for additional information regarding copyright
      14             :  *   ownership. The ASF licenses this file to you under the Apache
      15             :  *   License, Version 2.0 (the "License"); you may not use this file
      16             :  *   except in compliance with the License. You may obtain a copy of
      17             :  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
      18             :  */
      19             : 
      20             : #ifndef INCLUDED_CANVAS_VCLWRAPPER_HXX
      21             : #define INCLUDED_CANVAS_VCLWRAPPER_HXX
      22             : 
      23             : #include <osl/mutex.hxx>
      24             : #include <vcl/svapp.hxx>
      25             : 
      26             : namespace canvas
      27             : {
      28             :     namespace vcltools
      29             :     {
      30             :         /** This helper template wraps VCL objects, and protects
      31             :             object deletion with the Solar mutex. All other operations
      32             :             are unprotected, this must be handled by client code.
      33             : 
      34             :             The reason for this template is the fact that VCL objects
      35             :             hold by value in uno::Reference-handled classes are
      36             :             deleted without having the chance to get inbetween and
      37             :             lock the solar mutex.
      38             : 
      39             :             This template handles that problem transparently, the only
      40             :             inconvenience is the fact that object member access now
      41             :             has to be performed via operator->, since . is not
      42             :             overloadable.
      43             : 
      44             :             Otherwise, the template preserves the value semantics of
      45             :             the wrapped object, that is, copy operations are performed
      46             :             not by copying pointers, but by copying the underlying
      47             :             object. This includes constness, i.e. on a const
      48             :             VCLObject, only const methods of the wrapped object can be
      49             :             called. Simply imagine this to be a value object of type
      50             :             "template argument", with the only peculiarity that
      51             :             member/method access is performed by operator-> instead of
      52             :             the non-existing "operator.".
      53             :          */
      54             :         template< class _Wrappee > class VCLObject
      55             :         {
      56             :         public:
      57             :             typedef _Wrappee Wrappee;
      58             : 
      59           0 :             VCLObject() :
      60           0 :                 mpWrappee( new Wrappee() )
      61             :             {
      62           0 :             }
      63             : 
      64             :             // no explicit here. VCLObjects should be freely
      65             :             // constructible with Wrappees, and AFAIK there is no other
      66             :             // implicit conversion path that could cause harm here
      67           0 :             VCLObject( Wrappee* pWrappee ) :
      68           0 :                 mpWrappee( pWrappee )
      69             :             {
      70           0 :             }
      71             : 
      72             :             // This object has value semantics, thus, forward copy
      73             :             // to wrappee
      74             :             VCLObject( const VCLObject& rOrig )
      75             :             {
      76             :                 if( rOrig.mpWrappee )
      77             :                     mpWrappee = new Wrappee( *rOrig.mpWrappee );
      78             :                 else
      79             :                     mpWrappee = NULL;
      80             :             }
      81             : 
      82             :             // This object has value semantics, thus, forward copy
      83             :             // to wrappee
      84           0 :             VCLObject( const Wrappee& rOrig ) :
      85           0 :                 mpWrappee( new Wrappee( rOrig ) )
      86             :             {
      87           0 :             }
      88             : 
      89             :             // This object has value semantics, thus, forward
      90             :             // assignment to wrappee
      91           0 :             VCLObject& operator=( const VCLObject& rhs )
      92             :             {
      93           0 :                 if( mpWrappee )
      94             :                 {
      95           0 :                     if( rhs.mpWrappee )
      96           0 :                         *mpWrappee = *rhs.mpWrappee;
      97             :                 }
      98             :                 else
      99             :                 {
     100           0 :                     if( rhs.mpWrappee )
     101           0 :                         mpWrappee = new Wrappee( *rhs.mpWrappee );
     102             :                 }
     103             : 
     104           0 :                 return *this;
     105             :             }
     106             : 
     107           0 :             ~VCLObject()
     108             :             {
     109             :                 // This here is the whole purpose of the template:
     110             :                 // protecting object deletion with the solar mutex
     111           0 :                 SolarMutexGuard aGuard;
     112             : 
     113           0 :                 if( mpWrappee )
     114           0 :                     delete mpWrappee;
     115           0 :             }
     116             : 
     117           0 :             Wrappee*        operator->() { return mpWrappee; }
     118           0 :             const Wrappee*  operator->() const { return mpWrappee; }
     119             : 
     120           0 :             Wrappee&        operator*() { return *mpWrappee; }
     121           0 :             const Wrappee&  operator*() const { return *mpWrappee; }
     122             : 
     123           0 :             Wrappee&        get() { return *mpWrappee; }
     124           0 :             const Wrappee&  get() const { return *mpWrappee; }
     125             : 
     126             :             void swap( VCLObject& rOther )
     127             :             {
     128             :                 ::std::swap( mpWrappee, rOther.mpWrappee );
     129             :             }
     130             : 
     131             :         private:
     132             : 
     133             :             Wrappee* mpWrappee;
     134             :         };
     135             : 
     136             :     }
     137             : }
     138             : 
     139             : #endif /* INCLUDED_CANVAS_VCLWRAPPER_HXX */
     140             : 
     141             : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */