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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: */