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-rw-r--r-- | include/vcl/lazydelete.hxx | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/include/vcl/lazydelete.hxx b/include/vcl/lazydelete.hxx new file mode 100644 index 0000000000..e700582f12 --- /dev/null +++ b/include/vcl/lazydelete.hxx @@ -0,0 +1,139 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* + * This file is part of the LibreOffice project. + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + * + * This file incorporates work covered by the following license notice: + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed + * with this work for additional information regarding copyright + * ownership. The ASF licenses this file to you under the Apache + * License, Version 2.0 (the "License"); you may not use this file + * except in compliance with the License. You may obtain a copy of + * the License at http://www.apache.org/licenses/LICENSE-2.0 . + */ + +#ifndef INCLUDED_VCL_LAZYDELETE_HXX +#define INCLUDED_VCL_LAZYDELETE_HXX + +#include <vcl/dllapi.h> + +#include <com/sun/star/lang/XComponent.hpp> + +#include <optional> +#include <utility> + +namespace vcl +{ + /* + You may not access vcl objects after DeInitVCL has been called this includes their destruction + therefore disallowing the existence of static vcl object like e.g. a static BitmapEx + To work around this use DeleteOnDeinit<BitmapEx> which will allow you to have a static object container, + that will have its contents destroyed on DeinitVCL. The single drawback is that you need to check on the + container object whether it still contains content before actually accessing it. + + caveat: when constructing a vcl object, you certainly want to ensure that InitVCL has run already. + However this is not necessarily the case when using a class static member or a file level static variable. + In these cases make judicious use of the set() method of DeleteOnDeinit, but beware of the changing + ownership. + + example use case: use a lazy initialized on call BitmapEx in a paint method. Of course a paint method + would not normally be called after DeInitVCL anyway, so the check might not be necessary in a + Window::Paint implementation, but always checking is a good idea. + + SomeWindow::Paint() + { + static vcl::DeleteOnDeinit< BitmapEx > aBmp( ... ); + + if( aBmp.get() ) // check whether DeInitVCL has been called already + DrawBitmapEx( Point( 10, 10 ), *aBmp ); + } + */ + + class VCL_DLLPUBLIC DeleteOnDeinitBase + { + public: + static void SAL_DLLPRIVATE ImplDeleteOnDeInit(); + virtual ~DeleteOnDeinitBase(); + protected: + static void addDeinitContainer( DeleteOnDeinitBase* i_pContainer ); + + virtual void doCleanup() = 0; + }; + + enum class DeleteOnDeinitFlag { Empty }; + + template < typename T > + class DeleteOnDeinit final : public DeleteOnDeinitBase + { + std::optional<T> m_pT; + virtual void doCleanup() override { m_pT.reset(); } + public: + template <class... Args > + DeleteOnDeinit(Args&&... args ) + { + m_pT.emplace(args...); + addDeinitContainer( this ); + } + DeleteOnDeinit(DeleteOnDeinitFlag) + { + addDeinitContainer( this ); + } + + // get contents + T* get() { return m_pT ? &*m_pT : nullptr; } + + // set contents, returning old contents + // ownership is transferred ! + template <class... Args > + std::optional<T> set(Args&&... args) + { + auto pOld = std::move(m_pT); + m_pT.emplace(args...); + return pOld; + } + }; + + /** Similar to DeleteOnDeinit, the DeleteUnoReferenceOnDeinit + template class makes sure that a static UNO object is disposed + and released at the right time. + + Use like + static DeleteUnoReferenceOnDeinit<lang::XMultiServiceFactory> + xStaticFactory (\<create factory object>); + Reference<lang::XMultiServiceFactory> xFactory (xStaticFactory.get()); + if (xFactory.is()) + \<do something with xFactory> + */ + template <typename I> + class DeleteUnoReferenceOnDeinit final : public vcl::DeleteOnDeinitBase + { + css::uno::Reference<I> m_xI; + virtual void doCleanup() override { set(nullptr); } + public: + DeleteUnoReferenceOnDeinit(css::uno::Reference<I> _xI ) : m_xI(std::move( _xI )) { + addDeinitContainer( this ); } + + css::uno::Reference<I> get() { return m_xI; } + + void set (const css::uno::Reference<I>& r_xNew ) + { + css::uno::Reference< css::lang::XComponent> xComponent (m_xI, css::uno::UNO_QUERY); + m_xI = r_xNew; + if (xComponent.is()) try + { + xComponent->dispose(); + } + catch( css::uno::Exception& ) + { + } + } + }; +} + +#endif +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |