Adding upstream version 4:7.4.7.upstream/4%7.4.7upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 138 insertions, 0 deletions

diff --git a/include/vcl/lazydelete.hxx b/include/vcl/lazydelete.hxx
new file mode 100644
index 000000000..397bde883
--- /dev/null
+++ b/include/vcl/lazydelete.hxx
@@ -0,0 +1,138 @@
+/* -*- 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>
+
+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( new BitmapEx( ... ) );
+
+        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(const css::uno::Reference<I>& r_xI ) : m_xI( r_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: */