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++ // Copyright (C) 2016 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
++
++ /*!
++ \example activeqt/comapp
++ \title COM App Example (ActiveQt)
++ \examplecategory {Desktop}
++ \ingroup activeqt-examples
++
++ \brief The COM App example shows how to use ActiveQt to develop a Qt
++ application that can be automated via COM. Different QObject
++ based classes are exposed as COM objects that communicate with the
++ GUI of the running Qt application. The APIs of those COM objects
++ has been designed to resemble the APIs of standard COM
++ applications; i.e. those from Microsoft Office.
++
++ \snippet activeqt/comapp/main.cpp 2
++ The first class \c Application represents the application object. It
++ exposes read-only properties \c documents and \c id to get access to the
++ list of documents, and an identifier. A read/write property \c visible
++ controls whether the QTabWidget-based user interface of the application
++ should be visible, and a slot \c quit() terminates the application.
++
++ The \e RegisterObject attribute is set to make sure that instances of this
++ class are registered in COM's running object table (ROT) - this allows COM
++ clients to connect to an already instantiated COM object.
++
++ \snippet activeqt/comapp/main.cpp 1
++ The \c DocumentList class stores a list of documents. It provides an API
++ to read the number of documents, to access each document by index and to
++ create a new document. The \c application property returns the root object.
++
++ \snippet activeqt/comapp/main.cpp 0
++
++ The \c Document class finally represents a document in the application.
++ Each document is represented by a page in the application's tab widget, and
++ has a title that is readable and writable through the document's API.
++ The \c application property again returns the root object.
++
++ \snippet activeqt/comapp/main.cpp 3
++ The implementation of the \c Document class creates a new page for the tab
++ widget, and uses the title of that page for the title property. The page
++ is deleted when the document is deleted.
++
++ \snippet activeqt/comapp/main.cpp 4
++ The \c DocumentList implementation is straightforward.
++
++ \snippet activeqt/comapp/main.cpp 5
++ The \c Application class initializes the user interface in the constructor,
++ and shows and hides it in the implementation of \c setVisible(). The object
++ name (accessible through the \c id property) is set to \c "From QAxFactory"
++ to indicate that this COM object has been created by COM. Note that there is
++ no destructor that would delete the QTabWidget - this is instead done in the
++ \c quit() slot, before calling \l {QCoreApplication::}{quit()} through a single-shot-timer,
++ which is necessary to ensure that the COM call to the slot is complete.
++
++ \snippet activeqt/comapp/main.cpp 6
++ The classes are exported from the server using the QAxFactory macros. Only
++ \c Application objects can be instantiated from outside - the other APIs can
++ only be used after accessing the respective objects throughout the \c Application
++ API.
++
++ \snippet activeqt/comapp/main.cpp 7
++ The main() entry point function creates a QApplication, and just enters the
++ event loop if the application has been started by COM. If the application
++ has been started by the user, then the \c Application object is created and
++ the object name is set to "From Application". Then the COM server is started,
++ and the application object is registered with COM. It is now accessible to
++ COM clients through the client-specific APIs.
++
++ Application exiting is controlled explicitly - if COM started the application,
++ then the client code has to call quit(); if the user started the application,
++ then the application terminates when the last window has been closed.
++
++ Finally, the user interface is made visible, and the event loop is started.
++
++ A simple Visual Basic application could now access this Qt application. In VB,
++ start a new "Standard Exe" project and add a project reference to the comappLib
++ type library. Create a form with a listbox "DocumentList", a static label
++ "DocumentsCount" and a command button "NewDocument". Finally, implement the code
++ for the form like this:
++
++ \snippet activeqt/comapp/doc/snippets/doc_src_examples_activeqt_comapp.qdoc 0
++
++ To build the example you must first build the QAxServer library.
++ Then run \c qmake and your make tool in
++ \c{examples\activeqt\comapp}.
++ */