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/****************************************************************************
**
** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Free Documentation License Usage
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: http://www.gnu.org/copyleft/fdl.html.
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\example activeqt/comapp
\title COM App Example (ActiveQt)
\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 examples/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 examples/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 examples/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 examples/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 examples/activeqt/comapp/main.cpp 4
The \c DocumentList implementation is straightforward.
\snippet examples/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 QApplication::quit() through a single-shot-timer,
which is necessary ensure that the COM call to the slot is complete.
\snippet examples/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 throught the \c Application
API.
\snippet examples/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 doc/src/snippets/code/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}.
*/
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