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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
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** This file is part of the documentation of the Qt Toolkit.
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** No Commercial Usage
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** contained in the Technology Preview License Agreement accompanying
** this package.
**
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** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
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** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\page activeqt-container.html
\title Using ActiveX controls and COM objects in Qt
\brief The QAxContainer module is a Windows-only extension for
accessing ActiveX controls and COM objects.
The QAxContainer module is part of the \l ActiveQt framework. It
provides a library implementing a QWidget subclass, QAxWidget,
that acts as a container for ActiveX controls, and a QObject
subclass, QAxObject, that can be used to easily access non-visual
COM objects. Scripting COM objects embedded using these classes
is possible through the QAxScript, QAxScriptManager and
QAxScriptEngine classes, and a set of \l{Tools for ActiveQt}{tools}
makes it easy to access COM objects programmatically.
The module consists of six classes
\list 1
\o QAxBase is an abstract class that provides an API to initialize
and access a COM object or ActiveX control.
\o QAxObject provides a QObject that wraps a COM object.
\o QAxWidget is a QWidget that wraps an ActiveX control.
\o QAxScriptManager, QAxScript and QAxScriptEngine provide an
interface to the Windows Script Host.
\endlist
Some \l{ActiveQt Examples}{example applications} that use
standard ActiveX controls to provide high-level user interface
functionality are provided.
\sa {ActiveQt Framework}
Topics:
\tableofcontents
\section1 Using the Library
To build Qt applications that can host COM objects and ActiveX controls
link the application against the QAxContainer module by adding
\snippet doc/src/snippets/code/doc_src_qaxcontainer.qdoc 0
to your application's \c .pro file.
\section2 Distributing QAxContainer Applications
The QAxContainer library is static, so there is no need to redistribute
any additional files when using this module. Note however that the
ActiveX server binaries you are using might not be installed on the
target system, so you have to ship them with your package and register
them during the installation process of your application.
\section1 Instantiating COM Objects
To instantiate a COM object use the QAxBase::setControl() API, or pass
the name of the object directly into the constructor of the QAxBase
subclass you are using.
The control can be specified in a variety of formats, but the fastest
and most powerful format is to use the class ID (CLSID) of the object
directly. The class ID can be prepended with information about a remote
machine that the object should run on, and can include a license key
for licensed controls.
\section2 Typical Error Messages
ActiveQt prints error messages to the debug output when it
encounters error situations at runtime. Usually you must run
your program in the debugger to see these messages (e.g. in Visual
Studio's Debug output).
\section3 Requested control could not be instantiated
The control requested in QAxBase::setControl() is not installed
on this system, or is not accessible for the current user.
The control might require administrator rights, or a license key.
If the control is licensed, pass the license key to QAxBase::setControl
as documented.
\section1 Accessing the Object API
ActiveQt provides a Qt API to the COM object, and replaces COM
datatypes with Qt equivalents.
There are four ways to call APIs on the COM object:
\list
\o Generating a C++ namespace
\o Call-by-name
\o Through a script engine
\o Using the native COM interfaces
\endlist
\section2 Generating a C++ Namespace
To generate a C++ namespace for the type library you want to access,
use the \l dumpcpp tool. Run this tool manually on the type library you
want to use, or integrate it into the build system by adding the type
libraries to the \c TYPELIBS variable in your application's \c .pro file:
\snippet doc/src/snippets/code/doc_src_qaxcontainer.qdoc 1
Note that \l dumpcpp might not be able to expose all APIs in the type
library.
Include the resulting header file in your code to access the
object APIs through the generated C++ classes. See the
\l{activeqt/qutlook}{Qutlook} example for more information.
\section2 Call-by-Name
Use QAxBase::dynamicCall() and QAxBase::querySubObject() as well as
the QObject::setProperty() and QObject::property() APIs to call the
methods and properties of the COM object through their name. Use the
\l dumpdoc tool to get the documentation of the Qt API for any COM
object and its subobjects; note that not all of the COM object's APIs
might be available.
See the \l{activeqt/webbrowser}{Webbrowser} example for more information.
\section2 Calling Function Through a Script Engine
A Qt application can host any ActiveScript engine installed on the system.
The script engine can then run script code that accesses the COM objects.
To instantiate a script engine, use QAxScriptManager::addObject() to
register the COM objects you want to access from script, and
QAxScriptManager::load() to load the script code into the engine. Then
call the script functions using QAxScriptManager::call() or
QAxScript::call().
Which APIs of the COM object are available through scripting depends on
the script language used.
The \l{testcon - An ActiveX Test Container (ActiveQt)}{ActiveX Test Container}
demonstrates loading of script files.
\section2 Calling a Function Using the Native COM Interfaces
To call functions of the COM object that can not be accessed via any
of the above methods it is possible to request the COM interface directly
using QAxBase::queryInterface(). To get a C++ definition of the respective
interface classes use the \c #import directive with the type library
provided with the control; see your compiler manual for details.
\section2 Typical Error Messages
ActiveQt prints error messages to the debug output when it
encounters error situations at runtime. Usually you must run
your program in the debugger to see these messages (e.g. in Visual
Studio's Debug output).
\section3 QAxBase::internalInvoke: No such method
A QAxBase::dynamicCall() failed - the function prototype did not
match any function available in the object's API.
\section3 Error calling IDispatch member: Non-optional parameter missing
A QAxBase::dynamicCall() failed - the function prototype was correct,
but too few parameters were provided.
\section3 Error calling IDispatch member: Type mismatch in parameter n
A QAxBase::dynamicCall() failed - the function prototype was correct,
but the paramter at index \c n was of the wrong type and could
not be coerced to the correct type.
\section3 QAxScriptManager::call(): No script provides this function
You try to call a function that is provided through an engine
that doesn't provide introspection (ie. ActivePython or
ActivePerl). You need to call the function directly on the
respective QAxScript object.
*/
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