doc/src/examples/activeqt/comapp.qdoc
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    41 
       
    42 /*!
       
    43     \example activeqt/comapp
       
    44     \title COM App Example (ActiveQt)
       
    45 
       
    46     The COM App example shows how to use ActiveQt to develop a Qt
       
    47     application that can be automated via COM. Different QObject
       
    48     based classes are exposed as COM objects that communicate with the
       
    49     GUI of the running Qt application. The APIs of those COM objects
       
    50     has been designed to resemble the APIs of standard COM
       
    51     applications; i.e. those from Microsoft Office.
       
    52 
       
    53     \snippet examples/activeqt/comapp/main.cpp 2
       
    54     The first class \c Application represents the application object. It
       
    55     exposes read-only properties \c documents and \c id to get access to the
       
    56     list of documents, and an identifier. A read/write property \c visible
       
    57     controls whether the QTabWidget-based user interface of the application 
       
    58     should be visible, and a slot \c quit() terminates the application.
       
    59 
       
    60     The \e RegisterObject attribute is set to make sure that instances of this
       
    61     class are registered in COM's running object table (ROT) - this allows COM
       
    62     clients to connect to an already instantiated COM object.
       
    63 
       
    64     \snippet examples/activeqt/comapp/main.cpp 1
       
    65     The \c DocumentList class stores a list of documents. It provides an API
       
    66     to read the number of documents, to access each document by index and to 
       
    67     create a new document. The \c application property returns the root object.
       
    68 
       
    69     \snippet examples/activeqt/comapp/main.cpp 0
       
    70 
       
    71     The \c Document class finally represents a document in the application.
       
    72     Each document is represented by a page in the application's tab widget, and
       
    73     has a title that is readable and writable through the document's API.
       
    74     The \c application property again returns the root object.
       
    75 
       
    76     \snippet examples/activeqt/comapp/main.cpp 3
       
    77     The implementation of the \c Document class creates a new page for the tab
       
    78     widget, and uses the title of that page for the title property. The page 
       
    79     is deleted when the document is deleted.
       
    80 
       
    81     \snippet examples/activeqt/comapp/main.cpp 4
       
    82     The \c DocumentList implementation is straightforward.
       
    83 
       
    84     \snippet examples/activeqt/comapp/main.cpp 5
       
    85     The \c Application class initializes the user interface in the constructor,
       
    86     and shows and hides it in the implementation of \c setVisible(). The object
       
    87     name (accessible through the \c id property) is set to \c "From QAxFactory" 
       
    88     to indicate that this COM object has been created by COM. Note that there is 
       
    89     no destructor that would delete the QTabWidget - this is instead done in the 
       
    90     \c quit() slot, before calling QApplication::quit() through a single-shot-timer, 
       
    91     which is necessary ensure that the COM call to the slot is complete.
       
    92 
       
    93     \snippet examples/activeqt/comapp/main.cpp 6
       
    94     The classes are exported from the server using the QAxFactory macros. Only
       
    95     \c Application objects can be instantiated from outside - the other APIs can
       
    96     only be used after accessing the respective objects throught the \c Application
       
    97     API.
       
    98 
       
    99     \snippet examples/activeqt/comapp/main.cpp 7
       
   100     The main() entry point function creates a QApplication, and just enters the
       
   101     event loop if the application has been started by COM. If the application
       
   102     has been started by the user, then the \c Application object is created and 
       
   103     the object name is set to "From Application". Then the COM server is started,
       
   104     and the application object is registered with COM. It is now accessible to
       
   105     COM clients through the client-specific APIs.
       
   106 
       
   107     Application exiting is controlled explicitly - if COM started the application, 
       
   108     then the client code has to call quit(); if the user started the application,
       
   109     then the application terminates when the last window has been closed.
       
   110 
       
   111     Finally, the user interface is made visible, and the event loop is started.
       
   112 
       
   113     A simple Visual Basic application could now access this Qt application. In VB,
       
   114     start a new "Standard Exe" project and add a project reference to the comappLib
       
   115     type library. Create a form with a listbox "DocumentList", a static label 
       
   116     "DocumentsCount" and a command button "NewDocument". Finally, implement the code 
       
   117     for the form like this:
       
   118 
       
   119     \snippet doc/src/snippets/code/doc_src_examples_activeqt_comapp.qdoc 0
       
   120 
       
   121     To build the example you must first build the QAxServer library.
       
   122     Then run \c qmake and your make tool in
       
   123     \c{examples\activeqt\comapp}.
       
   124 */