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    41 

    42 /*!

    43     \example designer/taskmenuextension

    44     \title Task Menu Extension Example

    45 

    46     The Task Menu Extension example shows how to create a custom

    47     widget plugin for \l {Qt Designer Manual}{\QD}, and how to to use

    48     the QDesignerTaskMenuExtension class to provide custom task menu

    49     entries associated with the plugin.

    50 

    51     \image taskmenuextension-example-faded.png

    52 

    53     To provide a custom widget that can be used with \QD, we need to

    54     supply a self-contained implementation. In this example we use a

    55     custom widget designed to show the task menu extension feature:

    56     The TicTacToe widget.

    57 

    58     An extension is an object which modifies the behavior of \QD. The

    59     QDesignerTaskMenuExtension can provide custom task menu entries

    60     when a widget with this extension is selected.

    61 

    62     There are four available types of extensions in \QD:

    63 

    64     \list

    65         \o QDesignerContainerExtension provides an extension that allows

    66            you to add (and delete) pages to a multi-page container plugin

    67            in \QD.

    68         \o QDesignerMemberSheetExtension provides an extension that allows

    69            you to manipulate a widget's member functions which is displayed

    70            when configuring connections using Qt Designer's mode for editing

    71            signals and slots.

    72         \o QDesignerPropertySheetExtension provides an extension that

    73            allows you to manipulate a widget's properties which is displayed

    74            in Qt Designer's property editor.

    75         \o QDesignerTaskMenuExtension provides an extension that allows

    76            you to add custom menu entries to \QD's task menu.

    77     \endlist

    78 

    79     You can use all the extensions following the same pattern as in

    80     this example, only replacing the respective extension base

    81     class. For more information, see the \l {QtDesigner Module}.

    82 

    83     The Task Menu Extension example consists of five classes:

    84 

    85     \list

    86     \o \c TicTacToe is a custom widget that lets the user play

    87        the Tic-Tac-Toe game.

    88     \o \c TicTacToePlugin exposes the \c TicTacToe class to \QD.

    89     \o \c TicTacToeTaskMenuFactory creates a \c TicTacToeTaskMenu object.

    90     \o \c TicTacToeTaskMenu provides the task menu extension, i.e the

    91        plugin's associated task menu entries.

    92     \o \c TicTacToeDialog lets the user modify the state of a

    93        Tic-Tac-Toe plugin loaded into \QD.

    94     \endlist

    95 

    96     The project file for custom widget plugins needs some additional

    97     information to ensure that they will work within \QD. For example,

    98     custom widget plugins rely on components supplied with \QD, and

    99     this must be specified in the project file that we use. We will

   100     first take a look at the plugin's project file.

   101 

   102     Then we will continue by reviewing the \c TicTacToePlugin class,

   103     and take a look at the \c TicTacToeTaskMenuFactory and \c

   104     TicTacToeTaskMenu classes. Finally, we will review the \c

   105     TicTacToeDialog class before we take a quick look at the \c

   106     TicTacToe widget's class definition.

   107 

   108     \section1 The Project File: taskmenuextension.pro

   109 

   110     The project file must contain some additional information to

   111     ensure that the plugin will work as expected:

   112 

   113     \snippet examples/designer/taskmenuextension/taskmenuextension.pro 0

   114     \snippet examples/designer/taskmenuextension/taskmenuextension.pro 1

   115 

   116     The \c TEMPLATE variable's value makes \c qmake create the custom

   117     widget as a library. Later, we will ensure that the widget will be

   118     recognized as a plugin by Qt by using the Q_EXPORT_PLUGIN2() macro to

   119     export the relevant widget information.

   120 

   121     The \c CONFIG variable contains two values, \c designer and \c

   122     plugin:

   123 

   124     \list

   125         \o \c designer: Since custom widgets plugins rely on components

   126            supplied with \QD, this value ensures that our plugin links against

   127            \QD's library (\c libQtDesigner.so).

   128 

   129         \o \c plugin: We also need to ensure that \c qmake considers the

   130            custom widget a \e plugin library.

   131     \endlist

   132 

   133     When Qt is configured to build in both debug and release modes,

   134     \QD will be built in release mode.  When this occurs, it is

   135     necessary to ensure that plugins are also built in release

   136     mode. For that reason we add the \c debug_and_release value to

   137     the \c CONFIG variable. Otherwise, if a plugin is built in a mode

   138     that is incompatible with \QD, it won't be loaded and

   139     installed.

   140 

   141     The header and source files for the widget are declared in the

   142     usual way:

   143 

   144     \snippet examples/designer/taskmenuextension/taskmenuextension.pro 2

   145 

   146     We provide an implementation of the plugin interface so that \QD

   147     can use the custom widget.  In this particular example we also

   148     provide implementations of the task menu extension and the

   149     extension factory as well as a dialog implementation.

   150 

   151     It is important to ensure that the plugin is installed in a

   152     location that is searched by \QD. We do this by specifying a

   153     target path for the project and adding it to the list of items to

   154     install:

   155 

   156     \snippet doc/src/snippets/code/doc_src_examples_taskmenuextension.qdoc 0

   157 

   158     The task menu extension is created as a library, and will be

   159     installed alongside the other \QD plugins when the project is

   160     installed (using \c{make install} or an equivalent installation

   161     procedure).

   162 

   163     Note that if you want the plugins to appear in a Visual Studio

   164     integration, the plugins must be built in release mode and their

   165     libraries must be copied into the plugin directory in the install

   166     path of the integration (for an example, see \c {C:/program

   167     files/trolltech as/visual studio integration/plugins}).

   168 

   169     For more information about plugins, see the \l {How to Create Qt

   170     Plugins} documentation.

   171 

   172     \section1 TicTacToePlugin Class Definition

   173 

   174     The \c TicTacToePlugin class exposes \c the TicTacToe class to

   175     \QD. Its definition is equivalent to the \l

   176     {designer/customwidgetplugin}{Custom Widget Plugin} example's

   177     plugin class which is explained in detail. The only part of the

   178     class definition that is specific to this particular custom widget

   179     is the class name:

   180 

   181     \snippet examples/designer/taskmenuextension/tictactoeplugin.h 0

   182 

   183     The plugin class provides \QD with basic information about our

   184     plugin, such as its class name and its include file. Furthermore

   185     it knows how to create instances of the \c TicTacToe widget.

   186     TicTacToePlugin also defines the \l

   187     {QDesignerCustomWidgetInterface::initialize()}{initialize()}

   188     function which is called after the plugin is loaded into \QD. The

   189     function's QDesignerFormEditorInterface parameter provides the

   190     plugin with a gateway to all of \QD's API's.

   191 

   192     The \c TicTacToePlugin class inherits from both QObject and

   193     QDesignerCustomWidgetInterface. It is important to remember, when

   194     using multiple inheritance, to ensure that all the interfaces

   195     (i.e. the classes that doesn't inherit Q_OBJECT) are made known to

   196     the meta object system using the Q_INTERFACES() macro. This

   197     enables \QD to use \l qobject_cast() to query for supported

   198     interfaces using nothing but a QObject pointer.

   199 

   200     \section1 TicTacToePlugin Class Implementation

   201 

   202     The TicTacToePlugin class implementation is in most parts

   203     equivalent to the \l {designer/customwidgetplugin}{Custom Widget

   204     Plugin} example's plugin class:

   205 

   206     \snippet examples/designer/taskmenuextension/tictactoeplugin.cpp 0

   207 

   208     The only function that differs significantly is the initialize()

   209     function:

   210 

   211     \snippet examples/designer/taskmenuextension/tictactoeplugin.cpp 1

   212 

   213     The \c initialize() function takes a QDesignerFormEditorInterface

   214     object as argument.  The QDesignerFormEditorInterface class

   215     provides access to Qt Designer's components.

   216 

   217     In \QD you can create two kinds of plugins: custom widget plugins

   218     and tool plugins. QDesignerFormEditorInterface provides access to

   219     all the \QD components that you normally need to create a tool

   220     plugin: the extension manager, the object inspector, the property

   221     editor and the widget box. Custom widget plugins have access to

   222     the same components.

   223 

   224     \snippet examples/designer/taskmenuextension/tictactoeplugin.cpp 2

   225 

   226     When creating extensions associated with custom widget plugins, we

   227     need to access \QD's current extension manager which we retrieve

   228     from the QDesignerFormEditorInterface parameter.

   229 

   230     \QD's QDesignerFormEditorInterface holds information about all Qt

   231     Designer's components: The action editor, the object inspector,

   232     the property editor, the widget box, and the extension and form

   233     window managers.

   234 

   235     The QExtensionManager class provides extension management

   236     facilities for \QD. Using \QD's current extension manager you can

   237     retrieve the extension for a given object. You can also register

   238     and unregister an extension for a given object. Remember that an

   239     extension is an object which modifies the behavior of \QD.

   240 

   241     When registrering an extension, it is actually the associated

   242     extension factory that is registered. In \QD, extension factories

   243     are used to look up and create named extensions as they are

   244     required. So, in this example, the task menu extension itself is

   245     not created until a task menu is requested by the user.

   246 

   247     \snippet examples/designer/taskmenuextension/tictactoeplugin.cpp 3

   248 

   249     We create a \c TicTacToeTaskMenuFactory object that we register

   250     using \QD's current \l {QExtensionManager}{extension manager}

   251     retrieved from the QDesignerFormEditorInterface parameter. The

   252     first argument is the newly created factory and the second

   253     argument is an extension identifier which is a string. The \c

   254     Q_TYPEID() macro simply converts the string into a QLatin1String.

   255 

   256     The \c TicTacToeTaskMenuFactory class is a subclass of

   257     QExtensionFactory. When the user request a task menu by clicking

   258     the right mouse button over a widget with the specified task menu

   259     extension, \QD's extension manager will run through all its

   260     registered factories invoking the first one that is able to create

   261     a task menu extension for the selected widget. This factory will

   262     in turn create a \c TicTacToeTaskMenu object (the extension).

   263 

   264     We omit to reimplement the

   265     QDesignerCustomWidgetInterface::domXml() function (which include

   266     default settings for the widget in the standard XML format used by

   267     Qt Designer), since no default values are necessary.

   268 

   269     \snippet examples/designer/taskmenuextension/tictactoeplugin.cpp 4

   270 

   271     Finally, we use the Q_EXPORT_PLUGIN2() macro to export the

   272     TicTacToePlugin class for use with Qt's plugin handling classes:

   273     This macro ensures that \QD can access and construct the custom

   274     widget. Without this macro, there is no way for \QD to use the

   275     widget.

   276 

   277     \section1 TicTacToeTaskMenuFactory Class Definition

   278 

   279     The \c TicTacToeTaskMenuFactory class inherits QExtensionFactory

   280     which provides a standard extension factory for \QD.

   281 

   282     \snippet examples/designer/taskmenuextension/tictactoetaskmenu.h 1

   283 

   284     The subclass's purpose is to reimplement the

   285     QExtensionFactory::createExtension() function, making it able to

   286     create a \c TicTacToe task menu extension.

   287 

   288     \section1 TicTacToeTaskMenuFactory Class Implementation

   289 

   290     The class constructor simply calls the QExtensionFactory base

   291     class constructor:

   292 

   293     \snippet examples/designer/taskmenuextension/tictactoetaskmenu.cpp 4

   294 

   295     As described above, the factory is invoked when the user request a

   296     task menu by clicking the right mouse button over a widget with

   297     the specified task menu extension in \QD.

   298 

   299     \QD's behavior is the same whether the requested extension is

   300     associated with a container, a member sheet, a property sheet or a

   301     task menu: Its extension manager runs through all its registered

   302     extension factories calling \c createExtension() for each until

   303     one responds by creating the requested extension.

   304 

   305     \snippet examples/designer/taskmenuextension/tictactoetaskmenu.cpp 5

   306 

   307     So the first thing we do in \c

   308     TicTacToeTaskMenuFactory::createExtension() is to check if the

   309     requested extension is a task menu extension. If it is, and the

   310     widget requesting it is a \c TicTacToe widget, we create and

   311     return a \c TicTacToeTaskMenu object. Otherwise, we simply return

   312     a null pointer, allowing \QD's extension manager to continue its

   313     search through the registered factories.

   314 

   315 

   316     \section1 TicTacToeTaskMenu Class Definition

   317 

   318     \image taskmenuextension-menu.png

   319 

   320     The \c TicTacToeTaskMenu class inherits QDesignerTaskMenuExtension

   321     which allows you to add custom entries (in the form of QActions)

   322     to the task menu in \QD.

   323 

   324     \snippet examples/designer/taskmenuextension/tictactoetaskmenu.h 0

   325 

   326     We reimplement the \c preferredEditAction() and \c taskActions()

   327     functions. Note that we implement a constructor that takes \e two

   328     arguments: the parent widget, and the \c TicTacToe widget for

   329     which the task menu is requested.

   330 

   331     In addition we declare the private \c editState() slot, our custom

   332     \c editStateAction and a private pointer to the \c TicTacToe

   333     widget which state we want to modify.

   334 

   335     \section1 TicTacToeTaskMenu Class Implementation

   336 

   337     \snippet examples/designer/taskmenuextension/tictactoetaskmenu.cpp 0

   338 

   339     In the constructor we first save the reference to the \c TicTacToe

   340     widget sent as parameter, i.e the widget which state we want to

   341     modify. We will need this later when our custom action is

   342     invoked. We also create our custom \c editStateAction and connect

   343     it to the \c editState() slot.

   344 

   345     \snippet examples/designer/taskmenuextension/tictactoetaskmenu.cpp 1

   346 

   347     The \c editState() slot is called whenever the user chooses the

   348     \gui {Edit State...} option in a \c TicTacToe widget's task menu. The

   349     slot creates a \c TicTacToeDialog presenting the current state of

   350     the widget, and allowing the user to edit its state by playing the

   351     game.

   352 

   353     \snippet examples/designer/taskmenuextension/tictactoetaskmenu.cpp 2

   354 

   355     We reimplement the \c preferredEditAction() function to return our

   356     custom \c editStateAction as the action that should be invoked

   357     when selecting a \c TicTacToe widget and pressing \key F2 .

   358 

   359     \snippet examples/designer/taskmenuextension/tictactoetaskmenu.cpp 3

   360 

   361     We reimplement the \c taskActions() function to return a list of

   362     our custom actions making these appear on top of the default menu

   363     entries in a \c TicTacToe widget's task menu.

   364 

   365     \section1 TicTacToeDialog Class Definition

   366 

   367     \image taskmenuextension-dialog.png

   368 

   369     The \c TicTacToeDialog class inherits QDialog. The dialog lets the

   370     user modify the state of the currently selected Tic-Tac-Toe

   371     plugin.

   372 

   373     \snippet examples/designer/taskmenuextension/tictactoedialog.h 0

   374 

   375     We reimplement the \c sizeHint() function. We also declare two

   376     private slots: \c resetState() and \c saveState(). In addition to

   377     the dialog's buttons and layouts we declare two \c TicTacToe

   378     pointers, one to the widget the user can interact with and the

   379     other to the original custom widget plugin which state the user

   380     wants to edit.

   381 

   382     \section1 TicTacToeDialog Class Implementation

   383 

   384     \snippet examples/designer/taskmenuextension/tictactoedialog.cpp 0

   385 

   386     In the constructor we first save the reference to the TicTacToe

   387     widget sent as parameter, i.e the widget which state the user want

   388     to modify. Then we create a new \c TicTacToe widget, and set its

   389     state to be equivalent to the parameter widget's state.

   390 

   391     Finally, we create the dialog's buttons and layout.

   392 

   393     \snippet examples/designer/taskmenuextension/tictactoedialog.cpp 1

   394 

   395     We reimplement the \c sizeHint() function to ensure that the

   396     dialog is given a reasonable size.

   397 

   398     \snippet examples/designer/taskmenuextension/tictactoedialog.cpp 2

   399 

   400     The \c resetState() slot is called whenever the user press the

   401     \gui Reset button. The only thing we do is to call the \c

   402     clearBoard() function for the editor widget, i.e. the \c TicTacToe

   403     widget we created in the dialog's constructor.

   404 

   405     \snippet examples/designer/taskmenuextension/tictactoedialog.cpp 3

   406 

   407     The \c saveState() slot is called whenever the user press the \gui

   408     OK button, and transfers the state of the editor widget to the

   409     widget which state we want to modify. In order to make the change

   410     of state visible to \QD we need to set the latter widget's state

   411     property using the QDesignerFormWindowInterface class.

   412 

   413     QDesignerFormWindowInterface provides you with information about

   414     the associated form window as well as allowing you to alter its

   415     properties. The interface is not intended to be instantiated

   416     directly, but to provide access to Qt Designer's current form

   417     windows controlled by Qt Designer's form window manager.

   418 

   419     If you are looking for the form window containing a specific

   420     widget, you can use the static

   421     QDesignerFormWindowInterface::findFormWindow() function:

   422 

   423     \snippet examples/designer/taskmenuextension/tictactoedialog.cpp 4

   424 

   425     After retrieving the form window of the widget (which state we

   426     want to modify), we use the QDesignerFormWindowInterface::cursor()

   427     function to retrieve the form window's cursor.

   428 

   429     The QDesignerFormWindowCursorInterface class provides an interface

   430     to the form window's text cursor. Once we have cursor, we can

   431     finally set the state property using the

   432     QDesignerFormWindowCursorInterface::setProperty() function.

   433 

   434     \snippet examples/designer/taskmenuextension/tictactoedialog.cpp 5

   435 

   436     In the end we call the QEvent::accept() function which sets the

   437     accept flag of the event object. Setting the \c accept parameter

   438     indicates that the event receiver wants the event. Unwanted events

   439     might be propagated to the parent widget.

   440 

   441     \section1 TicTacToe Class Definition

   442 

   443     The \c TicTacToe class is a custom widget that lets the user play

   444     the Tic-Tac-Toe game.

   445 

   446     \snippet examples/designer/taskmenuextension/tictactoe.h 0

   447 

   448     The main details to observe in the \c TicTacToe class defintion is

   449     the declaration of the \c state property and its \c state() and \c

   450     setState() functions.

   451 

   452     We need to declare the \c TicTacToe widget's state as a property

   453     to make it visible to \QD; allowing \QD to manage it in the same

   454     way it manages the properties the \c TicTacToe widget inherits

   455     from QWidget and QObject, for example featuring the property

   456     editor.

   457 */