QAction Class Reference
[QtGui module]

Detailed Description

The QAction class provides an abstract user interface action that can be inserted into widgets.

In applications many common commands can be invoked via menus, toolbar buttons, and keyboard shortcuts. Since the user expects each command to be performed in the same way, regardless of the user interface used, it is useful to represent each command as an action.

Actions can be added to menus and toolbars, and will automatically keep them in sync. For example, in a word processor, if the user presses a Bold toolbar button, the Bold menu item will automatically be checked.

Actions can be created as independent objects, but they may also be created during the construction of menus; the QMenu class contains convenience functions for creating actions suitable for use as menu items.

A QAction may contain an icon, menu text, a shortcut, status text, "What's This?" text, and a tooltip. Most of these can be set in the constructor. They can also be set independently with setIcon(), setText(), setIconText(), setShortcut(), setStatusTip(), setWhatsThis(), and setToolTip(). For menu items, it is possible to set an individual font with setFont().

Actions are added to widgets using QWidget::addAction() or QGraphicsWidget::addAction(). Note that an action must be added to a widget before it can be used; this is also true when the shortcut should be global (i.e., Qt::ApplicationShortcut as Qt::ShortcutContext).

Once a QAction has been created it should be added to the relevant menu and toolbar, then connected to the slot which will perform the action. For example:

     openAct = new QAction(QIcon(":/images/open.png"), tr("&Open..."), this);
     openAct->setShortcuts(QKeySequence::Open);
     openAct->setStatusTip(tr("Open an existing file"));
     connect(openAct, SIGNAL(triggered()), this, SLOT(open()));

     fileMenu->addAction(openAct);
     fileToolBar->addAction(openAct);

We recommend that actions are created as children of the window they are used in. In most cases actions will be children of the application's main window.

See also QMenu, QToolBar, and Application Example.

Member Type Documentation

 QApplication app(argc, argv);
 app.setAttribute(Qt::AA_DontShowIconsInMenus);  // Icons are *no longer shown* in menus
 // ...
 QAction *myAction = new QAction();
 // ...
 myAction->setIcon(SomeIcon);
 myAction->setIconVisibleInMenu(true);   // Icon *will* be shown in menus for *this* action.