The QAction class provides an abstract user interface
action that can appear both in menus and tool bars.
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Detailed Description
The QAction class provides an abstract user interface
action that can appear both in menus and tool bars.
In GUI applications many commands can be invoked via a menu
option, a toolbar button and a keyboard accelerator. Since the
same action must be performed regardless of how the action was
invoked, and since the menu and toolbar should be kept in sync, it
is useful to represent a command as an action. An action can be
added to a menu and a toolbar and will automatically keep them in
sync. For example, if the user presses a Bold toolbar button the
Bold menu item will automatically be checked.
A QAction may contain an icon, a menu text, an accelerator, a
status text, a whats this text and a tool tip. Most of these can
be set in the constructor. They can also be set independently with
setIconSet(), setText(), setMenuText(), setToolTip(),
setStatusTip(), setWhatsThis() and setAccel().
An action may be a toggle action e.g. a Bold toolbar button, or a
command action, e.g. 'Open File' to invoke an open file dialog.
Toggle actions emit the toggled() signal when their state changes.
Both command and toggle actions emit the activated() signal when
they are invoked. Use setToggleAction() to set an action's toggled
status. To see if an action is a toggle action use
isToggleAction(). A toggle action may be "on", isOn() returns
TRUE, or "off", isOn() returns FALSE.
Actions are added to widgets (menus or toolbars) using addTo(),
and removed using removeFrom().
Once a QAction has been created it should be added to the relevant
menu and toolbar and then connected to the slot which will perform
the action. For example:
fileOpenAction = new QAction( QPixmap( fileopen ), "&Open...",
CTRL+Key_O, this, "open" );
connect( fileOpenAction, SIGNAL( activated() ) , this, SLOT( choose() ) );
We create a "File Save" action with a menu text of "&Save" and
Ctrl+S as the keyboard accelerator. We connect the
fileSaveAction's activated() signal to our own save() slot. Note
that at this point there is no menu or toolbar action, we'll add
them next:
QToolBar * fileTools = new QToolBar( this, "file operations" );
fileSaveAction->addTo( fileTools );
QPopupMenu * file = new QPopupMenu( this );
menuBar()->insertItem( "&File", file );
fileSaveAction->addTo( file );
We create a toolbar and add our fileSaveAction to it. Similarly we
create a menu, add a top-level menu item, and add our
fileSaveAction.
We recommend that actions are created as children of the window
that they are used in. In most cases actions will be children of
the application's main window.
To prevent recursion, don't create an action as a child of a
widget that the action is later added to.
See also Main Window and Related Classes and Basic Widgets.
Member Function Documentation
QAction::QAction ( QObject * parent, const char * name = 0 )
Constructs an action called name with parent parent.
If parent is a QActionGroup, the new action inserts itself into
parent.
For accelerators and status tips to work, parent must either be
a widget, or an action group whose parent is a widget.
Warning: To prevent recursion, don't create an action as a child
of a widget that the action is later added to.
QAction::QAction ( const QString & menuText, QKeySequence accel, QObject * parent, const char * name = 0 )
This constructor results in an icon-less action with the the menu
text menuText and keyboard accelerator accel. It is a child
of parent and called name.
If parent is a QActionGroup, the action automatically becomes
a member of it.
For accelerators and status tips to work, parent must either be
a widget, or an action group whose parent is a widget.
The action uses a stripped version of menuText (e.g. "&Menu
Option..." becomes "Menu Option") as descriptive text for
toolbuttons. You can override this by setting a specific
description with setText(). The same text and accel will be
used for tool tips and status tips unless you provide text for
these using setToolTip() and setStatusTip().
Call setToggleAction(TRUE) to make the action a toggle action.
Warning: To prevent recursion, don't create an action as a child
of a widget that the action is later added to.
QAction::QAction ( const QIconSet & icon, const QString & menuText, QKeySequence accel, QObject * parent, const char * name = 0 )
This constructor creates an action with the following properties:
the icon or iconset icon, the menu text menuText and
keyboard accelerator accel. It is a child of parent and
called name.
If parent is a QActionGroup, the action automatically becomes
a member of it.
For accelerators and status tips to work, parent must either be
a widget, or an action group whose parent is a widget.
The action uses a stripped version of menuText (e.g. "&Menu
Option..." becomes "Menu Option") as descriptive text for
toolbuttons. You can override this by setting a specific
description with setText(). The same text and accel will be
used for tool tips and status tips unless you provide text for
these using setToolTip() and setStatusTip().
Call setToggleAction(TRUE) to make the action a toggle action.
Warning: To prevent recursion, don't create an action as a child
of a widget that the action is later added to.
QAction::QAction ( const QString & text, const QIconSet & icon, const QString & menuText, QKeySequence accel, QObject * parent, const char * name = 0, bool toggle = FALSE )
This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.
This constructor creates an action with the following properties:
the description text, the icon or iconset icon, the menu
text menuText and keyboard accelerator accel. It is a child
of parent and called name. If toggle is TRUE the action
will be a toggle action, otherwise it will be a command action.
If parent is a QActionGroup, the action automatically becomes
a member of it.
For accelerators and status tips to work, parent must either be
a widget, or an action group whose parent is a widget.
The text and accel will be used for tool tips and status
tips unless you provide specific text for these using setToolTip()
and setStatusTip().
QAction::QAction ( const QString & text, const QString & menuText, QKeySequence accel, QObject * parent, const char * name = 0, bool toggle = FALSE )
This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.
This constructor results in an icon-less action with the
description text, the menu text menuText and the keyboard
accelerator accel. Its parent is parent and it is called name. If toggle is TRUE the action will be a toggle action,
otherwise it will be a command action.
The action automatically becomes a member of parent if parent is a QActionGroup.
For accelerators and status tips to work, parent must either be
a widget, or an action group whose parent is a widget.
The text and accel will be used for tool tips and status
tips unless you provide specific text for these using setToolTip()
and setStatusTip().
QAction::QAction ( QObject * parent, const char * name, bool toggle )
This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.
Constructs an action called name with parent parent.
If toggle is TRUE the action will be a toggle action, otherwise
it will be a command action.
If parent is a QActionGroup, the new action inserts itself into
parent.
For accelerators and status tips to work, parent must either be
a widget, or an action group whose parent is a widget.
QAction::~QAction ()
Destroys the object and frees allocated resources.
Returns the action's accelerator key.
See the "accel" property for details.
void QAction::activated () [signal]
This signal is emitted when an action is activated by the user,
e.g. when the user clicks a menu option or a toolbar button or
presses an action's accelerator key combination.
Connect to this signal for command actions. Connect to the
toggled() signal for toggle actions.
Examples: action/application.cpp, chart/chartform.cpp, and themes/themes.cpp.
bool QAction::addTo ( QWidget * w ) [virtual]
Adds this action to widget w.
Currently actions may be added to QToolBar and QPopupMenu widgets.
An action added to a tool bar is automatically displayed as a tool
button; an action added to a pop up menu appears as a menu option.
addTo() returns TRUE if the action was added successfully and
FALSE otherwise. (If w is not a QToolBar or QPopupMenu the
action will not be added and FALSE will be returned.)
See also removeFrom().
Examples: action/application.cpp, action/toggleaction/toggleaction.cpp, and chart/chartform.cpp.
Reimplemented in QActionGroup.
void QAction::addedTo ( QWidget * actionWidget, QWidget * container ) [virtual protected]
This function is called from the addTo() function when it has
created a widget (actionWidget) for the action in the container.
void QAction::addedTo ( int index, QPopupMenu * menu ) [virtual protected]
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
This function is called from the addTo() function when it has
created a menu item at the index position index in the popup
menu menu.
QIconSet QAction::iconSet () const
Returns the action's icon.
See the "iconSet" property for details.
bool QAction::isEnabled () const
Returns TRUE if the action is enabled; otherwise returns FALSE.
See the "enabled" property for details.
bool QAction::isOn () const
Returns TRUE if a toggle action is on; otherwise returns FALSE.
See the "on" property for details.
bool QAction::isToggleAction () const
Returns TRUE if the action is a toggle action; otherwise returns FALSE.
See the "toggleAction" property for details.
bool QAction::isVisible () const
Returns TRUE if the action can be seen (e.g. in menus and toolbars); otherwise returns FALSE.
See the "visible" property for details.
Returns the action's menu text.
See the "menuText" property for details.
bool QAction::removeFrom ( QWidget * w ) [virtual]
Removes the action from widget w.
Returns TRUE if the action was removed successfully; otherwise
returns FALSE.
See also addTo().
void QAction::setAccel ( const QKeySequence & key ) [virtual]
Sets the action's accelerator key to key.
See the "accel" property for details.
void QAction::setEnabled ( bool ) [virtual slot]
Sets whether the action is enabled.
See the "enabled" property for details.
void QAction::setIconSet ( const QIconSet & ) [virtual]
Sets the action's icon.
See the "iconSet" property for details.
void
Sets the action's menu text.
See the "menuText" property for details.
void QAction::setOn ( bool ) [virtual slot]
Sets whether a toggle action is on.
See the "on" property for details.
void QAction::setStatusTip ( const QString & ) [virtual]
Sets the action's status tip.
See the "statusTip" property for details.
void QAction::setText ( const QString & ) [virtual]
Sets the action's descriptive text.
See the "text" property for details.
void QAction::setToggleAction ( bool ) [virtual]
Sets whether the action is a toggle action.
See the "toggleAction" property for details.
void QAction::setToolTip ( const QString & ) [virtual]
Sets the action's tool tip.
See the "toolTip" property for details.
void QAction::setVisible ( bool ) [slot]
Sets whether the action can be seen (e.g. in menus and toolbars).
See the "visible" property for details.
void QAction::setWhatsThis ( const QString & ) [virtual]
Sets the action's "What's This?" help text.
See the "whatsThis" property for details.
QString QAction::statusTip () const
Returns the action's status tip.
See the "statusTip" property for details.
QString QAction::text () const
Returns the action's descriptive text.
See the "text" property for details.
void QAction::toggle () [slot]
Toggles the state of a toggle action.
See also on, toggled(), and toggleAction.
void QAction::toggled ( bool on ) [signal]
This signal is emitted when a toggle action changes state; command
actions and QActionGroups don't emit toggled().
The on argument denotes the new state: If on is TRUE the
toggle action is switched on, and if on is FALSE the toggle
action is switched off.
To trigger a user command depending on whether a toggle action has
been switched on or off connect it to a slot that takes a bool to
indicate the state, e.g.
QMainWindow * window = new QMainWindow;
QAction * labelonoffaction = new QAction( window, "labelonoff", TRUE );
QObject::connect( labelonoffaction, SIGNAL( toggled( bool ) ),
window, SLOT( setUsesTextLabel( bool ) ) );
See also activated(), toggleAction, and on.
Example: action/toggleaction/toggleaction.cpp.
QString QAction::toolTip () const
Returns the action's tool tip.
See the "toolTip" property for details.
QString QAction::whatsThis () const
Returns the action's "What's This?" help text.
See the "whatsThis" property for details.
Property Documentation
This property holds the action's accelerator key.
The keycodes can be found in Qt::Key and Qt::Modifier. There
is no default accelerator key.
Set this property's value with setAccel() and get this property's value with accel().
bool enabled
This property holds whether the action is enabled.
Disabled actions can't be chosen by the user. They don't disappear
from the menu/tool bar but are displayed in a way which indicates
that they are unavailable, e.g. they might be displayed grayed
out.
What's this? help on disabled actions is still available provided
the QAction::whatsThis property is set.
Set this property's value with setEnabled() and get this property's value with isEnabled().
This property holds the action's icon.
The icon is used as the tool button icon and in the menu to the
left of the menu text. There is no default icon.
If a null icon (QIconSet::isNull() is passed into this function,
the icon of the action is cleared.
(See the action/toggleaction/toggleaction.cpp example.)
Set this property's value with setIconSet() and get this property's value with iconSet().
This property holds the action's menu text.
If the action is added to a menu the menu option will consist of
the icon (if there is one), the menu text and the accelerator (if
there is one). If the menu text is not explicitly set in the
constructor or by using setMenuText() the action's description
text will be used as the menu text. There is no default menu text.
See also text.
Set this property's value with setMenuText() and get this property's value with menuText().
bool on
This property holds whether a toggle action is on.
This property is always on (TRUE) for command actions and
QActionGroups; setOn() has no effect on them. For action's
where isToggleAction() is TRUE, this property's default value is
off (FALSE).
See also toggleAction.
Set this property's value with setOn() and get this property's value with isOn().
This property holds the action's status tip.
The statusTip is displayed on all status bars that this action's
toplevel parent widget provides.
If no status tip is defined, the action uses the tool tip text.
There is no default statusTip text.
See also statusTip and toolTip.
Set this property's value with setStatusTip() and get this property's value with statusTip().
This property holds the action's descriptive text.
If QMainWindow::usesTextLabel is TRUE, the text appears as a
label in the relevant tool button. It also serves as the default
text in menus and tool tips if these have not been specifically
defined. There is no default text.
See also menuText, toolTip, and statusTip.
Set this property's value with setText() and get this property's value with text().
bool toggleAction
This property holds whether the action is a toggle action.
A toggle action is one which has an on/off state. For example a
Bold toolbar button is either on or off. An action which is not a
toggle action is a command action; a command action is simply
executed, e.g. file save. This property's default is FALSE.
In some situations, the state of one toggle action should depend
on the state of others. For example, "Left Align", "Center" and
"Right Align" toggle actions are mutually exclusive. To achieve
exclusive toggling, add the relevant toggle actions to a
QActionGroup with the QActionGroup::exclusive property set to
TRUE.
Set this property's value with setToggleAction() and get this property's value with isToggleAction().
This property holds the action's tool tip.
This text is used for the tool tip. If no status tip has been set
the tool tip will be used for the status tip.
If no tool tip is specified the action's text is used, and if that
hasn't been specified the description text is used as the tool tip
text.
There is no default tool tip text.
See also statusTip and accel.
Set this property's value with setToolTip() and get this property's value with toolTip().
bool visible
This property holds whether the action can be seen (e.g. in menus and toolbars).
If visible is TRUE the action can be seen (e.g. in menus and
toolbars) and chosen by the user; if visible is FALSE the
action cannot be seen or chosen by the user.
Actions which are not visible are not grayed out; they do not
appear at all.
Set this property's value with setVisible() and get this property's value with isVisible().
This property holds the action's "What's This?" help text.
The whats this text is used to provide a brief description of the
action. The text may contain rich text (HTML-like tags -- see
QStyleSheet for the list of supported tags). There is no default
"What's This" text.
See also QWhatsThis.
Set this property's value with setWhatsThis() and get this property's value with whatsThis().
This file is part of the Qt toolkit.
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Trolltech. All Rights Reserved.
