Q3Action Class Reference
^{[Qt3Support module]}

Detailed Description

The Q3Action 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 Q3Action may contain an icon, a menu text, an accelerator, a status text, a "What's 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 Q3Action has been created it should be added to the relevant menu and toolbar and then connected to the slot which will perform the action.

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.

Property Documentation

accel : QKeySequence

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.

Access functions:

• QKeySequence accel () const
• virtual void setAccel ( const QKeySequence & key )

enabled : bool

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 Q3Action::whatsThis property is set.

Access functions:

• bool isEnabled () const
• virtual void setEnabled ( bool )

iconSet : QIcon

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 (QIcon::isNull() is passed into this function, the icon of the action is cleared.

(See the action/toggleaction/toggleaction.cpp example.)

Access functions:

• QIcon iconSet () const
• virtual void setIconSet ( const QIcon & )

menuText : QString

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.

Access functions:

• QString menuText () const
• virtual void setMenuText ( const QString & )

See also text.

on : bool

This property holds whether a toggle action is on.

This property is always on (true) for command actions and Q3ActionGroups; setOn() has no effect on them. For action's where isToggleAction() is true, this property's default value is off (false).

Access functions:

• bool isOn () const
• virtual void setOn ( bool )

See also toggleAction.

statusTip : QString

This property holds the action's status tip.

The statusTip is displayed on all status bars that this action's top-level parent widget provides.

If no status tip is defined, the action uses the tool tip text.

There is no default statusTip text.

Access functions:

• QString statusTip () const
• virtual void setStatusTip ( const QString & )

See also setToolTip().

text : QString

This property holds the action's descriptive text.

Access functions:

• QString text () const
• virtual void setText ( const QString & )

See also setMenuText(), setToolTip(), and setStatusTip().

toggleAction : bool

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 Q3ActionGroup with the Q3ActionGroup::exclusive property set to true.

Access functions:

• bool isToggleAction () const
• virtual void setToggleAction ( bool )

toolTip : QString

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.

Access functions:

• QString toolTip () const
• virtual void setToolTip ( const QString & )

See also setStatusTip() and setAccel().

visible : bool

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.

Access functions:

• bool isVisible () const
• virtual void setVisible ( bool )

whatsThis : QString

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.

Access functions:

• QString whatsThis () const
• virtual void setWhatsThis ( const QString & )

See also QWhatsThis.

Member Function Documentation

Q3Action::Q3Action ( QObject * parent, const char * name = 0 )

Constructs an action called name with parent parent.

If parent is a Q3ActionGroup, 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.

Q3Action::Q3Action ( 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 Q3ActionGroup, 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.

Q3Action::Q3Action ( const QIcon & icon, const QString & menuText, QKeySequence accel, QObject * parent, const char * name = 0 )

This constructor creates an action with the following properties: the icon or icon icon, the menu text menuText and keyboard accelerator accel. It is a child of parent and called name.

If parent is a Q3ActionGroup, 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.

Q3Action::Q3Action ( const QString & text, const QIcon & icon, const QString & menuText, QKeySequence accel, QObject * parent, const char * name = 0, bool toggle = false )

This constructor creates an action with the following properties: the description text, the icon or icon 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 Q3ActionGroup, 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().

Q3Action::Q3Action ( const QString & text, const QString & menuText, QKeySequence accel, QObject * parent, const char * name = 0, bool toggle = false )

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 Q3ActionGroup.

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().

Q3Action::Q3Action ( QObject * parent, const char * name, bool toggle )

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 Q3ActionGroup, 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.

Q3Action::~Q3Action ()

Destroys the object and frees allocated resources.

void Q3Action::activate ()   [slot]

Activates the action and executes all connected slots. This only works for actions that are not toggle actions.

See also toggle().

void Q3Action::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.

bool Q3Action::addTo ( QWidget * w )   [virtual]

Adds this action to widget w.

Currently actions may be added to Q3ToolBar and Q3PopupMenu 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 Q3ToolBar or Q3PopupMenu the action will not be added and false will be returned.)

See also removeFrom().

void Q3Action::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 Q3Action::addedTo ( int index, Q3PopupMenu * menu )   [virtual protected]

This is an overloaded member function, provided for convenience.

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.

bool Q3Action::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 Q3Action::setDisabled ( bool disable )   [slot]

Disables the action if disable is true; otherwise enables the action.

See the enabled documentation for more information.

void Q3Action::toggle ()   [slot]

Toggles the state of a toggle action.

See also on, activate(), toggled(), and isToggleAction().

void Q3Action::toggled ( bool on )   [signal]

This signal is emitted when a toggle action changes state; command actions and Q3ActionGroups 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.

See also activated(), setToggleAction(), and setOn().