Question

The QToolTip class provides tool tips (balloon help) for any widget or rectangular part of a widget. More...

#include <qtooltip.h>

Inherits Qt.

List of all member functions.

Public Members

• QToolTip ( QWidget*widget, QToolTipGroup*group = 0 )
• QWidget * parentWidget () const
• QToolTipGroup * group () const

Static Public Members

• void add ( QWidget*widget, constQString&text )
• void add ( QWidget*widget, constQString&text, QToolTipGroup*group, constQString&longText )
• void remove ( QWidget*widget )
• void add ( QWidget*widget, constQRect&rect, constQString&text )
• void add ( QWidget*widget, constQRect&rect, constQString&text, QToolTipGroup*group, constQString&groupText )
• void remove ( QWidget*widget, constQRect&rect )
• QString textFor ( QWidget*widget, constQPoint&pos = QPoint ( ) )
• void hide ()
• QFont font ()
• void setFont ( constQFont&font )
• QPalette palette ()
• void setPalette ( constQPalette&palette )
• void setEnabled ( boolenable ) (obsolete)
• bool enabled () (obsolete)
• void setGloballyEnabled ( boolenable )
• bool isGloballyEnabled ()

Protected Members

• virtual void maybeTip ( constQPoint&p ) = 0
• void tip ( constQRect&rect, constQString&text )
• void tip ( constQRect&rect, constQString&text, constQString&groupText )
• void clear ()

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Detailed Description

The QToolTip class provides tool tips (balloon help) for any widget or rectangular part of a widget.

The tip is a short, single line of text reminding the user of the widget's or rectangle's function. It is drawn immediately below the region in a distinctive black-on-yellow combination.

QToolTipGroup provides a way for tool tips to display another text elsewhere (most often in a status bar).

At any point in time, QToolTip is either dormant or active. In dormant mode the tips are not shown and in active mode they are. The mode is global, not particular to any one widget.

QToolTip switches from dormant to active mode when the user hovers the mouse on a tip-equipped region for a second or so and remains active until the user either clicks a mouse button, presses a key, lets the mouse hover for five seconds or moves the mouse outside all tip-equipped regions for at least a second.

The QToolTip class can be used in three different ways:

1. Adding a tip to an entire widget.
2. Adding a tip to a fixed rectangle within a widget.
3. Adding a tip to a dynamic rectangle within a widget.

To add a tip to a widget, call the static function QToolTip::add() with the widget and tip as arguments:

    QToolTip::add( quitButton, "Leave the application" );
  

This is the simplest and most common use of QToolTip. The tip will be deleted automatically when quitButton is deleted, but you can remove it yourself, too:

    QToolTip::remove( quitButton );
  

You can also display another text (typically in a status bar), courtesy of QToolTipGroup. This example assumes that g is a QToolTipGroup * and is already connected to the appropriate status bar:

    QToolTip::add( quitButton, "Leave the application", g,
                   "Leave the application, prompting to save if necessary" );
    QToolTip::add( closeButton, "Close this window", g,
                   "Close this window, prompting to save if necessary" );
  

To add a tip to a fixed rectangle within a widget, call the static function QToolTip::add() with the widget, rectangle and tip as arguments. (See the tooltip/tooltip.cpp example.) Again, you can supply a QToolTipGroup * and another text if you want.

Both of these are one-liners and cover the majority of cases. The third and most general way to use QToolTip requires you to reimplement a pure virtual function to decide whether to pop up a tool tip. The tooltip/tooltip.cpp example demonstrates this too. This mode can be used to implement tips for text that can move as the user scrolls, for example.

To use QToolTip like this, you need to subclass QToolTip and reimplement maybeTip(). QToolTip calls maybeTip() when a tip should pop up, and maybeTip decides whether to show a tip.

Tool tips can be globally disabled using QToolTip::setGloballyEnabled() or disabled in groups with QToolTipGroup::setEnabled().

You can retreive the text of a tooltip for a given position within a widget using textFor().

The global tooltip font and palette can be set with the static setFont() and setPalette() functions respectively.

See also QStatusBar, QWhatsThis, QToolTipGroup, GUI Design Handbook: Tool Tip and Help System.

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Member Function Documentation

QToolTip::QToolTip ( QWidget*widget, QToolTipGroup*group = 0 )

Constructs a tool tip object. This is necessary only if you need tool tips on regions that can move within the widget (most often because the widget's contents can scroll).

widget is the widget you want to add dynamic tool tips to and group (optional) is the tool tip group they should belong to.

Warning: QToolTip is not a subclass of QObject, so the instance of QToolTip is not deleted when widget is deleted.

See also maybeTip().

void QToolTip::add ( QWidget*widget, constQString&text ) [static]

Adds a tool tip to widget. text is the text to be shown in the tool tip.

This is the most common entry point to the QToolTip class; it is suitable for adding tool tips to buttons, check boxes, combo boxes and so on.

Examples: qdir/qdir.cpp, scribble/scribble.cpp and tooltip/tooltip.cpp.

void QToolTip::add ( QWidget*widget, constQString&text, QToolTipGroup*group, constQString&longText ) [static]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Adds a tool tip to widget and to tool tip group group.

text is the text shown in the tool tip and longText is the text emitted from group.

Normally, longText is shown in a status bar or similar.

void QToolTip::add ( QWidget*widget, constQRect&rect, constQString&text ) [static]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Adds a tool tip to a fixed rectangle, rect, within widget. text is the text shown in the tool tip.

void QToolTip::add ( QWidget*widget, constQRect&rect, constQString&text, QToolTipGroup*group, constQString&groupText ) [static]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Adds a tool tip to an entire widget and to tool tip group group. The tooltip will disappear when the mouse leaves the rect.

text is the text shown in the tool tip and groupText is the text emitted from group.

Normally, groupText is shown in a status bar or similar.

void QToolTip::clear () [protected]

Immediately removes all tool tips for this tooltip's parent widget.

bool QToolTip::enabled () [static]

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

QFont QToolTip::font () [static]

Returns the font common to all tool tips.

See also setFont().

QToolTipGroup* QToolTip::group () const

Returns the tool tip group this QToolTip is a member of or 0 if it isn't a member of any group.

The tool tip group is the object responsible for maintaining contact between tool tips and a status bar or something else which can show the longer help text.

See also parentWidget() and QToolTipGroup.

void QToolTip::hide () [static]

Hides any tip that is currently being shown.

Normally, there is no need to call this function; QToolTip takes care of showing and hiding the tips as the user moves the mouse.

bool QToolTip::isGloballyEnabled () [static]

Returns whether tool tips are enabled globally.

See also setGloballyEnabled().

void QToolTip::maybeTip ( constQPoint&p ) [pure virtual protected]

This pure virtual function is half of the most versatile interface QToolTip offers.

It is called when there is a possibility that a tool tip should be shown and must decide whether there is a tool tip for the point p in the widget that this QToolTip object relates to. If so, maybeTip() must call tip() with the rectangle the tip applies to, the tip's text and optionally the QToolTipGroup details.

p is given in that widget's local coordinates. Most maybeTip() implementations will be of the form:

    if ( <something> ) {
        tip( <something>, <something> );
    }
  

The first argument to tip() (a rectangle) must encompass p, i.e. the tip must apply to the current mouse position; otherwise QToolTip's operation is undefined.

Note that the tip will disappear once the mouse moves outside the rectangle you give to tip(), and will not reappear if the mouse moves back in - maybeTip() is called again instead.

See also tip().

Example: tooltip/tooltip.cpp.

QPalette QToolTip::palette () [static]

Returns the palette common to all tool tips.

See also setPalette().

QWidget* QToolTip::parentWidget () const

Returns the widget this QToolTip applies to.

The tool tip is destroyed automatically when the parent widget is destroyed.

See also group().

void QToolTip::remove ( QWidget*widget ) [static]

Removes the tool tip from widget.

If there is more than one tool tip on widget, only the one covering the entire widget is removed.

void QToolTip::remove ( QWidget*widget, constQRect&rect ) [static]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Removes the tool tip for rect from widget.

If there is more than one tool tip on widget, only the one covering rectangle rect is removed.

void QToolTip::setEnabled ( boolenable ) [static]

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

void QToolTip::setFont ( constQFont&font ) [static]

Sets the font for all tool tips to font.

See also font().

void QToolTip::setGloballyEnabled ( boolenable ) [static]

If enable is TRUE sets all tool tips to be enabled (shown when needed); if enable is FALSE sets all tool tips to be disabled (never shown).

By default, tool tips are enabled. Note that this function affects all tool tips in the entire application.

See also QToolTipGroup::enabled.

void QToolTip::setPalette ( constQPalette&palette ) [static]

Sets the palette for all tool tips to palette.

See also palette().

QString QToolTip::textFor ( QWidget*widget, constQPoint&pos = QPoint ( ) ) [static]

Returns the text for widget at position pos, or a null string if there is no tool tip for the widget.

void QToolTip::tip ( constQRect&rect, constQString&text ) [protected]

Immediately pops up a tip saying text and removes the tip once the cursor moves out of rectangle rect (which is given in the coordinate system of the widget this QToolTip relates to).

The tip will not reappear if the cursor moves back; your maybeTip() has to reinstate it each time.

void QToolTip::tip ( constQRect&rect, constQString&text, constQString&groupText ) [protected]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Immediately pops up a tip saying text and removes that tip once the cursor moves out of rectangle rect. groupText is the text emitted from the group.

The tip will not reappear if the cursor moves back; your maybeTip() has to reinstate it each time.