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# Q3Header Class Reference
[Qt3Support module]

The Q3Header class provides a header row or column, e.g. for tables and listviews. More...

    #include <Q3Header>

This class is part of the Qt 3 support library. It is provided to keep old source code working. We strongly advise against using it in new code. See Porting to Qt 4 for more information.

Inherits QWidget.

- List of all members, including inherited members

### Properties

count : const int moving : bool offset : int | orientation : Qt::Orientation stretching : bool tracking : bool

- 54 properties inherited from QWidget
- 1 property inherited from QObject

### Public Functions

- Q3Header ( QWidget * parent = 0, const char * name = 0 )
- Q3Header ( int n, QWidget * parent = 0, const char * name = 0 )
- ~Q3Header ()
- int addLabel ( const QString & s, int size = -1 )
- int addLabel ( const QIcon & icon, const QString & s, int size = -1 )
- void adjustHeaderSize ()
- int cellAt ( int pos ) const
- int cellPos ( int i ) const
- int cellSize ( int i ) const
- int count () const
- int headerWidth () const
- QIcon * iconSet ( int section ) const
- bool isClickEnabled ( int section = -1 ) const
- bool isMovingEnabled () const
- bool isResizeEnabled ( int section = -1 ) const
- bool isStretchEnabled () const
- bool isStretchEnabled ( int section ) const
- QString label ( int section ) const
- int mapToActual ( int l ) const
- int mapToIndex ( int section ) const
- int mapToLogical ( int a ) const
- int mapToSection ( int index ) const
- virtual void moveCell ( int fromIdx, int toIdx )
- void moveSection ( int section, int toIndex )
- int offset () const
- Qt::Orientation orientation () const
- void removeLabel ( int section )
- void resizeSection ( int section, int s )
- int sectionAt ( int pos ) const
- int sectionPos ( int section ) const
- QRect sectionRect ( int section ) const
- int sectionSize ( int section ) const
- virtual void setCellSize ( int section, int s )
- virtual void setClickEnabled ( bool enable, int section = -1 )
- virtual void setLabel ( int section, const QString & s, int size = -1 )
- virtual void setLabel ( int section, const QIcon & icon, const QString & s, int size = -1 )
- virtual void setMovingEnabled ( bool )
- virtual void setOrientation ( Qt::Orientation )
- virtual void setResizeEnabled ( bool enable, int section = -1 )
- void setSortIndicator ( int section, Qt::SortOrder order )
- void setSortIndicator ( int section, bool ascending = true )
- virtual void setStretchEnabled ( bool b, int section )
- void setStretchEnabled ( bool b )
- virtual void setTracking ( bool enable )
- Qt::SortOrder sortIndicatorOrder () const
- int sortIndicatorSection () const
- bool tracking () const

- 188 public functions inherited from QWidget
- 28 public functions inherited from QObject
- 10 public functions inherited from QPaintDevice

### Public Slots

- virtual void setOffset ( int pos )

- 17 public slots inherited from QWidget
- 1 public slot inherited from QObject

### Signals

- void clicked ( int section )
- void indexChange ( int section, int fromIndex, int toIndex )
- void moved ( int fromIndex, int toIndex )
- void pressed ( int section )
- void released ( int section )
- void sectionClicked ( int index )
- void sectionHandleDoubleClicked ( int section )
- void sizeChange ( int section, int oldSize, int newSize )

- 1 signal inherited from QWidget
- 1 signal inherited from QObject

### Protected Functions

- virtual void paintSection ( QPainter * p, int index, const QRect & fr )
- virtual void paintSectionLabel ( QPainter * p, int index, const QRect & fr )
- QRect sRect ( int index )

- 39 protected functions inherited from QWidget
- 7 protected functions inherited from QObject

### Additional Inherited Members

- 4 static public members inherited from QWidget
- 4 static public members inherited from QObject

## Detailed Description

The Q3Header class provides a header row or column, e.g. for tables and listviews.

This class provides a header, e.g. a vertical header to display row labels, or a horizontal header to display column labels. It is used by Q3Table and Q3ListView for example.

A header is composed of one or more sections, each of which can display a text label and an icon. A sort indicator (an arrow) can also be displayed using setSortIndicator().

Sections are added with addLabel() and removed with removeLabel(). The label and icon are set in addLabel() and can be changed later with setLabel(). Use count() to retrieve the number of sections in the header.

The orientation of the header is set with setOrientation(). If setStretchEnabled() is true, the sections will expand to take up the full width (height for vertical headers) of the header. The user can resize the sections manually if setResizeEnabled() is true. Call adjustHeaderSize() to have the sections resize to occupy the full width (or height).

A section can be moved with moveSection(). If setMovingEnabled() is true (the default)the user may drag a section from one position to another. If a section is moved, the index positions at which sections were added (with addLabel()), may not be the same after the move. You don't have to worry about this in practice because the Q3Header API works in terms of section numbers, so it doesn't matter where a particular section has been moved to.

If you want the current index position of a section call mapToIndex() giving it the section number. (This is the number returned by the addLabel() call which created the section.) If you want to get the section number of a section at a particular index position call mapToSection() giving it the index number.

Here's an example to clarify mapToSection() and mapToIndex():

Index positions
0 | 1 | 2 | 3
Original section ordering
Sect 0 | Sect 1 | Sect 2 | Sect 3
Ordering after the user moves a section
Sect 0 | Sect 2 | Sect 3 | Sect 1

k | mapToSection(k) | mapToIndex(k)
--- | --- | ---
0 | 0 | 0
1 | 2 | 3
2 | 3 | 1
3 | 1 | 2

In the example above, if we wanted to find out which section is at index position 3 we'd call mapToSection(3) and get a section number of 1 since section 1 was moved. Similarly, if we wanted to know which index position section 2 occupied we'd call mapToIndex(2) and get an index of 1.

Q3Header provides the clicked(), pressed() and released() signals. If the user changes the size of a section, the sizeChange() signal is emitted. If you want to have a sizeChange() signal emitted continuously whilst the user is resizing (rather than just after the resizing is finished), use setTracking(). If the user moves a section the indexChange() signal is emitted.

See also Q3ListView and Q3Table.

## Property Documentation

### count : const int

This property holds the number of sections in the header.

Access functions:

- int count () const

### moving : bool

This property holds whether the header sections can be moved.

If this property is true (the default) the user can move sections. If the user moves a section the indexChange() signal is emitted.

Access functions:

- bool isMovingEnabled () const
- virtual void setMovingEnabled ( bool )

See also setClickEnabled() and setResizeEnabled().

### offset : int

This property holds the header's left-most (or top-most) visible pixel.

Setting this property will scroll the header so that offset becomes the left-most (or top-most for vertical headers) visible pixel.

Access functions:

- int offset () const
- virtual void setOffset ( int pos )

### orientation : Qt::Orientation

This property holds the header's orientation.

The orientation is either Qt::Vertical or Qt::Horizontal (the default).

Call setOrientation() before adding labels if you don't provide a size parameter otherwise the sizes will be incorrect.

Access functions:

- Qt::Orientation orientation () const
- virtual void setOrientation ( Qt::Orientation )

### stretching : bool

This property holds whether the header sections always take up the full width (or height) of the header.

Access functions:

- bool isStretchEnabled () const
- bool isStretchEnabled ( int section ) const
- virtual void setStretchEnabled ( bool b, int section )
- void setStretchEnabled ( bool b )

### tracking : bool

This property holds whether the sizeChange() signal is emitted continuously.

If tracking is on, the sizeChange() signal is emitted continuously while the mouse is moved (i.e. when the header is resized), otherwise it is only emitted when the mouse button is released at the end of resizing.

Tracking defaults to false.

Access functions:

- bool tracking () const
- virtual void setTracking ( bool enable )

## Member Function Documentation

### Q3Header::Q3Header ( QWidget * parent = 0, const char * name = 0 )

Constructs a horizontal header called name, with parent parent.

### Q3Header::Q3Header ( int n, QWidget * parent = 0, const char * name = 0 )

Constructs a horizontal header called name, with n sections and parent parent.

### Q3Header::~Q3Header ()

Destroys the header and all its sections.

### int Q3Header::addLabel ( const QString & s, int size = -1 )

Adds a new section with label text s. Returns the index position where the section was added (at the right for horizontal headers, at the bottom for vertical headers). The section's width is set to size. If size < 0, an appropriate size for the text s is chosen.

### int Q3Header::addLabel ( const QIcon & icon, const QString & s, int size = -1 )

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

Adds a new section with icon icon and label text s. Returns the index position where the section was added (at the right for horizontal headers, at the bottom for vertical headers). The section's width is set to size, unless size is negative in which case the size is calculated taking account of the size of the text.

### void Q3Header::adjustHeaderSize ()

Adjusts the size of the sections to fit the size of the header as completely as possible. Only sections for which isStretchEnabled() is true will be resized.

### int Q3Header::cellAt ( int pos ) const

Use sectionAt() instead.

Returns the index at which the section is displayed, which contains pos in widget coordinates, or -1 if pos is outside the header sections.

### int Q3Header::cellPos ( int i ) const

Use sectionPos() instead.

Returns the position in pixels of the section that is displayed at the index i. The position is measured from the start of the header.

### int Q3Header::cellSize ( int i ) const

Use sectionSize() instead.

Returns the size in pixels of the section that is displayed at the index i.

See also setCellSize().

### void Q3Header::clicked ( int section ) `[signal]`

If isClickEnabled() is true, this signal is emitted when the user clicks section section.

See also pressed() and released().

### int Q3Header::headerWidth () const

Returns the total width of all the header columns.

### QIcon * Q3Header::iconSet ( int section ) const

Returns the icon set for section section. If the section does not exist, 0 is returned.

### void Q3Header::indexChange ( int section, int fromIndex, int toIndex ) `[signal]`

This signal is emitted when the user moves section section from index position fromIndex, to index position toIndex.

### bool Q3Header::isClickEnabled ( int section = -1 ) const

Returns true if section section is clickable; otherwise returns false.

If section is out of range (negative or larger than count() - 1): returns true if all sections are clickable; otherwise returns false.

See also setClickEnabled().

### bool Q3Header::isResizeEnabled ( int section = -1 ) const

Returns true if section section is resizeable; otherwise returns false.

If section is -1 then this function applies to all sections, i.e. returns true if all sections are resizeable; otherwise returns false.

See also setResizeEnabled().

### QString Q3Header::label ( int section ) const

Returns the text for section section. If the section does not exist, returns an empty string.

See also setLabel().

### int Q3Header::mapToActual ( int l ) const

Use mapToIndex() instead.

Translates from logical index l to actual index (index at which the section l is displayed) . Returns -1 if l is outside the legal range.

See also mapToLogical().

### int Q3Header::mapToIndex ( int section ) const

Returns the index position at which section section is displayed.

### int Q3Header::mapToLogical ( int a ) const

Use mapToSection() instead.

Translates from actual index a (index at which the section is displayed) to logical index of the section. Returns -1 if a is outside the legal range.

See also mapToActual().

### int Q3Header::mapToSection ( int index ) const

Returns the number of the section that is displayed at index position index.

### void Q3Header::moveCell ( int fromIdx, int toIdx ) `[virtual]`

Use moveSection() instead.

Moves the section that is currently displayed at index fromIdx to index toIdx.

### void Q3Header::moveSection ( int section, int toIndex )

Moves section section to index position toIndex.

### void Q3Header::moved ( int fromIndex, int toIndex ) `[signal]`

Use indexChange() instead.

This signal is emitted when the user has moved the section which is displayed at the index fromIndex to the index toIndex.

### void Q3Header::paintSection ( QPainter * p, int index, const QRect & fr ) `[virtual protected]`

Paints the section at position index, inside rectangle fr (which uses widget coordinates) using painter p.

Calls paintSectionLabel().

### void Q3Header::paintSectionLabel ( QPainter * p, int index, const QRect & fr ) `[virtual protected]`

Paints the label of the section at position index, inside rectangle fr (which uses widget coordinates) using painter p.

Called by paintSection()

### void Q3Header::pressed ( int section ) `[signal]`

This signal is emitted when the user presses section section down.

See also released().

### void Q3Header::released ( int section ) `[signal]`

This signal is emitted when section section is released.

See also pressed().

### void Q3Header::removeLabel ( int section )

Removes section section. If the section does not exist, nothing happens.

### void Q3Header::resizeSection ( int section, int s )

Resizes section section to s pixels wide (or high).

### QRect Q3Header::sRect ( int index ) `[protected]`

Returns the rectangle covered by the section at index index.

### int Q3Header::sectionAt ( int pos ) const

Returns the index of the section which contains the position pos given in pixels from the left (or top).

See also offset().

### void Q3Header::sectionClicked ( int index ) `[signal]`

Use clicked() instead.

This signal is emitted when a part of the header is clicked. index is the index at which the section is displayed.

In a list view this signal would typically be connected to a slot that sorts the specified column (or row).

### void Q3Header::sectionHandleDoubleClicked ( int section ) `[signal]`

This signal is emitted when the user doubleclicks on the edge (handle) of section section.

### int Q3Header::sectionPos ( int section ) const

Returns the position (in pixels) at which the section starts.

See also offset().

### QRect Q3Header::sectionRect ( int section ) const

Returns the rectangle covered by section section.

### int Q3Header::sectionSize ( int section ) const

Returns the width (or height) of the section in pixels.

### void Q3Header::setCellSize ( int section, int s ) `[virtual]`

Use resizeSection() instead.

Sets the size of the section section to s pixels.

Warning: does not repaint or send out signals

See also cellSize().

### void Q3Header::setClickEnabled ( bool enable, int section = -1 ) `[virtual]`

If enable is true, any clicks on section section will result in clicked() signals being emitted; otherwise the section will ignore clicks.

If section is -1 (the default) then the enable value is set for all existing sections and will be applied to any new sections that are added.

See also isClickEnabled(), setMovingEnabled(), and setResizeEnabled().

### void Q3Header::setLabel ( int section, const QString & s, int size = -1 ) `[virtual]`

Sets the text of section section to s. The section's width is set to size if size >= 0; otherwise it is left unchanged. Any icon set that has been set for this section remains unchanged.

If the section does not exist, nothing happens.

See also label().

### void Q3Header::setLabel ( int section, const QIcon & icon, const QString & s, int size = -1 ) `[virtual]`

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

Sets the icon for section section to icon and the text to s. The section's width is set to size if size >= 0; otherwise it is left unchanged.

If the section does not exist, nothing happens.

### void Q3Header::setResizeEnabled ( bool enable, int section = -1 ) `[virtual]`

If enable is true the user may resize section section; otherwise the section may not be manually resized.

If section is negative (the default) then the enable value is set for all existing sections and will be applied to any new sections that are added. Example:

        // Allow resizing of all current and future sections
        header->setResizeEnabled(true);
        // Disable resizing of section 3, (the fourth section added)
        header->setResizeEnabled(false, 3);

If the user resizes a section, a sizeChange() signal is emitted.

See also isResizeEnabled(), setMovingEnabled(), setClickEnabled(), and setTracking().

### void Q3Header::setSortIndicator ( int section, Qt::SortOrder order )

Sets a sort indicator onto the specified section. The indicator's order is either Ascending or Descending.

Only one section can show a sort indicator at any one time. If you don't want any section to show a sort indicator pass a section number of -1.

See also sortIndicatorSection() and sortIndicatorOrder().

### void Q3Header::setSortIndicator ( int section, bool ascending = true )

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

Sets the sort indicator to ascending. Use the other overload instead.

### void Q3Header::sizeChange ( int section, int oldSize, int newSize ) `[signal]`

This signal is emitted when the user has changed the size of a section from oldSize to newSize. This signal is typically connected to a slot that repaints the table or list that contains the header.

### Qt::SortOrder Q3Header::sortIndicatorOrder () const

Returns the implied sort order of the Q3Headers sort indicator.

See also setSortIndicator() and sortIndicatorSection().

### int Q3Header::sortIndicatorSection () const

Returns the section showing the sort indicator or -1 if there is no sort indicator.

See also setSortIndicator() and sortIndicatorOrder().