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# QHeader Class Reference

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

`#include <qheader.h>`

Inherits QWidget.

List of all member functions.

## Public Members

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

## Public Slots

- virtual void setOffset ( int pos )

## Signals

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

## Properties

- int count - the number of sections in the header (read only)
- bool moving - whether the header sections can be moved
- int offset - the header's left-most (or top-most) visible pixel
- Orientation orientation - the header's orientation
- bool stretching - whether the header sections always take up the full width (or height) of the header
- bool tracking - whether the sizeChange() signal is emitted continuously

## Protected Members

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

## Detailed Description

The QHeader 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 QTable and QListView for example.

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

Sections are added with addLabel() and removed with removeLabel(). The label and iconset 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 QHeader 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.

QHeader 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 QListView, QTable, and Advanced Widgets.

## Member Function Documentation

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

Constructs a horizontal header called name, with parent parent.

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

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

### QHeader::~QHeader ()

Destroys the header and all its sections.

### int QHeader::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 QHeader::addLabel ( const QIconSet & iconset, 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 iconset iconset 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 QHeader::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 QHeader::cellAt ( int pos ) const

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

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 QHeader::cellPos ( int i ) const

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

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 QHeader::cellSize ( int i ) const

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

Use sectionSize() instead.

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

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

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

See also pressed() and released().

### int QHeader::count () const

Returns the number of sections in the header. See the "count" property for details.

### int QHeader::headerWidth () const

Returns the total width of all the header columns.

### QIconSet * QHeader::iconSet ( int section ) const

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

### void QHeader::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 QHeader::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 QHeader::isMovingEnabled () const

Returns TRUE if the header sections can be moved; otherwise returns FALSE. See the "moving" property for details.

### bool QHeader::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().

### bool QHeader::isStretchEnabled () const

Returns TRUE if the header sections always take up the full width (or height) of the header; otherwise returns FALSE. See the "stretching" property for details.

### bool QHeader::isStretchEnabled ( int section ) const

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

Returns TRUE if section section will resize to take up the full width (or height) of the header; otherwise returns FALSE. If at least one section has stretch enabled the sections will always take up the full width of the header.

See also setStretchEnabled().

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

Returns the text for section section. If the section does not exist, a QString::null is returned.

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

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

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 QHeader::mapToIndex ( int section ) const

Returns the index position at which section section is displayed.

For more explanation see the mapTo example.

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

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

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 QHeader::mapToSection ( int index ) const

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

For more explanation see the mapTo example.

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

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

Use moveSection() instead.

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

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

Moves section section to index position toIndex.

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

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

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.

### int QHeader::offset () const

Returns the header's left-most (or top-most) visible pixel. See the "offset" property for details.

### Orientation QHeader::orientation () const

Returns the header's orientation. See the "orientation" property for details.

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

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

See also released().

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

This signal is emitted when section section is released.

See also pressed().

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

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

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

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

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

Returns the rectangle covered by the section at index index.

### int QHeader::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 QHeader::sectionClicked ( int index )`[signal]`

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

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).

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

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

See also offset.

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

Returns the rectangle covered by section section.

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

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

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

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

Use resizeSection() instead.

Sets the size of the section section to s pixels.

Warning: does not repaint or send out signals

### void QHeader::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 moving and setResizeEnabled().

### void QHeader::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.

Examples: chart/setdataform.cpp and table/small-table-demo/main.cpp.

### void QHeader::setLabel ( int section, const QIconSet & iconset, 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 iconset 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 QHeader::setMovingEnabled ( bool )`[virtual]`

Sets whether the header sections can be moved. See the "moving" property for details.

### void QHeader::setOffset ( int pos )`[virtual slot]`

Sets the header's left-most (or top-most) visible pixel to pos. See the "offset" property for details.

### void QHeader::setOrientation ( Orientation )`[virtual]`

Sets the header's orientation. See the "orientation" property for details.

### void QHeader::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 moving, setClickEnabled(), and tracking.

### void QHeader::setSortIndicator ( int section, bool increasing = TRUE )

Because the QHeader is often used in conjunction with table and list widgets, QHeader can indicate a sort order. This is achieved by displaying an arrow at the right edge of a section.

If increasing is TRUE (the default) the arrow will point downwards; otherwise it will point upwards.

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.

### void QHeader::setStretchEnabled ( bool b, int section )`[virtual]`

If b is TRUE, section section will be resized when the header is resized, so that the sections take up the full width (or height for vertical headers) of the header; otherwise section section will be set to be unstretchable and will not resize when the header is resized.

If section is -1, and if b is TRUE, then all sections will be resized equally when the header is resized so that they take up the full width (or height for vertical headers) of the header; otherwise all the sections will be set to be unstretchable and will not resize when the header is resized.

See also adjustHeaderSize().

### void QHeader::setStretchEnabled ( bool b )

Sets whether the header sections always take up the full width (or height) of the header to b. See the "stretching" property for details.

### void QHeader::setTracking ( bool enable )`[virtual]`

Sets whether the sizeChange() signal is emitted continuously to enable. See the "tracking" property for details.

### void QHeader::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.

### bool QHeader::tracking () const

Returns TRUE if the sizeChange() signal is emitted continuously; otherwise returns FALSE. See the "tracking" property for details.

## Property Documentation

### int count

This property holds the number of sections in the header.

Get this property's value with count().

### bool moving

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.

See also setClickEnabled() and setResizeEnabled().

Set this property's value with setMovingEnabled() and get this property's value with isMovingEnabled().

### int offset

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.

Set this property's value with setOffset() and get this property's value with offset().

### Orientation orientation

This property holds the header's orientation.

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

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

Set this property's value with setOrientation() and get this property's value with orientation().

### bool stretching

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

Set this property's value with setStretchEnabled() and get this property's value with isStretchEnabled().

### bool tracking

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.

Set this property's value with setTracking() and get this property's value with tracking().

This file is part of the Qt toolkit. Copyright © 1995-2003 Trolltech. All Rights Reserved.