QSplitter Class Reference

The QSplitter class implements a splitter widget. More...

 #include <QSplitter>

Inherits: QFrame.


  • 6 properties inherited from QFrame
  • 58 properties inherited from QWidget
  • 1 property inherited from QObject

Public Functions

QSplitter ( QWidget * parent = 0 )
QSplitter ( Qt::Orientation orientation, QWidget * parent = 0 )
~QSplitter ()
void addWidget ( QWidget * widget )
bool childrenCollapsible () const
int count () const
void getRange ( int index, int * min, int * max ) const
QSplitterHandle * handle ( int index ) const
int handleWidth () const
int indexOf ( QWidget * widget ) const
void insertWidget ( int index, QWidget * widget )
bool isCollapsible ( int index ) const
bool opaqueResize () const
Qt::Orientation orientation () const
void refresh ()
bool restoreState ( const QByteArray & state )
QByteArray saveState () const
void setChildrenCollapsible ( bool )
void setCollapsible ( int index, bool collapse )
void setHandleWidth ( int )
void setOpaqueResize ( bool opaque = true )
void setOrientation ( Qt::Orientation )
void setSizes ( const QList<int> & list )
void setStretchFactor ( int index, int stretch )
QList<int> sizes () const
QWidget * widget ( int index ) const

Reimplemented Public Functions

virtual QSize minimumSizeHint () const
virtual QSize sizeHint () const
  • 14 public functions inherited from QFrame
  • 221 public functions inherited from QWidget
  • 29 public functions inherited from QObject
  • 13 public functions inherited from QPaintDevice


void splitterMoved ( int pos, int index )

Protected Functions

int closestLegalPosition ( int pos, int index )
virtual QSplitterHandle * createHandle ()
void moveSplitter ( int pos, int index )
void setRubberBand ( int pos )

Reimplemented Protected Functions

virtual void changeEvent ( QEvent * ev )
virtual void childEvent ( QChildEvent * c )
virtual bool event ( QEvent * e )
virtual void resizeEvent ( QResizeEvent * )
  • 3 protected functions inherited from QFrame
  • 37 protected functions inherited from QWidget
  • 8 protected functions inherited from QObject
  • 1 protected function inherited from QPaintDevice

Additional Inherited Members

  • 19 public slots inherited from QWidget
  • 1 public slot inherited from QObject
  • 4 static public members inherited from QWidget
  • 7 static public members inherited from QObject
  • 1 protected slot inherited from QWidget

Detailed Description

The QSplitter class implements a splitter widget.

A splitter lets the user control the size of child widgets by dragging the boundary between the children. Any number of widgets may be controlled by a single splitter. The typical use of a QSplitter is to create several widgets and add them using insertWidget() or addWidget().

The following example will show a QListView, QTreeView, and QTextEdit side by side, with two splitter handles:

     QSplitter *splitter = new QSplitter(parent);
     QListView *listview = new QListView;
     QTreeView *treeview = new QTreeView;
     QTextEdit *textedit = new QTextEdit;

If a widget is already inside a QSplitter when insertWidget() or addWidget() is called, it will move to the new position. This can be used to reorder widgets in the splitter later. You can use indexOf(), widget(), and count() to get access to the widgets inside the splitter.

A default QSplitter lays out its children horizontally (side by side); you can use setOrientation(Qt::Vertical) to lay its children out vertically.

By default, all widgets can be as large or as small as the user wishes, between the minimumSizeHint() (or minimumSize()) and maximumSize() of the widgets.

QSplitter resizes its children dynamically by default. If you would rather have QSplitter resize the children only at the end of a resize operation, call setOpaqueResize(false).

The initial distribution of size between the widgets is determined by multiplying the initial size with the stretch factor. You can also use setSizes() to set the sizes of all the widgets. The function sizes() returns the sizes set by the user. Alternatively, you can save and restore the sizes of the widgets from a QByteArray using saveState() and restoreState() respectively.

When you hide() a child its space will be distributed among the other children. It will be reinstated when you show() it again.

See also QSplitterHandle, QHBoxLayout, QVBoxLayout, and QTabWidget.

Property Documentation

childrenCollapsible : bool

This property holds whether child widgets can be resized down to size 0 by the user.

By default, children are collapsible. It is possible to enable and disable the collapsing of individual children using setCollapsible().

Access functions:

bool childrenCollapsible () const
void setChildrenCollapsible ( bool )

See also setCollapsible().

handleWidth : int

This property holds the width of the splitter handles.

By default, this property contains a value that depends on the user's platform and style preferences.

If you set handleWidth to 1, the actual grab area will grow to overlap a few pixels of it's respective widgets.

Access functions:

int handleWidth () const
void setHandleWidth ( int )

opaqueResize : bool

This property holds whether resizing is opaque.

Opaque resizing is on by default.

Access functions:

bool opaqueResize () const
void setOpaqueResize ( bool opaque = true )

orientation : Qt::Orientation

This property holds the orientation of the splitter.

By default the orientation is horizontal (i.e., the widgets are laid out side by side). The possible orientations are Qt::Horizontal and Qt::Vertical.

Access functions:

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

See also QSplitterHandle::orientation().

Member Function Documentation

QSplitter::QSplitter ( QWidget * parent = 0 )

Constructs a horizontal splitter with the parent argument passed on to the QFrame constructor.

See also setOrientation().

QSplitter::QSplitter ( Qt::Orientation orientation, QWidget * parent = 0 )

Constructs a splitter with the given orientation and parent.

See also setOrientation().

QSplitter::~QSplitter ()

Destroys the splitter. All children are deleted.

void QSplitter::addWidget ( QWidget * widget )

Adds the given widget to the splitter's layout after all the other items.

If widget is already in the splitter, it will be moved to the new position.

See also insertWidget(), widget(), and indexOf().

void QSplitter::changeEvent ( QEvent * ev ) [virtual protected]

Reimplemented from QWidget::changeEvent().

void QSplitter::childEvent ( QChildEvent * c ) [virtual protected]

Reimplemented from QObject::childEvent().

Tells the splitter that the child widget described by c has been inserted or removed.

This method is also used to handle the situation where a widget is created with the splitter as a parent but not explicitly added with insertWidget() or addWidget(). This is for compatibility and not the recommended way of putting widgets into a splitter in new code. Please use insertWidget() or addWidget() in new code.

See also addWidget() and insertWidget().

int QSplitter::closestLegalPosition ( int pos, int index ) [protected]

Returns the closest legal position to pos of the widget with index index.

For right-to-left languages such as Arabic and Hebrew, the layout of horizontal splitters is reversed. Positions are then measured from the right edge of the widget.

See also getRange().

int QSplitter::count () const

Returns the number of widgets contained in the splitter's layout.

See also widget() and handle().

QSplitterHandle * QSplitter::createHandle () [virtual protected]

Returns a new splitter handle as a child widget of this splitter. This function can be reimplemented in subclasses to provide support for custom handles.

See also handle() and indexOf().

bool QSplitter::event ( QEvent * e ) [virtual protected]

Reimplemented from QObject::event().

void QSplitter::getRange ( int index, int * min, int * max ) const

Returns the valid range of the splitter with index index in *min and *max if min and max are not 0.

QSplitterHandle * QSplitter::handle ( int index ) const

Returns the handle to the left (or above) for the item in the splitter's layout at the given index. The handle at index 0 is always hidden.

For right-to-left languages such as Arabic and Hebrew, the layout of horizontal splitters is reversed. The handle will be to the right of the widget at index.

See also count(), widget(), indexOf(), createHandle(), and setHandleWidth().

int QSplitter::indexOf ( QWidget * widget ) const

Returns the index in the splitter's layout of the specified widget. This also works for handles.

Handles are numbered from 0. There are as many handles as there are child widgets, but the handle at position 0 is always hidden.

See also count() and widget().

void QSplitter::insertWidget ( int index, QWidget * widget )

Inserts the widget specified into the splitter's layout at the given index.

If widget is already in the splitter, it will be moved to the new position.

if index is an invalid index, then the widget will be inserted at the end.

See also addWidget(), indexOf(), and widget().

bool QSplitter::isCollapsible ( int index ) const

Returns true if the widget at index is collapsible, otherwise returns false

QSize QSplitter::minimumSizeHint () const [virtual]

Reimplemented from QWidget::minimumSizeHint().

void QSplitter::moveSplitter ( int pos, int index ) [protected]

Moves the left or top edge of the splitter handle at index as close as possible to position pos, which is the distance from the left or top edge of the widget.

For right-to-left languages such as Arabic and Hebrew, the layout of horizontal splitters is reversed. pos is then the distance from the right edge of the widget.

See also splitterMoved(), closestLegalPosition(), and getRange().

void QSplitter::refresh ()

Updates the splitter's state. You should not need to call this function.

void QSplitter::resizeEvent ( QResizeEvent * ) [virtual protected]

Reimplemented from QWidget::resizeEvent().

bool QSplitter::restoreState ( const QByteArray & state )

Restores the splitter's layout to the state specified. Returns true if the state is restored; otherwise returns false.

Typically this is used in conjunction with QSettings to restore the size from a past session. Here is an example:

Restore the splitters's state:

     QSettings settings;

A failure to restore the splitter's layout may result from either invalid or out-of-date data in the supplied byte array.

See also saveState().

QByteArray QSplitter::saveState () const

Saves the state of the splitter's layout.

Typically this is used in conjunction with QSettings to remember the size for a future session. A version number is stored as part of the data. Here is an example:

     QSettings settings;
     settings.setValue("splitterSizes", splitter->saveState());

See also restoreState().

void QSplitter::setCollapsible ( int index, bool collapse )

Sets whether the child widget at index index is collapsible to collapse.

By default, children are collapsible, meaning that the user can resize them down to size 0, even if they have a non-zero minimumSize() or minimumSizeHint(). This behavior can be changed on a per-widget basis by calling this function, or globally for all the widgets in the splitter by setting the childrenCollapsible property.

See also isCollapsible() and childrenCollapsible.

void QSplitter::setRubberBand ( int pos ) [protected]

Displays a rubber band at position pos. If pos is negative, the rubber band is removed.

void QSplitter::setSizes ( const QList<int> & list )

Sets the child widgets respective sizes to the values given in the list.

If the splitter is horizontal, the values set the widths of each widget in pixels, from left to right. If the splitter is vertical, the heights of each widget is set, from top to bottom.

Extra values in the list are ignored. If list contains too few values, the result is undefined but the program will still be well-behaved.

The overall size of the splitter widget is not affected. Instead, any additional/missing space is distributed amongst the widgets according to the relative weight of the sizes.

If you specify a size of 0, the widget will be invisible. The size policies of the widgets are preserved. That is, a value smaller then the minimal size hint of the respective widget will be replaced by the value of the hint.

See also sizes().

void QSplitter::setStretchFactor ( int index, int stretch )

Updates the size policy of the widget at position index to have a stretch factor of stretch.

stretch is not the effective stretch factor; the effective stretch factor is calculated by taking the initial size of the widget and multiplying it with stretch.

This function is provided for convenience. It is equivalent to

 QWidget *widget = splitter->widget(index);
 QSizePolicy policy = widget->sizePolicy();

See also setSizes() and widget().

QSize QSplitter::sizeHint () const [virtual]

Reimplemented from QWidget::sizeHint().

QList<int> QSplitter::sizes () const

Returns a list of the size parameters of all the widgets in this splitter.

If the splitter's orientation is horizontal, the list contains the widgets width in pixels, from left to right; if the orientation is vertical, the list contains the widgets height in pixels, from top to bottom.

Giving the values to another splitter's setSizes() function will produce a splitter with the same layout as this one.

Note that invisible widgets have a size of 0.

See also setSizes().

void QSplitter::splitterMoved ( int pos, int index ) [signal]

This signal is emitted when the splitter handle at a particular index has been moved to position pos.

For right-to-left languages such as Arabic and Hebrew, the layout of horizontal splitters is reversed. pos is then the distance from the right edge of the widget.

See also moveSplitter().

QWidget * QSplitter::widget ( int index ) const

Returns the widget at the given index in the splitter's layout.

See also count(), handle(), indexOf(), and insertWidget().

Notes provided by the Qt Community
  • 5

Votes: 1

Coverage: Qt library 4.7, 4.8, qt 5.0

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Lab Rat
3 notes

Layout in QSplitter

There is potential pitfall with layouts in in QSplitter, resulting to high CPU usage and possibly UI unresposiveness.

Avoid this:

  1. QSplitter *parent = new QSplitter();
  2. QHBoxLayout *parentLayout = new QHBoxLayout();
  3. parent->setLayout(parentLayout);
  4. QTabWidget *tabWidget = new QTabWidget();
  5. parentLayout->addWidget(tabWidget);
  7. setCentralWidget(parent);

but instead use:

  1. QSplitter *parent = new QSplitter();
  2. QWidget *widget = new QWidget();
  3. QHBoxLayout *parentLayout = new QHBoxLayout();
  4. widget->setLayout(parentLayout);
  5. parent->addWidget(widget);
  6. QTabWidget *tabWidget = new QTabWidget();
  7. parentLayout->addWidget(tabWidget);
  9. setCentralWidget(parent);