QTreeView Class

The QTreeView class provides a default model/view implementation of a tree view. More...

Header:	#include <QTreeView>
qmake:	QT += widgets
Inherits:	QAbstractItemView
Inherited By:	QTreeWidget

• List of all members, including inherited members
• Obsolete members

Properties

allColumnsShowFocus : bool animated : bool autoExpandDelay : int expandsOnDoubleClick : bool headerHidden : bool indentation : int

itemsExpandable : bool rootIsDecorated : bool sortingEnabled : bool uniformRowHeights : bool wordWrap : bool

Public Functions

	QTreeView(QWidget *parent = nullptr)
virtual	~QTreeView()
bool	allColumnsShowFocus() const
int	autoExpandDelay() const
int	columnAt(int x) const
int	columnViewportPosition(int column) const
int	columnWidth(int column) const
bool	expandsOnDoubleClick() const
QHeaderView *	header() const
int	indentation() const
QModelIndex	indexAbove(const QModelIndex &index) const
QModelIndex	indexBelow(const QModelIndex &index) const
bool	isAnimated() const
bool	isColumnHidden(int column) const
bool	isExpanded(const QModelIndex &index) const
bool	isFirstColumnSpanned(int row, const QModelIndex &parent) const
bool	isHeaderHidden() const
bool	isRowHidden(int row, const QModelIndex &parent) const
bool	isSortingEnabled() const
bool	itemsExpandable() const
void	resetIndentation()
bool	rootIsDecorated() const
void	setAllColumnsShowFocus(bool enable)
void	setAnimated(bool enable)
void	setAutoExpandDelay(int delay)
void	setColumnHidden(int column, bool hide)
void	setColumnWidth(int column, int width)
void	setExpanded(const QModelIndex &index, bool expanded)
void	setExpandsOnDoubleClick(bool enable)
void	setFirstColumnSpanned(int row, const QModelIndex &parent, bool span)
void	setHeader(QHeaderView *header)
void	setHeaderHidden(bool hide)
void	setIndentation(int i)
void	setItemsExpandable(bool enable)
void	setRootIsDecorated(bool show)
void	setRowHidden(int row, const QModelIndex &parent, bool hide)
void	setSortingEnabled(bool enable)
void	setTreePosition(int index)
void	setUniformRowHeights(bool uniform)
void	setWordWrap(bool on)
int	treePosition() const
bool	uniformRowHeights() const
bool	wordWrap() const

Reimplemented Public Functions

virtual void	dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int>()) override
virtual QModelIndex	indexAt(const QPoint &point) const override
virtual void	keyboardSearch(const QString &search) override
virtual void	reset() override
virtual void	scrollTo(const QModelIndex &index, QAbstractItemView::ScrollHint hint = EnsureVisible) override
virtual void	selectAll() override
virtual void	setModel(QAbstractItemModel *model) override
virtual void	setRootIndex(const QModelIndex &index) override
virtual void	setSelectionModel(QItemSelectionModel *selectionModel) override
virtual QRect	visualRect(const QModelIndex &index) const override

Public Slots

void	collapse(const QModelIndex &index)
void	collapseAll()
void	expand(const QModelIndex &index)
void	expandAll()
void	expandRecursively(const QModelIndex &index, int depth = -1)
void	expandToDepth(int depth)
void	hideColumn(int column)
void	resizeColumnToContents(int column)
void	showColumn(int column)
void	sortByColumn(int column, Qt::SortOrder order)

Signals

void	collapsed(const QModelIndex &index)
void	expanded(const QModelIndex &index)

Protected Functions

virtual void	drawBranches(QPainter *painter, const QRect &rect, const QModelIndex &index) const
virtual void	drawRow(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
void	drawTree(QPainter *painter, const QRegion &region) const
int	indexRowSizeHint(const QModelIndex &index) const
int	rowHeight(const QModelIndex &index) const

Reimplemented Protected Functions

virtual void	currentChanged(const QModelIndex &current, const QModelIndex &previous) override
virtual void	dragMoveEvent(QDragMoveEvent *event) override
virtual int	horizontalOffset() const override
virtual bool	isIndexHidden(const QModelIndex &index) const override
virtual void	keyPressEvent(QKeyEvent *event) override
virtual void	mouseDoubleClickEvent(QMouseEvent *event) override
virtual void	mouseMoveEvent(QMouseEvent *event) override
virtual void	mousePressEvent(QMouseEvent *event) override
virtual void	mouseReleaseEvent(QMouseEvent *event) override
virtual QModelIndex	moveCursor(QAbstractItemView::CursorAction cursorAction, Qt::KeyboardModifiers modifiers) override
virtual void	paintEvent(QPaintEvent *event) override
virtual void	rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end) override
virtual void	rowsInserted(const QModelIndex &parent, int start, int end) override
virtual void	scrollContentsBy(int dx, int dy) override
virtual QModelIndexList	selectedIndexes() const override
virtual void	selectionChanged(const QItemSelection &selected, const QItemSelection &deselected) override
virtual void	setSelection(const QRect &rect, QItemSelectionModel::SelectionFlags command) override
virtual int	sizeHintForColumn(int column) const override
virtual void	timerEvent(QTimerEvent *event) override
virtual void	updateGeometries() override
virtual int	verticalOffset() const override
virtual bool	viewportEvent(QEvent *event) override
virtual QSize	viewportSizeHint() const override
virtual QRegion	visualRegionForSelection(const QItemSelection &selection) const override

Protected Slots

void	columnCountChanged(int oldCount, int newCount)
void	columnMoved()
void	columnResized(int column, int oldSize, int newSize)
void	rowsRemoved(const QModelIndex &parent, int start, int end)

Detailed Description

A QTreeView implements a tree representation of items from a model. This class is used to provide standard hierarchical lists that were previously provided by the QListView class, but using the more flexible approach provided by Qt's model/view architecture.

The QTreeView class is one of the Model/View Classes and is part of Qt's model/view framework.

QTreeView implements the interfaces defined by the QAbstractItemView class to allow it to display data provided by models derived from the QAbstractItemModel class.

It is simple to construct a tree view displaying data from a model. In the following example, the contents of a directory are supplied by a QFileSystemModel and displayed as a tree:

    QFileSystemModel *model = new QFileSystemModel;
    model->setRootPath(QDir::currentPath());
    QTreeView *tree = new QTreeView(splitter);
    tree->setModel(model);

The model/view architecture ensures that the contents of the tree view are updated as the model changes.

Items that have children can be in an expanded (children are visible) or collapsed (children are hidden) state. When this state changes a collapsed() or expanded() signal is emitted with the model index of the relevant item.

The amount of indentation used to indicate levels of hierarchy is controlled by the indentation property.

Headers in tree views are constructed using the QHeaderView class and can be hidden using header()->hide(). Note that each header is configured with its stretchLastSection property set to true, ensuring that the view does not waste any of the space assigned to it for its header. If this value is set to true, this property will override the resize mode set on the last section in the header.

By default, all columns in a tree view are movable except the first. To disable movement of these columns, use QHeaderView's setSectionsMovable() function. For more information about rearranging sections, see Moving Header Sections.

Key Bindings

QTreeView supports a set of key bindings that enable the user to navigate in the view and interact with the contents of items:

Key	Action
Up	Moves the cursor to the item in the same column on the previous row. If the parent of the current item has no more rows to navigate to, the cursor moves to the relevant item in the last row of the sibling that precedes the parent.
Down	Moves the cursor to the item in the same column on the next row. If the parent of the current item has no more rows to navigate to, the cursor moves to the relevant item in the first row of the sibling that follows the parent.
Left	Hides the children of the current item (if present) by collapsing a branch.
Minus	Same as Left.
Right	Reveals the children of the current item (if present) by expanding a branch.
Plus	Same as Right.
Asterisk	Expands the current item and all its children (if present).
PageUp	Moves the cursor up one page.
PageDown	Moves the cursor down one page.
Home	Moves the cursor to an item in the same column of the first row of the first top-level item in the model.
End	Moves the cursor to an item in the same column of the last row of the last top-level item in the model.
F2	In editable models, this opens the current item for editing. The Escape key can be used to cancel the editing process and revert any changes to the data displayed.

Improving Performance

It is possible to give the view hints about the data it is handling in order to improve its performance when displaying large numbers of items. One approach that can be taken for views that are intended to display items with equal heights is to set the uniformRowHeights property to true.

See also QListView, QTreeWidget, View Classes, QAbstractItemModel, QAbstractItemView, and Dir View Example.

Member Function Documentation

QTreeView::QTreeView(QWidget *parent = nullptr)

Constructs a tree view with a parent to represent a model's data. Use setModel() to set the model.

See also QAbstractItemModel.

[slot] void QTreeView::collapse(const QModelIndex &index)

Collapses the model item specified by the index.

See also collapsed().

[slot] void QTreeView::collapseAll()

Collapses all expanded items.

This function was introduced in Qt 4.2.

See also expandAll(), expand(), collapse(), and setExpanded().

[signal] void QTreeView::collapsed(const QModelIndex &index)

This signal is emitted when the item specified by index is collapsed.

[protected slot] void QTreeView::columnCountChanged(int oldCount, int newCount)

Informs the tree view that the number of columns in the tree view has changed from oldCount to newCount.

[protected slot] void QTreeView::columnMoved()

This slot is called whenever a column has been moved.

[protected slot] void QTreeView::columnResized(int column, int oldSize, int newSize)

This function is called whenever column's size is changed in the header. oldSize and newSize give the previous size and the new size in pixels.

See also setColumnWidth().

[slot] void QTreeView::expand(const QModelIndex &index)

Expands the model item specified by the index.

See also expanded().

[slot] void QTreeView::expandAll()

Expands all expandable items.

Warning: : if the model contains a large number of items, this function will take some time to execute.

This function was introduced in Qt 4.2.

See also collapseAll(), expand(), collapse(), and setExpanded().

[slot] void QTreeView::expandRecursively(const QModelIndex &index, int depth = -1)

Expands the item at the given index and all its children to the given depth. The depth is relative to the given index. A depth of -1 will expand all children, a depth of 0 will only expand the given index.

Warning: : if the model contains a large number of items, this function will take some time to execute.

This function was introduced in Qt 5.13.

See also expandAll().

[slot] void QTreeView::expandToDepth(int depth)

Expands all expandable items to the given depth.

This function was introduced in Qt 4.3.

See also expandAll(), collapseAll(), expand(), collapse(), and setExpanded().

[signal] void QTreeView::expanded(const QModelIndex &index)

This signal is emitted when the item specified by index is expanded.

See also setExpanded().

[slot] void QTreeView::hideColumn(int column)

Hides the column given.

Note: This function should only be called after the model has been initialized, as the view needs to know the number of columns in order to hide column.

See also showColumn() and setColumnHidden().

[slot] void QTreeView::resizeColumnToContents(int column)

Resizes the column given to the size of its contents.

See also columnWidth(), setColumnWidth(), sizeHintForColumn(), and QHeaderView::resizeContentsPrecision().

[protected slot] void QTreeView::rowsRemoved(const QModelIndex &parent, int start, int end)

Informs the view that the rows from the start row to the end row inclusive have been removed from the given parent model item.

This function was introduced in Qt 4.1.

[slot] void QTreeView::showColumn(int column)

Shows the given column in the tree view.

See also hideColumn() and setColumnHidden().

[slot] void QTreeView::sortByColumn(int column, Qt::SortOrder order)

Sorts the model by the values in the given column and order.

column may be -1, in which case no sort indicator will be shown and the model will return to its natural, unsorted order. Note that not all models support this and may even crash in this case.

This function was introduced in Qt 4.2.

See also sortingEnabled.

[virtual] QTreeView::~QTreeView()

Destroys the tree view.

int QTreeView::columnAt(int x) const

Returns the column in the tree view whose header covers the x coordinate given.

int QTreeView::columnViewportPosition(int column) const

Returns the horizontal position of the column in the viewport.

int QTreeView::columnWidth(int column) const

Returns the width of the column.

See also resizeColumnToContents() and setColumnWidth().

[override virtual protected] void QTreeView::currentChanged(const QModelIndex &current, const QModelIndex &previous)

Reimplements: QAbstractItemView::currentChanged(const QModelIndex &current, const QModelIndex &previous).

[override virtual] void QTreeView::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int>())

Reimplements: QAbstractItemView::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles).

[override virtual protected] void QTreeView::dragMoveEvent(QDragMoveEvent *event)

Reimplements: QAbstractItemView::dragMoveEvent(QDragMoveEvent *event).

[virtual protected] void QTreeView::drawBranches(QPainter *painter, const QRect &rect, const QModelIndex &index) const

Draws the branches in the tree view on the same row as the model item index, using the painter given. The branches are drawn in the rectangle specified by rect.

[virtual protected] void QTreeView::drawRow(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const

Draws the row in the tree view that contains the model item index, using the painter given. The option controls how the item is displayed.

See also setAlternatingRowColors().

[protected] void QTreeView::drawTree(QPainter *painter, const QRegion &region) const

Draws the part of the tree intersecting the given region using the specified painter.

This function was introduced in Qt 4.2.

See also paintEvent().

QHeaderView *QTreeView::header() const

Returns the header for the tree view.

See also setHeader() and QAbstractItemModel::headerData().

[override virtual protected] int QTreeView::horizontalOffset() const

Reimplements: QAbstractItemView::horizontalOffset() const.

Returns the horizontal offset of the items in the treeview.

Note that the tree view uses the horizontal header section positions to determine the positions of columns in the view.

See also verticalOffset().

QModelIndex QTreeView::indexAbove(const QModelIndex &index) const

Returns the model index of the item above index.

[override virtual] QModelIndex QTreeView::indexAt(const QPoint &point) const

Reimplements: QAbstractItemView::indexAt(const QPoint &point) const.

QModelIndex QTreeView::indexBelow(const QModelIndex &index) const

Returns the model index of the item below index.

[protected] int QTreeView::indexRowSizeHint(const QModelIndex &index) const

Returns the size hint for the row indicated by index.

See also sizeHintForColumn() and uniformRowHeights().

bool QTreeView::isColumnHidden(int column) const

Returns true if the column is hidden; otherwise returns false.

See also hideColumn() and isRowHidden().

bool QTreeView::isExpanded(const QModelIndex &index) const

Returns true if the model item index is expanded; otherwise returns false.

See also expand(), expanded(), and setExpanded().

bool QTreeView::isFirstColumnSpanned(int row, const QModelIndex &parent) const

Returns true if the item in first column in the given row of the parent is spanning all the columns; otherwise returns false.

This function was introduced in Qt 4.3.

See also setFirstColumnSpanned().

[override virtual protected] bool QTreeView::isIndexHidden(const QModelIndex &index) const

Reimplements: QAbstractItemView::isIndexHidden(const QModelIndex &index) const.

bool QTreeView::isRowHidden(int row, const QModelIndex &parent) const

Returns true if the item in the given row of the parent is hidden; otherwise returns false.

See also setRowHidden() and isColumnHidden().

[override virtual protected] void QTreeView::keyPressEvent(QKeyEvent *event)

Reimplements: QAbstractItemView::keyPressEvent(QKeyEvent *event).

[override virtual] void QTreeView::keyboardSearch(const QString &search)

Reimplements: QAbstractItemView::keyboardSearch(const QString &search).

[override virtual protected] void QTreeView::mouseDoubleClickEvent(QMouseEvent *event)

Reimplements: QAbstractItemView::mouseDoubleClickEvent(QMouseEvent *event).

[override virtual protected] void QTreeView::mouseMoveEvent(QMouseEvent *event)

Reimplements: QAbstractItemView::mouseMoveEvent(QMouseEvent *event).

[override virtual protected] void QTreeView::mousePressEvent(QMouseEvent *event)

Reimplements: QAbstractItemView::mousePressEvent(QMouseEvent *event).

[override virtual protected] void QTreeView::mouseReleaseEvent(QMouseEvent *event)

Reimplements: QAbstractItemView::mouseReleaseEvent(QMouseEvent *event).

[override virtual protected] QModelIndex QTreeView::moveCursor(QAbstractItemView::CursorAction cursorAction, Qt::KeyboardModifiers modifiers)

Reimplements: QAbstractItemView::moveCursor(QAbstractItemView::CursorAction cursorAction, Qt::KeyboardModifiers modifiers).

Move the cursor in the way described by cursorAction, using the information provided by the button modifiers.

[override virtual protected] void QTreeView::paintEvent(QPaintEvent *event)

Reimplements: QAbstractScrollArea::paintEvent(QPaintEvent *event).

[override virtual] void QTreeView::reset()

Reimplements: QAbstractItemView::reset().

[protected] int QTreeView::rowHeight(const QModelIndex &index) const

Returns the height of the row indicated by the given index.

This function was introduced in Qt 4.3.

See also indexRowSizeHint().

[override virtual protected] void QTreeView::rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end)

Reimplements: QAbstractItemView::rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end).

Informs the view that the rows from the start row to the end row inclusive are about to removed from the given parent model item.

[override virtual protected] void QTreeView::rowsInserted(const QModelIndex &parent, int start, int end)

Reimplements: QAbstractItemView::rowsInserted(const QModelIndex &parent, int start, int end).

Informs the view that the rows from the start row to the end row inclusive have been inserted into the parent model item.

[override virtual protected] void QTreeView::scrollContentsBy(int dx, int dy)

Reimplements: QAbstractScrollArea::scrollContentsBy(int dx, int dy).

Scrolls the contents of the tree view by (dx, dy).

[override virtual] void QTreeView::scrollTo(const QModelIndex &index, QAbstractItemView::ScrollHint hint = EnsureVisible)

Reimplements: QAbstractItemView::scrollTo(const QModelIndex &index, QAbstractItemView::ScrollHint hint).

Scroll the contents of the tree view until the given model item index is visible. The hint parameter specifies more precisely where the item should be located after the operation. If any of the parents of the model item are collapsed, they will be expanded to ensure that the model item is visible.

[override virtual] void QTreeView::selectAll()

Reimplements: QAbstractItemView::selectAll().

[override virtual protected] QModelIndexList QTreeView::selectedIndexes() const

Reimplements: QAbstractItemView::selectedIndexes() const.

[override virtual protected] void QTreeView::selectionChanged(const QItemSelection &selected, const QItemSelection &deselected)

Reimplements: QAbstractItemView::selectionChanged(const QItemSelection &selected, const QItemSelection &deselected).

void QTreeView::setColumnHidden(int column, bool hide)

If hide is true the column is hidden, otherwise the column is shown.

See also isColumnHidden(), hideColumn(), and setRowHidden().

void QTreeView::setColumnWidth(int column, int width)

Sets the width of the given column to the width specified.

This function was introduced in Qt 4.2.

See also columnWidth() and resizeColumnToContents().

void QTreeView::setExpanded(const QModelIndex &index, bool expanded)

Sets the item referred to by index to either collapse or expanded, depending on the value of expanded.

See also expanded(), expand(), and isExpanded().

void QTreeView::setFirstColumnSpanned(int row, const QModelIndex &parent, bool span)

If span is true the item in the first column in the row with the given parent is set to span all columns, otherwise all items on the row are shown.

This function was introduced in Qt 4.3.

See also isFirstColumnSpanned().

void QTreeView::setHeader(QHeaderView *header)

Sets the header for the tree view, to the given header.

The view takes ownership over the given header and deletes it when a new header is set.

See also QAbstractItemModel::headerData().

[override virtual] void QTreeView::setModel(QAbstractItemModel *model)

Reimplements: QAbstractItemView::setModel(QAbstractItemModel *model).

[override virtual] void QTreeView::setRootIndex(const QModelIndex &index)

Reimplements: QAbstractItemView::setRootIndex(const QModelIndex &index).

void QTreeView::setRowHidden(int row, const QModelIndex &parent, bool hide)

If hide is true the row with the given parent is hidden, otherwise the row is shown.

See also isRowHidden() and setColumnHidden().

[override virtual protected] void QTreeView::setSelection(const QRect &rect, QItemSelectionModel::SelectionFlags command)

Reimplements: QAbstractItemView::setSelection(const QRect &rect, QItemSelectionModel::SelectionFlags flags).

Applies the selection command to the items in or touched by the rectangle, rect.

See also selectionCommand().

[override virtual] void QTreeView::setSelectionModel(QItemSelectionModel *selectionModel)

Reimplements: QAbstractItemView::setSelectionModel(QItemSelectionModel *selectionModel).

void QTreeView::setTreePosition(int index)

This specifies that the tree structure should be placed at logical index index. If set to -1 then the tree will always follow visual index 0.

This function was introduced in Qt 5.2.

See also treePosition(), QHeaderView::swapSections(), and QHeaderView::moveSection().

[override virtual protected] int QTreeView::sizeHintForColumn(int column) const

Reimplements: QAbstractItemView::sizeHintForColumn(int column) const.

Returns the size hint for the column's width or -1 if there is no model.

If you need to set the width of a given column to a fixed value, call QHeaderView::resizeSection() on the view's header.

If you reimplement this function in a subclass, note that the value you return is only used when resizeColumnToContents() is called. In that case, if a larger column width is required by either the view's header or the item delegate, that width will be used instead.

See also QWidget::sizeHint, header(), and QHeaderView::resizeContentsPrecision().

[override virtual protected] void QTreeView::timerEvent(QTimerEvent *event)

Reimplements: QAbstractItemView::timerEvent(QTimerEvent *event).

int QTreeView::treePosition() const

Return the logical index the tree is set on. If the return value is -1 then the tree is placed on the visual index 0.

This function was introduced in Qt 5.2.

See also setTreePosition().

[override virtual protected] void QTreeView::updateGeometries()

Reimplements: QAbstractItemView::updateGeometries().

[override virtual protected] int QTreeView::verticalOffset() const

Reimplements: QAbstractItemView::verticalOffset() const.

Returns the vertical offset of the items in the tree view.

See also horizontalOffset().

[override virtual protected] bool QTreeView::viewportEvent(QEvent *event)

Reimplements: QAbstractItemView::viewportEvent(QEvent *event).

[override virtual protected] QSize QTreeView::viewportSizeHint() const

Reimplements: QAbstractItemView::viewportSizeHint() const.

[override virtual] QRect QTreeView::visualRect(const QModelIndex &index) const

Reimplements: QAbstractItemView::visualRect(const QModelIndex &index) const.

Returns the rectangle on the viewport occupied by the item at index. If the index is not visible or explicitly hidden, the returned rectangle is invalid.

[override virtual protected] QRegion QTreeView::visualRegionForSelection(const QItemSelection &selection) const

Reimplements: QAbstractItemView::visualRegionForSelection(const QItemSelection &selection) const.

Returns the rectangle from the viewport of the items in the given selection.

Since 4.7, the returned region only contains rectangles intersecting (or included in) the viewport.