QTextBrowser Class

The QTextBrowser class provides a rich text browser with hypertext navigation. More...

Header:	#include <QTextBrowser>
qmake:	QT += widgets
Inherits:	QTextEdit

• List of all members, including inherited members

Properties

modified : const bool openExternalLinks : bool openLinks : bool readOnly : const bool

searchPaths : QStringList source : QUrl sourceType : const QTextDocument::ResourceType undoRedoEnabled : const bool

Public Functions

	QTextBrowser(QWidget *parent = nullptr)
int	backwardHistoryCount() const
void	clearHistory()
int	forwardHistoryCount() const
QString	historyTitle(int i) const
QUrl	historyUrl(int i) const
bool	isBackwardAvailable() const
bool	isForwardAvailable() const
bool	openExternalLinks() const
bool	openLinks() const
QStringList	searchPaths() const
void	setOpenExternalLinks(bool open)
void	setOpenLinks(bool open)
void	setSearchPaths(const QStringList &paths)
QUrl	source() const
QTextDocument::ResourceType	sourceType() const

Reimplemented Public Functions

virtual QVariant

loadResource(int type, const QUrl &name) override

Public Slots

virtual void	backward()
virtual void	forward()
virtual void	home()
virtual void	reload()
void	setSource(const QUrl &url, QTextDocument::ResourceType type)
virtual void	setSource(const QUrl &name)

Signals

void	anchorClicked(const QUrl &link)
void	backwardAvailable(bool available)
void	forwardAvailable(bool available)
void	highlighted(const QString &link)
void	highlighted(const QUrl &link)
void	historyChanged()
void	sourceChanged(const QUrl &src)

Protected Functions

void	doSetSource(const QUrl &url, QTextDocument::ResourceType type = QTextDocument::UnknownResource)

Reimplemented Protected Functions

virtual bool	event(QEvent *e) override
virtual bool	focusNextPrevChild(bool next) override
virtual void	focusOutEvent(QFocusEvent *ev) override
virtual void	keyPressEvent(QKeyEvent *ev) override
virtual void	mouseMoveEvent(QMouseEvent *e) override
virtual void	mousePressEvent(QMouseEvent *e) override
virtual void	mouseReleaseEvent(QMouseEvent *e) override
virtual void	paintEvent(QPaintEvent *e) override

Detailed Description

This class extends QTextEdit (in read-only mode), adding some navigation functionality so that users can follow links in hypertext documents.

If you want to provide your users with an editable rich text editor, use QTextEdit. If you want a text browser without hypertext navigation use QTextEdit, and use QTextEdit::setReadOnly() to disable editing. If you just need to display a small piece of rich text use QLabel.

Document Source and Contents

The contents of QTextEdit are set with setHtml() or setPlainText(), but QTextBrowser also implements the setSource() function, making it possible to use a named document as the source text. The name is looked up in a list of search paths and in the directory of the current document factory.

If a document name ends with an anchor (for example, "#anchor"), the text browser automatically scrolls to that position (using scrollToAnchor()). When the user clicks on a hyperlink, the browser will call setSource() itself with the link's href value as argument. You can track the current source by connecting to the sourceChanged() signal.

Navigation

QTextBrowser provides backward() and forward() slots which you can use to implement Back and Forward buttons. The home() slot sets the text to the very first document displayed. The anchorClicked() signal is emitted when the user clicks an anchor. To override the default navigation behavior of the browser, call the setSource() function to supply new document text in a slot connected to this signal.

If you want to load documents stored in the Qt resource system use qrc as the scheme in the URL to load. For example, for the document resource path :/docs/index.html use qrc:/docs/index.html as the URL with setSource().

See also QTextEdit and QTextDocument.

Member Function Documentation

QTextBrowser::QTextBrowser(QWidget *parent = nullptr)

Constructs an empty QTextBrowser with parent parent.

[signal] void QTextBrowser::anchorClicked(const QUrl &link)

This signal is emitted when the user clicks an anchor. The URL referred to by the anchor is passed in link.

Note that the browser will automatically handle navigation to the location specified by link unless the openLinks property is set to false or you call setSource() in a slot connected. This mechanism is used to override the default navigation features of the browser.

[virtual slot] void QTextBrowser::backward()

Changes the document displayed to the previous document in the list of documents built by navigating links. Does nothing if there is no previous document.

See also forward() and backwardAvailable().

[signal] void QTextBrowser::backwardAvailable(bool available)

This signal is emitted when the availability of backward() changes. available is false when the user is at home(); otherwise it is true.

[virtual slot] void QTextBrowser::forward()

Changes the document displayed to the next document in the list of documents built by navigating links. Does nothing if there is no next document.

See also backward() and forwardAvailable().

[signal] void QTextBrowser::forwardAvailable(bool available)

This signal is emitted when the availability of forward() changes. available is true after the user navigates backward() and false when the user navigates or goes forward().

[signal] void QTextBrowser::highlighted(const QString &link)

This is an overloaded function.

Convenience signal that allows connecting to a slot that takes just a QString, like for example QStatusBar's message().

Note: Signal highlighted is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

connect(textBrowser, QOverload<const QString &>::of(&QTextBrowser::highlighted),
    [=](const QString &link){ /* ... */ });

[signal] void QTextBrowser::highlighted(const QUrl &link)

This signal is emitted when the user has selected but not activated an anchor in the document. The URL referred to by the anchor is passed in link.

Note: Signal highlighted is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

connect(textBrowser, QOverload<const QUrl &>::of(&QTextBrowser::highlighted),
    [=](const QUrl &link){ /* ... */ });

[signal] void QTextBrowser::historyChanged()

This signal is emitted when the history changes.

This function was introduced in Qt 4.4.

See also historyTitle() and historyUrl().

[virtual slot] void QTextBrowser::home()

Changes the document displayed to be the first document from the history.

[virtual slot] void QTextBrowser::reload()

Reloads the current set source.

[slot] void QTextBrowser::setSource(const QUrl &url, QTextDocument::ResourceType type)

Attempts to load the document at the given url with the specified type.

If type is UnknownResource (the default), the document type will be detected: that is, if the url ends with an extension of .md, .mkd or .markdown, the document will be loaded via QTextDocument::setMarkdown(); otherwise it will be loaded via QTextDocument::setHtml(). This detection can be bypassed by specifying the type explicitly.

Note: Setter function for property source.

[signal] void QTextBrowser::sourceChanged(const QUrl &src)

This signal is emitted when the source has changed, src being the new source.

Source changes happen both programmatically when calling setSource(), forward(), backword() or home() or when the user clicks on links or presses the equivalent key sequences.

int QTextBrowser::backwardHistoryCount() const

Returns the number of locations backward in the history.

This function was introduced in Qt 4.4.

void QTextBrowser::clearHistory()

Clears the history of visited documents and disables the forward and backward navigation.

This function was introduced in Qt 4.2.

See also backward() and forward().

[protected] void QTextBrowser::doSetSource(const QUrl &url, QTextDocument::ResourceType type = QTextDocument::UnknownResource)

Attempts to load the document at the given url with the specified type.

setSource() calls doSetSource. In Qt 5, setSource(const QUrl &url) was virtual. In Qt 6, doSetSource() is virtual instead, so that it can be overridden in subclasses.

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

Reimplements: QAbstractScrollArea::event(QEvent *event).

[override virtual protected] bool QTextBrowser::focusNextPrevChild(bool next)

Reimplements: QTextEdit::focusNextPrevChild(bool next).

[override virtual protected] void QTextBrowser::focusOutEvent(QFocusEvent *ev)

Reimplements: QTextEdit::focusOutEvent(QFocusEvent *e).

int QTextBrowser::forwardHistoryCount() const

Returns the number of locations forward in the history.

This function was introduced in Qt 4.4.

QString QTextBrowser::historyTitle(int i) const

Returns the documentTitle() of the HistoryItem.

Input	Return
i < 0	backward() history
i == 0	current, see QTextBrowser::source()
i > 0	forward() history

backaction.setToolTip(browser.historyTitle(-1));
forwardaction.setToolTip(browser.historyTitle(+1));

This function was introduced in Qt 4.4.

QUrl QTextBrowser::historyUrl(int i) const

Returns the url of the HistoryItem.

Input	Return
i < 0	backward() history
i == 0	current, see QTextBrowser::source()
i > 0	forward() history

This function was introduced in Qt 4.4.

bool QTextBrowser::isBackwardAvailable() const

Returns true if the text browser can go backward in the document history using backward().

This function was introduced in Qt 4.2.

See also backwardAvailable() and backward().

bool QTextBrowser::isForwardAvailable() const

Returns true if the text browser can go forward in the document history using forward().

This function was introduced in Qt 4.2.

See also forwardAvailable() and forward().

[override virtual protected] void QTextBrowser::keyPressEvent(QKeyEvent *ev)

Reimplements: QTextEdit::keyPressEvent(QKeyEvent *e).

The event ev is used to provide the following keyboard shortcuts:

Keypress	Action
Alt+Left Arrow	backward()
Alt+Right Arrow	forward()
Alt+Up Arrow	home()

[override virtual] QVariant QTextBrowser::loadResource(int type, const QUrl &name)

Reimplements: QTextEdit::loadResource(int type, const QUrl &name).

This function is called when the document is loaded and for each image in the document. The type indicates the type of resource to be loaded. An invalid QVariant is returned if the resource cannot be loaded.

The default implementation ignores type and tries to locate the resources by interpreting name as a file name. If it is not an absolute path it tries to find the file in the paths of the searchPaths property and in the same directory as the current source. On success, the result is a QVariant that stores a QByteArray with the contents of the file.

If you reimplement this function, you can return other QVariant types. The table below shows which variant types are supported depending on the resource type:

ResourceType	QVariant::Type
QTextDocument::HtmlResource	QString or QByteArray
QTextDocument::ImageResource	QImage, QPixmap or QByteArray
QTextDocument::StyleSheetResource	QString or QByteArray
QTextDocument::MarkdownResource	QString or QByteArray

[override virtual protected] void QTextBrowser::mouseMoveEvent(QMouseEvent *e)

Reimplements: QTextEdit::mouseMoveEvent(QMouseEvent *e).

[override virtual protected] void QTextBrowser::mousePressEvent(QMouseEvent *e)

Reimplements: QTextEdit::mousePressEvent(QMouseEvent *e).

[override virtual protected] void QTextBrowser::mouseReleaseEvent(QMouseEvent *e)

Reimplements: QTextEdit::mouseReleaseEvent(QMouseEvent *e).

[override virtual protected] void QTextBrowser::paintEvent(QPaintEvent *e)

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