\reentrant \inmodule QtGui More...

#include <qsyntaxhighlighter.h>

Inheritance diagram for QSyntaxHighlighter:

Collaboration diagram for QSyntaxHighlighter:

Public Slots
void	rehighlight ()

void	rehighlightBlock (const QTextBlock &block)

Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

Public Member Functions
	QSyntaxHighlighter (QObject *parent)
	Constructs a QSyntaxHighlighter with the given parent.

	QSyntaxHighlighter (QTextDocument *parent)
	Constructs a QSyntaxHighlighter and installs it on parent.

	~QSyntaxHighlighter ()
	Destructor.

void	setDocument (QTextDocument *doc)
	Installs the syntax highlighter on the given QTextDocument doc.

QTextDocument *	document () const
	Returns the QTextDocument on which this syntax highlighter is installed.

Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.

virtual	~QObject ()
	Destroys the object, deleting all its child objects.

virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.

virtual bool	eventFilter (QObject watched, QEvent event)
	Filters events if this object has been installed as an event filter for the watched object.

QString	objectName () const

Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.

void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

QBindable< QString >	bindableObjectName ()

bool	isWidgetType () const
	Returns `true` if the object is a widget; otherwise returns `false`.

bool	isWindowType () const
	Returns `true` if the object is a window; otherwise returns `false`.

bool	isQuickItemType () const
	Returns `true` if the object is a QQuickItem; otherwise returns `false`.

bool	signalsBlocked () const noexcept
	Returns `true` if signals are blocked; otherwise returns `false`.

bool	blockSignals (bool b) noexcept
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).

QThread *	thread () const
	Returns the thread in which the object lives.

bool	moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
	Changes the thread affinity for this object and its children and returns `true` on success.

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.

int	startTimer (std::chrono::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)

void	killTimer (int id)
	Kills the timer with timer identifier, id.

void	killTimer (Qt::TimerId id)

template<typename T >
T	findChild (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.

template<typename T >
QList< T >	findChildren (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.

template<typename T >
T	findChild (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

const QObjectList &	children () const
	Returns a list of child objects.

void	setParent (QObject *parent)
	Makes the object a child of parent.

void	installEventFilter (QObject *filterObj)
	Installs an event filter filterObj on this object.

void	removeEventFilter (QObject *obj)
	Removes an event filter object obj from this object.

QMetaObject::Connection	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=nullptr, const QObject receiver=nullptr, const char *member=nullptr) const

bool	disconnect (const QObject receiver, const char member=nullptr) const

void	dumpObjectTree () const
	Dumps a tree of children to the debug output.

void	dumpObjectInfo () const
	Dumps information about signal connections, etc.

bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value.

bool	setProperty (const char *name, QVariant &&value)

QVariant	property (const char *name) const
	Returns the value of the object's name property.

QList< QByteArray >	dynamicPropertyNames () const

QBindingStorage *	bindingStorage ()

const QBindingStorage *	bindingStorage () const

QObject *	parent () const
	Returns a pointer to the parent object.

bool	inherits (const char *classname) const
	Returns `true` if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns `false`.

Protected Member Functions
virtual void	highlightBlock (const QString &text)=0
	Highlights the given text block.

void	setFormat (int start, int count, const QTextCharFormat &format)
	This function is applied to the syntax highlighter's current text block (i.e.

void	setFormat (int start, int count, const QColor &color)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.The specified color is applied to the current text block from the start position for a length of count characters.

void	setFormat (int start, int count, const QFont &font)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.The specified font is applied to the current text block from the start position for a length of count characters.

QTextCharFormat	format (int pos) const
	Returns the format at position inside the syntax highlighter's current text block.

int	previousBlockState () const
	Returns the end state of the text block previous to the syntax highlighter's current block.

int	currentBlockState () const
	Returns the state of the current text block.

void	setCurrentBlockState (int newState)
	Sets the state of the current text block to newState.

void	setCurrentBlockUserData (QTextBlockUserData *data)
	Attaches the given data to the current text block.

QTextBlockUserData *	currentBlockUserData () const
	Returns the QTextBlockUserData object previously attached to the current text block.

QTextBlock	currentBlock () const

Protected Member Functions inherited from QObject
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.

int	senderSignalIndex () const

int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal.

bool	isSignalConnected (const QMetaMethod &signal) const

virtual void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object.

virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.

virtual void	customEvent (QEvent *event)
	This event handler can be reimplemented in a subclass to receive custom events.

virtual void	connectNotify (const QMetaMethod &signal)

virtual void	disconnectNotify (const QMetaMethod &signal)

	QObject (QObjectPrivate &dd, QObject *parent=nullptr)

Additional Inherited Members
Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.

void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.

Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	\threadsafe

static QMetaObject::Connection	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	\threadsafe

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a connection.

template<typename Func1 , typename Func2 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object receiver, Func2 slot)

template<typename Func1 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject receiver, void **zero)

Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Properties inherited from QObject
QString	objectName
	the name of this object

Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.

template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

\reentrant \inmodule QtGui

The QSyntaxHighlighter class allows you to define syntax highlighting rules, and in addition you can use the class to query a document's current formatting or user data.

Since: 4.1

The QSyntaxHighlighter class is a base class for implementing QTextDocument syntax highlighters. A syntax highligher automatically highlights parts of the text in a QTextDocument. Syntax highlighters are often used when the user is entering text in a specific format (for example source code) and help the user to read the text and identify syntax errors.

To provide your own syntax highlighting, you must subclass QSyntaxHighlighter and reimplement highlightBlock().

When you create an instance of your QSyntaxHighlighter subclass, pass it the QTextDocument that you want the syntax highlighting to be applied to. For example:

QTextEdit *editor = new QTextEdit;

MyHighlighter *highlighter = new MyHighlighter(editor->document());

After this your highlightBlock() function will be called automatically whenever necessary. Use your highlightBlock() function to apply formatting (e.g. setting the font and color) to the text that is passed to it. QSyntaxHighlighter provides the setFormat() function which applies a given QTextCharFormat on the current text block. For example:

void MyHighlighter::highlightBlock(const QString &text)
{
    QTextCharFormat myClassFormat;
    myClassFormat.setFontWeight(QFont::Bold);
    myClassFormat.setForeground(Qt::darkMagenta);
 
    QRegularExpression expression("\\bMy[A-Za-z]+\\b");
    QRegularExpressionMatchIterator i = expression.globalMatch(text);
    while (i.hasNext()) {
        QRegularExpressionMatch match = i.next();
        setFormat(match.capturedStart(), match.capturedLength(), myClassFormat);
    }
}

\target QSyntaxHighlighter multiblock

Some syntaxes can have constructs that span several text blocks. For example, a C++ syntax highlighter should be able to cope with {/}{...}{/} multiline comments. To deal with these cases it is necessary to know the end state of the previous text block (e.g. "in comment").

Inside your highlightBlock() implementation you can query the end state of the previous text block using the previousBlockState() function. After parsing the block you can save the last state using setCurrentBlockState().

The currentBlockState() and previousBlockState() functions return an int value. If no state is set, the returned value is -1. You can designate any other value to identify any given state using the setCurrentBlockState() function. Once the state is set the QTextBlock keeps that value until it is set again or until the corresponding paragraph of text is deleted.

For example, if you're writing a simple C++ syntax highlighter, you might designate 1 to signify "in comment":

QTextCharFormat multiLineCommentFormat;
multiLineCommentFormat.setForeground(Qt::red);
 
QRegularExpression startExpression("/\\*");
QRegularExpression endExpression("\\*/");
 
setCurrentBlockState(0);
 
int startIndex = 0;
if (previousBlockState() != 1)
    startIndex = text.indexOf(startExpression);
 
while (startIndex >= 0) {
    QRegularExpressionMatch endMatch;
    int endIndex = text.indexOf(endExpression, startIndex, &endMatch);
    int commentLength;
    if (endIndex == -1) {
        setCurrentBlockState(1);
        commentLength = text.length() - startIndex;
    } else {
        commentLength = endIndex - startIndex
                        + endMatch.capturedLength();
    }
    setFormat(startIndex, commentLength, multiLineCommentFormat);
    startIndex = text.indexOf(startExpression,
                              startIndex + commentLength);
}

In the example above, we first set the current block state to

Then, if the previous block ended within a comment, we highlight from the beginning of the current block ({startIndex = 0}). Otherwise, we search for the given start expression. If the specified end expression cannot be found in the text block, we change the current block state by calling setCurrentBlockState(), and make sure that the rest of the block is highlighted.

In addition you can query the current formatting and user data using the format() and currentBlockUserData() functions respectively. You can also attach user data to the current text block using the setCurrentBlockUserData() function. QTextBlockUserData can be used to store custom settings. In the case of syntax highlighting, it is in particular interesting as cache storage for information that you may figure out while parsing the paragraph's text. For an example, see the setCurrentBlockUserData() documentation.

See also: QTextDocument, {Syntax Highlighter Example}

Definition at line 24 of file qsyntaxhighlighter.h.

Constructor & Destructor Documentation

◆ QSyntaxHighlighter() [1/2]

QSyntaxHighlighter::QSyntaxHighlighter ( QObject * parent )

explicit

Constructs a QSyntaxHighlighter with the given parent.

If the parent is a QTextEdit, it installs the syntax highlighter on the parents document. The specified QTextEdit also becomes the owner of the QSyntaxHighlighter.

Definition at line 258 of file qsyntaxhighlighter.cpp.

◆ QSyntaxHighlighter() [2/2]

QSyntaxHighlighter::QSyntaxHighlighter ( QTextDocument * parent )

explicit

Constructs a QSyntaxHighlighter and installs it on parent.

The specified QTextDocument also becomes the owner of the QSyntaxHighlighter.

Definition at line 273 of file qsyntaxhighlighter.cpp.

◆ ~QSyntaxHighlighter()

QSyntaxHighlighter::~QSyntaxHighlighter ( )

Destructor.

Uninstalls this syntax highlighter from the text document.

Definition at line 282 of file qsyntaxhighlighter.cpp.

Member Function Documentation

◆ currentBlock()

QTextBlock QSyntaxHighlighter::currentBlock ( ) const

protected

Since: 4.4

Returns the current text block.

Definition at line 574 of file qsyntaxhighlighter.cpp.

◆ currentBlockState()

int QSyntaxHighlighter::currentBlockState ( ) const

protected

Returns the state of the current text block.

If no value is set, the returned value is -1.

Definition at line 488 of file qsyntaxhighlighter.cpp.

◆ currentBlockUserData()

QTextBlockUserData * QSyntaxHighlighter::currentBlockUserData ( ) const

protected

Returns the QTextBlockUserData object previously attached to the current text block.

See also: QTextBlock::userData(), setCurrentBlockUserData()

Definition at line 560 of file qsyntaxhighlighter.cpp.

◆ document()

QTextDocument * QSyntaxHighlighter::document ( ) const

Returns the QTextDocument on which this syntax highlighter is installed.

Definition at line 319 of file qsyntaxhighlighter.cpp.

◆ format()

QTextCharFormat QSyntaxHighlighter::format ( int pos ) const

protected

Returns the format at position inside the syntax highlighter's current text block.

Definition at line 456 of file qsyntaxhighlighter.cpp.

◆ highlightBlock()

virtual void QSyntaxHighlighter::highlightBlock ( const QString & text )

protectedpure virtual

Highlights the given text block.

This function is called when necessary by the rich text engine, i.e. on text blocks which have changed.

To provide your own syntax highlighting, you must subclass QSyntaxHighlighter and reimplement highlightBlock(). In your reimplementation you should parse the block's text and call setFormat() as often as necessary to apply any font and color changes that you require. For example:

void MyHighlighter::highlightBlock(const QString &text)
{
    QTextCharFormat myClassFormat;
    myClassFormat.setFontWeight(QFont::Bold);
    myClassFormat.setForeground(Qt::darkMagenta);
 
    QRegularExpression expression("\\bMy[A-Za-z]+\\b");
    QRegularExpressionMatchIterator i = expression.globalMatch(text);
    while (i.hasNext()) {
        QRegularExpressionMatch match = i.next();
        setFormat(match.capturedStart(), match.capturedLength(), myClassFormat);
    }
}

See the \l{QSyntaxHighlighter multiblock}{Detailed Description} for examples of using setCurrentBlockState(), currentBlockState() and previousBlockState() to handle syntaxes with constructs that span several text blocks

See also: previousBlockState(), setFormat(), setCurrentBlockState()

Implemented in MessageHighlighter, qdesigner_internal::CssHighlighter, qdesigner_internal::HtmlHighlighter, src_gui_text_qsyntaxhighlighter::MyHighlighter, and src_gui_text_qsyntaxhighlighter::MyHighlighter.

◆ previousBlockState()

int QSyntaxHighlighter::previousBlockState ( ) const

protected

Returns the end state of the text block previous to the syntax highlighter's current block.

If no value was previously set, the returned value is -1.

See also: highlightBlock(), setCurrentBlockState()

Definition at line 471 of file qsyntaxhighlighter.cpp.

◆ rehighlight

void QSyntaxHighlighter::rehighlight ( )

slot

Since: 4.2

Reapplies the highlighting to the whole document.

See also: rehighlightBlock()

Definition at line 332 of file qsyntaxhighlighter.cpp.

◆ rehighlightBlock

void QSyntaxHighlighter::rehighlightBlock ( const QTextBlock & block )

slot

Since: 4.6

Reapplies the highlighting to the given QTextBlock block.

See also: rehighlight()

Definition at line 350 of file qsyntaxhighlighter.cpp.

◆ setCurrentBlockState()

void QSyntaxHighlighter::setCurrentBlockState ( int newState )

protected

Sets the state of the current text block to newState.

See also: highlightBlock()

Definition at line 502 of file qsyntaxhighlighter.cpp.

◆ setCurrentBlockUserData()

void QSyntaxHighlighter::setCurrentBlockUserData ( QTextBlockUserData * data )

protected

Attaches the given data to the current text block.

The ownership is passed to the underlying text document, i.e. the provided QTextBlockUserData object will be deleted if the corresponding text block gets deleted.

QTextBlockUserData can be used to store custom settings. In the case of syntax highlighting, it is in particular interesting as cache storage for information that you may figure out while parsing the paragraph's text.

For example while parsing the text, you can keep track of parenthesis characters that you encounter ('{[(' and the like), and store their relative position and the actual QChar in a simple class derived from QTextBlockUserData:

struct ParenthesisInfo
{
    QChar character;
    int position;
};
 
struct BlockData : public QTextBlockUserData
{
    QList<ParenthesisInfo> parentheses;
};

During cursor navigation in the associated editor, you can ask the current QTextBlock (retrieved using the QTextCursor::block() function) if it has a user data object set and cast it to your BlockData object. Then you can check if the current cursor position matches with a previously recorded parenthesis position, and, depending on the type of parenthesis (opening or closing), find the next opening or closing parenthesis on the same level.

In this way you can do a visual parenthesis matching and highlight from the current cursor position to the matching parenthesis. That makes it easier to spot a missing parenthesis in your code and to find where a corresponding opening/closing parenthesis is when editing parenthesis intensive code.

See also: QTextBlock::setUserData()

Definition at line 545 of file qsyntaxhighlighter.cpp.

◆ setDocument()

void QSyntaxHighlighter::setDocument ( QTextDocument * doc )

Installs the syntax highlighter on the given QTextDocument doc.

A QSyntaxHighlighter can only be used with one document at a time.

Definition at line 291 of file qsyntaxhighlighter.cpp.

◆ setFormat() [1/3]

void QSyntaxHighlighter::setFormat	(	int	start,
		int	count,
		const QColor &	color )

protected

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.The specified color is applied to the current text block from the start position for a length of count characters.

The other attributes of the current text block, e.g. the font and background color, are reset to default values.

See also: format(), highlightBlock()

Definition at line 425 of file qsyntaxhighlighter.cpp.

◆ setFormat() [2/3]

void QSyntaxHighlighter::setFormat	(	int	start,
		int	count,
		const QFont &	font )

protected

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.The specified font is applied to the current text block from the start position for a length of count characters.

The other attributes of the current text block, e.g. the font and background color, are reset to default values.

See also: format(), highlightBlock()

Definition at line 443 of file qsyntaxhighlighter.cpp.

◆ setFormat() [3/3]

void QSyntaxHighlighter::setFormat	(	int	start,
		int	count,
		const QTextCharFormat &	format )

protected

This function is applied to the syntax highlighter's current text block (i.e.

the text that is passed to the highlightBlock() function).

The specified format is applied to the text from the start position for a length of count characters (if count is 0, nothing is done). The formatting properties set in format are merged at display time with the formatting information stored directly in the document, for example as previously set with QTextCursor's functions. Note that the document itself remains unmodified by the format set through this function.

See also: format(), highlightBlock()

Definition at line 403 of file qsyntaxhighlighter.cpp.

The documentation for this class was generated from the following files:

qtbase/src/gui/text/qsyntaxhighlighter.h (05fc3aef53348fb58be6308076e000825b704e58)
qtbase/src/gui/text/qsyntaxhighlighter.cpp (8ecd81ae86b07ef0ec10f17a343d349c07b1a29b)

Public Slots

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QSyntaxHighlighter() [1/2]

◆ QSyntaxHighlighter() [2/2]

◆ ~QSyntaxHighlighter()

Member Function Documentation

◆ currentBlock()

◆ currentBlockState()

◆ currentBlockUserData()

◆ document()

◆ format()

◆ highlightBlock()

◆ previousBlockState()

◆ rehighlight

◆ rehighlightBlock

◆ setCurrentBlockState()

◆ setCurrentBlockUserData()

◆ setDocument()

◆ setFormat() [1/3]

◆ setFormat() [2/3]

◆ setFormat() [3/3]