The QTextLayout class is used to lay out and render text. \inmodule QtGui. More...

#include <qtextlayout.h>

Classes
class	FormatRange
	The QTextLayout::FormatRange structure is used to apply extra formatting information for a specified area in the text layout's content. \inmodule QtGui. More...

Public Types
enum	CursorMode { SkipCharacters , SkipWords }

Public Member Functions
	QTextLayout ()

	QTextLayout (const QString &text)

	QTextLayout (const QString &text, const QFont &font, const QPaintDevice *paintdevice=nullptr)

	QTextLayout (const QTextBlock &b)

	~QTextLayout ()

void	setFont (const QFont &f)

QFont	font () const

void	setRawFont (const QRawFont &rawFont)

void	setText (const QString &string)

QString	text () const

void	setTextOption (const QTextOption &option)

const QTextOption &	textOption () const

void	setPreeditArea (int position, const QString &text)

int	preeditAreaPosition () const

QString	preeditAreaText () const

void	setFormats (const QList< FormatRange > &overrides)

QList< FormatRange >	formats () const

void	clearFormats ()

void	setCacheEnabled (bool enable)

bool	cacheEnabled () const

void	setCursorMoveStyle (Qt::CursorMoveStyle style)

Qt::CursorMoveStyle	cursorMoveStyle () const

void	beginLayout ()

void	endLayout ()

void	clearLayout ()

QTextLine	createLine ()

int	lineCount () const

QTextLine	lineAt (int i) const

QTextLine	lineForTextPosition (int pos) const

bool	isValidCursorPosition (int pos) const

int	nextCursorPosition (int oldPos, CursorMode mode=SkipCharacters) const

int	previousCursorPosition (int oldPos, CursorMode mode=SkipCharacters) const

int	leftCursorPosition (int oldPos) const

int	rightCursorPosition (int oldPos) const

void	draw (QPainter *p, const QPointF &pos, const QList< FormatRange > &selections=QList< FormatRange >(), const QRectF &clip=QRectF()) const

void	drawCursor (QPainter *p, const QPointF &pos, int cursorPosition) const

void	drawCursor (QPainter *p, const QPointF &pos, int cursorPosition, int width) const

QPointF	position () const

void	setPosition (const QPointF &p)

QRectF	boundingRect () const

qreal	minimumWidth () const

qreal	maximumWidth () const

QList< QGlyphRun >	glyphRuns (int from=-1, int length=-1) const

QTextEngine *	engine () const

void	setFlags (int flags)

Friends
class	QPainter

class	QGraphicsSimpleTextItemPrivate

class	QGraphicsSimpleTextItem

void	qt_format_text (const QFont &font, const QRectF &_r, int tf, const QTextOption , const QString &str, QRectF brect, int tabstops, int tabarray, int tabarraylen, QPainter painter)

Detailed Description

The QTextLayout class is used to lay out and render text. \inmodule QtGui.

\reentrant

It offers many features expected from a modern text layout engine, including Unicode compliant rendering, line breaking and handling of cursor positioning. It can also produce and render device independent layout, something that is important for WYSIWYG applications.

The class has a rather low level API and unless you intend to implement your own text rendering for some specialized widget, you probably won't need to use it directly.

QTextLayout can be used with both plain and rich text.

QTextLayout can be used to create a sequence of QTextLine instances with given widths and can position them independently on the screen. Once the layout is done, these lines can be drawn on a paint device.

The text to be laid out can be provided in the constructor or set with setText().

The layout can be seen as a sequence of QTextLine objects; use createLine() to create a QTextLine instance, and lineAt() or lineForTextPosition() to retrieve created lines.

Here is a code snippet that demonstrates the layout phase:

The text can then be rendered by calling the layout's draw() function:

For a given position in the text you can find a valid cursor position with isValidCursorPosition(), nextCursorPosition(), and previousCursorPosition().

The QTextLayout itself can be positioned with setPosition(); it has a boundingRect(), and a minimumWidth() and a maximumWidth().

See also: QStaticText

Definition at line 105 of file qtextlayout.h.

Member Enumeration Documentation

◆ CursorMode

enum QTextLayout::CursorMode

\value SkipCharacters \value SkipWords

Enumerator
SkipCharacters
SkipWords

Definition at line 162 of file qtextlayout.h.

Constructor & Destructor Documentation

◆ QTextLayout() [1/4]

QTextLayout::QTextLayout ( )

Constructs an empty text layout.

See also: setText()

Definition at line 332 of file qtextlayout.cpp.

◆ QTextLayout() [2/4]

QTextLayout::QTextLayout ( const QString & text )

Constructs a text layout to lay out the given text.

Definition at line 338 of file qtextlayout.cpp.

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◆ QTextLayout() [3/4]

QTextLayout::QTextLayout	(	const QString &	text,
		const QFont &	font,
		const QPaintDevice *	paintdevice = `nullptr`
	)

Since: 5.13

Constructs a text layout to lay out the given text with the specified font.

All the metric and layout calculations will be done in terms of the paint device, paintdevice. If paintdevice is \nullptr the calculations will be done in screen metrics.

Definition at line 355 of file qtextlayout.cpp.

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◆ QTextLayout() [4/4]

QTextLayout::QTextLayout ( const QTextBlock & b )

Definition at line 365 of file qtextlayout.cpp.

◆ ~QTextLayout()

QTextLayout::~QTextLayout ( )

Destructs the layout.

Definition at line 374 of file qtextlayout.cpp.

Member Function Documentation

◆ beginLayout()

void QTextLayout::beginLayout ( )

Begins the layout process.

Warning: This will invalidate the layout, so all existing QTextLine objects that refer to the previous contents should now be discarded.

See also: endLayout()

Definition at line 605 of file qtextlayout.cpp.

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◆ boundingRect()

QRectF QTextLayout::boundingRect ( ) const

The smallest rectangle that contains all the lines in the layout.

Definition at line 888 of file qtextlayout.cpp.

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◆ cacheEnabled()

bool QTextLayout::cacheEnabled ( ) const

Returns true if the complete layout information is cached; otherwise returns false.

See also: setCacheEnabled()

Definition at line 568 of file qtextlayout.cpp.

◆ clearFormats()

void QTextLayout::clearFormats ( )

Since: 5.6

Clears the list of additional formats supported by the text layout.

See also: formats(), setFormats()

Definition at line 542 of file qtextlayout.cpp.

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◆ clearLayout()

void QTextLayout::clearLayout ( )

Since: 4.4

Clears the line information in the layout. After having called this function, lineCount() returns 0.

Warning: This will invalidate the layout, so all existing QTextLine objects that refer to the previous contents should now be discarded.

Definition at line 650 of file qtextlayout.cpp.

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◆ createLine()

QTextLine QTextLayout::createLine ( )

Returns a new text line to be laid out if there is text to be inserted into the layout; otherwise returns an invalid text line.

The text layout creates a new line object that starts after the last line in the layout, or at the beginning if the layout is empty. The layout maintains an internal cursor, and each line is filled with text from the cursor position onwards when the QTextLine::setLineWidth() function is called.

Once QTextLine::setLineWidth() is called, a new line can be created and filled with text. Repeating this process will lay out the whole block of text contained in the QTextLayout. If there is no text left to be inserted into the layout, the QTextLine returned will not be valid (isValid() will return false).

Definition at line 795 of file qtextlayout.cpp.

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◆ cursorMoveStyle()

Qt::CursorMoveStyle QTextLayout::cursorMoveStyle ( ) const

The cursor movement style of this QTextLayout. The default is Qt::LogicalMoveStyle.

See also: setCursorMoveStyle()

Definition at line 592 of file qtextlayout.cpp.

◆ draw()

void QTextLayout::draw	(	QPainter *	p,
		const QPointF &	pos,
		const QList< FormatRange > &	selections = `QList<FormatRange>()`,
		const QRectF &	clip = `QRectF()`
	)		const

Draws the whole layout on the painter p at the position specified by pos. The rendered layout includes the given selections and is clipped within the rectangle specified by clip.

Definition at line 1064 of file qtextlayout.cpp.

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◆ drawCursor() [1/2]

void QTextLayout::drawCursor	(	QPainter *	painter,
		const QPointF &	position,
		int	cursorPosition
	)		const

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

Draws a text cursor with the current pen at the given position using the painter specified. The corresponding position within the text is specified by cursorPosition.

Definition at line 1249 of file qtextlayout.cpp.

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◆ drawCursor() [2/2]

void QTextLayout::drawCursor	(	QPainter *	painter,
		const QPointF &	position,
		int	cursorPosition,
		int	width
	)		const

Draws a text cursor with the current pen and the specified width at the given position using the painter specified. The corresponding position within the text is specified by cursorPosition.

Definition at line 1261 of file qtextlayout.cpp.

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◆ endLayout()

void QTextLayout::endLayout ( )

Ends the layout process.

See also: beginLayout()

Definition at line 624 of file qtextlayout.cpp.

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◆ engine()

QTextEngine * QTextLayout::engine ( ) const

inline

Definition at line 190 of file qtextlayout.h.

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◆ font()

QFont QTextLayout::font ( ) const

Returns the current font that is used for the layout, or a default font if none is set.

See also: setFont()

Definition at line 417 of file qtextlayout.cpp.

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◆ formats()

QList< QTextLayout::FormatRange > QTextLayout::formats ( ) const

Since: 5.6

Returns the list of additional formats supported by the text layout.

See also: setFormats(), clearFormats()

Definition at line 530 of file qtextlayout.cpp.

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◆ glyphRuns()

QList< QGlyphRun > QTextLayout::glyphRuns	(	int	from = `-1`,
		int	length = `-1`
	)		const

Returns the glyph indexes and positions for all glyphs corresponding to the length characters starting at the position from in this QTextLayout. This is an expensive function, and should not be called in a time sensitive context.

If from is less than zero, then the glyph run will begin at the first character in the layout. If length is less than zero, it will span the entire string from the start position.

Since: 4.8

See also: draw(), QPainter::drawGlyphRun()

Definition at line 1013 of file qtextlayout.cpp.

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◆ isValidCursorPosition()

bool QTextLayout::isValidCursorPosition ( int pos ) const

/ Returns true if position pos is a valid cursor position.

In a Unicode context some positions in the text are not valid cursor positions, because the position is inside a Unicode surrogate or a grapheme cluster.

A grapheme cluster is a sequence of two or more Unicode characters that form one indivisible entity on the screen. For example the latin character ‘\unicode{0xC4}’ can be represented in Unicode by two characters, ‘A’ (0x41), and the combining diaeresis (0x308). A text cursor can only validly be positioned before or after these two characters, never between them since that wouldn't make sense. In indic languages every syllable forms a grapheme cluster.

Definition at line 771 of file qtextlayout.cpp.

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◆ leftCursorPosition()

int QTextLayout::leftCursorPosition ( int oldPos ) const

Returns the cursor position to the left of oldPos, next to it. It's dependent on the visual position of characters, after bi-directional reordering.

See also: rightCursorPosition(), previousCursorPosition()

Definition at line 749 of file qtextlayout.cpp.

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◆ lineAt()

QTextLine QTextLayout::lineAt ( int i ) const

Returns the {i}-th line of text in this text layout.

See also: lineCount(), lineForTextPosition()

Definition at line 846 of file qtextlayout.cpp.

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◆ lineCount()

int QTextLayout::lineCount ( ) const

Returns the number of lines in this text layout.

See also: lineAt()

Definition at line 836 of file qtextlayout.cpp.

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◆ lineForTextPosition()

QTextLine QTextLayout::lineForTextPosition ( int pos ) const

Returns the line that contains the cursor position specified by pos.

See also: isValidCursorPosition(), lineAt()

Definition at line 856 of file qtextlayout.cpp.

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◆ maximumWidth()

qreal QTextLayout::maximumWidth ( ) const

The maximum width the layout could expand to; this is essentially the width of the entire text.

Warning: This function only returns a valid value after the layout has been done.

See also: minimumWidth()

Definition at line 932 of file qtextlayout.cpp.

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◆ minimumWidth()

qreal QTextLayout::minimumWidth ( ) const

The minimum width the layout needs. This is the width of the layout's smallest non-breakable substring.

Warning: This function only returns a valid value after the layout has been done.

See also: maximumWidth()

Definition at line 918 of file qtextlayout.cpp.

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◆ nextCursorPosition()

int QTextLayout::nextCursorPosition	(	int	oldPos,
		CursorMode	mode = `SkipCharacters`
	)		const

Returns the next valid cursor position after oldPos that respects the given cursor mode. Returns value of oldPos, if oldPos is not a valid cursor position.

See also: isValidCursorPosition(), previousCursorPosition()

Definition at line 662 of file qtextlayout.cpp.

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◆ position()

QPointF QTextLayout::position ( ) const

Since: 4.2

The global position of the layout. This is independent of the bounding rectangle and of the layout process.

See also: setPosition()

Definition at line 870 of file qtextlayout.cpp.

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◆ preeditAreaPosition()

int QTextLayout::preeditAreaPosition ( ) const

Returns the position of the area in the text layout that will be processed before editing occurs.

See also: preeditAreaText()

Definition at line 492 of file qtextlayout.cpp.

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◆ preeditAreaText()

QString QTextLayout::preeditAreaText ( ) const

Returns the text that is inserted in the layout before editing occurs.

See also: preeditAreaPosition()

Definition at line 502 of file qtextlayout.cpp.

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◆ previousCursorPosition()

int QTextLayout::previousCursorPosition	(	int	oldPos,
		CursorMode	mode = `SkipCharacters`
	)		const

Returns the first valid cursor position before oldPos that respects the given cursor mode. Returns value of oldPos, if oldPos is not a valid cursor position.

See also: isValidCursorPosition(), nextCursorPosition()

Definition at line 698 of file qtextlayout.cpp.

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◆ rightCursorPosition()

int QTextLayout::rightCursorPosition ( int oldPos ) const

Returns the cursor position to the right of oldPos, next to it. It's dependent on the visual position of characters, after bi-directional reordering.

See also: leftCursorPosition(), nextCursorPosition()

Definition at line 735 of file qtextlayout.cpp.

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◆ setCacheEnabled()

void QTextLayout::setCacheEnabled ( bool enable )

Enables caching of the complete layout information if enable is true; otherwise disables layout caching. Usually QTextLayout throws most of the layouting information away after a call to endLayout() to reduce memory consumption. If you however want to draw the laid out text directly afterwards enabling caching might speed up drawing significantly.

See also: cacheEnabled()

Definition at line 557 of file qtextlayout.cpp.

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◆ setCursorMoveStyle()

void QTextLayout::setCursorMoveStyle ( Qt::CursorMoveStyle style )

Sets the visual cursor movement style to the given style. If the QTextLayout is backed by a document, you can ignore this and use the option in QTextDocument, this option is for widgets like QLineEdit or custom widgets without a QTextDocument. Default value is Qt::LogicalMoveStyle.

See also: cursorMoveStyle()

Definition at line 581 of file qtextlayout.cpp.

◆ setFlags()

void QTextLayout::setFlags ( int flags )

Definition at line 941 of file qtextlayout.cpp.

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◆ setFont()

void QTextLayout::setFont ( const QFont & font )

Sets the layout's font to the given font. The layout is invalidated and must be laid out again.

See also: font()

Definition at line 402 of file qtextlayout.cpp.

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◆ setFormats()

void QTextLayout::setFormats ( const QList< FormatRange > & formats )

Since: 5.6

Sets the additional formats supported by the text layout to formats. The formats are applied with preedit area text in place.

See also: formats(), clearFormats()

Definition at line 515 of file qtextlayout.cpp.

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◆ setPosition()

void QTextLayout::setPosition ( const QPointF & p )

Moves the text layout to point p.

See also: position()

Definition at line 880 of file qtextlayout.cpp.

◆ setPreeditArea()

void QTextLayout::setPreeditArea	(	int	position,
		const QString &	text
	)

Sets the position and text of the area in the layout that is processed before editing occurs. The layout is invalidated and must be laid out again.

See also: preeditAreaPosition(), preeditAreaText()

Definition at line 476 of file qtextlayout.cpp.

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◆ setRawFont()

void QTextLayout::setRawFont ( const QRawFont & rawFont )

Definition at line 388 of file qtextlayout.cpp.

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◆ setText()

void QTextLayout::setText ( const QString & string )

Sets the layout's text to the given string. The layout is invalidated and must be laid out again.

Notice that when using this QTextLayout as part of a QTextDocument this method will have no effect.

See also: text()

Definition at line 431 of file qtextlayout.cpp.

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◆ setTextOption()

void QTextLayout::setTextOption ( const QTextOption & option )

Sets the text option structure that controls the layout process to the given option.

See also: textOption()

Definition at line 454 of file qtextlayout.cpp.

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◆ text()

QString QTextLayout::text ( ) const

Returns the layout's text.

See also: setText()

Definition at line 443 of file qtextlayout.cpp.

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◆ textOption()

const QTextOption & QTextLayout::textOption ( ) const

Returns the current text option used to control the layout process.

See also: setTextOption()

Definition at line 464 of file qtextlayout.cpp.

Friends And Related Function Documentation

◆ QGraphicsSimpleTextItem

friend class QGraphicsSimpleTextItem

friend

Definition at line 198 of file qtextlayout.h.

◆ QGraphicsSimpleTextItemPrivate

friend class QGraphicsSimpleTextItemPrivate

friend

Definition at line 197 of file qtextlayout.h.

◆ QPainter

friend class QPainter

friend

Definition at line 196 of file qtextlayout.h.

◆ qt_format_text

void qt_format_text	(	const QFont &	font,
		const QRectF &	_r,
		int	tf,
		const QTextOption *	opt,
		const QString &	str,
		QRectF *	brect,
		int	tabstops,
		int *	tabarray,
		int	tabarraylen,
		QPainter *	painter
	)

friend

Definition at line 7100 of file qpainter.cpp.

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

src/gui/text/qtextlayout.h
src/gui/text/qtextlayout.cpp

Classes

Public Types

Public Member Functions

Friends

Detailed Description

Member Enumeration Documentation

◆ CursorMode

Constructor & Destructor Documentation

◆ QTextLayout() [1/4]

◆ QTextLayout() [2/4]

◆ QTextLayout() [3/4]

◆ QTextLayout() [4/4]

◆ ~QTextLayout()

Member Function Documentation

◆ beginLayout()

◆ boundingRect()

◆ cacheEnabled()

◆ clearFormats()

◆ clearLayout()

◆ createLine()

◆ cursorMoveStyle()

◆ draw()

◆ drawCursor() [1/2]

◆ drawCursor() [2/2]

◆ endLayout()

◆ engine()

◆ font()

◆ formats()

◆ glyphRuns()

◆ isValidCursorPosition()

◆ leftCursorPosition()

◆ lineAt()

◆ lineCount()

◆ lineForTextPosition()

◆ maximumWidth()

◆ minimumWidth()

◆ nextCursorPosition()

◆ position()

◆ preeditAreaPosition()

◆ preeditAreaText()

◆ previousCursorPosition()

◆ rightCursorPosition()

◆ setCacheEnabled()

◆ setCursorMoveStyle()

◆ setFlags()

◆ setFont()

◆ setFormats()

◆ setPosition()

◆ setPreeditArea()

◆ setRawFont()

◆ setText()

◆ setTextOption()

◆ text()

◆ textOption()

Friends And Related Function Documentation

◆ QGraphicsSimpleTextItem

◆ QGraphicsSimpleTextItemPrivate

◆ QPainter

◆ qt_format_text