CopperSpice API  1.7.2
QTextLayout Class Reference

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

## Classes

class  FormatRange
This structure is used to apply extra formatting information More...

enum  CursorMode

## Public Methods

QTextLayout ()

QTextLayout (const QString &text)

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

~QTextLayout ()

void beginLayout ()

QRectF boundingRect () const

bool cacheEnabled () const

void clearFormats ()

void clearLayout ()

QTextLine createLine ()

Qt::CursorMoveStyle cursorMoveStyle () const

void draw (QPainter *p, const QPointF &pos, const QVector< FormatRange > &selections=QVector< 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

void endLayout ()

QFont font () const

QVector< FormatRangeformats () const

QList< QGlyphRunglyphRuns (int from=-1, int length=-1) const

bool isValidCursorPosition (int pos) const

int leftCursorPosition (int oldPos) const

QTextLine lineAt (int i) const

int lineCount () const

QTextLine lineForTextPosition (int pos) const

qreal maximumWidth () const

qreal minimumWidth () const

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

QPointF position () const

int preeditAreaPosition () const

QString preeditAreaText () const

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

int rightCursorPosition (int oldPos) const

void setCacheEnabled (bool enable)

void setCursorMoveStyle (Qt::CursorMoveStyle style)

void setFont (const QFont &f)

void setFormats (const QVector< FormatRange > &overrides)

void setPosition (const QPointF &p)

void setPreeditArea (int position, const QString &text)

void setRawFont (const QRawFont &rawFont)

void setText (const QString &string)

void setTextOption (const QTextOption &option)

QString text () const

const QTextOptiontextOption () const

## Friends

class QGraphicsSimpleTextItem

class QPainter

## Detailed Description

The QTextLayout class is used to lay out and render text. 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 low level API and unless you intend to implement your own text rendering for some specialized widget, you probably will not need to use it directly.

QTextLayout can be used with both plain and rich text. It can also 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.

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().

### Example

The following code demonstrates the layout and draw process.

void MyClass::layoutText() {
qreal height = 0;
textLayout.beginLayout();
while (1) {
QTextLine line = textLayout.createLine();
if (! line.isValid()) {
break;
}
line.setLineWidth(lineWidth);
line.setPosition(QPointF(0, height));
height += line.height();
}
textLayout.endLayout();
}
void MyClass::drawText() {
// used to draw the text
QPainter painter(this);
textLayout.draw(&painter, QPoint(0, 0));
}
QStaticText

## Member Enumeration Documentation

ConstantValue
QTextLayout::SkipCharacters0
QTextLayout::SkipWords1

## Constructor & Destructor Documentation

 QTextLayout::QTextLayout ( )

Constructs an empty text layout.

setText()
 QTextLayout::QTextLayout ( const QString & text )

Constructs a text layout to lay out the given text.

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

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 paintdevice. If paintdevice is a nullptr the calculations will be done in screen metrics.

 QTextLayout::~QTextLayout ( )

Destructs the layout.

## Method Documentation

 void QTextLayout::beginLayout ( )

Begins the layout process.

endLayout()
 QRectF QTextLayout::boundingRect ( ) const

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

 bool QTextLayout::cacheEnabled ( ) const

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

setCacheEnabled()
 void QTextLayout::clearFormats ( )

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

formats(), setFormats()
 void QTextLayout::clearLayout ( )

Clears the line information in the layout. After having called this method lineCount() will return 0.

 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).

 Qt::CursorMoveStyle QTextLayout::cursorMoveStyle ( ) const

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

setCursorMoveStyle()
 void QTextLayout::draw ( QPainter * p, const QPointF & pos, const QVector< FormatRange > & selections = QVector(), 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.

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

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.

 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.

 void QTextLayout::endLayout ( )

Ends the layout process.

beginLayout()
 QFont QTextLayout::font ( ) const

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

setFont()
 QVector< FormatRange > QTextLayout::formats ( ) const

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

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

Returns the glyphs corresponding to length code points of this text fragment starting at position from. The positions of the glyphs are relative to the position of the QTextBlock layout. If from is less than 0 the glyphs will start at the beginning. If length is less than 0 the glyphs will stop at the end of the fragment.

draw(), QPainter::drawGlyphRun()
 bool QTextLayout::isValidCursorPosition ( int pos ) const

Returns true if position pos is a valid cursor position. Some positions in the text are not valid cursor positions because the position is within a grapheme cluster.

 int QTextLayout::leftCursorPosition ( int oldPos ) const

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

rightCursorPosition(), previousCursorPosition()
 QTextLine QTextLayout::lineAt ( int i ) const

Returns the line of text at position i in this text layout.

lineCount(), lineForTextPosition()
 int QTextLayout::lineCount ( ) const

Returns the number of lines in this text layout.

lineAt()
 QTextLine QTextLayout::lineForTextPosition ( int pos ) const

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

isValidCursorPosition(), lineAt()
 qreal QTextLayout::maximumWidth ( ) const

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

Warning
This method only returns a valid value after the layout has been done.
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 method only returns a valid value after the layout has been done.
maximumWidth()
 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.

isValidCursorPosition(), previousCursorPosition()
 QPointF QTextLayout::position ( ) const

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

setPosition()
 int QTextLayout::preeditAreaPosition ( ) const

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

preeditAreaText()
 QString QTextLayout::preeditAreaText ( ) const

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

preeditAreaPosition()
 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.

isValidCursorPosition(), nextCursorPosition()
 int QTextLayout::rightCursorPosition ( int oldPos ) const

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

leftCursorPosition(), nextCursorPosition()
 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 layout 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.

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

Set the cursor movement 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.

cursorMoveStyle()
 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.

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

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

formats(), clearFormats()
 void QTextLayout::setPosition ( const QPointF & p )

Moves the text layout to point p.

position()
 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.

preeditAreaPosition(), preeditAreaText()
 void QTextLayout::setRawFont ( const QRawFont & rawFont )

Property documentation pending.

 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. When using this QTextLayout as part of a QTextDocument this method will have no effect.

text()
 void QTextLayout::setTextOption ( const QTextOption & option )

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

textOption()
 QString QTextLayout::text ( ) const

Returns the layout's text.

setText()
 const QTextOption & QTextLayout::textOption ( ) const

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