CopperSpice API  1.7.2
QPen Class Reference

The QPen class defines how a QPainter should draw lines and outlines of shapes. More...

Public Methods

 QPen ()
 
 QPen (const QBrush &brush, qreal width, Qt::PenStyle s=Qt::SolidLine, Qt::PenCapStyle c=Qt::SquareCap, Qt::PenJoinStyle j=Qt::BevelJoin)
 
 QPen (const QColor &color)
 
 QPen (const QPen &pen)
 
 QPen (QPen &&other)
 
 QPen (Qt::PenStyle)
 
 ~QPen ()
 
QBrush brush () const
 
Qt::PenCapStyle capStyle () const
 
QColor color () const
 
qreal dashOffset () const
 
QVector< qrealdashPattern () const
 
bool isCosmetic () const
 
bool isSolid () const
 
Qt::PenJoinStyle joinStyle () const
 
qreal miterLimit () const
 
 operator QVariant () const
 
bool operator!= (const QPen &p) const
 
QPen & operator= (const QPen &pen)
 
QPen & operator= (QPen &&other)
 
bool operator== (const QPen &p) const
 
void setBrush (const QBrush &brush)
 
void setCapStyle (Qt::PenCapStyle pcs)
 
void setColor (const QColor &color)
 
void setCosmetic (bool cosmetic)
 
void setDashOffset (qreal doffset)
 
void setDashPattern (const QVector< qreal > &pattern)
 
void setJoinStyle (Qt::PenJoinStyle pcs)
 
void setMiterLimit (qreal limit)
 
void setStyle (Qt::PenStyle)
 
void setWidth (int width)
 
void setWidthF (qreal width)
 
Qt::PenStyle style () const
 
void swap (QPen &other)
 
int width () const
 
qreal widthF () const
 

Friends

QDataStreamoperator<< (QDataStream &, const QPen &)
 
QDataStreamoperator>> (QDataStream &, QPen &)
 

Detailed Description

The QPen class defines how a QPainter should draw lines and outlines of shapes. A pen has a style(), width(), brush(), capStyle() and joinStyle().

The pen style defines the line type. The brush is used to fill strokes generated with the pen. Use the QBrush class to specify fill styles. The cap style determines the line end caps that can be drawn using QPainter, while the join style describes how joins between two lines are drawn. The pen width can be specified in both integer (width()) and floating point (widthF()) precision. A line width of zero indicates a cosmetic pen. This means that the pen width is always drawn one pixel wide, independent of the transformation set on the painter.

The various settings can easily be modified using the corresponding setStyle(), setWidth(), setBrush(), setCapStyle() and setJoinStyle() functions (note that the painter's pen must be reset when altering the pen's properties).

For example:

QPainter painter(this);
QPen pen(Qt::green, 3, Qt::DashDotLine, Qt::RoundCap, Qt::RoundJoin);
painter.setPen(pen);

which is equivalent to

QPainter painter(this);
QPen pen; // creates a default pen
pen.setStyle(Qt::DashDotLine);
pen.setWidth(3);
pen.setBrush(Qt::green);
pen.setCapStyle(Qt::RoundCap);
pen.setJoinStyle(Qt::RoundJoin);
painter.setPen(pen);

The default pen is a solid black brush with 0 width, square cap style (Qt::SquareCap), and bevel join style (Qt::BevelJoin).

In addition QPen provides the color() and setColor() convenience functions to extract and set the color of the pen's brush, respectively. Pens may also be compared and streamed.

For more information about painting in general, see the Paint System documentation.

Pen Style

CopperSpice provides several built-in styles represented by the Qt::PenStyle enum:

Qt::SolidLine Qt::DashLine Qt::DotLine
Qt::DashDotLine Qt::DashDotDotLine Qt::CustomDashLine

Simply use the setStyle() function to convert the pen style to either of the built-in styles, except the Qt::CustomDashLine style which we will come back to shortly. Setting the style to Qt::NoPen tells the painter to not draw lines or outlines. The default pen style is Qt::SolidLine.

It is also possible to specify a custom dash pattern using the setDashPattern() function which implicitly converts the style of the pen to Qt::CustomDashLine. The pattern argument, a QVector, must be specified as an even number of qreal entries where the entries 1, 3, 5... are the dashes and 2, 4, 6... are the spaces. For example, the custom pattern shown above is created using the following code:

QPen pen;
qreal space = 4;
dashes << 1 << space << 3 << space << 9 << space
<< 27 << space << 9 << space;
pen.setDashPattern(dashes);

Note that the dash pattern is specified in units of the pens width, e.g. a dash of length 5 in width 10 is 50 pixels long.

The currently set dash pattern can be retrieved using the dashPattern() function. Use the isSolid() function to determine whether the pen has a solid fill, or not.

Cap Style

The cap style defines how the end points of lines are drawn using QPainter. The cap style only apply to wide lines, i.e. when the width is 1 or greater. The Qt::PenCapStyle enum provides the following styles:

Qt::SquareCapQt::FlatCapQt::RoundCap

The Qt::SquareCap style is a square line end that covers the end point and extends beyond it by half the line width. The Qt::FlatCap style is a square line end that does not cover the end point of the line. And the Qt::RoundCap style is a rounded line end covering the end point.

The default is Qt::SquareCap.

Whether or not end points are drawn when the pen width is 0 or 1 depends on the cap style. Using Qt::SquareCap or Qt::RoundCap they are drawn, using Qt::FlatCap they are not drawn.

Join Style

The join style defines how joins between two connected lines can be drawn using QPainter. The join style only apply to wide lines, i.e. when the width is 1 or greater. The Qt::PenJoinStyle enum provides the following styles:

Qt::BevelJoin Qt::MiterJoin Qt::RoundJoin

The Qt::BevelJoin style fills the triangular notch between the two lines. The Qt::MiterJoin style extends the lines to meet at an angle. And the Qt::RoundJoin style fills a circular arc between the two lines.

The default is Qt::BevelJoin.

When the Qt::MiterJoin style is applied, it is possible to use the setMiterLimit() function to specify how far the miter join can extend from the join point. The miterLimit() is used to reduce artifacts between line joins where the lines are close to parallel.

The miterLimit() must be specified in units of the pens width, e.g. a miter limit of 5 in width 10 is 50 pixels long. The default miter limit is 2, i.e. twice the pen width in pixels.

See also
QPainter, QBrush

Constructor & Destructor Documentation

QPen::QPen ( )

Constructs a default black solid line pen with 0 width.

QPen::QPen ( Qt::PenStyle  style)

Constructs a black pen with 0 width and the given style.

See also
setStyle()
QPen::QPen ( const QColor color)

Constructs a solid line pen with 0 width and the given color.

See also
setBrush(), setColor()
QPen::QPen ( const QBrush brush,
qreal  width,
Qt::PenStyle  style = Qt::SolidLine,
Qt::PenCapStyle  cap = Qt::SquareCap,
Qt::PenJoinStyle  join = Qt::BevelJoin 
)

Constructs a pen with the specified brush, width, pen style, cap style and join style.

See also
setBrush(), setWidth(), setStyle(), setCapStyle(), setJoinStyle()
QPen::QPen ( const QPen &  pen)

Constructs a pen that is a copy of the given pen.

QPen::QPen ( QPen &&  other)
inline

Move constructs a new QPen from other.

QPen::~QPen ( )

Destroys the pen.

Method Documentation

QBrush QPen::brush ( ) const

Returns the brush used to fill strokes generated with this pen.

See also
setBrush()
Qt::PenCapStyle QPen::capStyle ( ) const

Returns the pen's cap style.

See also
setCapStyle(), Cap Style
QColor QPen::color ( ) const

Returns the color of this pen's brush.

See also
brush(), setColor()
qreal QPen::dashOffset ( ) const

Returns the dash offset for the pen.

See also
setDashOffset()
QVector< qreal > QPen::dashPattern ( ) const

Returns the dash pattern of this pen.

See also
setDashPattern(), style(), isSolid()
bool QPen::isCosmetic ( ) const

Returns true if the pen is cosmetic, otherwise returns false.

Cosmetic pens are used to draw strokes that have a constant width regardless of any transformations applied to the QPainter they are used with. Drawing a shape with a cosmetic pen ensures that its outline will have the same thickness at different scale factors.

A zero width pen is cosmetic by default; pens with a non-zero width are non-cosmetic.

See also
setCosmetic(), widthF()
bool QPen::isSolid ( ) const

Returns true if the pen has a solid fill, otherwise false.

See also
style(), dashPattern()
Qt::PenJoinStyle QPen::joinStyle ( ) const

Returns the pen's join style.

See also
setJoinStyle(), Join Style
qreal QPen::miterLimit ( ) const

Returns the miter limit of the pen. The miter limit is only relevant when the join style is set to Qt::MiterJoin.

See also
setMiterLimit(), Join Style
QPen::operator QVariant ( ) const

Returns the pen as a QVariant.

bool QPen::operator!= ( const QPen &  pen) const
inline

Returns true if the pen is different from the given pen, otherwise false. Two pens are different if they have different styles, widths or colors.

See also
operator==()
QPen & QPen::operator= ( const QPen &  pen)

Assigns the given pen to this pen and returns a reference to this pen.

QPen & QPen::operator= ( QPen &&  other)
inline

Move assigns from other and returns a reference to this object.

bool QPen::operator== ( const QPen &  pen) const

Returns true if the pen is equal to the given pen, otherwise false. Two pens are equal if they have equal styles, widths and colors.

See also
operator!=()
void QPen::setBrush ( const QBrush brush)

Sets the brush used to fill strokes generated with this pen to the given brush.

See also
brush(), setColor()
void QPen::setCapStyle ( Qt::PenCapStyle  style)

Sets the pen's cap style to the given style. The default value is Qt::SquareCap.

See also
capStyle(), Cap Style
void QPen::setColor ( const QColor color)

Sets the color of this pen's brush to the given color.

See also
setBrush(), color()
void QPen::setCosmetic ( bool  cosmetic)

Sets this pen to cosmetic or non-cosmetic, depending on the value of cosmetic.

See also
isCosmetic()
void QPen::setDashOffset ( qreal  offset)

Sets the dash offset (the starting point on the dash pattern) for this pen to the offset specified. The offset is measured in terms of the units used to specify the dash pattern.

For example, a pattern where each stroke is four units long, followed by a gap of two units, will begin with the stroke when drawn as a line.However, if the dash offset is set to 4.0, any line drawn will begin with the gap. Values of the offset up to 4.0 will cause part of the stroke to be drawn first, and values of the offset between 4.0 and 6.0 will cause the line to begin with part of the gap.
Note
This implicitly converts the style of the pen to Qt::CustomDashLine.
See also
dashOffset()
void QPen::setDashPattern ( const QVector< qreal > &  pattern)

Sets the dash pattern for this pen to the given pattern. This implicitly converts the style of the pen to Qt::CustomDashLine.

The pattern must be specified as an even number of positive entries where the entries 1, 3, 5... are the dashes and 2, 4, 6... are the spaces. For example:

QPen pen;
qreal space = 4;
dashes << 1 << space << 3 << space << 9 << space << 27 << space << 9 << space;
pen.setDashPattern(dashes);

The dash pattern is specified in units of the pens width; e.g. a dash of length 5 in width 10 is 50 pixels long. Note that a pen with zero width is equivalent to a cosmetic pen with a width of 1 pixel.

Each dash is also subject to cap styles so a dash of 1 with square cap set will extend 0.5 pixels out in each direction resulting in a total width of 2.

Note that the default cap style is Qt::SquareCap, meaning that a square line end covers the end point and extends beyond it by half the line width.

See also
setStyle(), dashPattern(), setCapStyle(), setCosmetic()
void QPen::setJoinStyle ( Qt::PenJoinStyle  style)

Sets the pen's join style to the given style. The default value is Qt::BevelJoin.

See also
joinStyle(), Join Style
void QPen::setMiterLimit ( qreal  limit)

Sets the miter limit of this pen to the given limit.

The miter limit describes how far a miter join can extend from the join point. This is used to reduce artifacts between line joins where the lines are close to parallel.

This value does only have effect when the pen style is set to Qt::MiterJoin. The value is specified in units of the pen's width, e.g. a miter limit of 5 in width 10 is 50 pixels long. The default miter limit is 2, i.e. twice the pen width in pixels.

See also
miterLimit(), setJoinStyle(), Join Style
void QPen::setStyle ( Qt::PenStyle  style)

Sets the pen style to the given style.

See the Qt::PenStyle documentation for a list of the available styles. It is also possible to specify a custom dash pattern using the setDashPattern() function which implicitly converts the style of the pen to Qt::CustomDashLine.

Note
This function resets the dash offset to zero.
See also
style(), Pen Style
void QPen::setWidth ( int  width)

Sets the pen width to the given width in pixels with integer precision.

A line width of zero indicates a cosmetic pen. This means that the pen width is always drawn one pixel wide, independent of the transformation set on the painter.

Setting a pen width with a negative value is not supported.

See also
setWidthF(), width()
void QPen::setWidthF ( qreal  width)

Sets the pen width to the given width in pixels with floating point precision.

A line width of zero indicates a cosmetic pen. This means that the pen width is always drawn one pixel wide, independent of the transformation on the painter.

Setting a pen width with a negative value is not supported.

See also
setWidth(), widthF()
Qt::PenStyle QPen::style ( ) const

Returns the pen style.

See also
setStyle(), Pen Style
void QPen::swap ( QPen &  other)
inline

Swaps pen other with this pen. This operation is very fast and never fails.

int QPen::width ( ) const

Returns the pen width with integer precision.

See also
setWidth(), widthF()
qreal QPen::widthF ( ) const

Returns the pen width with floating point precision.

See also
setWidthF(), width()

Friends And Related Function Documentation

QDataStream & operator<< ( QDataStream stream,
const QPen &  pen 
)
friend

Writes the given pen to the given stream and returns a reference to the stream.

See also
Refer to Serializing Data Types for additional information
QDataStream & operator>> ( QDataStream stream,
QPen &  pen 
)
friend

Reads a pen from the given stream into the given pen and returns a reference to the stream.

See also
Refer to Serializing Data Types for additional information