QPen

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

Inheritance diagram of PySide2.QtGui.QPen

Synopsis

Functions

Detailed Description

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:

painter = QPainter(self)
pen = QPen(Qt.green, 3, Qt.DashDotLine, Qt.RoundCap, Qt.RoundJoin)
painter.setPen(pen)

which is equivalent to

painter = QPainter(self)
pen = QPen()  # 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 1 width, square cap style ( SquareCap ), and bevel join style ( 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

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

qpen-solid1

qpen-dash2

qpen-dot3

SolidLine

DashLine

DotLine

qpen-dashdot4

qpen-dashdotdot5

qpen-custom6

DashDotLine

DashDotDotLine

CustomDashLine

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

Since Qt 4.1 it is also possible to specify a custom dash pattern using the setDashPattern() function which implicitly converts the style of the pen to 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:

pen = QPen()
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 PenCapStyle enum provides the following styles:

qpen-square7

qpen-flat8

qpen-roundcap9

SquareCap

FlatCap

RoundCap

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

The default is SquareCap .

Whether or not end points are drawn when the pen width is 0 or 1 depends on the cap style. Using SquareCap or RoundCap they are drawn, using 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 PenJoinStyle enum provides the following styles:

qpen-bevel10

qpen-miter11

qpen-roundjoin12

BevelJoin

MiterJoin

RoundJoin

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

The default is BevelJoin .

../../_images/qpen-miterlimit.png

When the 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.

qpen-demo13

**** The Path Stroking Example ****

The Path Stroking example shows Qt’s built-in dash patterns and shows how custom patterns can be used to extend the range of available patterns.

See also

QPainter QBrush Path Stroking Example Scribble Example

class QPen

QPen(arg__1)

QPen(brush, width[, s=Qt.SolidLine[, c=Qt.SquareCap[, j=Qt.BevelJoin]]])

QPen(color)

QPen(pen)

param j

PenJoinStyle

param arg__1

PenStyle

param brush

QBrush

param color

QColor

param s

PenStyle

param width

qreal

param c

PenCapStyle

param pen

QPen

Constructs a default black solid line pen with 1 width.

Constructs a black pen with 1 width and the given style .

See also

setStyle()

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

PySide2.QtGui.QPen.brush()
Return type

QBrush

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

See also

setBrush()

PySide2.QtGui.QPen.capStyle()
Return type

PenCapStyle

Returns the pen’s cap style.

See also

setCapStyle() Cap Style

PySide2.QtGui.QPen.color()
Return type

QColor

Returns the color of this pen’s brush.

See also

brush() setColor()

PySide2.QtGui.QPen.dashOffset()
Return type

qreal

Returns the dash offset for the pen.

See also

setDashOffset()

PySide2.QtGui.QPen.dashPattern()
Return type

Returns the dash pattern of this pen.

PySide2.QtGui.QPen.isCosmetic()
Return type

bool

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.

PySide2.QtGui.QPen.isSolid()
Return type

bool

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

PySide2.QtGui.QPen.joinStyle()
Return type

PenJoinStyle

Returns the pen’s join style.

See also

setJoinStyle() Join Style

PySide2.QtGui.QPen.miterLimit()
Return type

qreal

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

See also

setMiterLimit() Join Style

PySide2.QtGui.QPen.__ne__(p)
Parameters

pQPen

Return type

bool

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==()

PySide2.QtGui.QPen.__eq__(p)
Parameters

pQPen

Return type

bool

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!=()

PySide2.QtGui.QPen.setBrush(brush)
Parameters

brushQBrush

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

See also

brush() setColor()

PySide2.QtGui.QPen.setCapStyle(pcs)
Parameters

pcsPenCapStyle

Sets the pen’s cap style to the given style . The default value is SquareCap .

See also

capStyle() Cap Style

PySide2.QtGui.QPen.setColor(color)
Parameters

colorQColor

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

See also

setBrush() color()

PySide2.QtGui.QPen.setCosmetic(cosmetic)
Parameters

cosmeticbool

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

See also

isCosmetic()

PySide2.QtGui.QPen.setDashOffset(doffset)
Parameters

doffsetqreal

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.

qpen-dashpattern1

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 CustomDashLine .

See also

dashOffset()

PySide2.QtGui.QPen.setDashPattern(pattern)
Parameters

pattern

Sets the dash pattern for this pen to the given pattern . This implicitly converts the style of the pen to 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-custom1

pen = QPen()
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 SquareCap , meaning that a square line end covers the end point and extends beyond it by half the line width.

PySide2.QtGui.QPen.setJoinStyle(pcs)
Parameters

pcsPenJoinStyle

Sets the pen’s join style to the given style . The default value is BevelJoin .

See also

joinStyle() Join Style

PySide2.QtGui.QPen.setMiterLimit(limit)
Parameters

limitqreal

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

../../_images/qpen-miterlimit.png

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 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

PySide2.QtGui.QPen.setStyle(arg__1)
Parameters

arg__1PenStyle

Sets the pen style to the given style .

See the PenStyle documentation for a list of the available styles. Since Qt 4.1 it is also possible to specify a custom dash pattern using the setDashPattern() function which implicitly converts the style of the pen to CustomDashLine .

Note

This function resets the dash offset to zero.

See also

style() Pen Style

PySide2.QtGui.QPen.setWidth(width)
Parameters

widthint

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()

PySide2.QtGui.QPen.setWidthF(width)
Parameters

widthqreal

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()

PySide2.QtGui.QPen.style()
Return type

PenStyle

Returns the pen style.

See also

setStyle() Pen Style

PySide2.QtGui.QPen.swap(other)
Parameters

otherQPen

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

PySide2.QtGui.QPen.width()
Return type

int

Returns the pen width with integer precision.

See also

setWidth() widthF()

PySide2.QtGui.QPen.widthF()
Return type

qreal

Returns the pen width with floating point precision.

See also

setWidthF() width()