- Qt 6.9
- Qt GUI
- C++ Classes
- QPainterPathStroker
- Qt 6.9.3 Reference Documentation

# QPainterPathStroker Class

The QPainterPathStroker class is used to generate fillable outlines for a given painter path. More...

Header: | `#include <QPainterPathStroker>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Gui)` `target_link_libraries(mytarget PRIVATE Qt6::Gui)`
qmake: | `QT += gui`

- List of all members, including inherited members
- QPainterPathStroker is part of Painting Classes.

## Public Functions

| QPainterPathStroker()
| QPainterPathStroker(const QPen &pen)
| ~QPainterPathStroker()
Qt::PenCapStyle | capStyle() const
QPainterPath | createStroke(const QPainterPath &path) const
qreal | curveThreshold() const
qreal | dashOffset() const
QList<qreal> | dashPattern() const
Qt::PenJoinStyle | joinStyle() const
qreal | miterLimit() const
void | setCapStyle(Qt::PenCapStyle style)
void | setCurveThreshold(qreal threshold)
void | setDashOffset(qreal offset)
void | setDashPattern(Qt::PenStyle style)
void | setDashPattern(const QList<qreal> &dashPattern)
void | setJoinStyle(Qt::PenJoinStyle style)
void | setMiterLimit(qreal limit)
void | setWidth(qreal width)
qreal | width() const

## Detailed Description

By calling the createStroke() function, passing a given QPainterPath as argument, a new painter path representing the outline of the given path is created. The newly created painter path can then be filled to draw the original painter path's outline.

You can control the various design aspects (width, cap styles, join styles and dash pattern) of the outlining using the following functions:

- setWidth()
- setCapStyle()
- setJoinStyle()
- setDashPattern()

The setDashPattern() function accepts both a Qt::PenStyle object and a list representation of the pattern as argument.

In addition you can specify a curve's threshold, controlling the granularity with which a curve is drawn, using the setCurveThreshold() function. The default threshold is a well adjusted value (0.25), and normally you should not need to modify it. However, you can make the curve's appearance smoother by decreasing its value.

You can also control the miter limit for the generated outline using the setMiterLimit() function. The miter limit describes how far from each join the miter join can extend. The limit is specified in the units of width so the pixelwise miter limit will be `miterlimit * width`. This value is only used if the join style is Qt::MiterJoin.

The painter path generated by the createStroke() function should only be used for outlining the given painter path. Otherwise it may cause unexpected behavior. Generated outlines also require the Qt::WindingFill rule which is set by default.

See also QPen and QBrush.

## Member Function Documentation

### QPainterPathStroker::QPainterPathStroker()

Creates a new stroker.

### `[explicit]` QPainterPathStroker::QPainterPathStroker(const QPen &pen)

Creates a new stroker based on pen.

### `[noexcept]` QPainterPathStroker::~QPainterPathStroker()

Destroys the stroker.

### Qt::PenCapStyle QPainterPathStroker::capStyle() const

Returns the cap style of the generated outlines.

See also setCapStyle().

### QPainterPath QPainterPathStroker::createStroke(const QPainterPath &path) const

Generates a new path that is a fillable area representing the outline of the given path.

The various design aspects of the outline are based on the stroker's properties: width(), capStyle(), joinStyle(), dashPattern(), curveThreshold() and miterLimit().

The generated path should only be used for outlining the given painter path. Otherwise it may cause unexpected behavior. Generated outlines also require the Qt::WindingFill rule which is set by default.

### qreal QPainterPathStroker::curveThreshold() const

Returns the curve flattening threshold for the generated outlines.

See also setCurveThreshold().

### qreal QPainterPathStroker::dashOffset() const

Returns the dash offset for the generated outlines.

See also setDashOffset().

### QList<qreal> QPainterPathStroker::dashPattern() const

Returns the dash pattern for the generated outlines.

See also setDashPattern().

### Qt::PenJoinStyle QPainterPathStroker::joinStyle() const

Returns the join style of the generated outlines.

See also setJoinStyle().

### qreal QPainterPathStroker::miterLimit() const

Returns the miter limit for the generated outlines.

See also setMiterLimit().

### void QPainterPathStroker::setCapStyle(Qt::PenCapStyle style)

Sets the cap style of the generated outlines to style. If a dash pattern is set, each segment of the pattern is subject to the cap style.

See also capStyle().

### void QPainterPathStroker::setCurveThreshold(qreal threshold)

Specifies the curve flattening threshold, controlling the granularity with which the generated outlines' curve is drawn.

The default threshold is a well adjusted value (0.25), and normally you should not need to modify it. However, you can make the curve's appearance smoother by decreasing its value.

See also curveThreshold().

### void QPainterPathStroker::setDashOffset(qreal offset)

Sets the dash offset for the generated outlines to offset.

See the documentation for QPen::setDashOffset() for a description of the dash offset.

See also dashOffset().

### void QPainterPathStroker::setDashPattern(Qt::PenStyle style)

Sets the dash pattern for the generated outlines to style.

See also dashPattern().

### void QPainterPathStroker::setDashPattern(const QList<qreal> &dashPattern)

Sets the dash pattern for the generated outlines to dashPattern. This function makes it possible to specify custom dash patterns.

Each element in the list contains the lengths of the dashes and spaces in the stroke, beginning with the first dash in the first element, the first space in the second element, and alternating between dashes and spaces for each following pair of elements.

The list can contain an odd number of elements, in which case the last element will be extended by the length of the first element when the pattern repeats.

This is an overloaded function.

### void QPainterPathStroker::setJoinStyle(Qt::PenJoinStyle style)

Sets the join style of the generated outlines to style.

See also joinStyle().

### void QPainterPathStroker::setMiterLimit(qreal limit)

Sets the miter limit of the generated outlines to limit.

The miter limit describes how far from each join the miter join can extend. The limit is specified in units of the currently set width. So the pixelwise miter limit will be `miterlimit * width`.

This value is only used if the join style is Qt::MiterJoin.

See also miterLimit().

### void QPainterPathStroker::setWidth(qreal width)

Sets the width of the generated outline painter path to width.

The generated outlines will extend approximately 50% of width to each side of the given input path's original outline.

See also width().

### qreal QPainterPathStroker::width() const

Returns the width of the generated outlines.

See also setWidth().