QPainterPath Class

The QPainterPath class is a shape made of lines and curves, for QPainter to fill and stroke. More…

List of all members, including inherited members

Public Types

Public Functions

Detailed Description

A path is a list of subpaths. Each starts with moveTo() and goes on with lineTo(), cubicTo(), quadTo() and arcTo(); closeSubpath() joins its end to its start. Shapes are added whole with addRect(), addEllipse(), addRoundedRect() and addPolygon():

QPainterPath petal;
petal.moveTo(0, 0);
petal.cubicTo(20, -30, 60, -30, 80, 0);
petal.cubicTo(60, 30, 20, 30, 0, 0);

QPainter painter(&image);
painter.setRenderHint(QPainter::Antialiasing);
painter.translate(100, 100);
for (int i = 0; i < 8; ++i) {
    painter.rotate(45);
    painter.fillPath(petal, QColor(200, 80, 120));
}

The fill rule decides which parts of a path that crosses itself are inside.

See also QPainter::drawPath() and QPainter::fillPath().

Differences from Qt

Member Type Documentation

enum QPainterPath::ElementType

Member Function Documentation

QPainterPath::QPainterPath()

Constructs an empty path.

[explicit] QPainterPath::QPainterPath(const QPointF &startPoint)

Constructs a path that starts at startPoint.

void QPainterPath::addEllipse(const QRectF &boundingRectangle)

Adds the ellipse that fits in boundingRectangle as a closed subpath.

void QPainterPath::addEllipse(qreal x, qreal y, qreal width, qreal height)

This is an overloaded function.

Adds the ellipse in the rectangle at (x, y) of width by height.

void QPainterPath::addEllipse(const QPointF &center, qreal rx, qreal ry)

This is an overloaded function.

Adds the ellipse at center with the radii rx and ry.

void QPainterPath::addPath(const QPainterPath &path)

Adds the subpaths of path.

void QPainterPath::addPolygon(const QPolygonF &polygon)

Adds polygon as a subpath; it is closed only if its last point is its first.

void QPainterPath::addRect(const QRectF &rectangle)

Adds rectangle as a closed subpath.

void QPainterPath::addRect(qreal x, qreal y, qreal width, qreal height)

This is an overloaded function.

Adds the rectangle at (x, y) of width by height.

void QPainterPath::addRoundedRect(const QRectF &rect, qreal xRadius, qreal yRadius, Qt::SizeMode mode = Qt::AbsoluteSize)

Adds rect with corners rounded by xRadius and yRadius, in units or, with mode Qt::RelativeSize, in percent of half the width and height.

void QPainterPath::addRoundedRect(qreal x, qreal y, qreal w, qreal h, qreal xRadius, qreal yRadius, Qt::SizeMode mode = Qt::AbsoluteSize)

This is an overloaded function.

Adds the rectangle at (x, y) of w by h with corners rounded by xRadius and yRadius in the given mode.

qreal QPainterPath::angleAtPercent(qreal t) const

Returns the angle, in degrees counterclockwise from 3 o'clock, of the path at the fraction t of its length.

void QPainterPath::arcMoveTo(const QRectF &rectangle, qreal angle)

Starts a new subpath at the point at angle degrees of the ellipse that fits in rectangle.

void QPainterPath::arcMoveTo(qreal x, qreal y, qreal w, qreal h, qreal angle)

This is an overloaded function.

Starts a new subpath on the ellipse in the rectangle at (x, y) of w by h, at angle.

void QPainterPath::arcTo(const QRectF &rectangle, qreal startAngle, qreal sweepLength)

Adds an arc of the ellipse that fits in rectangle, from startAngle for sweepLength degrees. Angles are counterclockwise from 3 o'clock. A line joins the current position to the start of the arc.

void QPainterPath::arcTo(qreal x, qreal y, qreal w, qreal h, qreal startAngle, qreal arcLength)

This is an overloaded function.

Adds an arc of the ellipse in the rectangle at (x, y) of w by h, from startAngle for arcLength degrees.

QRectF QPainterPath::boundingRect() const

Returns the smallest rectangle that contains the path, curves included.

int QPainterPath::capacity() const

Returns the number of points there is room for.

void QPainterPath::clear()

Removes all points.

void QPainterPath::closeSubpath()

Closes the current subpath with a line to its start, and starts a new one there.

void QPainterPath::connectPath(const QPainterPath &path)

Adds path, joining its first subpath to the current position with a line.

bool QPainterPath::contains(const QPointF &point) const

Returns true if point is inside the path, by its fill rule; otherwise returns false.

bool QPainterPath::contains(const QRectF &rectangle) const

This is an overloaded function.

Returns true if rectangle is inside the path; otherwise returns false.

QRectF QPainterPath::controlPointRect() const

Returns the smallest rectangle that contains all the points of the path, control points included.

void QPainterPath::cubicTo(const QPointF &c1, const QPointF &c2, const QPointF &endPoint)

Adds a cubic Bezier curve from the current position to endPoint, with the control points c1 and c2.

void QPainterPath::cubicTo(qreal c1X, qreal c1Y, qreal c2X, qreal c2Y, qreal endPointX, qreal endPointY)

This is an overloaded function.

Adds a cubic curve to (endPointX, endPointY) with the control points (c1X, c1Y) and (c2X, c2Y).

QPointF QPainterPath::currentPosition() const

Returns the end of the last subpath.

QPainterPath::Element QPainterPath::elementAt(int index) const

Returns the point at index.

int QPainterPath::elementCount() const

Returns the number of points of the path, control points included.

Qt::FillRule QPainterPath::fillRule() const

Returns the fill rule; Qt::OddEvenFill by default.

bool QPainterPath::intersects(const QRectF &rectangle) const

Returns true if the path and rectangle overlap; otherwise returns false.

bool QPainterPath::isEmpty() const

Returns true if the path has nothing but a start point; otherwise returns false.

qreal QPainterPath::length() const

Returns the length of the path.

void QPainterPath::lineTo(const QPointF &endPoint)

Adds a line from the current position to endPoint.

void QPainterPath::lineTo(qreal x, qreal y)

This is an overloaded function.

Adds a line to (x, y).

void QPainterPath::moveTo(const QPointF &point)

Starts a new subpath at point.

void QPainterPath::moveTo(qreal x, qreal y)

This is an overloaded function.

Starts a new subpath at (x, y).

bool QPainterPath::operator!=(const QPainterPath &path) const

Returns true if path differs from this one.

QPainterPath QPainterPath::operator+(const QPainterPath &other) const

Returns this path with the subpaths of other added.

QPainterPath & QPainterPath::operator+=(const QPainterPath &other)

Adds the subpaths of other and returns a reference to this path.

bool QPainterPath::operator==(const QPainterPath &path) const

Returns true if path has the same points and fill rule; otherwise returns false.

qreal QPainterPath::percentAtLength(qreal len) const

Returns where along the path, from 0 to 1, the length len is reached.

QPointF QPainterPath::pointAtPercent(qreal t) const

Returns the point at the fraction t, from 0 to 1, of the length of the path.

void QPainterPath::quadTo(const QPointF &c, const QPointF &endPoint)

Adds a quadratic Bezier curve from the current position to endPoint, with the control point c.

void QPainterPath::quadTo(qreal cx, qreal cy, qreal endPointX, qreal endPointY)

This is an overloaded function.

Adds a quadratic curve to (endPointX, endPointY) with the control point (cx, cy).

void QPainterPath::reserve(int size)

Reserves room for size points.

void QPainterPath::setElementPositionAt(int index, qreal x, qreal y)

Moves the point at index to (x, y).

void QPainterPath::setFillRule(Qt::FillRule fillRule)

Sets the fill rule to fillRule.

qreal QPainterPath::slopeAtPercent(qreal t) const

Returns the slope, dy/dx, of the path at the fraction t of its length.

void QPainterPath::swap(QPainterPath &other)

Swaps this path with other.

QPolygonF QPainterPath::toFillPolygon(const QTransform &matrix = QTransform()) const

Returns all subpaths as one closed polygon, mapped by matrix.

QList<QPolygonF> QPainterPath::toFillPolygons(const QTransform &matrix = QTransform()) const

Returns the subpaths as closed polygons, mapped by matrix.

QList<QPolygonF> QPainterPath::toSubpathPolygons(const QTransform &matrix = QTransform()) const

Returns the subpaths as polylines, mapped by matrix: curves are divided into short lines.

void QPainterPath::translate(qreal dx, qreal dy)

Moves each point by dx and dy.

void QPainterPath::translate(const QPointF &offset)

This is an overloaded function.

Moves each point by offset.

QPainterPath QPainterPath::translated(qreal dx, qreal dy) const

Returns a copy moved by dx and dy.

QPainterPath QPainterPath::translated(const QPointF &offset) const

This is an overloaded function.

Returns a copy moved by offset.