Qt Jambi Home

com.trolltech.qt.gui
Class QPen

java.lang.Object
  extended by com.trolltech.qt.QSignalEmitter
      extended by com.trolltech.qt.QtJambiObject
          extended by com.trolltech.qt.gui.QPen
All Implemented Interfaces:
QtJambiInterface

public class QPen
extends QtJambiObject

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

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

Qt::SolidLineQt::DashLineQt::DotLine
Qt::DashDotLineQt::DashDotDotLineQt::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.

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 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;
    QVector<qreal> dashes;
    qreal space = 4;

    dashes << 1 << space << 3 << space << 9 << space
               << 27 << space << 9;

    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::BevelJoinQt::MiterJoinQt::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.

The Path Stroking Demo

The Path Stroking demo 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, Stroking Demo, Example

Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I>
 
Field Summary
static QPen NoPen
           
 
Constructor Summary
QPen()
          Constructs a default black solid line pen with 0 width.
QPen(QBrush brush, double width)
          Equivalent to QPen(brush, width, Qt::SolidLine, Qt::SquareCap, Qt::BevelJoin).
QPen(QBrush brush, double width, Qt.PenStyle s)
          Equivalent to QPen(brush, width, s, Qt::SquareCap, Qt::BevelJoin).
QPen(QBrush brush, double width, Qt.PenStyle s, Qt.PenCapStyle c)
          Equivalent to QPen(brush, width, s, c, Qt::BevelJoin).
QPen(QBrush brush, double width, Qt.PenStyle s, Qt.PenCapStyle c, Qt.PenJoinStyle j)
          Constructs a pen with the specified brush, width, pen s, c style and j style.
QPen(QColor color)
          Constructs a solid line pen with 0 width and the given color.
QPen(QColor color, double width)
          This is an overloaded constructor provided for convenience.
QPen(QColor color, double width, Qt.PenStyle s)
          This is an overloaded constructor provided for convenience.
QPen(QColor color, double width, Qt.PenStyle s, Qt.PenCapStyle c)
          Constructs a pen with the specified color, width, pen style s, and c cap style.
QPen(QColor color, double width, Qt.PenStyle s, Qt.PenCapStyle c, Qt.PenJoinStyle j)
          Constructs a pen with the specified color, width, pen style s, pen cap style c, and pen join style j
QPen(QPen pen)
          Constructs a pen that is a copy of the given pen.
QPen(Qt.PenStyle arg__1)
          Constructs a black pen with 0 width and the given arg__1.
 
Method Summary
 QBrush brush()
          Returns the brush used to fill strokes generated with this pen.
 Qt.PenCapStyle capStyle()
          Returns the pen's cap style.
 QColor color()
          Returns the color of this pen's brush.
 double dashOffset()
          Returns the dash offset for the pen.
 java.util.List<java.lang.Double> dashPattern()
          Returns the dash pattern of this pen.
 boolean equals(java.lang.Object other)
          
static QPen fromNativePointer(QNativePointer nativePointer)
          This function returns the QPen instance pointed to by nativePointer
 boolean isCosmetic()
          Returns true if the pen is cosmetic; otherwise returns false.
 boolean isSolid()
          Returns true if the pen has a solid fill, otherwise false.
 Qt.PenJoinStyle joinStyle()
          Returns the pen's join style.
 double miterLimit()
          Returns the miter limit of the pen.
static QNativePointer nativePointerArray(QPen[] array)
          This function returns a QNativePointer that is pointing to the specified QPen array.
 void readFrom(QDataStream arg__1)
          Reads a QPen from arg__1.
 void setBrush(QBrush brush)
          Sets the brush used to fill strokes generated with this pen to the given brush.
 void setCapStyle(Qt.PenCapStyle pcs)
          Sets the pen's cap style to the given pcs.
 void setColor(QColor color)
          Sets the color of this pen's brush to the given color.
 void setCosmetic(boolean cosmetic)
          Sets this pen to cosmetic or non-cosmetic, depending on the value of cosmetic.
 void setDashOffset(double doffset)
          Sets the dash offset for this pen to the given doffset.
 void setDashPattern(java.util.List<java.lang.Double> pattern)
          Sets the dash pattern for this pen to the given pattern.
 void setJoinStyle(Qt.PenJoinStyle pcs)
          Sets the pen's join style to the given pcs.
 void setMiterLimit(double limit)
          Sets the miter limit of this pen to the given limit.
 void setStyle(Qt.PenStyle arg__1)
          Sets the pen style to the given arg__1.
 void setWidth(int width)
          Sets the pen width to the given width in pixels with integer precision.
 void setWidthF(double width)
          Sets the pen width to the given width in pixels with floating point precision.
 Qt.PenStyle style()
          Returns the pen style.
 int width()
          Returns the pen width with integer precision.
 double widthF()
          Returns the pen width with floating point precision.
 void writeTo(QDataStream arg__1)
          Writes thisQPen to arg__1.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Field Detail

NoPen

public static final QPen NoPen
Constructor Detail

QPen

public QPen(QPen pen)

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


QPen

public QPen()

Constructs a default black solid line pen with 0 width.


QPen

public QPen(Qt.PenStyle arg__1)

Constructs a black pen with 0 width and the given arg__1.

See Also:
setStyle

QPen

public QPen(QColor color)

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

See Also:
setBrush, setColor

QPen

public QPen(QBrush brush,
            double width,
            Qt.PenStyle s,
            Qt.PenCapStyle c)

Equivalent to QPen(brush, width, s, c, Qt::BevelJoin).


QPen

public QPen(QBrush brush,
            double width,
            Qt.PenStyle s)

Equivalent to QPen(brush, width, s, Qt::SquareCap, Qt::BevelJoin).


QPen

public QPen(QBrush brush,
            double width)

Equivalent to QPen(brush, width, Qt::SolidLine, Qt::SquareCap, Qt::BevelJoin).


QPen

public QPen(QBrush brush,
            double width,
            Qt.PenStyle s,
            Qt.PenCapStyle c,
            Qt.PenJoinStyle j)

Constructs a pen with the specified brush, width, pen s, c style and j style.

See Also:
setBrush, setWidth, setStyle, setCapStyle, setJoinStyle

QPen

public QPen(QColor color,
            double width,
            Qt.PenStyle s,
            Qt.PenCapStyle c,
            Qt.PenJoinStyle j)
Constructs a pen with the specified color, width, pen style s, pen cap style c, and pen join style j


QPen

public QPen(QColor color,
            double width,
            Qt.PenStyle s,
            Qt.PenCapStyle c)
Constructs a pen with the specified color, width, pen style s, and c cap style.


QPen

public QPen(QColor color,
            double width,
            Qt.PenStyle s)
This is an overloaded constructor provided for convenience.


QPen

public QPen(QColor color,
            double width)
This is an overloaded constructor provided for convenience.

Method Detail

brush

public final QBrush brush()

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

See Also:
setBrush

capStyle

public final Qt.PenCapStyle capStyle()

Returns the pen's cap style.

See Also:
setCapStyle, Style

color

public final QColor color()

Returns the color of this pen's brush.

See Also:
brush, setColor

dashOffset

public final double dashOffset()

Returns the dash offset for the pen.

See Also:
setDashOffset

dashPattern

public final java.util.List<java.lang.Double> dashPattern()

Returns the dash pattern of this pen.

See Also:
setDashPattern, style, isSolid

isCosmetic

public final boolean isCosmetic()

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

isSolid

public final boolean isSolid()

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

See Also:
style, dashPattern

joinStyle

public final Qt.PenJoinStyle joinStyle()

Returns the pen's join style.

See Also:
setJoinStyle, Style

miterLimit

public final double miterLimit()

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, Style

writeTo

public final void writeTo(QDataStream arg__1)
Writes thisQPen to arg__1.


readFrom

public final void readFrom(QDataStream arg__1)
Reads a QPen from arg__1.


setBrush

public final void setBrush(QBrush brush)

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

See Also:
brush, setColor

setCapStyle

public final void setCapStyle(Qt.PenCapStyle pcs)

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

See Also:
capStyle, Style

setColor

public final void setColor(QColor color)

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

See Also:
setBrush, color

setCosmetic

public final void setCosmetic(boolean cosmetic)

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

See Also:
isCosmetic

setDashOffset

public final void setDashOffset(double doffset)

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

See Also:
dashOffset

setDashPattern

public final void setDashPattern(java.util.List<java.lang.Double> 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 entries where the entries 1, 3, 5... are the dashes and 2, 4, 6... are the spaces. For example:

    QPen pen;
    QVector<qreal> dashes;
    qreal space = 4;
    dashes << 1 << space << 3 << space << 9 << space
               << 27 << space << 9;
    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. 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

setJoinStyle

public final void setJoinStyle(Qt.PenJoinStyle pcs)

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

See Also:
joinStyle, Style

setMiterLimit

public final void setMiterLimit(double 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, Style

setStyle

public final void setStyle(Qt.PenStyle arg__1)

Sets the pen style to the given arg__1.

See the Qt::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 Qt::CustomDashLine.

See Also:
style, Style

setWidth

public final void 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

setWidthF

public final void setWidthF(double 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

style

public final Qt.PenStyle style()

Returns the pen style.

See Also:
setStyle, Style

width

public final int width()

Returns the pen width with integer precision.

See Also:
setWidth, widthF

widthF

public final double widthF()

Returns the pen width with floating point precision.

See Also:
setWidthF, width

fromNativePointer

public static QPen fromNativePointer(QNativePointer nativePointer)
This function returns the QPen instance pointed to by nativePointer

Parameters:
nativePointer - the QNativePointer of which object should be returned.

nativePointerArray

public static QNativePointer nativePointerArray(QPen[] array)
This function returns a QNativePointer that is pointing to the specified QPen array.

Parameters:
array - the array that the returned pointer will point to.
Returns:
a QNativePointer that is pointing to the specified array.

equals

public boolean equals(java.lang.Object other)

Overrides:
equals in class java.lang.Object

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