com.trolltech.qt.gui
Class QPen

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

public class QPen
extends QtJambiObject
implements java.lang.Cloneable

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 = new QPainter(this);
        QPen pen = new QPen(QColor.green, 3, Qt.PenStyle.DashDotLine, Qt.PenCapStyle.RoundCap, Qt.PenJoinStyle.RoundJoin);
        painter.setPen(pen);
which is equivalent to
        QPainter painter = new QPainter(this);
        QPen pen = new QPen();  // creates a default pen

        pen.setStyle(Qt.PenStyle.DashDotLine);
        pen.setWidth(3);
        pen.setBrush(new QBrush(QColor.green));
        pen.setCapStyle(Qt.PenCapStyle.RoundCap);
        pen.setJoinStyle(Qt.PenJoinStyle.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::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 .

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 = new QPen();
        List<Double> dashes = new ArrayList<Double>();

        double space = 4;

        dashes.add(1.0);
        dashes.add(space);
        dashes.add(3.0);
        dashes.add(space);
        dashes.add(9.0);
        dashes.add(space);
        dashes.add(27.0);
        dashes.add(space);
        dashes.add(9.0);

        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::SquareCap Qt::FlatCap Qt::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.



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, Path Stroking Demo, and Scribble Example.


Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
static QPen NoPen
           
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QPen()
          Constructs a default black solid line pen with 0 width.
QPen(QBrush brush, double width)
          Constructs a pen with the specified brush, width, pen style, cap style and join style.
QPen(QBrush brush, double width, Qt.PenStyle s)
          Constructs a pen with the specified brush, width, pen style, cap style and join style.
QPen(QBrush brush, double width, Qt.PenStyle s, Qt.PenCapStyle c)
          Constructs a pen with the specified brush, width, pen style, cap style and join style.
QPen(QBrush brush, double width, Qt.PenStyle s, Qt.PenCapStyle c, Qt.PenJoinStyle j)
          Constructs a pen with the specified brush, width, pen style, cap style and join 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)
          Constructs a pen with the specified brush, width, pen style, cap style and join style.
QPen(QColor color, double width, Qt.PenStyle s, Qt.PenCapStyle c)
          Constructs a pen with the specified brush, width, pen style, cap style and join style.
QPen(QColor color, double width, Qt.PenStyle s, Qt.PenCapStyle c, Qt.PenJoinStyle j)
          Constructs a pen with the specified brush, width, pen style, cap style and join style.
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 style.
 
Method Summary
 QBrush brush()
          Returns the brush used to fill strokes generated with this pen.
 Qt.PenCapStyle capStyle()
          Returns the pen's cap style.
 QPen clone()
          This method is reimplemented for internal reasons
 QColor color()
          Returns the color of this pen's brush.
 double dashOffset()
          Returns the dash offset for the pen.
 java.util.List dashPattern()
          Returns the dash pattern of this pen.
 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.
 void readFrom(QDataStream arg__1)
          Reads a QPen
 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 style.
 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 (the starting point on the dash pattern) for this pen to the offset specified.
 void setDashPattern(java.util.List 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 style.
 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 style.
 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.
 java.lang.String toString()
          Returns a string representation of the this QPen.
 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
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
getClass, hashCode, notify, notifyAll, 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()
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 style.

See also:
setStyle().


QPen

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

See also:
setBrush(), setWidth(), setStyle(), setCapStyle(), and setJoinStyle().


QPen

public QPen(QBrush brush,
            double width,
            Qt.PenStyle s)
Constructs a pen with the specified brush, width, pen style, cap style and join style.

See also:
setBrush(), setWidth(), setStyle(), setCapStyle(), and setJoinStyle().


QPen

public QPen(QBrush brush,
            double width)
Constructs a pen with the specified brush, width, pen style, cap style and join style.

See also:
setBrush(), setWidth(), setStyle(), setCapStyle(), and setJoinStyle().


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 style, cap style and join style.

See also:
setBrush(), setWidth(), setStyle(), setCapStyle(), and setJoinStyle().


QPen

public QPen(QColor color)
Constructs a solid line pen with 0 width and the given color.

See also:
setBrush(), and setColor().


QPen

public QPen(QPen pen)
Constructs a pen that is a copy of the given pen.


QPen

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

See also:
setBrush(), setWidth(), setStyle(), setCapStyle(), and setJoinStyle().


QPen

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

See also:
setBrush(), setWidth(), setStyle(), setCapStyle(), and setJoinStyle().


QPen

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

See also:
setBrush(), setWidth(), setStyle(), setCapStyle(), and setJoinStyle().


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(), and Cap Style.


color

public final QColor color()
Returns the color of this pen's brush.

See also:
brush(), and setColor().


dashOffset

public final double dashOffset()
Returns the dash offset for the pen.

See also:
setDashOffset().


dashPattern

public final java.util.List dashPattern()
Returns the dash pattern of this pen.

See also:
setDashPattern(), style(), and 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(), and widthF().


isSolid

public final boolean isSolid()
Returns true if the pen has a solid fill, otherwise false.

See also:
style(), and dashPattern().


joinStyle

public final Qt.PenJoinStyle joinStyle()
Returns the pen's join style.

See also:
setJoinStyle(), and Join 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(), and Join Style.


writeTo

public final void writeTo(QDataStream arg__1)
Writes thisQPen


readFrom

public final void readFrom(QDataStream arg__1)
Reads a QPen


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(), and setColor().


setCapStyle

public final void setCapStyle(Qt.PenCapStyle pcs)
Sets the pen's cap style to the given style. The default value is Qt::SquareCap .

See also:
capStyle(), and Cap Style.


setColor

public final void setColor(QColor color)
Sets the color of this pen's brush to the given color.

See also:
setBrush(), and 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 (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().


setDashPattern

public final void setDashPattern(java.util.List 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 = new QPen();
        List<Double> dashes = new ArrayList<Double>();

        double space = 4;

        dashes.add(1.0);
        dashes.add(space);
        dashes.add(3.0);
        dashes.add(space);
        dashes.add(9.0);
        dashes.add(space);
        dashes.add(27.0);
        dashes.add(space);
        dashes.add(9.0);

        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(), and setCosmetic().


setJoinStyle

public final void setJoinStyle(Qt.PenJoinStyle pcs)
Sets the pen's join style to the given style. The default value is Qt::BevelJoin .

See also:
joinStyle(), and Join 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(), and Join Style.


setStyle

public final void setStyle(Qt.PenStyle arg__1)
Sets the pen style to the given style.

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(), and Pen 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(), and 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(), and widthF().


style

public final Qt.PenStyle style()
Returns the pen style.

See also:
setStyle(), and Pen Style.


width

public final int width()
Returns the pen width with integer precision.

See also:
setWidth(), and widthF().


widthF

public final double widthF()
Returns the pen width with floating point precision.

See also:
setWidthF(), and width().


toString

public java.lang.String toString()
Returns a string representation of the this QPen.

Overrides:
toString in class java.lang.Object

clone

public QPen clone()
This method is reimplemented for internal reasons

Overrides:
clone in class java.lang.Object