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43 #include "qdatastream.h"
51 typedef QPenPrivate QPenData;
59 \brief The QPen class defines how a QPainter should draw lines and outlines
62 A pen has a style(), width(), brush(), capStyle() and joinStyle().
64 The pen style defines the line type. The brush is used to fill
65 strokes generated with the pen. Use the QBrush class to specify
66 fill styles. The cap style determines the line end caps that can
67 be drawn using QPainter, while the join style describes how joins
68 between two lines are drawn. The pen width can be specified in
69 both integer (width()) and floating point (widthF()) precision. A
70 line width of zero indicates a cosmetic pen. This means that the
71 pen width is always drawn one pixel wide, independent of the \l
72 {QPainter#Coordinate Transformations}{transformation} set on the
75 The various settings can easily be modified using the
76 corresponding setStyle(), setWidth(), setBrush(), setCapStyle()
77 and setJoinStyle() functions (note that the painter's pen must be
78 reset when altering the pen's properties).
82 \snippet doc/src/snippets/code/src_gui_painting_qpen.cpp 0
84 which is equivalent to
86 \snippet doc/src/snippets/code/src_gui_painting_qpen.cpp 1
88 The default pen is a solid black brush with 0 width, square
89 cap style (Qt::SquareCap), and bevel join style (Qt::BevelJoin).
91 In addition QPen provides the color() and setColor()
92 convenience functions to extract and set the color of the pen's
93 brush, respectively. Pens may also be compared and streamed.
95 For more information about painting in general, see the \l{Paint
96 System} documentation.
102 Qt provides several built-in styles represented by the
107 \li \inlineimage qpen-solid.png
108 \li \inlineimage qpen-dash.png
109 \li \inlineimage qpen-dot.png
115 \li \inlineimage qpen-dashdot.png
116 \li \inlineimage qpen-dashdotdot.png
117 \li \inlineimage qpen-custom.png
120 \li Qt::DashDotDotLine
121 \li Qt::CustomDashLine
124 Simply use the setStyle() function to convert the pen style to
125 either of the built-in styles, except the Qt::CustomDashLine style
126 which we will come back to shortly. Setting the style to Qt::NoPen
127 tells the painter to not draw lines or outlines. The default pen
128 style is Qt::SolidLine.
130 Since Qt 4.1 it is also possible to specify a custom dash pattern
131 using the setDashPattern() function which implicitly converts the
132 style of the pen to Qt::CustomDashLine. The pattern argument, a
133 QVector, must be specified as an even number of \l qreal entries
134 where the entries 1, 3, 5... are the dashes and 2, 4, 6... are the
135 spaces. For example, the custom pattern shown above is created
136 using the following code:
138 \snippet doc/src/snippets/code/src_gui_painting_qpen.cpp 2
140 Note that the dash pattern is specified in units of the pens
141 width, e.g. a dash of length 5 in width 10 is 50 pixels long.
143 The currently set dash pattern can be retrieved using the
144 dashPattern() function. Use the isSolid() function to determine
145 whether the pen has a solid fill, or not.
149 The cap style defines how the end points of lines are drawn using
150 QPainter. The cap style only apply to wide lines, i.e. when the
151 width is 1 or greater. The Qt::PenCapStyle enum provides the
156 \li \inlineimage qpen-square.png
157 \li \inlineimage qpen-flat.png
158 \li \inlineimage qpen-roundcap.png
165 The Qt::SquareCap style is a square line end that covers the end
166 point and extends beyond it by half the line width. The
167 Qt::FlatCap style is a square line end that does not cover the end
168 point of the line. And the Qt::RoundCap style is a rounded line
169 end covering the end point.
171 The default is Qt::SquareCap.
173 Whether or not end points are drawn when the pen width is 0 or 1
174 depends on the cap style. Using Qt::SquareCap or Qt::RoundCap they
175 are drawn, using Qt::FlatCap they are not drawn.
179 The join style defines how joins between two connected lines can
180 be drawn using QPainter. The join style only apply to wide lines,
181 i.e. when the width is 1 or greater. The Qt::PenJoinStyle enum
182 provides the following styles:
186 \li \inlineimage qpen-bevel.png
187 \li \inlineimage qpen-miter.png
188 \li \inlineimage qpen-roundjoin.png
195 The Qt::BevelJoin style fills the triangular notch between the two
196 lines. The Qt::MiterJoin style extends the lines to meet at an
197 angle. And the Qt::RoundJoin style fills a circular arc between
200 The default is Qt::BevelJoin.
202 \image qpen-miterlimit.png
204 When the Qt::MiterJoin style is applied, it is possible to use the
205 setMiterLimit() function to specify how far the miter join can
206 extend from the join point. The miterLimit() is used to reduce
207 artifacts between line joins where the lines are close to
210 The miterLimit() must be specified in units of the pens width,
211 e.g. a miter limit of 5 in width 10 is 50 pixels long. The
212 default miter limit is 2, i.e. twice the pen width in pixels.
216 \li \inlineimage qpen-demo.png
217 \li \b {\l {painting/pathstroke}{The Path Stroking Example}}
219 The Path Stroking example shows Qt's built-in dash patterns and shows
220 how custom patterns can be used to extend the range of available
224 \sa QPainter, QBrush, {painting/pathstroke}{Path Stroking Example},
231 inline QPenPrivate::QPenPrivate(const QBrush &_brush, qreal _width, Qt::PenStyle penStyle,
232 Qt::PenCapStyle _capStyle, Qt::PenJoinStyle _joinStyle)
233 : ref(1), dashOffset(0), miterLimit(2),
239 capStyle = _capStyle;
240 joinStyle = _joinStyle;
243 static const Qt::PenCapStyle qpen_default_cap = Qt::SquareCap;
244 static const Qt::PenJoinStyle qpen_default_join = Qt::BevelJoin;
250 QPenDataHolder(const QBrush &brush, qreal width, Qt::PenStyle penStyle,
251 Qt::PenCapStyle penCapStyle, Qt::PenJoinStyle _joinStyle)
252 : pen(new QPenData(brush, width, penStyle, penCapStyle, _joinStyle))
256 if (!pen->ref.deref())
262 Q_GLOBAL_STATIC_WITH_ARGS(QPenDataHolder, defaultPenInstance,
263 (Qt::black, 0, Qt::SolidLine, qpen_default_cap, qpen_default_join))
264 Q_GLOBAL_STATIC_WITH_ARGS(QPenDataHolder, nullPenInstance,
265 (Qt::black, 0, Qt::NoPen, qpen_default_cap, qpen_default_join))
268 Constructs a default black solid line pen with 0 width.
273 d = defaultPenInstance()->pen;
278 Constructs a black pen with 0 width and the given \a style.
283 QPen::QPen(Qt::PenStyle style)
285 if (style == Qt::NoPen) {
286 d = nullPenInstance()->pen;
289 d = new QPenData(Qt::black, 0, style, qpen_default_cap, qpen_default_join);
295 Constructs a solid line pen with 0 width and the given \a color.
297 \sa setBrush(), setColor()
300 QPen::QPen(const QColor &color)
302 d = new QPenData(color, 0, Qt::SolidLine, qpen_default_cap, qpen_default_join);
307 \fn QPen::QPen(const QBrush &brush, qreal width, Qt::PenStyle style, Qt::PenCapStyle cap, Qt::PenJoinStyle join)
309 Constructs a pen with the specified \a brush, \a width, pen \a style,
310 \a cap style and \a join style.
312 \sa setBrush(), setWidth(), setStyle(), setCapStyle(), setJoinStyle()
315 QPen::QPen(const QBrush &brush, qreal width, Qt::PenStyle s, Qt::PenCapStyle c, Qt::PenJoinStyle j)
317 d = new QPenData(brush, width, s, c, j);
321 \fn QPen::QPen(const QPen &pen)
323 Constructs a pen that is a copy of the given \a pen.
326 QPen::QPen(const QPen &p)
344 \fn void QPen::detach()
345 Detaches from shared pen data to make sure that this pen is the
346 only one referring the data.
348 If multiple pens share common data, this pen dereferences the data
349 and gets a copy of the data. Nothing is done if there is just a
355 if (d->ref.load() == 1)
358 QPenData *x = new QPenData(*static_cast<QPenData *>(d));
367 \fn QPen &QPen::operator=(const QPen &pen)
369 Assigns the given \a pen to this pen and returns a reference to
373 QPen &QPen::operator=(const QPen &p)
375 qAtomicAssign(d, p.d);
380 \fn void QPen::swap(QPen &other)
383 Swaps pen \a other with this pen. This operation is very
384 fast and never fails.
388 Returns the pen as a QVariant.
390 QPen::operator QVariant() const
392 return QVariant(QVariant::Pen, this);
396 \fn Qt::PenStyle QPen::style() const
398 Returns the pen style.
400 \sa setStyle(), {QPen#Pen Style}{Pen Style}
402 Qt::PenStyle QPen::style() const
407 \fn void QPen::setStyle(Qt::PenStyle style)
409 Sets the pen style to the given \a style.
411 See the \l Qt::PenStyle documentation for a list of the available
412 styles. Since Qt 4.1 it is also possible to specify a custom dash
413 pattern using the setDashPattern() function which implicitly
414 converts the style of the pen to Qt::CustomDashLine.
416 \note This function resets the dash offset to zero.
418 \sa style(), {QPen#Pen Style}{Pen Style}
421 void QPen::setStyle(Qt::PenStyle s)
427 QPenData *dd = static_cast<QPenData *>(d);
428 dd->dashPattern.clear();
433 Returns the dash pattern of this pen.
435 \sa style(), isSolid()
437 QVector<qreal> QPen::dashPattern() const
439 QPenData *dd = static_cast<QPenData *>(d);
440 if (d->style == Qt::SolidLine || d->style == Qt::NoPen) {
441 return QVector<qreal>();
442 } else if (dd->dashPattern.isEmpty()) {
443 const qreal space = 2;
445 const qreal dash = 4;
449 dd->dashPattern << dash << space;
452 dd->dashPattern << dot << space;
454 case Qt::DashDotLine:
455 dd->dashPattern << dash << space << dot << space;
457 case Qt::DashDotDotLine:
458 dd->dashPattern << dash << space << dot << space << dot << space;
464 return dd->dashPattern;
468 Sets the dash pattern for this pen to the given \a pattern. This
469 implicitly converts the style of the pen to Qt::CustomDashLine.
471 The pattern must be specified as an even number of positive entries
472 where the entries 1, 3, 5... are the dashes and 2, 4, 6... are the
477 \li \inlineimage qpen-custom.png
479 \snippet doc/src/snippets/code/src_gui_painting_qpen.cpp 3
482 The dash pattern is specified in units of the pens width; e.g. a
483 dash of length 5 in width 10 is 50 pixels long. Note that a pen
484 with zero width is equivalent to a cosmetic pen with a width of 1
487 Each dash is also subject to cap styles so a dash of 1 with square
488 cap set will extend 0.5 pixels out in each direction resulting in
491 Note that the default cap style is Qt::SquareCap, meaning that a
492 square line end covers the end point and extends beyond it by half
495 \sa setStyle(), dashPattern(), setCapStyle(), setCosmetic()
497 void QPen::setDashPattern(const QVector<qreal> &pattern)
499 if (pattern.isEmpty())
503 QPenData *dd = static_cast<QPenData *>(d);
504 dd->dashPattern = pattern;
505 d->style = Qt::CustomDashLine;
507 if ((dd->dashPattern.size() % 2) == 1) {
508 qWarning("QPen::setDashPattern: Pattern not of even length");
509 dd->dashPattern << 1;
515 Returns the dash offset for the pen.
519 qreal QPen::dashOffset() const
521 QPenData *dd = static_cast<QPenData *>(d);
522 return dd->dashOffset;
525 Sets the dash offset (the starting point on the dash pattern) for this pen
526 to the \a offset specified. The offset is measured in terms of the units used
527 to specify the dash pattern.
530 \row \li \inlineimage qpen-dashpattern.png
531 \li For example, a pattern where each stroke is four units long, followed by a gap
532 of two units, will begin with the stroke when drawn as a line.
534 However, if the dash offset is set to 4.0, any line drawn will begin with the gap.
535 Values of the offset up to 4.0 will cause part of the stroke to be drawn first,
536 and values of the offset between 4.0 and 6.0 will cause the line to begin with
540 \note This implicitly converts the style of the pen to Qt::CustomDashLine.
542 void QPen::setDashOffset(qreal offset)
544 if (qFuzzyCompare(offset, static_cast<QPenData *>(d)->dashOffset))
547 QPenData *dd = static_cast<QPenData *>(d);
548 dd->dashOffset = offset;
549 if (d->style != Qt::CustomDashLine) {
550 dd->dashPattern = dashPattern();
551 d->style = Qt::CustomDashLine;
556 Returns the miter limit of the pen. The miter limit is only
557 relevant when the join style is set to Qt::MiterJoin.
559 \sa setMiterLimit(), {QPen#Join Style}{Join Style}
561 qreal QPen::miterLimit() const
563 const QPenData *dd = static_cast<QPenData *>(d);
564 return dd->miterLimit;
568 Sets the miter limit of this pen to the given \a limit.
570 \image qpen-miterlimit.png
572 The miter limit describes how far a miter join can extend from the
573 join point. This is used to reduce artifacts between line joins
574 where the lines are close to parallel.
576 This value does only have effect when the pen style is set to
577 Qt::MiterJoin. The value is specified in units of the pen's width,
578 e.g. a miter limit of 5 in width 10 is 50 pixels long. The default
579 miter limit is 2, i.e. twice the pen width in pixels.
581 \sa miterLimit(), setJoinStyle(), {QPen#Join Style}{Join Style}
583 void QPen::setMiterLimit(qreal limit)
586 QPenData *dd = static_cast<QPenData *>(d);
587 dd->miterLimit = limit;
592 \fn qreal QPen::width() const
594 Returns the pen width with integer precision.
596 \sa setWidth(), widthF()
599 int QPen::width() const
601 return qRound(d->width);
605 \fn qreal QPen::widthF() const
607 Returns the pen width with floating point precision.
609 \sa setWidthF() width()
611 qreal QPen::widthF() const
617 \fn QPen::setWidth(int width)
619 Sets the pen width to the given \a width in pixels with integer
622 A line width of zero indicates a cosmetic pen. This means that the
623 pen width is always drawn one pixel wide, independent of the \l
624 {QPainter#Coordinate Transformations}{transformation} set on the
627 Setting a pen width with a negative value is not supported.
629 \sa setWidthF(), width()
631 void QPen::setWidth(int width)
634 qWarning("QPen::setWidth: Setting a pen width with a negative value is not defined");
635 if ((qreal)width == d->width)
642 Sets the pen width to the given \a width in pixels with floating point
645 A line width of zero indicates a cosmetic pen. This means that the
646 pen width is always drawn one pixel wide, independent of the \l
647 {QPainter#Coordinate Transformations}{transformation} on the
650 Setting a pen width with a negative value is not supported.
652 \sa setWidth() widthF()
655 void QPen::setWidthF(qreal width)
658 qWarning("QPen::setWidthF: Setting a pen width with a negative value is not defined");
659 if (qAbs(d->width - width) < 0.00000001f)
667 Returns the pen's cap style.
669 \sa setCapStyle(), {QPen#Cap Style}{Cap Style}
671 Qt::PenCapStyle QPen::capStyle() const
677 \fn void QPen::setCapStyle(Qt::PenCapStyle style)
679 Sets the pen's cap style to the given \a style. The default value
682 \sa capStyle(), {QPen#Cap Style}{Cap Style}
685 void QPen::setCapStyle(Qt::PenCapStyle c)
687 if (d->capStyle == c)
694 Returns the pen's join style.
696 \sa setJoinStyle(), {QPen#Join Style}{Join Style}
698 Qt::PenJoinStyle QPen::joinStyle() const
704 \fn void QPen::setJoinStyle(Qt::PenJoinStyle style)
706 Sets the pen's join style to the given \a style. The default value
709 \sa joinStyle(), {QPen#Join Style}{Join Style}
712 void QPen::setJoinStyle(Qt::PenJoinStyle j)
714 if (d->joinStyle == j)
721 \fn const QColor &QPen::color() const
723 Returns the color of this pen's brush.
725 \sa brush(), setColor()
727 QColor QPen::color() const
729 return d->brush.color();
733 \fn void QPen::setColor(const QColor &color)
735 Sets the color of this pen's brush to the given \a color.
737 \sa setBrush(), color()
740 void QPen::setColor(const QColor &c)
743 d->brush = QBrush(c);
748 Returns the brush used to fill strokes generated with this pen.
750 QBrush QPen::brush() const
756 Sets the brush used to fill strokes generated with this pen to the given
759 \sa brush(), setColor()
761 void QPen::setBrush(const QBrush &brush)
769 Returns true if the pen has a solid fill, otherwise false.
771 \sa style(), dashPattern()
773 bool QPen::isSolid() const
775 return d->brush.style() == Qt::SolidPattern;
780 Returns true if the pen is cosmetic; otherwise returns false.
782 Cosmetic pens are used to draw strokes that have a constant width
783 regardless of any transformations applied to the QPainter they are
784 used with. Drawing a shape with a cosmetic pen ensures that its
785 outline will have the same thickness at different scale factors.
787 A zero width pen is cosmetic by default; pens with a non-zero width
790 \sa setCosmetic(), widthF()
793 bool QPen::isCosmetic() const
795 QPenData *dd = static_cast<QPenData *>(d);
796 return (dd->cosmetic == true) || d->width == 0;
801 Sets this pen to cosmetic or non-cosmetic, depending on the value of
807 void QPen::setCosmetic(bool cosmetic)
810 QPenData *dd = static_cast<QPenData *>(d);
811 dd->cosmetic = cosmetic;
817 \fn bool QPen::operator!=(const QPen &pen) const
819 Returns true if the pen is different from the given \a pen;
820 otherwise false. Two pens are different if they have different
821 styles, widths or colors.
827 \fn bool QPen::operator==(const QPen &pen) const
829 Returns true if the pen is equal to the given \a pen; otherwise
830 false. Two pens are equal if they have equal styles, widths and
836 bool QPen::operator==(const QPen &p) const
838 QPenData *dd = static_cast<QPenData *>(d);
839 QPenData *pdd = static_cast<QPenData *>(p.d);
841 || (p.d->style == d->style
842 && p.d->capStyle == d->capStyle
843 && p.d->joinStyle == d->joinStyle
844 && p.d->width == d->width
845 && pdd->miterLimit == dd->miterLimit
846 && (d->style != Qt::CustomDashLine
847 || (qFuzzyCompare(pdd->dashOffset, dd->dashOffset) &&
848 pdd->dashPattern == dd->dashPattern))
849 && p.d->brush == d->brush
850 && pdd->cosmetic == dd->cosmetic);
855 \fn bool QPen::isDetached()
860 bool QPen::isDetached()
862 return d->ref.load() == 1;
866 /*****************************************************************************
867 QPen stream functions
868 *****************************************************************************/
869 #ifndef QT_NO_DATASTREAM
871 \fn QDataStream &operator<<(QDataStream &stream, const QPen &pen)
874 Writes the given \a pen to the given \a stream and returns a reference to
877 \sa {Serializing Qt Data Types}
880 QDataStream &operator<<(QDataStream &s, const QPen &p)
882 QPenData *dd = static_cast<QPenData *>(p.d);
883 if (s.version() < 3) {
884 s << (quint8)p.style();
885 } else if (s.version() < QDataStream::Qt_4_3) {
886 s << (quint8)(p.style() | p.capStyle() | p.joinStyle());
888 s << (quint16)(p.style() | p.capStyle() | p.joinStyle());
889 s << (bool)(dd->cosmetic);
892 if (s.version() < 7) {
893 s << (quint8)p.width();
896 s << double(p.widthF());
898 s << double(p.miterLimit());
899 if (sizeof(qreal) == sizeof(double)) {
900 s << p.dashPattern();
902 // ensure that we write doubles here instead of streaming the pattern
903 // directly; otherwise, platforms that redefine qreal might generate
904 // data that cannot be read on other platforms.
905 QVector<qreal> pattern = p.dashPattern();
906 s << quint32(pattern.size());
907 for (int i = 0; i < pattern.size(); ++i)
908 s << double(pattern.at(i));
910 if (s.version() >= 9)
911 s << double(p.dashOffset());
917 \fn QDataStream &operator>>(QDataStream &stream, QPen &pen)
920 Reads a pen from the given \a stream into the given \a pen and
921 returns a reference to the \a stream.
923 \sa {Serializing Qt Data Types}
926 QDataStream &operator>>(QDataStream &s, QPen &p)
933 double miterLimit = 2;
934 QVector<qreal> dashPattern;
935 double dashOffset = 0;
936 bool cosmetic = false;
937 if (s.version() < QDataStream::Qt_4_3) {
945 if (s.version() < 7) {
954 if (sizeof(qreal) == sizeof(double)) {
960 for (quint32 i = 0; i < numDashes; ++i) {
965 if (s.version() >= 9)
970 QPenData *dd = static_cast<QPenData *>(p.d);
973 dd->style = Qt::PenStyle(style & Qt::MPenStyle);
974 dd->capStyle = Qt::PenCapStyle(style & Qt::MPenCapStyle);
975 dd->joinStyle = Qt::PenJoinStyle(style & Qt::MPenJoinStyle);
976 dd->dashPattern = dashPattern;
977 dd->miterLimit = miterLimit;
978 dd->dashOffset = dashOffset;
979 dd->cosmetic = cosmetic;
983 #endif //QT_NO_DATASTREAM
985 #ifndef QT_NO_DEBUG_STREAM
986 QDebug operator<<(QDebug dbg, const QPen &p)
988 const char *PEN_STYLES[] = {
998 dbg.nospace() << "QPen(" << p.width() << ',' << p.brush()
999 << ',' << PEN_STYLES[p.style()] << ',' << int(p.capStyle())
1000 << ',' << int(p.joinStyle()) << ',' << p.dashPattern()
1001 << ',' << p.dashOffset()
1002 << ',' << p.miterLimit() << ')';
1008 \fn DataPtr &QPen::data_ptr()
1013 \typedef QPen::DataPtr
1020 #undef QT_COMPILING_QPEN