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Eneboo - Documentación para desarrolladores
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Eneboo - Documentación para desarrolladores
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The QPen class defines how a QPainter should draw lines and outlines of shapes. Más...
#include <qpen.h>
The QPen class defines how a QPainter should draw lines and outlines of shapes.
A pen has a style, width, color, cap style and join style.
The pen style defines the line type. The default pen style is Qt::SolidLine. Setting the style to NoPen tells the painter to not draw lines or outlines.
When drawing 1 pixel wide diagonal lines you can either use a very fast algorithm (specified by a line width of 0, which is the default), or a slower but more accurate algorithm (specified by a line width of 1). For horizontal and vertical lines a line width of 0 is the same as a line width of 1. The cap and join style have no effect on 0-width lines.
The pen color defines the color of lines and text. The default line color is black. The QColor documentation lists predefined colors.
The cap style defines how the end points of lines are drawn. The join style defines how the joins between two lines are drawn when multiple connected lines are drawn (QPainter::drawPolyline() etc.). The cap and join styles only apply to wide lines, i.e. when the width is 1 or greater.
Use the QBrush class to specify fill styles.
Example:
QPainter painter; QPen pen( red, 2 ); // red solid line, 2 pixels wide painter.begin( &anyPaintDevice ); // paint something painter.setPen( pen ); // set the red, wide pen painter.drawRect( 40,30, 200,100 ); // draw a rectangle painter.setPen( blue ); // set blue pen, 0 pixel width painter.drawLine( 40,30, 240,130 ); // draw a diagonal in rectangle painter.end(); // painting done
See the Qt::PenStyle enum type for a complete list of pen styles.
With reference to the end points of lines, for wide (non-0-width) pens it depends on the cap style whether the end point is drawn or not. QPainter will try to make sure that the end point is drawn for 0-width pens, but this cannot be absolutely guaranteed because the underlying drawing engine is free to use any (typically accelerated) algorithm for drawing 0-width lines. On all tested systems, however, the end point of at least all non-diagonal lines are drawn.
A pen's color(), width(), style(), capStyle() and joinStyle() can be set in the constructor or later with setColor(), setWidth(), setStyle(), setCapStyle() and setJoinStyle(). Pens may also be compared and streamed.
pen-styles.png Pen styles
| QPen::QPen | ( | ) |
Constructs a default black solid line pen with 0 width, which renders lines 1 pixel wide (fast diagonals).
| QPen::QPen | ( | PenStyle | style | ) |
Constructs a black pen with 0 width (fast diagonals) and style style.
Constructs a pen with the specified color, width and style.
| QPen::QPen | ( | const QColor & | cl, |
| uint | w, | ||
| PenStyle | s, | ||
| PenCapStyle | c, | ||
| PenJoinStyle | j | ||
| ) |
Constructs a pen with the specified color cl and width w. The pen style is set to s, the pen cap style to c and the pen join style to j.
A line width of 0 will produce a 1 pixel wide line using a fast algorithm for diagonals. A line width of 1 will also produce a 1 pixel wide line, but uses a slower more accurate algorithm for diagonals. For horizontal and vertical lines a line width of 0 is the same as a line width of 1. The cap and join style have no effect on 0-width lines.
| QPen::QPen | ( | const QPen & | p | ) |
Constructs a pen that is a copy of p.
| QPen::~QPen | ( | ) |
Destroys the pen.
| QPen::QPen | ( | ) |
| QPen::QPen | ( | PenStyle | ) |
| QPen::QPen | ( | const QColor & | cl, |
| uint | w, | ||
| PenStyle | s, | ||
| PenCapStyle | c, | ||
| PenJoinStyle | j | ||
| ) |
| QPen::QPen | ( | const QPen & | ) |
| QPen::~QPen | ( | ) |
| Qt::PenCapStyle QPen::capStyle | ( | ) | const |
Returns the pen's cap style.
| PenCapStyle QPen::capStyle | ( | ) | const |
| const QColor& QPen::color | ( | ) | const [inline] |
| const QColor & QPen::color | ( | ) | const [inline] |
Returns the pen color.
| Qt::PenJoinStyle QPen::joinStyle | ( | ) | const |
Returns the pen's join style.
| PenJoinStyle QPen::joinStyle | ( | ) | const |
Returns TRUE if the pen is different from p; otherwise returns FALSE.
Two pens are different if they have different styles, widths or colors.
Returns TRUE if the pen is equal to p; otherwise returns FALSE.
Two pens are equal if they have equal styles, widths and colors.
| void QPen::setCapStyle | ( | PenCapStyle | c | ) |
Sets the pen's cap style to c.
The default value is FlatCap. The cap style has no effect on 0-width pens.
pen-cap-styles.png Pen Cap Styles
SquareCap.| void QPen::setCapStyle | ( | PenCapStyle | ) |
| void QPen::setColor | ( | const QColor & | ) |
| void QPen::setJoinStyle | ( | PenJoinStyle | j | ) |
Sets the pen's join style to j.
The default value is MiterJoin. The join style has no effect on 0-width pens.
pen-join-styles.png Pen Join Styles
BevelJoin.| void QPen::setJoinStyle | ( | PenJoinStyle | ) |
| void QPen::setStyle | ( | PenStyle | ) |
| void QPen::setStyle | ( | PenStyle | s | ) |
Sets the pen style to s.
See the Qt::PenStyle documentation for a list of all the styles.
NoPen and SolidLine) have no effect as they are not implemented by the underlying system.NoPen and SolidLine) has no effect for lines with width greater than 1.| void QPen::setWidth | ( | uint | ) |
| void QPen::setWidth | ( | uint | w | ) |
Sets the pen width to w.
A line width of 0 will produce a 1 pixel wide line using a fast algorithm for diagonals. A line width of 1 will also produce a 1 pixel wide line, but uses a slower more accurate algorithm for diagonals. For horizontal and vertical lines a line width of 0 is the same as a line width of 1. The cap and join style have no effect on 0-width lines.
| PenStyle QPen::style | ( | ) | const [inline] |
| PenStyle QPen::style | ( | ) | const [inline] |
Returns the pen style.
| uint QPen::width | ( | ) | const [inline] |
Returns the pen width.
| uint QPen::width | ( | ) | const [inline] |
| QDataStream & operator<< | ( | QDataStream & | s, |
| const QPen & | p | ||
| ) | [related] |
Writes the pen p to the stream s and returns a reference to the stream.
| QDataStream & operator>> | ( | QDataStream & | s, |
| QPen & | p | ||
| ) | [related] |
Reads a pen from the stream s into p and returns a reference to the stream.
QPainter [friend] |
1.7.4