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QCanvasPolygonalItem(3qt)			     QCanvasPolygonalItem(3qt)

NAME
       QCanvasPolygonalItem - Polygonal canvas item on a QCanvas

SYNOPSIS
       #include <qcanvas.h>

       Inherits QCanvasItem.

       Inherited by QCanvasRectangle, QCanvasPolygon, QCanvasLine, and
       QCanvasEllipse.

   Public Members
       QCanvasPolygonalItem ( QCanvas * canvas )
       virtual ~QCanvasPolygonalItem ()
       virtual void setPen ( QPen p )
       virtual void setBrush ( QBrush b )
       QPen pen () const
       QBrush brush () const
       virtual QPointArray areaPoints () const = 0
       virtual QPointArray areaPointsAdvanced () const
       virtual QRect boundingRect () const
       virtual int rtti () const

   Protected Members
       virtual void draw ( QPainter & p )
       virtual void drawShape ( QPainter & p ) = 0
       bool winding () const
       void setWinding ( bool enable )
       void invalidate ()
       bool isValid () const

DESCRIPTION
       The QCanvasPolygonalItem class provides a polygonal canvas item on a
       QCanvas.

       The mostly rectangular classes, such as QCanvasSprite and QCanvasText,
       use the object's bounding rectangle for movement, repainting and
       collision calculations. For most other items, the bounding rectangle
       can be far too large -- a diagonal line being the worst case, and there
       are many other cases which are also bad. QCanvasPolygonalItem provides
       polygon-based bounding rectangle handling, etc., which is much faster
       for non-rectangular items.

       Derived classes should try to define as small an area as possible to
       maximize efficiency, but the polygon must definitely be contained
       completely within the polygonal area. Calculating the exact
       requirements is usually difficult, but if you allow a small
       overestimate it can be easy and quick, while still getting almost all
       of QCanvasPolygonalItem's speed.

       Note that all subclasses must call hide() in their destructor since
       hide() needs to be able to access areaPoints().

       Normally, QCanvasPolygonalItem uses the odd-even algorithm for
       determining whether an object intersects this object. You can change
       this to the winding algorithm using setWinding().

       The bounding rectangle is available using boundingRect(). The points
       bounding the polygonal item are retrieved with areaPoints(). Use
       areaPointsAdvanced() to retrieve the bounding points the polygonal item
       will have after QCanvasItem::advance(1) has been called.

       If the shape of the polygonal item is about to change while the item is
       visible, call invalidate() before updating with a different result from
       areaPoints().

       By default, QCanvasPolygonalItem objects have a black pen and no brush
       (the default QPen and QBrush constructors). You can change this with
       setPen() and setBrush(), but note that some QCanvasPolygonalItem
       subclasses only use the brush, ignoring the pen setting.

       The polygonal item can be drawn on a painter with draw(). Subclasses
       must reimplement drawShape() to draw themselves.

       Like any other canvas item polygonal items can be moved with
       QCanvasItem::move() and QCanvasItem::moveBy(), or by setting
       coordinates with QCanvasItem::setX(), QCanvasItem::setY() and
       QCanvasItem::setZ().

       See also Graphics Classes and Image Processing Classes.

MEMBER FUNCTION DOCUMENTATION
QCanvasPolygonalItem::QCanvasPolygonalItem ( QCanvas * canvas )
       Constructs a QCanvasPolygonalItem on the canvas canvas.

QCanvasPolygonalItem::~QCanvasPolygonalItem () [virtual]
       Note that all subclasses must call hide() in their destructor since
       hide() needs to be able to access areaPoints().

QPointArray QCanvasPolygonalItem::areaPoints () const [pure virtual]
       This function must be reimplemented by subclasses. It must return the
       points bounding (i.e. outside and not touching) the shape or drawing
       errors will occur.

       Reimplemented in QCanvasPolygon.

QPointArray QCanvasPolygonalItem::areaPointsAdvanced () const [virtual]
       Returns the points the polygonal item will have after
       QCanvasItem::advance(1) is called, i.e. what the points are when
       advanced by the current xVelocity() and yVelocity().

QRect QCanvasPolygonalItem::boundingRect () const [virtual]
       Returns the bounding rectangle of the polygonal item, based on
       areaPoints().

       Reimplemented from QCanvasItem.

QBrush QCanvasPolygonalItem::brush () const
       Returns the QBrush used to fill the item, if filled.

       See also setBrush().

void QCanvasPolygonalItem::draw ( QPainter & p ) [virtual protected]
       Reimplemented from QCanvasItem, this draws the polygonal item by
       setting the pen and brush for the item on the painter p and calling
       drawShape().

       Reimplemented from QCanvasItem.

void QCanvasPolygonalItem::drawShape ( QPainter & p ) [pure virtual protected]

       Subclasses must reimplement this function to draw their shape. The pen
       and brush of p are already set to pen() and brush() prior to calling
       this function.

       Warning: When you reimplement this function, make sure that you leave
       the painter in the same state as you found it. For example, if you
       start by calling QPainter::translate(50, 50), end your code by calling
       QPainter::translate(-50, -50). Be also aware that the painter might
       already have some transformations set (i.e., don't call
       QPainter::resetXForm() when you're done).

       See also draw().

       Reimplemented in QCanvasRectangle, QCanvasPolygon, and QCanvasEllipse.

void QCanvasPolygonalItem::invalidate () [protected]
       Invalidates all information about the area covered by the canvas item.
       The item will be updated automatically on the next call that changes
       the item's status, for example, move() or update(). Call this function
       if you are going to change the shape of the item (as returned by
       areaPoints()) while the item is visible.

bool QCanvasPolygonalItem::isValid () const [protected]
       Returns TRUE if the polygonal item's area information has not been
       invalidated; otherwise returns FALSE.

       See also invalidate().

QPen QCanvasPolygonalItem::pen () const
       Returns the QPen used to draw the outline of the item, if any.

       See also setPen().

int QCanvasPolygonalItem::rtti () const [virtual]
       Returns 2 (QCanvasItem::Rtti_PolygonalItem).

       See also QCanvasItem::rtti().

       Reimplemented from QCanvasItem.

       Reimplemented in QCanvasRectangle, QCanvasPolygon, QCanvasLine, and
       QCanvasEllipse.

void QCanvasPolygonalItem::setBrush ( QBrush b ) [virtual]
       Sets the QBrush used when drawing the polygonal item to the brush b.

       See also setPen(), brush(), and drawShape().

       Examples:

void QCanvasPolygonalItem::setPen ( QPen p ) [virtual]
       Sets the QPen used when drawing the item to the pen p. Note that many
       QCanvasPolygonalItems do not use the pen value.

       See also setBrush(), pen(), and drawShape().

       Examples:

void QCanvasPolygonalItem::setWinding ( bool enable ) [protected]
       If enable is TRUE, the polygonal item will use the winding algorithm to
       determine the "inside" of the polygon; otherwise the odd-even algorithm
       will be used.

       The default is to use the odd-even algorithm.

       See also winding().

bool QCanvasPolygonalItem::winding () const [protected]
       Returns TRUE if the polygonal item uses the winding algorithm to
       determine the "inside" of the polygon. Returns FALSE if it uses the
       odd-even algorithm.

       The default is to use the odd-even algorithm.

       See also setWinding().

SEE ALSO
       http://doc.trolltech.com/qcanvaspolygonalitem.html
       http://www.trolltech.com/faq/tech.html

COPYRIGHT
       Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com.  See the
       license file included in the distribution for a complete license
       statement.

AUTHOR
       Generated automatically from the source code.

BUGS
       If you find a bug in Qt, please report it as described in
       http://doc.trolltech.com/bughowto.html.	Good bug reports help us to
       help you. Thank you.

       The definitive Qt documentation is provided in HTML format; it is
       located at $QTDIR/doc/html and can be read using Qt Assistant or with a
       web browser. This man page is provided as a convenience for those users
       who prefer man pages, although this format is not officially supported
       by Trolltech.

       If you find errors in this manual page, please report them to qt-
       bugs@trolltech.com.  Please include the name of the manual page
       (qcanvaspolygonalitem.3qt) and the Qt version (3.3.8).

Trolltech AS			2 February 2007	     QCanvasPolygonalItem(3qt)
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