|Q3CanvasPolygonalItem(Q3Canvas * canvas)|
|virtual Q3PointArray||areaPoints() const = 0|
|virtual Q3PointArray||areaPointsAdvanced() const|
|virtual void||setBrush(QBrush b)|
|virtual void||setPen(QPen p)|
Reimplemented Public Functions
|virtual QRect||boundingRect() const|
|virtual bool||collidesWith(const Q3CanvasItem * i) const|
|virtual int||rtti() const|
- 34 public functions inherited from Q3CanvasItem
|virtual void||drawShape(QPainter & p) = 0|
Reimplemented Protected Functions
|virtual void||draw(QPainter & p)|
- 1 protected function inherited from Q3CanvasItem
The mostly rectangular classes, such as Q3CanvasSprite and Q3CanvasText, 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. Q3CanvasPolygonalItem 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 Q3CanvasPolygonalItem's speed.
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 Q3CanvasItem::advance(1) has been called.
By default, Q3CanvasPolygonalItem 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 Q3CanvasPolygonalItem subclasses only use the brush, ignoring the pen setting.
Like any other canvas item polygonal items can be moved with Q3CanvasItem::move() and Q3CanvasItem::moveBy(), or by setting coordinates with Q3CanvasItem::setX(), Q3CanvasItem::setY() and Q3CanvasItem::setZ().
Member Function Documentation
Q3CanvasPolygonalItem::Q3CanvasPolygonalItem(Q3Canvas * canvas)
Constructs a Q3CanvasPolygonalItem on the canvas canvas.
[pure virtual] Q3PointArray Q3CanvasPolygonalItem::areaPoints() const
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.
[virtual] Q3PointArray Q3CanvasPolygonalItem::areaPointsAdvanced() const
[virtual] QRect Q3CanvasPolygonalItem::boundingRect() const
Reimplemented from Q3CanvasItem::boundingRect().
Returns the bounding rectangle of the polygonal item, based on areaPoints().
QBrush Q3CanvasPolygonalItem::brush() const
Returns the QBrush used to fill the item, if filled.
See also setBrush().
[virtual] bool Q3CanvasPolygonalItem::collidesWith(const Q3CanvasItem * i) const
Reimplemented from Q3CanvasItem::collidesWith().
[virtual protected] void Q3CanvasPolygonalItem::draw(QPainter & p)
Reimplemented from Q3CanvasItem::draw().
[pure virtual protected] void Q3CanvasPolygonalItem::drawShape(QPainter & p)
See also draw().
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.
Returns true if the polygonal item's area information has not been invalidated; otherwise returns false.
See also invalidate().
QPen Q3CanvasPolygonalItem::pen() const
Returns the QPen used to draw the outline of the item, if any.
See also setPen().
Reimplemented from Q3CanvasItem::rtti().
Returns 2 (Q3CanvasItem::Rtti_PolygonalItem).
See also Q3CanvasItem::rtti().
[virtual] void Q3CanvasPolygonalItem::setBrush(QBrush b)
Sets the QBrush used when drawing the polygonal item to the brush b.
[virtual] void Q3CanvasPolygonalItem::setPen(QPen p)
Sets the QPen used when drawing the item to the pen p. Note that many Q3CanvasPolygonalItems do not use the pen value.
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().
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().
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