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# Q3CanvasSpline Class Reference
[Qt3Support module]

The Q3CanvasSpline class provides multi-bezier splines on a Q3Canvas. More...

     #include <Q3CanvasSpline>

This class is part of the Qt 3 support library. It is provided to keep old source code working. We strongly advise against using it in new code. See Porting to Qt 4 for more information.

Note to Qt Desktop Light Edition users: This class is only available in the Qt Desktop Edition.

Inherits Q3CanvasPolygon.

- List of all members, including inherited members

### Public Functions

- Q3CanvasSpline ( Q3Canvas * canvas )
- ~Q3CanvasSpline ()
- bool closed () const
- Q3PointArray controlPoints () const
- virtual int rtti () const
- void setControlPoints ( Q3PointArray ctrl, bool close = true )

- 4 public functions inherited from Q3CanvasPolygon
- 8 public functions inherited from Q3CanvasPolygonalItem
- 34 public functions inherited from Q3CanvasItem

### Additional Inherited Members

- 1 protected function inherited from Q3CanvasPolygon
- 6 protected functions inherited from Q3CanvasPolygonalItem
- 1 protected function inherited from Q3CanvasItem

## Detailed Description

The Q3CanvasSpline class provides multi-bezier splines on a Q3Canvas.

A Q3CanvasSpline is a sequence of 4-point bezier curves joined together to make a curved shape.

You set the control points of the spline with setControlPoints().

If the bezier is closed(), then the first control point will be re-used as the last control point. Therefore, a closed bezier must have a multiple of 3 control points and an open bezier must have one extra point.

The beziers are not necessarily joined "smoothly". To ensure this, set control points appropriately (general reference texts about beziers will explain this in detail).

Like any other canvas item splines can be moved with Q3CanvasItem::move() and Q3CanvasItem::moveBy(), or by setting coordinates with Q3CanvasItem::setX(), Q3CanvasItem::setY() and Q3CanvasItem::setZ().

See also QtCanvas and Porting to Graphics View.

## Member Function Documentation

### Q3CanvasSpline::Q3CanvasSpline ( Q3Canvas * canvas )

Create a spline with no control points on the canvas canvas.

See also setControlPoints().

### Q3CanvasSpline::~Q3CanvasSpline ()

Destroy the spline.

### bool Q3CanvasSpline::closed () const

Returns true if the control points are a closed set; otherwise returns false.

### Q3PointArray Q3CanvasSpline::controlPoints () const

Returns the current set of control points.

See also setControlPoints() and closed().

### int Q3CanvasSpline::rtti () const `[virtual]`

Returns 8 (Q3CanvasItem::Rtti_Spline).

Reimplemented from Q3CanvasItem.

See also Q3CanvasItem::rtti().

### void Q3CanvasSpline::setControlPoints ( Q3PointArray ctrl, bool close = true )

Set the spline control points to ctrl.

If close is true, then the first point in ctrl will be re-used as the last point, and the number of control points must be a multiple of 3. If close is false, one additional control point is required, and the number of control points must be one of (4, 7, 10, 13, ...).

If the number of control points doesn't meet the above conditions, the number of points will be truncated to the largest number of points that do meet the requirement.

See also controlPoints().