QPointArray Class Reference
The QPointArray class provides an array of points.
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#include <qpointarray.h>
Inherits QArray.
List of all member functions.
Public Members
Static Public Members
Related Functions
(Note that these are not member functions.)
- QDataStream & operator<< (QDataStream & s, const QPointArray & a)
- QDataStream & operator>> (QDataStream & s, QPointArray & a)
Detailed Description
The QPointArray class provides an array of points.
The QPointArray is an array of QPoint objects. In addition to the
functions provided by QArray, QPointArray provides some
point-specific functions.
For convenient reading and writing of the point data: setPoints(),
putPoints(), point(), and setPoint().
For geometry operations: boundingRect() and translate(). There is
also a QWMatrix::map() function for more general transformation of
QPointArrays.
QPointArray is used by QPainter::drawLineSegments(),
QPainter::drawPolyline(), QPainter::drawPolygon() and
QPainter::drawQuadBezier(), among other things.
Note that since this class is a QArray, it is explicitly shared and
works with shallow copies by default.
Transformations used in QPointArray are based on parelarc.c from
Graphics Gems III
VanAken / Simar, "A Parametric Elliptical Arc Algorithm"
See also QPainter, QWMatrix and QArray.
Examples:
picture/picture.cpp
desktop/desktop.cpp
Member Function Documentation
QPointArray::QPointArray ()
Constructs a null point array.
See also isNull().
QPointArray::QPointArray ( const QRect & r, bool closed=FALSE )
Constructs a point array from the rectangle r.
If closed is FALSE, then the point array just contains the
following four points in the listed order: r.topLeft(),
r.topRight(), r.bottomRight() and r.bottomLeft().
If closed is TRUE, then a fifth point is set to r.topLeft().
QPointArray::QPointArray ( const QPointArray & a )
Constructs a shallow copy of the point array a.
See also copy().
QPointArray::QPointArray ( int nPoints, const QCOORD * points )
Constructs a point array with nPoints points, taken from the
points array.
Equivalent to setPoints(nPoints,points).
QPointArray::QPointArray ( int size )
Constructs a point array with room for size points. Makes a null
array if size == 0.
See also resize() and isNull().
QPointArray::~QPointArray ()
Destructs the point array.
QRect QPointArray::boundingRect () const
Returns the bounding rectangle of the points in the array, or
QRect(0,0,0,0) if the array is empty.
QPointArray QPointArray::copy () const
Creates a deep copy of the array.
void QPointArray::makeArc ( int x, int y, int w, int h, int a1, int a2 )
Sets the points of the array to those describing an arc of an
ellipse with size w by h and position (x, y ), starting
from angle a1, spanning a2. The resulting array has sufficient
resolution for pixel accuracy (see the overloaded function which
takes an additional QWMatrix parameter).
Angles are specified in 16ths of a degree, i.e. a full circle equals
5760 (16*360). Positive values mean counter-clockwise while
negative values mean clockwise direction. Zero degrees is at the 3
o'clock position.
void QPointArray::makeArc ( int x, int y, int w, int h, int a1, int a2, const QWMatrix & xf )
Sets the points of the array to those describing an arc of an
ellipse with size w by h and position (x, y ), starting
from angle a1, spanning a2, transformed by the matrix xf.
The resulting array has sufficient resolution for pixel accuracy.
Angles are specified in 16ths of a degree, i.e. a full circle equals
5760 (16*360). Positive values mean counter-clockwise while negative
values mean clockwise direction. Zero degrees is at the 3 o'clock
position.
void QPointArray::makeEllipse ( int xx, int yy, int w, int h )
Sets the points of the array to those describing an ellipse with
size w by h and position (x, y ).
The returned array has sufficient resolution for use as pixels.
QPointArray & QPointArray::operator= ( const QPointArray & a )
Assigns a shallow copy of a to this point array and returns a
reference to this point array.
Equivalent to assign( a ).
See also copy().
QPoint QPointArray::point ( uint index ) const
Returns the point at position index in the array.
void QPointArray::point ( uint index, int * x, int * y ) const
Returns the point at position index in the array in *x and *y.
bool QPointArray::putPoints ( int index, int nPoints, const QCOORD * points )
Copies nPoints points from the points array into this point array.
Will resize this point array if index+nPoints exceeds
the size of the array.
Returns TRUE if successful, or FALSE if the array could not be
resized (typcailly due to lack of memory).
The example code creates an array with three points: (1,2), (3,4)
and (5,6):
QPointArray a( 1 );
a[0] = QPoint( 1, 2 );
static QCOORD points[] = { 3,4, 5,6 };
a.putPoints( 1, 2, points );
This function differs from setPoints() in that it does not resize the
array unless the array size is exceeded.
See also resize() and setPoints().
bool QPointArray::putPoints ( int index, int nPoints, int firstx, int firsty, ... )
Copies nPoints points from the variable argument list into this point
array. Will resize this point array if index+nPoints exceeds
the size of the array.
Returns TRUE if successful, or FALSE if the array could not be
resized (typically due to lack of memory).
The example code creates an array with two points (1,2), (3,4) and (5,6):
QPointArray a( 1 );
a[0] = QPoint( 1, 2 );
a.putPoints( 1, 2, 3,4, 5,6 );
This function differs from setPoints() in that it does not resize the
array unless the array size is exceeded.
See also resize() and setPoints().
QPointArray QPointArray::quadBezier () const
Returns the Bezier points for the four control points in this array.
void QPointArray::setPoint ( uint i, const QPoint & p )
Equivalent to setPoint( i, p.x(), p.y() ).
void QPointArray::setPoint ( uint index, int x, int y )
Sets the point at position index in the array to (x,y).
bool QPointArray::setPoints ( int nPoints, const QCOORD * points )
Resizes the array to nPoints and sets the points in the array to
the values taken from points.
Returns TRUE if successful, or FALSE if the array could not be
resized (normally due to lack of memory).
The example code creates an array with two points (1,2) and (3,4):
static QCOORD points[] = { 1,2, 3,4 };
QPointArray a;
a.setPoints( 2, points );
See also resize() and putPoints().
bool QPointArray::setPoints ( int nPoints, int firstx, int firsty, ... )
Resizes the array to nPoints and sets the points in the array to
the values taken from the variable argument list.
Returns TRUE if successful, or FALSE if the array could not be
resized (typically due to lack of memory).
The example code creates an array with two points (1,2) and (3,4):
QPointArray a;
a.setPoints( 2, 1,2, 3,4 );
See also resize() and putPoints().
void QPointArray::translate ( int dx, int dy )
Translates all points in the array (dx,dy).
void QPointArray::cleanBuffers () [static]
For internal use only.
void* QPointArray::shortPoints ( int index = 0, int nPoints = -1 ) const
For internal use only.
Related Functions
Writes a point array to the stream and returns a reference to the stream.
See also Format of the QDataStream operators
Reads a point array from the stream and returns a reference to the stream.
See also Format of the QDataStream operators
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