qpointarray.cpp

Trolltech公司发布的基于C++图形开发环境

/****************************************************************************
** $Id: qt/src/3rdparty/kernel/qpointarray.cpp   2.3.10   edited 2005-01-24 $
**
** Implementation of QPointArray class
**
** Created : 940213
**
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** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
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#include "qpointarray.h"
#include "qrect.h"
#include "qbitarray.h"
#include "qdatastream.h"
#include "qwmatrix.h"
#include <stdarg.h>

const double Q_PI = 3.14159265358979323846;   // pi // one more useful comment

/*!
  \class QPointArray qpointarray.h
  \brief 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.

  \mustquote

  Transformations used in QPointArray are based on parelarc.c from
  Graphics Gems III
  VanAken / Simar, "A Parametric Elliptical Arc Algorithm"

  \sa QPainter QWMatrix QArray
*/


/*****************************************************************************
  QPointArray member functions
 *****************************************************************************/

/*!
  \fn QPointArray::QPointArray()
  Constructs a null point array.

  \sa isNull()
*/

/*!
  \fn QPointArray::QPointArray( int size )

  Constructs a point array with room for \a size points. Makes a null
  array if \a size == 0.

  \sa resize(), isNull()
*/

/*!
  \fn QPointArray::QPointArray( const QPointArray &a )

  Constructs a shallow copy of the point array \a a.

  \sa copy()
*/

/*!
  Constructs a point array from the rectangle \a r.

  If \a 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 \a closed is TRUE, then a fifth point is set to r.topLeft().
*/

QPointArray::QPointArray( const QRect &r, bool closed )
{
    setPoints( 4, r.left(),  r.top(),
		  r.right(), r.top(),
		  r.right(), r.bottom(),
		  r.left(),  r.bottom() );
    if ( closed ) {
	resize( 5 );
	setPoint( 4, r.left(), r.top() );
    }
}

/*!
  Constructs a point array with \a nPoints points, taken from the
  \a points array.

  Equivalent to setPoints(nPoints,points).
*/

QPointArray::QPointArray( int nPoints, const QCOORD *points )
{
    setPoints( nPoints, points );
}


/*!
  \fn QPointArray::~QPointArray()

  Destructs the point array.
*/


/*!
  \fn QPointArray &QPointArray::operator=( const QPointArray &a )

  Assigns a shallow copy of \a a to this point array and returns a
  reference to this point array.

  Equivalent to assign( a ).

  \sa copy()
*/

/*!
  \fn QPointArray QPointArray::copy() const

  Creates a deep copy of the array.
*/



/*!
  Translates all points in the array \a (dx,dy).
*/

void QPointArray::translate( int dx, int dy )
{
    register QPoint *p = data();
    register int i = size();
    QPoint pt( dx, dy );
    while ( i-- ) {
	*p += pt;
	p++;
    }
}


/*!
  Returns the point at position \a index in the array in \a *x and \a *y.
*/

void QPointArray::point( uint index, int *x, int *y ) const
{
    QPoint p = QArray<QPoint>::at( index );
    *x = (int)p.x();
    *y = (int)p.y();
}

/*!
  Returns the point at position \a index in the array.
*/

QPoint QPointArray::point( uint index ) const
{
    return QArray<QPoint>::at( index );
}

/*!
  Sets the point at position \a index in the array to \a (x,y).
*/

void QPointArray::setPoint( uint index, int x, int y )
{
    QArray<QPoint>::at( index ) = QPoint( x, y );
}

/*!
  Resizes the array to \a nPoints and sets the points in the array to
  the values taken from \a 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):
  \code
    static QCOORD points[] = { 1,2, 3,4 };
    QPointArray a;
    a.setPoints( 2, points );
  \endcode

  \sa resize(), putPoints()
*/

bool QPointArray::setPoints( int nPoints, const QCOORD *points )
{
    if ( !resize(nPoints) )
	return FALSE;
    int i = 0;
    while ( nPoints-- ) {			// make array of points
	setPoint( i++, *points, *(points+1) );
	points++;
	points++;
    }
    return TRUE;
}

/*!
  \fn void QPointArray::setPoint( uint i, const QPoint &p )

  Equivalent to setPoint( i, p.x(), p.y() ).
*/

/*!
  Resizes the array to \a 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):

  \code
    QPointArray a;
    a.setPoints( 2, 1,2, 3,4 );
  \endcode

  \sa resize(), putPoints()
*/

bool QPointArray::setPoints( int nPoints, int firstx, int firsty, ... )
{
    va_list ap;
    if ( !resize(nPoints) )
	return FALSE;
    setPoint( 0, firstx, firsty );		// set first point
    int i = 1, x, y;
    nPoints--;
    va_start( ap, firsty );
    while ( nPoints-- ) {
	x = va_arg( ap, int );
	y = va_arg( ap, int );
	setPoint( i++, x, y );
    }
    va_end( ap );
    return TRUE;
}

/*!
  Copies \a nPoints points from the \a points array into this point array.
  Will resize this point array if <code>index+nPoints</code> 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):
  \code
    QPointArray a( 1 );
    a[0] = QPoint( 1, 2 );
    static QCOORD points[] = { 3,4, 5,6 };
    a.putPoints( 1, 2, points );
  \endcode

  This function differs from setPoints() in that it does not resize the
  array unless the array size is exceeded.

  \sa resize(), setPoints()
*/

bool QPointArray::putPoints( int index, int nPoints, const QCOORD *points )
{
    if ( index + nPoints > (int)size() ) {	// extend array
	if ( !resize( index + nPoints ) )
	    return FALSE;
    }
    int i = index;
    while ( nPoints-- ) {			// make array of points
	setPoint( i++, *points, *(points+1) );
	points++;
	points++;
    }
    return TRUE;
}

/*!
  Copies \a nPoints points from the variable argument list into this point
  array. Will resize this point array if <code>index+nPoints</code> 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):
  \code
    QPointArray a( 1 );
    a[0] = QPoint( 1, 2 );
    a.putPoints( 1, 2, 3,4, 5,6 );
  \endcode

  This function differs from setPoints() in that it does not resize the
  array unless the array size is exceeded.

  \sa resize(), setPoints()
*/

bool QPointArray::putPoints( int index, int nPoints, int firstx, int firsty,
			     ... )
{
    va_list ap;
    if ( index + nPoints > (int)size() ) {	// extend array
	if ( !resize(index + nPoints) )
	    return FALSE;
    }
    if ( nPoints <= 0 )
	return TRUE;
    setPoint( index, firstx, firsty );		// set first point
    int i = index + 1, x, y;
    nPoints--;
    va_start( ap, firsty );
    while ( nPoints-- ) {
	x = va_arg( ap, int );
	y = va_arg( ap, int );
	setPoint( i++, x, y );
    }
    va_end( ap );
    return TRUE;
}


/*!
  Returns the bounding rectangle of the points in the array, or
  QRect(0,0,0,0) if the array is empty.
*/

QRect QPointArray::boundingRect() const
{
    if ( isEmpty() )
	return QRect( 0, 0, 0, 0 );		// null rectangle
    register QPoint *pd = data();
    int minx, maxx, miny, maxy;
    minx = maxx = pd->x();
    miny = maxy = pd->y();
    pd++;
    for ( int i=1; i<(int)size(); i++ ) {	// find min+max x and y
	if ( pd->x() < minx )
	    minx = pd->x();
	else if ( pd->x() > maxx )
	    maxx = pd->x();
	if ( pd->y() < miny )
	    miny = pd->y();
	else if ( pd->y() > maxy )
	    maxy = pd->y();
	pd++;
    }
    return QRect( QPoint(minx,miny), QPoint(maxx,maxy) );
}


static inline int fix_angle( int a )
{
    if ( a > 16*360 )
	a %= 16*360;
    else if ( a < -16*360 ) {
	a = -( (-a) % (16*360) );
    }
    return a;
}

/*!
  Sets the points of the array to those describing an arc of an
  ellipse with size \a w by \a h and position (\a x, \a y ), starting
  from angle \a a1, spanning \a 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 )
{
#if !defined(QT_OLD_MAKEELLIPSE) && !defined(QT_NO_TRANSFORMATIONS)
    QWMatrix unit;
    makeArc(x,y,w,h,a1,a2,unit);
#else
    a1 = fix_angle( a1 );
    if ( a1 < 0 )
	a1 += 16*360;
    a2 = fix_angle( a2 );
    int a3 = a2 > 0 ? a2 : -a2;			// abs angle
    makeEllipse( x, y, w, h );
    int npts = a3*size()/(16*360);		// # points in arc array
    QPointArray a(npts);
    int i = a1*size()/(16*360);
    int j = 0;
    if ( a2 > 0 ) {
	while ( npts-- ) {
	    if ( i >= (int)size() )			// wrap index
		i = 0;
	    a.QArray<QPoint>::at( j++ ) = QArray<QPoint>::at( i++ );
	}
    } else {
	while ( npts-- ) {
	    if ( i < 0 )				// wrap index
		i = (int)size()-1;
	    a.QArray<QPoint>::at( j++ ) = QArray<QPoint>::at( i-- );
	}
    }
    *this = a;
    return;
#endif
}

#ifndef QT_NO_TRANSFORMATIONS
// Based upon:
//   parelarc.c from Graphics Gems III
//   VanAken / Simar, "A Parametric Elliptical Arc Algorithm"
//
static void
qtr_elips(QPointArray& a, int off, double dxP, double dyP, double dxQ, double dyQ, double dxK, double dyK, int m)
{
#define PIV2  102944     /* fixed point PI/2 */
#define TWOPI 411775     /* fixed point 2*PI */
#define HALF  32768      /* fixed point 1/2 */

    int xP, yP, xQ, yQ, xK, yK;
    xP = int(dxP * 65536.0); yP = int(dyP * 65536.0);
    xQ = int(dxQ * 65536.0); yQ = int(dyQ * 65536.0);
    xK = int(dxK * 65536.0); yK = int(dyK * 65536.0);

    int i;
    int vx, ux, vy, uy, xJ, yJ;

    vx = xK - xQ;                 /* displacements from center */
    ux = xK - xP;
    vy = yK - yQ;
    uy = yK - yP;
    xJ = xP - vx + HALF;          /* center of ellipse J */
    yJ = yP - vy + HALF;

    int r;
    ux -= (r = ux >> (2*m + 3));  /* cancel 2nd-order error */
    ux -= (r >>= (2*m + 4));      /* cancel 4th-order error */
    ux -= r >> (2*m + 3);         /* cancel 6th-order error */
    ux += vx >> (m + 1);          /* cancel 1st-order error */
    uy -= (r = uy >> (2*m + 3));  /* cancel 2nd-order error */
    uy -= (r >>= (2*m + 4));      /* cancel 4th-order error */
    uy -= r >> (2*m + 3);         /* cancel 6th-order error */
    uy += vy >> (m + 1);          /* cancel 1st-order error */

    const int qn = a.size()/4;
    for (i = 0; i < qn; i++) {
        a[off+i] = QPoint((xJ + vx) >> 16, (yJ + vy) >> 16);
        ux -= vx >> m;
        vx += ux >> m;
        uy -= vy >> m;
        vy += uy >> m;
    }

#undef PIV2
#undef TWOPI
#undef HALF
}


/*!
  Sets the points of the array to those describing an arc of an
  ellipse with size \a w by \a h and position (\a x, \a y ), starting
  from angle \a a1, spanning \a a2, transformed by the matrix \a 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.