source: vendor/trolltech/current/src/kernel/qregion.cpp

/****************************************************************************
** $Id: qregion.cpp 2 2005-11-16 15:49:26Z dmik $
**
** Implementation of QRegion class
**
** Created : 950726
**
** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
**
** This file is part of the kernel module of the Qt GUI Toolkit.
**
** This file may be distributed under the terms of the Q Public License
** as defined by Trolltech AS of Norway and appearing in the file
** LICENSE.QPL included in the packaging of this file.
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
**
** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition
** licenses may use this file in accordance with the Qt Commercial License
** Agreement provided with the Software.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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**   information about Qt Commercial License Agreements.
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**********************************************************************/

#include "qregion.h"
#include "qpointarray.h"
#include "qbuffer.h"
#include "qdatastream.h"

// BEING REVISED: paul
/*!
    \class QRegion qregion.h
    \brief The QRegion class specifies a clip region for a painter.

    \ingroup images
    \ingroup graphics

    QRegion is used with QPainter::setClipRegion() to limit the paint
    area to what needs to be painted. There is also a
    QWidget::repaint() that takes a QRegion parameter. QRegion is the
    best tool for reducing flicker.

    A region can be created from a rectangle, an ellipse, a polygon or
    a bitmap. Complex regions may be created by combining simple
    regions using unite(), intersect(), subtract() or eor() (exclusive
    or). You can move a region using translate().

    You can test whether a region isNull(), isEmpty() or if it
    contains() a QPoint or QRect. The bounding rectangle is given by
    boundingRect().

    The function rects() gives a decomposition of the region into
    rectangles.

    Example of using complex regions:
    \code
        void MyWidget::paintEvent( QPaintEvent * )
        {
            QPainter p;                         // our painter
            QRegion r1( QRect(100,100,200,80),  // r1 = elliptic region
                        QRegion::Ellipse );
            QRegion r2( QRect(100,120,90,30) ); // r2 = rectangular region
            QRegion r3 = r1.intersect( r2 );    // r3 = intersection
            p.begin( this );                    // start painting widget
            p.setClipRegion( r3 );              // set clip region
            ...                                 // paint clipped graphics
            p.end();                            // painting done
        }
    \endcode

    QRegion is an \link shclass.html implicitly shared\endlink class.

    \warning Due to window system limitations, the whole coordinate
    space for a region is limited to the points between -32767 and
    32767 on Windows 95/98/ME.

    \sa QPainter::setClipRegion(), QPainter::setClipRect()
*/


/*!
    \enum QRegion::RegionType

    Specifies the shape of the region to be created.

    \value Rectangle  the region covers the entire rectangle.
    \value Ellipse  the region is an ellipse inside the rectangle.
*/

/*!
    \fn Region  QRegion::handle() const

    Returns the region's handle.
*/

/*****************************************************************************
  QRegion member functions
 *****************************************************************************/

/*!
    Constructs a rectangular or elliptic region.

    If \a t is \c Rectangle, the region is the filled rectangle (\a x,
    \a y, \a w, \a h). If \a t is \c Ellipse, the region is the filled
    ellipse with center at (\a x + \a w / 2, \a y + \a h / 2) and size
    (\a w ,\a h ).
*/
QRegion::QRegion( int x, int y, int w, int h, RegionType t )
{
    QRegion tmp(QRect(x,y,w,h),t);
    tmp.data->ref();
    data = tmp.data;
}

/*!
    Detaches from shared region data to make sure that this region is
    the only one referring to the data.

    \sa copy(), \link shclass.html shared classes\endlink
*/

void QRegion::detach()
{
    if ( data->count != 1 )
        *this = copy();
}

#ifndef QT_NO_DATASTREAM
/*
    Executes region commands in the internal buffer and rebuilds the
    original region.

    We do this when we read a region from the data stream.

    If \a ver is non-0, uses the format version \a ver on reading the
    byte array.
*/

void QRegion::exec( const QByteArray &buffer, int ver )
{
    QBuffer buf( buffer );
    QDataStream s( &buf );
    if ( ver )
        s.setVersion( ver );
    buf.open( IO_ReadOnly );
    QRegion rgn;
#if defined(QT_CHECK_STATE)
    int test_cnt = 0;
#endif
    while ( !s.eof() ) {
        Q_INT32 id;
        if ( s.version() == 1 ) {
            int id_int;
            s >> id_int;
            id = id_int;
        } else {
            s >> id;
        }
#if defined(QT_CHECK_STATE)
        if ( test_cnt > 0 && id != QRGN_TRANSLATE )
            qWarning( "QRegion::exec: Internal error" );
        test_cnt++;
#endif
        if ( id == QRGN_SETRECT || id == QRGN_SETELLIPSE ) {
            QRect r;
            s >> r;
            rgn = QRegion( r, id == QRGN_SETRECT ? Rectangle : Ellipse );
        } else if ( id == QRGN_SETPTARRAY_ALT || id == QRGN_SETPTARRAY_WIND ) {
            QPointArray a;
            s >> a;
            rgn = QRegion( a, id == QRGN_SETPTARRAY_WIND );
        } else if ( id == QRGN_TRANSLATE ) {
            QPoint p;
            s >> p;
            rgn.translate( p.x(), p.y() );
        } else if ( id >= QRGN_OR && id <= QRGN_XOR ) {
            QByteArray bop1, bop2;
            QRegion r1, r2;
            s >> bop1;  r1.exec( bop1 );
            s >> bop2;  r2.exec( bop2 );
            switch ( id ) {
                case QRGN_OR:
                    rgn = r1.unite( r2 );
                    break;
                case QRGN_AND:
                    rgn = r1.intersect( r2 );
                    break;
                case QRGN_SUB:
                    rgn = r1.subtract( r2 );
                    break;
                case QRGN_XOR:
                    rgn = r1.eor( r2 );
                    break;
            }
        } else if ( id == QRGN_RECTS ) {
            // (This is the only form used in Qt 2.0)
            Q_UINT32 n;
            s >> n;
            QRect r;
            for ( int i=0; i<(int)n; i++ ) {
                s >> r;
                rgn = rgn.unite( QRegion(r) );
            }
        }
    }
    buf.close();
    *this = rgn;
}


/*****************************************************************************
  QRegion stream functions
 *****************************************************************************/

/*!
    \relates QRegion

    Writes the region \a r to the stream \a s and returns a reference
    to the stream.

    \sa \link datastreamformat.html Format of the QDataStream operators \endlink
*/

QDataStream &operator<<( QDataStream &s, const QRegion &r )
{
    QMemArray<QRect> a = r.rects();
    if ( a.isEmpty() ) {
        s << (Q_UINT32)0;
    } else {
        if ( s.version() == 1 ) {
            int i;
            for ( i=(int)a.size()-1; i>0; i-- ) {
                s << (Q_UINT32)(12+i*24);
                s << (int)QRGN_OR;
            }
            for ( i=0; i<(int)a.size(); i++ ) {
                s << (Q_UINT32)(4+8) << (int)QRGN_SETRECT << a[i];
            }
        }
        else {
            s << (Q_UINT32)(4+4+16*a.size()); // 16: storage size of QRect
            s << (Q_INT32)QRGN_RECTS;
            s << (Q_UINT32)a.size();
            for ( int i=0; i<(int)a.size(); i++ )
                s << a[i];
        }
    }
    return s;
}

/*!
    \relates QRegion

    Reads a region from the stream \a s into \a r and returns a
    reference to the stream.

    \sa \link datastreamformat.html Format of the QDataStream operators \endlink
*/

QDataStream &operator>>( QDataStream &s, QRegion &r )
{
    QByteArray b;
    s >> b;
    r.exec( b, s.version() );
    return s;
}
#endif //QT_NO_DATASTREAM

// These are not inline - they can be implemented better on some platforms
//  (eg. Windows at least provides 3-variable operations).  For now, simple.


/*!
    Applies the unite() function to this region and \a r. \c r1|r2 is
    equivalent to \c r1.unite(r2)

    \sa unite(), operator+()
*/
const QRegion QRegion::operator|( const QRegion &r ) const
    { return unite(r); }

/*!
    Applies the unite() function to this region and \a r. \c r1+r2 is
    equivalent to \c r1.unite(r2)

    \sa unite(), operator|()
*/
const QRegion QRegion::operator+( const QRegion &r ) const
    { return unite(r); }

/*!
    Applies the intersect() function to this region and \a r. \c r1&r2
    is equivalent to \c r1.intersect(r2)

    \sa intersect()
*/
const QRegion QRegion::operator&( const QRegion &r ) const
    { return intersect(r); }

/*!
    Applies the subtract() function to this region and \a r. \c r1-r2
    is equivalent to \c r1.subtract(r2)

    \sa subtract()
*/
const QRegion QRegion::operator-( const QRegion &r ) const
    { return subtract(r); }

/*!
    Applies the eor() function to this region and \a r. \c r1^r2 is
    equivalent to \c r1.eor(r2)

    \sa eor()
*/
const QRegion QRegion::operator^( const QRegion &r ) const
    { return eor(r); }

/*!
    Applies the unite() function to this region and \a r and assigns
    the result to this region. \c r1|=r2 is equivalent to \c
    r1=r1.unite(r2)

    \sa unite()
*/
QRegion& QRegion::operator|=( const QRegion &r )
    { return *this = *this | r; }

/*!
    Applies the unite() function to this region and \a r and assigns
    the result to this region. \c r1+=r2 is equivalent to \c
    r1=r1.unite(r2)

    \sa intersect()
*/
QRegion& QRegion::operator+=( const QRegion &r )
    { return *this = *this + r; }

/*!
    Applies the intersect() function to this region and \a r and
    assigns the result to this region. \c r1&=r2 is equivalent to \c
    r1=r1.intersect(r2)

    \sa intersect()
*/
QRegion& QRegion::operator&=( const QRegion &r )
    { return *this = *this & r; }

/*!
    Applies the subtract() function to this region and \a r and
    assigns the result to this region. \c r1-=r2 is equivalent to \c
    r1=r1.subtract(r2)

    \sa subtract()
*/
QRegion& QRegion::operator-=( const QRegion &r )
    { return *this = *this - r; }

/*!
    Applies the eor() function to this region and \a r and
    assigns the result to this region. \c r1^=r2 is equivalent to \c
    r1=r1.eor(r2)

    \sa eor()
*/
QRegion& QRegion::operator^=( const QRegion &r )
    { return *this = *this ^ r; }