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/*************************************************************************
*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* Copyright 2000, 2010 Oracle and/or its affiliates.
*
* OpenOffice.org - a multi-platform office productivity suite
*
* This file is part of OpenOffice.org.
*
* OpenOffice.org is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 3
* only, as published by the Free Software Foundation.
*
* OpenOffice.org is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License version 3 for more details
* (a copy is included in the LICENSE file that accompanied this code).
*
* You should have received a copy of the GNU Lesser General Public License
* version 3 along with OpenOffice.org. If not, see
* <http://www.openoffice.org/license.html>
* for a copy of the LGPLv3 License.
*
************************************************************************/
// MARKER(update_precomp.py): autogen include statement, do not remove
#include "precompiled_basegfx.hxx"
#include "basegfx/tools/tools.hxx"
#include "basegfx/numeric/ftools.hxx"
#include "basegfx/range/b2drange.hxx"
namespace basegfx
{
namespace tools
{
namespace
{
// see Foley/vanDam, pp. 122 for the Liang-Barsky line
// clipping algorithm
inline bool liangBarskyClipT( double nDenom,
double nNumerator,
double& io_rTE,
double& io_rTL )
{
double t;
if( nDenom > 0 )
{
t = nNumerator / nDenom;
if( t > io_rTL )
return false;
else if( t > io_rTE )
io_rTE = t;
}
else if( nDenom < 0 )
{
t = nNumerator / nDenom;
if( t < io_rTE )
return false;
else
io_rTL = t;
}
else if( nNumerator > 0 )
{
return false;
}
return true;
}
}
// see Foley/vanDam, pp. 122 for the Liang-Barsky line
// clipping algorithm
bool liangBarskyClip2D( ::basegfx::B2DPoint& io_rStart,
::basegfx::B2DPoint& io_rEnd,
const ::basegfx::B2DRange& rClipRect )
{
const double nDX( io_rEnd.getX() - io_rStart.getX() );
const double nDY( io_rEnd.getY() - io_rStart.getY() );
if( ::basegfx::fTools::equalZero( nDX ) &&
::basegfx::fTools::equalZero( nDY ) )
{
return rClipRect.isInside( io_rStart );
}
else
{
double nTE( 0.0 );
double nTL( 1.0 );
if( liangBarskyClipT(nDX, rClipRect.getMinX() - io_rStart.getX(),
nTE, nTL ) ) // inside wrt. left edge
{
if( liangBarskyClipT(-nDX, io_rStart.getX() - rClipRect.getMaxX(),
nTE, nTL ) ) // inside wrt. right edge
{
if( liangBarskyClipT(nDY, rClipRect.getMinY() - io_rStart.getY(),
nTE, nTL ) ) // inside wrt. bottom edge
{
if( liangBarskyClipT(-nDY, io_rStart.getY() - rClipRect.getMaxY(),
nTE, nTL ) ) // inside wrt. top edge
{
// compute actual intersection points,
// if nTL has changed
if( nTL < 1.0 )
{
io_rEnd.setX( io_rStart.getX() + nTL*nDX );
io_rEnd.setY( io_rStart.getY() + nTL*nDY );
}
// compute actual intersection points,
// if nTE has changed
if( nTE > 0.0 )
{
io_rStart.setX( io_rStart.getX() + nTE*nDX );
io_rStart.setY( io_rStart.getY() + nTE*nDY );
}
// line is (at least partially) visible
return true;
}
}
}
}
}
return false;
}
}
}
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