141 lines
5.3 KiB
C++
141 lines
5.3 KiB
C++
/*************************************************************************
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*
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* OpenOffice.org - a multi-platform office productivity suite
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*
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* $RCSfile: liangbarsky.cxx,v $
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*
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* $Revision: 1.4 $
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*
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* last change: $Author: obo $ $Date: 2006-09-17 08:05:50 $
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*
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* The Contents of this file are made available subject to
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* the terms of GNU Lesser General Public License Version 2.1.
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*
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*
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* GNU Lesser General Public License Version 2.1
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* =============================================
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* Copyright 2005 by Sun Microsystems, Inc.
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* 901 San Antonio Road, Palo Alto, CA 94303, USA
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License version 2.1, as published by the Free Software Foundation.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*
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************************************************************************/
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// MARKER(update_precomp.py): autogen include statement, do not remove
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#include "precompiled_basegfx.hxx"
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#include "basegfx/tools/tools.hxx"
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#include "basegfx/numeric/ftools.hxx"
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#include "basegfx/range/b2drange.hxx"
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namespace basegfx
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{
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namespace tools
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{
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namespace
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{
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// see Foley/vanDam, pp. 122 for the Liang-Barsky line
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// clipping algorithm
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inline bool liangBarskyClipT( double nDenom,
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double nNumerator,
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double& io_rTE,
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double& io_rTL )
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{
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double t;
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if( nDenom > 0 )
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{
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t = nNumerator / nDenom;
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if( t > io_rTL )
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return false;
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else if( t > io_rTE )
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io_rTE = t;
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}
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else if( nDenom < 0 )
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{
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t = nNumerator / nDenom;
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if( t < io_rTE )
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return false;
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else
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io_rTL = t;
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}
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else if( nNumerator > 0 )
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{
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return false;
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}
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return true;
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}
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}
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// see Foley/vanDam, pp. 122 for the Liang-Barsky line
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// clipping algorithm
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bool liangBarskyClip2D( ::basegfx::B2DPoint& io_rStart,
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::basegfx::B2DPoint& io_rEnd,
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const ::basegfx::B2DRange& rClipRect )
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{
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const double nDX( io_rEnd.getX() - io_rStart.getX() );
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const double nDY( io_rEnd.getY() - io_rStart.getY() );
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if( ::basegfx::fTools::equalZero( nDX ) &&
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::basegfx::fTools::equalZero( nDY ) )
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{
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return rClipRect.isInside( io_rStart );
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}
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else
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{
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double nTE( 0.0 );
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double nTL( 1.0 );
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if( liangBarskyClipT(nDX, rClipRect.getMinX() - io_rStart.getX(),
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nTE, nTL ) ) // inside wrt. left edge
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{
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if( liangBarskyClipT(-nDX, io_rStart.getX() - rClipRect.getMaxX(),
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nTE, nTL ) ) // inside wrt. right edge
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{
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if( liangBarskyClipT(nDY, rClipRect.getMinY() - io_rStart.getY(),
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nTE, nTL ) ) // inside wrt. bottom edge
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{
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if( liangBarskyClipT(-nDY, io_rStart.getY() - rClipRect.getMaxY(),
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nTE, nTL ) ) // inside wrt. top edge
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{
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// compute actual intersection points,
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// if nTL has changed
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if( nTL < 1.0 )
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{
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io_rEnd.setX( io_rStart.getX() + nTL*nDX );
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io_rEnd.setY( io_rStart.getY() + nTL*nDY );
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}
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// compute actual intersection points,
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// if nTE has changed
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if( nTE > 0.0 )
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{
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io_rStart.setX( io_rStart.getX() + nTE*nDX );
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io_rStart.setY( io_rStart.getY() + nTE*nDY );
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}
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// line is (at least partially) visible
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return true;
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}
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}
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}
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}
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}
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return false;
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}
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}
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}
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