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Diffstat (limited to 'basegfx/source/tools')
| -rw-r--r-- | basegfx/source/tools/liangbarsky.cxx | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/basegfx/source/tools/liangbarsky.cxx b/basegfx/source/tools/liangbarsky.cxx new file mode 100644 index 000000000000..b4fd9b47be33 --- /dev/null +++ b/basegfx/source/tools/liangbarsky.cxx @@ -0,0 +1,163 @@ +/************************************************************************* + * + * $RCSfile: liangbarsky.cxx,v $ + * + * $Revision: 1.2 $ + * + * last change: $Author: kz $ $Date: 2005-01-13 18:00:43 $ + * + * The Contents of this file are made available subject to the terms of + * either of the following licenses + * + * - GNU Lesser General Public License Version 2.1 + * - Sun Industry Standards Source License Version 1.1 + * + * Sun Microsystems Inc., October, 2000 + * + * GNU Lesser General Public License Version 2.1 + * ============================================= + * Copyright 2000 by Sun Microsystems, Inc. + * 901 San Antonio Road, Palo Alto, CA 94303, USA + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License version 2.1, as published by the Free Software Foundation. + * + * This library 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 for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + * + * + * Sun Industry Standards Source License Version 1.1 + * ================================================= + * The contents of this file are subject to the Sun Industry Standards + * Source License Version 1.1 (the "License"); You may not use this file + * except in compliance with the License. You may obtain a copy of the + * License at http://www.openoffice.org/license.html. + * + * Software provided under this License is provided on an "AS IS" basis, + * WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, + * WITHOUT LIMITATION, WARRANTIES THAT THE SOFTWARE IS FREE OF DEFECTS, + * MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE, OR NON-INFRINGING. + * See the License for the specific provisions governing your rights and + * obligations concerning the Software. + * + * The Initial Developer of the Original Code is: Sun Microsystems, Inc. + * + * Copyright: 2000 by Sun Microsystems, Inc. + * + * All Rights Reserved. + * + * Contributor(s): _______________________________________ + * + * + ************************************************************************/ + +#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; + } + } +} |