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Diffstat (limited to 'basegfx/source/tools/liangbarsky.cxx')
-rw-r--r-- | basegfx/source/tools/liangbarsky.cxx | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/basegfx/source/tools/liangbarsky.cxx b/basegfx/source/tools/liangbarsky.cxx new file mode 100644 index 000000000000..5c1d25918ed5 --- /dev/null +++ b/basegfx/source/tools/liangbarsky.cxx @@ -0,0 +1,135 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/************************************************************************* + * + * 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; + } + } +} + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |