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Diffstat (limited to 'basegfx/inc/basegfx/polygon/b2dpolypolygoncutter.hxx')
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diff --git a/basegfx/inc/basegfx/polygon/b2dpolypolygoncutter.hxx b/basegfx/inc/basegfx/polygon/b2dpolypolygoncutter.hxx new file mode 100644 index 000000000000..09519396846c --- /dev/null +++ b/basegfx/inc/basegfx/polygon/b2dpolypolygoncutter.hxx @@ -0,0 +1,122 @@ +/* -*- 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. + * + ************************************************************************/ + +#ifndef _BGFX_POLYGON_B2DPOLYPOLYGONCUTTER_HXX +#define _BGFX_POLYGON_B2DPOLYPOLYGONCUTTER_HXX + +#include <basegfx/polygon/b2dpolypolygon.hxx> + +////////////////////////////////////////////////////////////////////////////// + +namespace basegfx +{ + namespace tools + { + // Solve all crossovers in a polyPolygon. This re-layouts all contained polygons so that the + // result will contain only non-cutting polygons. For that reason, points will be added at + // crossover and touch points and the single Polygons may be re-combined. The orientations + // of the contained polygons in not changed but used as topological information. + // Self crossovers of the contained sub-polygons are implicitely handled, but to not lose + // the topological information, it may be necessary to remove self-intersections of the + // contained sub-polygons in a preparing step and to explicitely correct their orientations. + B2DPolyPolygon solveCrossovers(const B2DPolyPolygon& rCandidate); + + // Version for single polygons. This is for solving self-intersections. Result will be free of + // crossovers. When result contains multiple polygons, it may be necessary to rearrange their + // orientations since holes may have been created (use correctOrientations eventually). + B2DPolyPolygon solveCrossovers(const B2DPolygon& rCandidate); + + // Neutral polygons will be stripped. Neutral polygons are ones who's orientation is + // neutral, so normally they have no volume -> just closed paths. A polygon with the same + // positive and negative oriented volume is also neutral, so this may not be wanted. It is + // safe to call with crossover-free polygons, though (that's where it's mostly used). + B2DPolyPolygon stripNeutralPolygons(const B2DPolyPolygon& rCandidate); + + // Remove not necessary polygons. Works only correct with crossover-free polygons. For each + // polygon, the depth for the PolyPolygon is calculated. The orientation is used to identify holes. + // Start value for holes is -1, for polygons it's zero. Ech time a polygon is contained in another one, + // it's depth is increased when inside a polygon, decreased when inside a hole. The result is a depth + // which e.g. is -1 for holes outside everything, 1 for a polygon covered by another polygon and zero + // for e.g. holes in a polygon or polygons outside everythig else. + // In the 2nd step, all polygons with depth other than zero are removed. If bKeepAboveZero is used, + // all polygons < 1 are removed. The bKeepAboveZero mode is useful for clipping, e.g. just append + // one polygon to another and use this mode -> only parts where two polygons overlapped will be kept. + // In combination with correct orientation of the input orientations and the SolveCrossover calls this + // can be combined for logical polygon operations or polygon clipping. + B2DPolyPolygon stripDispensablePolygons(const B2DPolyPolygon& rCandidate, bool bKeepAboveZero = false); + + // For convenience: The four basic operations OR, XOR, AND and DIFF for + // two PolyPolygons. These are combinations of the above methods. To not be forced + // to do evtl. already done preparations twice, You have to do the operations Yourself. + // + // A source preparation consists of preparing it to be seen as XOR-Rule PolyPolygon, + // so it is freed of intersections, self-intersections and the orientations are corrected. + // Important is that it will define the same areas as before, but is intersection-free. + // As an example think about a single polygon looping in itself and having holes. To + // topologically correctly handle this, it is necessary to remove all intersections and + // to correct the orientations. The orientation of the isolated holes e.g. will be negative. + // Topologically it is necessary to prepare each polygon which is seen as entity. It is + // not sufficient just to concatenate them and prepare the result, this may be topologically + // different since the simple concatenation will be seen as XOR. To work correctly, You + // may need to OR those polygons. + + // Preparations: solve self-intersections and intersections, remove neutral + // parts and correct orientations. + B2DPolyPolygon prepareForPolygonOperation(const B2DPolygon& rCandidate); + B2DPolyPolygon prepareForPolygonOperation(const B2DPolyPolygon& rCandidate); + + // OR: Return all areas where CandidateA or CandidateB exist + B2DPolyPolygon solvePolygonOperationOr(const B2DPolyPolygon& rCandidateA, const B2DPolyPolygon& rCandidateB); + + // XOR: Return all areas where CandidateA or CandidateB exist, but not both + B2DPolyPolygon solvePolygonOperationXor(const B2DPolyPolygon& rCandidateA, const B2DPolyPolygon& rCandidateB); + + // AND: Return all areas where CandidateA and CandidateB exist + B2DPolyPolygon solvePolygonOperationAnd(const B2DPolyPolygon& rCandidateA, const B2DPolyPolygon& rCandidateB); + + // DIFF: Return all areas where CandidateA is not covered by CandidateB (cut B out of A) + B2DPolyPolygon solvePolygonOperationDiff(const B2DPolyPolygon& rCandidateA, const B2DPolyPolygon& rCandidateB); + + /** merge all single PolyPolygons to a single, OR-ed PolyPolygon + + @param rInput + The source PolyPolygons + + @return A single PolyPolygon containing the Or-merged result + */ + B2DPolyPolygon mergeToSinglePolyPolygon(const std::vector< basegfx::B2DPolyPolygon >& rInput); + + } // end of namespace tools +} // end of namespace basegfx + +////////////////////////////////////////////////////////////////////////////// + + +#endif /* _BGFX_POLYGON_B2DPOLYPOLYGONCUTTER_HXX */ + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |