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/*************************************************************************
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************************************************************************/
#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 */
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