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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed
+ * with this work for additional information regarding copyright
+ * ownership. The ASF licenses this file to you under the Apache
+ * License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <basegfx/polygon/b2dtrapezoid.hxx>
+#include <basegfx/range/b1drange.hxx>
+#include <basegfx/polygon/b2dpolygontools.hxx>
+#include <basegfx/polygon/b2dpolypolygon.hxx>
+
+#include <osl/diagnose.h>
+
+#include <list>
+
+namespace basegfx::trapezoidhelper
+{
+
+ // helper class to hold a simple edge. This is only used for horizontal edges
+ // currently, thus the YPositions will be equal. I did not create a special
+ // class for this since holding the pointers is more effective and also can be
+ // used as baseclass for the traversing edges
+
+ namespace {
+
+ class TrDeSimpleEdge
+ {
+ protected:
+ // pointers to start and end point
+ const B2DPoint* mpStart;
+ const B2DPoint* mpEnd;
+
+ public:
+ // constructor
+ TrDeSimpleEdge(
+ const B2DPoint* pStart,
+ const B2DPoint* pEnd)
+ : mpStart(pStart),
+ mpEnd(pEnd)
+ {
+ }
+
+ // data read access
+ const B2DPoint& getStart() const { return *mpStart; }
+ const B2DPoint& getEnd() const { return *mpEnd; }
+ };
+
+ }
+
+ // define vector of simple edges
+
+ typedef std::vector< TrDeSimpleEdge > TrDeSimpleEdges;
+
+ // helper class for holding a traversing edge. It will always have some
+ // distance in YPos. The slope (in a numerically useful form, see comments) is
+ // hold and used in SortValue to allow sorting traversing edges by Y, X and slope
+ // (in that order)
+
+ namespace {
+
+ class TrDeEdgeEntry : public TrDeSimpleEdge
+ {
+ private:
+ // the slope in a numerical useful form for sorting
+ sal_uInt32 mnSortValue;
+
+ public:
+ // convenience data read access
+ double getDeltaX() const { return mpEnd->getX() - mpStart->getX(); }
+ double getDeltaY() const { return mpEnd->getY() - mpStart->getY(); }
+
+ // convenience data read access. SortValue is created on demand since
+ // it is not always used
+ sal_uInt32 getSortValue() const
+ {
+ if(mnSortValue != 0)
+ return mnSortValue;
+
+ // get radiant; has to be in the range ]0.0 .. pi[, thus scale to full
+ // sal_uInt32 range for maximum precision
+ const double fRadiant(atan2(getDeltaY(), getDeltaX()) * (SAL_MAX_UINT32 / F_PI));
+
+ // convert to sal_uInt32 value
+ const_cast< TrDeEdgeEntry* >(this)->mnSortValue = sal_uInt32(fRadiant);
+
+ return mnSortValue;
+ }
+
+ // constructor. SortValue can be given when known, use zero otherwise
+ TrDeEdgeEntry(
+ const B2DPoint* pStart,
+ const B2DPoint* pEnd,
+ sal_uInt32 nSortValue)
+ : TrDeSimpleEdge(pStart, pEnd),
+ mnSortValue(nSortValue)
+ {
+ // force traversal of deltaY downward
+ if(mpEnd->getY() < mpStart->getY())
+ {
+ std::swap(mpStart, mpEnd);
+ }
+
+ // no horizontal edges allowed, all need to traverse vertically
+ OSL_ENSURE(mpEnd->getY() > mpStart->getY(), "Illegal TrDeEdgeEntry constructed (!)");
+ }
+
+ // data write access to StartPoint
+ void setStart( const B2DPoint* pNewStart)
+ {
+ OSL_ENSURE(pNewStart != nullptr, "No null pointer allowed here (!)");
+
+ if(mpStart != pNewStart)
+ {
+ mpStart = pNewStart;
+
+ // no horizontal edges allowed, all need to traverse vertically
+ OSL_ENSURE(mpEnd->getY() > mpStart->getY(), "Illegal TrDeEdgeEntry constructed (!)");
+ }
+ }
+
+ // data write access to EndPoint
+ void setEnd( const B2DPoint* pNewEnd)
+ {
+ OSL_ENSURE(pNewEnd != nullptr, "No null pointer allowed here (!)");
+
+ if(mpEnd != pNewEnd)
+ {
+ mpEnd = pNewEnd;
+
+ // no horizontal edges allowed, all need to traverse vertically
+ OSL_ENSURE(mpEnd->getY() > mpStart->getY(), "Illegal TrDeEdgeEntry constructed (!)");
+ }
+ }
+
+ // operator for sort support. Sort by Y, X and slope (in that order)
+ bool operator<(const TrDeEdgeEntry& rComp) const
+ {
+ if(fTools::equal(getStart().getY(), rComp.getStart().getY()))
+ {
+ if(fTools::equal(getStart().getX(), rComp.getStart().getX()))
+ {
+ // when start points are equal, use the direction the edge is pointing
+ // to. That value is created on demand and derived from atan2 in the
+ // range ]0.0 .. pi[ (without extremas, we always have a deltaY in this
+ // class) and scaled to sal_uInt32 range for best precision. 0 means no angle,
+ // while SAL_MAX_UINT32 means pi. Thus, the higher the value, the more left
+ // the edge traverses.
+ return (getSortValue() > rComp.getSortValue());
+ }
+ else
+ {
+ return fTools::less(getStart().getX(), rComp.getStart().getX());
+ }
+ }
+ else
+ {
+ return fTools::less(getStart().getY(), rComp.getStart().getY());
+ }
+ }
+
+ // method for cut support
+ B2DPoint getCutPointForGivenY(double fGivenY) const
+ {
+ // Calculate cut point locally (do not use interpolate) since it is numerically
+ // necessary to guarantee the new, equal Y-coordinate
+ const double fFactor((fGivenY - getStart().getY()) / getDeltaY());
+ const double fDeltaXNew(fFactor * getDeltaX());
+
+ return B2DPoint(getStart().getX() + fDeltaXNew, fGivenY);
+ }
+ };
+
+ }
+
+ // define double linked list of edges (for fast random insert)
+
+ typedef std::list< TrDeEdgeEntry > TrDeEdgeEntries;
+
+
+
+ // FIXME: templatize this and use it for TrDeEdgeEntries too ...
+
+ namespace {
+
+ /// Class to allow efficient allocation and release of B2DPoints
+ class PointBlockAllocator
+ {
+ static const size_t nBlockSize = 32;
+ size_t nCurPoint;
+ B2DPoint *mpPointBase;
+ /// Special case the first allocation to avoid it.
+ B2DPoint maFirstStackBlock[nBlockSize];
+ std::vector< B2DPoint * > maBlocks;
+ public:
+ PointBlockAllocator() :
+ nCurPoint( nBlockSize ),
+ mpPointBase( maFirstStackBlock )
+ {
+ }
+
+ ~PointBlockAllocator()
+ {
+ while(!maBlocks.empty())
+ {
+ delete [] maBlocks.back();
+ maBlocks.pop_back();
+ }
+ }
+
+ B2DPoint *allocatePoint()
+ {
+ if(nCurPoint >= nBlockSize)
+ {
+ mpPointBase = new B2DPoint[nBlockSize];
+ maBlocks.push_back(mpPointBase);
+ nCurPoint = 0;
+ }
+ return mpPointBase + nCurPoint++;
+ }
+
+ B2DPoint *allocatePoint(const B2DTuple &rPoint)
+ {
+ B2DPoint *pPoint = allocatePoint();
+ *pPoint = rPoint;
+ return pPoint;
+ }
+
+ /// This is a very uncommon case but why not ...
+ void freeIfLast(B2DPoint const *pPoint)
+ {
+ // just re-use the last point if we can.
+ if ( nCurPoint > 0 && pPoint == mpPointBase + nCurPoint - 1 )
+ nCurPoint--;
+ }
+ };
+
+ // helper class to handle the complete trapezoid subdivision of a PolyPolygon
+ class TrapezoidSubdivider
+ {
+ private:
+ // local data
+ sal_uInt32 mnInitialEdgeEntryCount;
+ TrDeEdgeEntries maTrDeEdgeEntries;
+ std::vector< B2DPoint > maPoints;
+ /// new points allocated for cuts
+ PointBlockAllocator maNewPoints;
+
+ void addEdgeSorted(
+ TrDeEdgeEntries::iterator aCurrent,
+ const TrDeEdgeEntry& rNewEdge)
+ {
+ // Loop while new entry is bigger, use operator<
+ while(aCurrent != maTrDeEdgeEntries.end() && (*aCurrent) < rNewEdge)
+ {
+ ++aCurrent;
+ }
+
+ // Insert before first which is smaller or equal or at end
+ maTrDeEdgeEntries.insert(aCurrent, rNewEdge);
+ }
+
+ bool splitEdgeAtGivenPoint(
+ TrDeEdgeEntries::reference aEdge,
+ const B2DPoint& rCutPoint,
+ const TrDeEdgeEntries::iterator& aCurrent)
+ {
+ // do not create edges without deltaY: do not split when start is identical
+ if(aEdge.getStart().equal(rCutPoint))
+ {
+ return false;
+ }
+
+ // do not create edges without deltaY: do not split when end is identical
+ if(aEdge.getEnd().equal(rCutPoint))
+ {
+ return false;
+ }
+
+ const double fOldDeltaYStart(rCutPoint.getY() - aEdge.getStart().getY());
+
+ if(fTools::lessOrEqual(fOldDeltaYStart, 0.0))
+ {
+ // do not split: the resulting edge would be horizontal
+ // correct it to new start point
+ aEdge.setStart(&rCutPoint);
+ return false;
+ }
+
+ const double fNewDeltaYStart(aEdge.getEnd().getY() - rCutPoint.getY());
+
+ if(fTools::lessOrEqual(fNewDeltaYStart, 0.0))
+ {
+ // do not split: the resulting edge would be horizontal
+ // correct it to new end point
+ aEdge.setEnd(&rCutPoint);
+ return false;
+ }
+
+ // Create new entry
+ const TrDeEdgeEntry aNewEdge(
+ &rCutPoint,
+ &aEdge.getEnd(),
+ aEdge.getSortValue());
+
+ // Correct old entry
+ aEdge.setEnd(&rCutPoint);
+
+ // Insert sorted (to avoid new sort)
+ addEdgeSorted(aCurrent, aNewEdge);
+
+ return true;
+ }
+
+ bool testAndCorrectEdgeIntersection(
+ TrDeEdgeEntries::reference aEdgeA,
+ TrDeEdgeEntries::reference aEdgeB,
+ const TrDeEdgeEntries::iterator& aCurrent)
+ {
+ // Exclude simple cases: same start or end point
+ if(aEdgeA.getStart().equal(aEdgeB.getStart()))
+ {
+ return false;
+ }
+
+ if(aEdgeA.getStart().equal(aEdgeB.getEnd()))
+ {
+ return false;
+ }
+
+ if(aEdgeA.getEnd().equal(aEdgeB.getStart()))
+ {
+ return false;
+ }
+
+ if(aEdgeA.getEnd().equal(aEdgeB.getEnd()))
+ {
+ return false;
+ }
+
+ // Exclude simple cases: one of the edges has no length anymore
+ if(aEdgeA.getStart().equal(aEdgeA.getEnd()))
+ {
+ return false;
+ }
+
+ if(aEdgeB.getStart().equal(aEdgeB.getEnd()))
+ {
+ return false;
+ }
+
+ // check if one point is on the other edge (a touch, not a cut)
+ const B2DVector aDeltaB(aEdgeB.getDeltaX(), aEdgeB.getDeltaY());
+
+ if(utils::isPointOnEdge(aEdgeA.getStart(), aEdgeB.getStart(), aDeltaB))
+ {
+ return splitEdgeAtGivenPoint(aEdgeB, aEdgeA.getStart(), aCurrent);
+ }
+
+ if(utils::isPointOnEdge(aEdgeA.getEnd(), aEdgeB.getStart(), aDeltaB))
+ {
+ return splitEdgeAtGivenPoint(aEdgeB, aEdgeA.getEnd(), aCurrent);
+ }
+
+ const B2DVector aDeltaA(aEdgeA.getDeltaX(), aEdgeA.getDeltaY());
+
+ if(utils::isPointOnEdge(aEdgeB.getStart(), aEdgeA.getStart(), aDeltaA))
+ {
+ return splitEdgeAtGivenPoint(aEdgeA, aEdgeB.getStart(), aCurrent);
+ }
+
+ if(utils::isPointOnEdge(aEdgeB.getEnd(), aEdgeA.getStart(), aDeltaA))
+ {
+ return splitEdgeAtGivenPoint(aEdgeA, aEdgeB.getEnd(), aCurrent);
+ }
+
+ // check for cut inside edges. Use both t-values to choose the more precise
+ // one later
+ double fCutA(0.0);
+ double fCutB(0.0);
+
+ if(utils::findCut(
+ aEdgeA.getStart(), aDeltaA,
+ aEdgeB.getStart(), aDeltaB,
+ CutFlagValue::LINE,
+ &fCutA,
+ &fCutB) != CutFlagValue::NONE)
+ {
+ // use a simple metric (length criteria) for choosing the numerically
+ // better cut
+ const double fSimpleLengthA(aDeltaA.getX() + aDeltaA.getY());
+ const double fSimpleLengthB(aDeltaB.getX() + aDeltaB.getY());
+ const bool bAIsLonger(fSimpleLengthA > fSimpleLengthB);
+ B2DPoint* pNewPoint = bAIsLonger
+ ? maNewPoints.allocatePoint(aEdgeA.getStart() + (fCutA * aDeltaA))
+ : maNewPoints.allocatePoint(aEdgeB.getStart() + (fCutB * aDeltaB));
+
+ // try to split both edges
+ bool bRetval = splitEdgeAtGivenPoint(aEdgeA, *pNewPoint, aCurrent);
+ bRetval |= splitEdgeAtGivenPoint(aEdgeB, *pNewPoint, aCurrent);
+
+ if(!bRetval)
+ maNewPoints.freeIfLast(pNewPoint);
+
+ return bRetval;
+ }
+
+ return false;
+ }
+
+ void solveHorizontalEdges(TrDeSimpleEdges& rTrDeSimpleEdges)
+ {
+ if(rTrDeSimpleEdges.empty() || maTrDeEdgeEntries.empty())
+ return;
+
+ // there were horizontal edges. These can be excluded, but
+ // cuts with other edges need to be solved and added before
+ // ignoring them
+ for(const TrDeSimpleEdge & rHorEdge : rTrDeSimpleEdges)
+ {
+ // get horizontal edge as candidate; prepare its range and fixed Y
+ const B1DRange aRange(rHorEdge.getStart().getX(), rHorEdge.getEnd().getX());
+ const double fFixedY(rHorEdge.getStart().getY());
+
+ // loop over traversing edges
+ TrDeEdgeEntries::iterator aCurrent(maTrDeEdgeEntries.begin());
+
+ do
+ {
+ // get compare edge
+ TrDeEdgeEntries::reference aCompare(*aCurrent++);
+
+ if(fTools::lessOrEqual(aCompare.getEnd().getY(), fFixedY))
+ {
+ // edge ends above horizontal edge, continue
+ continue;
+ }
+
+ if(fTools::moreOrEqual(aCompare.getStart().getY(), fFixedY))
+ {
+ // edge starts below horizontal edge, continue
+ continue;
+ }
+
+ // vertical overlap, get horizontal range
+ const B1DRange aCompareRange(aCompare.getStart().getX(), aCompare.getEnd().getX());
+
+ if(aRange.overlaps(aCompareRange))
+ {
+ // possible cut, get cut point
+ const B2DPoint aSplit(aCompare.getCutPointForGivenY(fFixedY));
+
+ if(fTools::more(aSplit.getX(), aRange.getMinimum())
+ && fTools::less(aSplit.getX(), aRange.getMaximum()))
+ {
+ // cut is in XRange of horizontal edge, potentially needed cut
+ B2DPoint* pNewPoint = maNewPoints.allocatePoint(aSplit);
+
+ if(!splitEdgeAtGivenPoint(aCompare, *pNewPoint, aCurrent))
+ {
+ maNewPoints.freeIfLast(pNewPoint);
+ }
+ }
+ }
+ }
+ while(aCurrent != maTrDeEdgeEntries.end()
+ && fTools::less(aCurrent->getStart().getY(), fFixedY));
+ }
+ }
+
+ public:
+ explicit TrapezoidSubdivider(
+ const B2DPolyPolygon& rSourcePolyPolygon)
+ : mnInitialEdgeEntryCount(0),
+ maTrDeEdgeEntries(),
+ maPoints(),
+ maNewPoints()
+ {
+ B2DPolyPolygon aSource(rSourcePolyPolygon);
+ TrDeSimpleEdges aTrDeSimpleEdges;
+ sal_uInt32 nAllPointCount(0);
+
+ // ensure there are no curves used
+ if(aSource.areControlPointsUsed())
+ {
+ aSource = aSource.getDefaultAdaptiveSubdivision();
+ }
+
+ for(const auto& aPolygonCandidate : aSource)
+ {
+ // 1st run: count points
+ const sal_uInt32 nCount(aPolygonCandidate.count());
+
+ if(nCount > 2)
+ {
+ nAllPointCount += nCount;
+ }
+ }
+
+ if(nAllPointCount)
+ {
+ // reserve needed points. CAUTION: maPoints size is NOT to be changed anymore
+ // after 2nd loop since pointers to it are used in the edges
+ maPoints.reserve(nAllPointCount);
+
+ for(const auto& aPolygonCandidate : aSource)
+ {
+ // 2nd run: add points
+ const sal_uInt32 nCount(aPolygonCandidate.count());
+
+ if(nCount > 2)
+ {
+ for(sal_uInt32 b = 0; b < nCount; b++)
+ {
+ maPoints.push_back(aPolygonCandidate.getB2DPoint(b));
+ }
+ }
+ }
+
+ // Moved the edge construction to a 3rd run: doing it in the 2nd run is
+ // possible (and I used it), but requires a working vector::reserve()
+ // implementation, else the vector will be reallocated and the pointers
+ // in the edges may be wrong. Security first here.
+ sal_uInt32 nStartIndex(0);
+
+ for(const auto& aPolygonCandidate : aSource)
+ {
+ const sal_uInt32 nCount(aPolygonCandidate.count());
+
+ if(nCount > 2)
+ {
+ // get the last point of the current polygon
+ B2DPoint* pPrev(&maPoints[nCount + nStartIndex - 1]);
+
+ for(sal_uInt32 b = 0; b < nCount; b++)
+ {
+ // get next point
+ B2DPoint* pCurr(&maPoints[nStartIndex++]);
+
+ if(fTools::equal(pPrev->getY(), pCurr->getY()))
+ {
+ // horizontal edge, check for single point
+ if(!fTools::equal(pPrev->getX(), pCurr->getX()))
+ {
+ // X-order not needed, just add
+ aTrDeSimpleEdges.emplace_back(pPrev, pCurr);
+
+ const double fMiddle((pPrev->getY() + pCurr->getY()) * 0.5);
+ pPrev->setY(fMiddle);
+ pCurr->setY(fMiddle);
+ }
+ }
+ else
+ {
+ // vertical edge. Positive Y-direction is guaranteed by the
+ // TrDeEdgeEntry constructor
+ maTrDeEdgeEntries.emplace_back(pPrev, pCurr, 0);
+ mnInitialEdgeEntryCount++;
+ }
+
+ // prepare next step
+ pPrev = pCurr;
+ }
+ }
+ }
+ }
+
+ if(!maTrDeEdgeEntries.empty())
+ {
+ // single and initial sort of traversing edges
+ maTrDeEdgeEntries.sort();
+
+ // solve horizontal edges if there are any detected
+ solveHorizontalEdges(aTrDeSimpleEdges);
+ }
+ }
+
+ void Subdivide(B2DTrapezoidVector& ro_Result)
+ {
+ // This is the central subdivider. The strategy is to use the first two entries
+ // from the traversing edges as a potential trapezoid and do the needed corrections
+ // and adaptations on the way.
+
+ // There always must be two edges with the same YStart value: When adding the polygons
+ // in the constructor, there is always a topmost point from which two edges start; when
+ // the topmost is an edge, there is a start and end of this edge from which two edges
+ // start. All cases have two edges with same StartY (QED).
+
+ // Based on this these edges get corrected when:
+ // - one is longer than the other
+ // - they intersect
+ // - they intersect with other edges
+ // - another edge starts inside the thought trapezoid
+
+ // All this cases again produce a valid state so that the first two edges have a common
+ // Ystart again. Some cases lead to a restart of the process, some allow consuming the
+ // edges and create the intended trapezoid.
+
+ // Be careful when doing changes here: it is essential to keep all possible paths
+ // in valid states and to be numerically correct. This is especially needed e.g.
+ // by using fTools::equal(..) in the more robust small-value incarnation.
+ B1DRange aLeftRange;
+ B1DRange aRightRange;
+
+ if(!maTrDeEdgeEntries.empty())
+ {
+ // measuring shows that the relation between edges and created trapezoids is
+ // mostly in the 1:1 range, thus reserve as much trapezoids as edges exist. Do
+ // not use maTrDeEdgeEntries.size() since that may be a non-constant time
+ // operation for Lists. Instead, use mnInitialEdgeEntryCount which will contain
+ // the roughly counted adds to the List
+ ro_Result.reserve(ro_Result.size() + mnInitialEdgeEntryCount);
+ }
+
+ while(!maTrDeEdgeEntries.empty())
+ {
+ // Prepare current operator and get first edge
+ TrDeEdgeEntries::iterator aCurrent(maTrDeEdgeEntries.begin());
+ TrDeEdgeEntries::reference aLeft(*aCurrent++);
+
+ if(aCurrent == maTrDeEdgeEntries.end())
+ {
+ // Should not happen: No 2nd edge; consume the single edge
+ // to not have an endless loop and start next. During development
+ // I constantly had breakpoints here, so I am sure enough to add an
+ // assertion here
+ OSL_FAIL("Trapezoid decomposer in illegal state (!)");
+ maTrDeEdgeEntries.pop_front();
+ continue;
+ }
+
+ // get second edge
+ TrDeEdgeEntries::reference aRight(*aCurrent++);
+
+ if(!fTools::equal(aLeft.getStart().getY(), aRight.getStart().getY()))
+ {
+ // Should not happen: We have a 2nd edge, but YStart is on another
+ // line; consume the single edge to not have an endless loop and start
+ // next. During development I constantly had breakpoints here, so I am
+ // sure enough to add an assertion here
+ OSL_FAIL("Trapezoid decomposer in illegal state (!)");
+ maTrDeEdgeEntries.pop_front();
+ continue;
+ }
+
+ // aLeft and aRight build a thought trapezoid now. They have a common
+ // start line (same Y for start points). Potentially, one of the edges
+ // is longer than the other. It is only needed to look at the shorter
+ // length which build the potential trapezoid. To do so, get the end points
+ // locally and adapt the evtl. longer one. Use only aLeftEnd and aRightEnd
+ // from here on, not the aLeft.getEnd() or aRight.getEnd() accesses.
+ B2DPoint aLeftEnd(aLeft.getEnd());
+ B2DPoint aRightEnd(aRight.getEnd());
+
+ // check if end points are on the same line. If yes, no adaptation
+ // needs to be prepared. Also remember which one actually is longer.
+ const bool bEndOnSameLine(fTools::equal(aLeftEnd.getY(), aRightEnd.getY()));
+ bool bLeftIsLonger(false);
+
+ if(!bEndOnSameLine)
+ {
+ // check which edge is longer and correct accordingly
+ bLeftIsLonger = fTools::more(aLeftEnd.getY(), aRightEnd.getY());
+
+ if(bLeftIsLonger)
+ {
+ aLeftEnd = aLeft.getCutPointForGivenY(aRightEnd.getY());
+ }
+ else
+ {
+ aRightEnd = aRight.getCutPointForGivenY(aLeftEnd.getY());
+ }
+ }
+
+ // check for same start and end points
+ const bool bSameStartPoint(aLeft.getStart().equal(aRight.getStart()));
+ const bool bSameEndPoint(aLeftEnd.equal(aRightEnd));
+
+ // check the simple case that the edges form a 'blind' edge (deadend)
+ if(bSameStartPoint && bSameEndPoint)
+ {
+ // correct the longer edge if prepared
+ if(!bEndOnSameLine)
+ {
+ if(bLeftIsLonger)
+ {
+ B2DPoint* pNewPoint = maNewPoints.allocatePoint(aLeftEnd);
+
+ if(!splitEdgeAtGivenPoint(aLeft, *pNewPoint, aCurrent))
+ {
+ maNewPoints.freeIfLast(pNewPoint);
+ }
+ }
+ else
+ {
+ B2DPoint* pNewPoint = maNewPoints.allocatePoint(aRightEnd);
+
+ if(!splitEdgeAtGivenPoint(aRight, *pNewPoint, aCurrent))
+ {
+ maNewPoints.freeIfLast(pNewPoint);
+ }
+ }
+ }
+
+ // consume both edges and start next run
+ maTrDeEdgeEntries.pop_front();
+ maTrDeEdgeEntries.pop_front();
+
+ continue;
+ }
+
+ // check if the edges self-intersect. This can only happen when
+ // start and end point are different
+ bool bRangesSet(false);
+
+ if(!(bSameStartPoint || bSameEndPoint))
+ {
+ // get XRanges of edges
+ aLeftRange = B1DRange(aLeft.getStart().getX(), aLeftEnd.getX());
+ aRightRange = B1DRange(aRight.getStart().getX(), aRightEnd.getX());
+ bRangesSet = true;
+
+ // use fast range test first
+ if(aLeftRange.overlaps(aRightRange))
+ {
+ // real cut test and correction. If correction was needed,
+ // start new run
+ if(testAndCorrectEdgeIntersection(aLeft, aRight, aCurrent))
+ {
+ continue;
+ }
+ }
+ }
+
+ // now we need to check if there are intersections with other edges
+ // or if other edges start inside the candidate trapezoid
+ if(aCurrent != maTrDeEdgeEntries.end()
+ && fTools::less(aCurrent->getStart().getY(), aLeftEnd.getY()))
+ {
+ // get XRanges of edges
+ if(!bRangesSet)
+ {
+ aLeftRange = B1DRange(aLeft.getStart().getX(), aLeftEnd.getX());
+ aRightRange = B1DRange(aRight.getStart().getX(), aRightEnd.getX());
+ }
+
+ // build full XRange for fast check
+ B1DRange aAllRange(aLeftRange);
+ aAllRange.expand(aRightRange);
+
+ // prepare loop iterator; aCurrent needs to stay unchanged for
+ // possibly sorted insertions of new EdgeNodes. Also prepare stop flag
+ TrDeEdgeEntries::iterator aLoop(aCurrent);
+ bool bDone(false);
+
+ do
+ {
+ // get compare edge and its XRange
+ TrDeEdgeEntries::reference aCompare(*aLoop++);
+
+ // avoid edges using the same start point as one of
+ // the edges. These can neither have their start point
+ // in the thought trapezoid nor cut with one of the edges
+ if(aCompare.getStart().equal(aRight.getStart()))
+ {
+ continue;
+ }
+
+ // get compare XRange
+ const B1DRange aCompareRange(aCompare.getStart().getX(), aCompare.getEnd().getX());
+
+ // use fast range test first
+ if(aAllRange.overlaps(aCompareRange))
+ {
+ // check for start point inside thought trapezoid
+ if(fTools::more(aCompare.getStart().getY(), aLeft.getStart().getY()))
+ {
+ // calculate the two possible split points at compare's Y
+ const B2DPoint aSplitLeft(aLeft.getCutPointForGivenY(aCompare.getStart().getY()));
+ const B2DPoint aSplitRight(aRight.getCutPointForGivenY(aCompare.getStart().getY()));
+
+ // check for start point of aCompare being inside thought
+ // trapezoid
+ if(aCompare.getStart().getX() >= aSplitLeft.getX() &&
+ aCompare.getStart().getX() <= aSplitRight.getX())
+ {
+ // is inside, correct and restart loop
+ B2DPoint* pNewLeft = maNewPoints.allocatePoint(aSplitLeft);
+
+ if(splitEdgeAtGivenPoint(aLeft, *pNewLeft, aCurrent))
+ {
+ bDone = true;
+ }
+ else
+ {
+ maNewPoints.freeIfLast(pNewLeft);
+ }
+
+ B2DPoint* pNewRight = maNewPoints.allocatePoint(aSplitRight);
+
+ if(splitEdgeAtGivenPoint(aRight, *pNewRight, aCurrent))
+ {
+ bDone = true;
+ }
+ else
+ {
+ maNewPoints.freeIfLast(pNewRight);
+ }
+ }
+ }
+
+ if(!bDone && aLeftRange.overlaps(aCompareRange))
+ {
+ // test for concrete cut of compare edge with left edge
+ bDone = testAndCorrectEdgeIntersection(aLeft, aCompare, aCurrent);
+ }
+
+ if(!bDone && aRightRange.overlaps(aCompareRange))
+ {
+ // test for concrete cut of compare edge with Right edge
+ bDone = testAndCorrectEdgeIntersection(aRight, aCompare, aCurrent);
+ }
+ }
+ }
+ while(!bDone
+ && aLoop != maTrDeEdgeEntries.end()
+ && fTools::less(aLoop->getStart().getY(), aLeftEnd.getY()));
+
+ if(bDone)
+ {
+ // something needed to be changed; start next loop
+ continue;
+ }
+ }
+
+ // when we get here, the intended trapezoid can be used. It needs to
+ // be corrected possibly (if prepared); but this is no reason not to
+ // use it in the same loop iteration
+ if(!bEndOnSameLine)
+ {
+ if(bLeftIsLonger)
+ {
+ B2DPoint* pNewPoint = maNewPoints.allocatePoint(aLeftEnd);
+
+ if(!splitEdgeAtGivenPoint(aLeft, *pNewPoint, aCurrent))
+ {
+ maNewPoints.freeIfLast(pNewPoint);
+ }
+ }
+ else
+ {
+ B2DPoint* pNewPoint = maNewPoints.allocatePoint(aRightEnd);
+
+ if(!splitEdgeAtGivenPoint(aRight, *pNewPoint, aCurrent))
+ {
+ maNewPoints.freeIfLast(pNewPoint);
+ }
+ }
+ }
+
+ // the two edges start at the same Y, they use the same DeltaY, they
+ // do not cut themselves and not any other edge in range. Create a
+ // B2DTrapezoid and consume both edges
+ ro_Result.emplace_back(
+ aLeft.getStart().getX(),
+ aRight.getStart().getX(),
+ aLeft.getStart().getY(),
+ aLeftEnd.getX(),
+ aRightEnd.getX(),
+ aLeftEnd.getY());
+
+ maTrDeEdgeEntries.pop_front();
+ maTrDeEdgeEntries.pop_front();
+ }
+ }
+ };
+
+ }
+} // end of namespace
+
+namespace basegfx
+{
+ B2DTrapezoid::B2DTrapezoid(
+ const double& rfTopXLeft,
+ const double& rfTopXRight,
+ const double& rfTopY,
+ const double& rfBottomXLeft,
+ const double& rfBottomXRight,
+ const double& rfBottomY)
+ : mfTopXLeft(rfTopXLeft),
+ mfTopXRight(rfTopXRight),
+ mfTopY(rfTopY),
+ mfBottomXLeft(rfBottomXLeft),
+ mfBottomXRight(rfBottomXRight),
+ mfBottomY(rfBottomY)
+ {
+ // guarantee mfTopXRight >= mfTopXLeft
+ if(mfTopXLeft > mfTopXRight)
+ {
+ std::swap(mfTopXLeft, mfTopXRight);
+ }
+
+ // guarantee mfBottomXRight >= mfBottomXLeft
+ if(mfBottomXLeft > mfBottomXRight)
+ {
+ std::swap(mfBottomXLeft, mfBottomXRight);
+ }
+
+ // guarantee mfBottomY >= mfTopY
+ if(mfTopY > mfBottomY)
+ {
+ std::swap(mfTopY, mfBottomY);
+ std::swap(mfTopXLeft, mfBottomXLeft);
+ std::swap(mfTopXRight, mfBottomXRight);
+ }
+ }
+
+ B2DPolygon B2DTrapezoid::getB2DPolygon() const
+ {
+ B2DPolygon aRetval;
+
+ aRetval.append(B2DPoint(getTopXLeft(), getTopY()));
+ aRetval.append(B2DPoint(getTopXRight(), getTopY()));
+ aRetval.append(B2DPoint(getBottomXRight(), getBottomY()));
+ aRetval.append(B2DPoint(getBottomXLeft(), getBottomY()));
+ aRetval.setClosed(true);
+
+ return aRetval;
+ }
+} // end of namespace basegfx
+
+namespace basegfx::utils
+{
+ // convert Source utils::PolyPolygon to trapezoids
+ void trapezoidSubdivide(B2DTrapezoidVector& ro_Result, const B2DPolyPolygon& rSourcePolyPolygon)
+ {
+ trapezoidhelper::TrapezoidSubdivider aTrapezoidSubdivider(rSourcePolyPolygon);
+
+ aTrapezoidSubdivider.Subdivide(ro_Result);
+ }
+
+ void createLineTrapezoidFromEdge(
+ B2DTrapezoidVector& ro_Result,
+ const B2DPoint& rPointA,
+ const B2DPoint& rPointB,
+ double fLineWidth)
+ {
+ if(fTools::lessOrEqual(fLineWidth, 0.0))
+ {
+ // no line width
+ return;
+ }
+
+ if(rPointA.equal(rPointB))
+ {
+ // points are equal, no edge
+ return;
+ }
+
+ const double fHalfLineWidth(0.5 * fLineWidth);
+
+ if(fTools::equal(rPointA.getX(), rPointB.getX()))
+ {
+ // vertical line
+ const double fLeftX(rPointA.getX() - fHalfLineWidth);
+ const double fRightX(rPointA.getX() + fHalfLineWidth);
+
+ ro_Result.emplace_back(
+ fLeftX,
+ fRightX,
+ std::min(rPointA.getY(), rPointB.getY()),
+ fLeftX,
+ fRightX,
+ std::max(rPointA.getY(), rPointB.getY()));
+ }
+ else if(fTools::equal(rPointA.getY(), rPointB.getY()))
+ {
+ // horizontal line
+ const double fLeftX(std::min(rPointA.getX(), rPointB.getX()));
+ const double fRightX(std::max(rPointA.getX(), rPointB.getX()));
+
+ ro_Result.emplace_back(
+ fLeftX,
+ fRightX,
+ rPointA.getY() - fHalfLineWidth,
+ fLeftX,
+ fRightX,
+ rPointA.getY() + fHalfLineWidth);
+ }
+ else
+ {
+ // diagonal line
+ // create perpendicular vector
+ const B2DVector aDelta(rPointB - rPointA);
+ B2DVector aPerpendicular(-aDelta.getY(), aDelta.getX());
+ aPerpendicular.setLength(fHalfLineWidth);
+
+ // create StartLow, StartHigh, EndLow and EndHigh
+ const B2DPoint aStartLow(rPointA + aPerpendicular);
+ const B2DPoint aStartHigh(rPointA - aPerpendicular);
+ const B2DPoint aEndHigh(rPointB - aPerpendicular);
+ const B2DPoint aEndLow(rPointB + aPerpendicular);
+
+ // create EdgeEntries
+ basegfx::trapezoidhelper::TrDeEdgeEntries aTrDeEdgeEntries;
+
+ aTrDeEdgeEntries.emplace_back(&aStartLow, &aStartHigh, 0);
+ aTrDeEdgeEntries.emplace_back(&aStartHigh, &aEndHigh, 0);
+ aTrDeEdgeEntries.emplace_back(&aEndHigh, &aEndLow, 0);
+ aTrDeEdgeEntries.emplace_back(&aEndLow, &aStartLow, 0);
+ aTrDeEdgeEntries.sort();
+
+ // here we know we have exactly four edges, and they do not cut, touch or
+ // intersect. This makes processing much easier. Get the first two as start
+ // edges for the thought trapezoid
+ basegfx::trapezoidhelper::TrDeEdgeEntries::iterator aCurrent(aTrDeEdgeEntries.begin());
+ basegfx::trapezoidhelper::TrDeEdgeEntries::reference aLeft(*aCurrent++);
+ basegfx::trapezoidhelper::TrDeEdgeEntries::reference aRight(*aCurrent++);
+ const bool bEndOnSameLine(fTools::equal(aLeft.getEnd().getY(), aRight.getEnd().getY()));
+
+ if(bEndOnSameLine)
+ {
+ // create two triangle trapezoids
+ ro_Result.emplace_back(
+ aLeft.getStart().getX(),
+ aRight.getStart().getX(),
+ aLeft.getStart().getY(),
+ aLeft.getEnd().getX(),
+ aRight.getEnd().getX(),
+ aLeft.getEnd().getY());
+
+ basegfx::trapezoidhelper::TrDeEdgeEntries::reference aLeft2(*aCurrent++);
+ basegfx::trapezoidhelper::TrDeEdgeEntries::reference aRight2(*aCurrent++);
+
+ ro_Result.emplace_back(
+ aLeft2.getStart().getX(),
+ aRight2.getStart().getX(),
+ aLeft2.getStart().getY(),
+ aLeft2.getEnd().getX(),
+ aRight2.getEnd().getX(),
+ aLeft2.getEnd().getY());
+ }
+ else
+ {
+ // create three trapezoids. Check which edge is longer and
+ // correct accordingly
+ const bool bLeftIsLonger(fTools::more(aLeft.getEnd().getY(), aRight.getEnd().getY()));
+
+ if(bLeftIsLonger)
+ {
+ basegfx::trapezoidhelper::TrDeEdgeEntries::reference aRight2(*aCurrent++);
+ basegfx::trapezoidhelper::TrDeEdgeEntries::reference aLeft2(*aCurrent++);
+ const B2DPoint aSplitLeft(aLeft.getCutPointForGivenY(aRight.getEnd().getY()));
+ const B2DPoint aSplitRight(aRight2.getCutPointForGivenY(aLeft.getEnd().getY()));
+
+ ro_Result.emplace_back(
+ aLeft.getStart().getX(),
+ aRight.getStart().getX(),
+ aLeft.getStart().getY(),
+ aSplitLeft.getX(),
+ aRight.getEnd().getX(),
+ aRight.getEnd().getY());
+
+ ro_Result.emplace_back(
+ aSplitLeft.getX(),
+ aRight.getEnd().getX(),
+ aRight.getEnd().getY(),
+ aLeft2.getStart().getX(),
+ aSplitRight.getX(),
+ aLeft2.getStart().getY());
+
+ ro_Result.emplace_back(
+ aLeft2.getStart().getX(),
+ aSplitRight.getX(),
+ aLeft2.getStart().getY(),
+ aLeft2.getEnd().getX(),
+ aRight2.getEnd().getX(),
+ aLeft2.getEnd().getY());
+ }
+ else
+ {
+ basegfx::trapezoidhelper::TrDeEdgeEntries::reference aLeft2(*aCurrent++);
+ basegfx::trapezoidhelper::TrDeEdgeEntries::reference aRight2(*aCurrent++);
+ const B2DPoint aSplitRight(aRight.getCutPointForGivenY(aLeft.getEnd().getY()));
+ const B2DPoint aSplitLeft(aLeft2.getCutPointForGivenY(aRight.getEnd().getY()));
+
+ ro_Result.emplace_back(
+ aLeft.getStart().getX(),
+ aRight.getStart().getX(),
+ aLeft.getStart().getY(),
+ aLeft.getEnd().getX(),
+ aSplitRight.getX(),
+ aLeft.getEnd().getY());
+
+ ro_Result.emplace_back(
+ aLeft.getEnd().getX(),
+ aSplitRight.getX(),
+ aLeft.getEnd().getY(),
+ aSplitLeft.getX(),
+ aRight.getEnd().getX(),
+ aRight2.getStart().getY());
+
+ ro_Result.emplace_back(
+ aSplitLeft.getX(),
+ aRight.getEnd().getX(),
+ aRight2.getStart().getY(),
+ aLeft2.getEnd().getX(),
+ aRight2.getEnd().getX(),
+ aLeft2.getEnd().getY());
+ }
+ }
+ }
+ }
+
+ void createLineTrapezoidFromB2DPolygon(
+ B2DTrapezoidVector& ro_Result,
+ const B2DPolygon& rPolygon,
+ double fLineWidth)
+ {
+ if(fTools::lessOrEqual(fLineWidth, 0.0))
+ {
+ return;
+ }
+
+ // ensure there are no curves used
+ B2DPolygon aSource(rPolygon);
+
+ if(aSource.areControlPointsUsed())
+ {
+ const double fPrecisionFactor = 0.25;
+ aSource = adaptiveSubdivideByDistance( aSource, fLineWidth * fPrecisionFactor );
+ }
+
+ const sal_uInt32 nPointCount(aSource.count());
+
+ if(!nPointCount)
+ {
+ return;
+ }
+
+ const sal_uInt32 nEdgeCount(aSource.isClosed() ? nPointCount : nPointCount - 1);
+ B2DPoint aCurrent(aSource.getB2DPoint(0));
+
+ ro_Result.reserve(ro_Result.size() + (3 * nEdgeCount));
+
+ for(sal_uInt32 a(0); a < nEdgeCount; a++)
+ {
+ const sal_uInt32 nNextIndex((a + 1) % nPointCount);
+ const B2DPoint aNext(aSource.getB2DPoint(nNextIndex));
+
+ createLineTrapezoidFromEdge(ro_Result, aCurrent, aNext, fLineWidth);
+ aCurrent = aNext;
+ }
+ }
+
+
+} // end of namespace
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-19 13:15:31 +0000