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| -rw-r--r-- | include/basegfx/range/b2dconnectedranges.hxx | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/include/basegfx/range/b2dconnectedranges.hxx b/include/basegfx/range/b2dconnectedranges.hxx new file mode 100644 index 000000000..0d7a81481 --- /dev/null +++ b/include/basegfx/range/b2dconnectedranges.hxx @@ -0,0 +1,240 @@ +/* -*- 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 . + */ + +#pragma once + +#include <osl/diagnose.h> +#include <basegfx/range/b2drange.hxx> +#include <list> +#include <utility> +#include <algorithm> + + +namespace basegfx +{ + /** Calculate connected ranges from input ranges. + + This template constructs a list of connected ranges from the + given input ranges. That is, the output will contain a set of + ranges, itself containing a number of input ranges, which will + be mutually non-intersecting. + + Example: + <code> + ------------------- + | -------| + | | || + | --- | || + | | | -------| -------- + | | +--------- | | | + | --+ | | | | + | | | | -------- + | ---------- | + ------------------- + </code + + Here, the outer rectangles represent the output + ranges. Contained are the input rectangles that comprise these + output ranges. + + @tpl UserData + User data to be stored along with the range, to later identify + which range went into which connected component. Must be + assignable, default- and copy-constructible. + */ + template< typename UserData > class B2DConnectedRanges + { + public: + /// Type of the basic entity (rect + user data) + typedef ::std::pair< B2DRange, UserData > ComponentType; + typedef ::std::list< ComponentType > ComponentListType; + + /// List of (intersecting) components, plus overall bounds + struct ConnectedComponents + { + ComponentListType maComponentList; + B2DRange maTotalBounds; + }; + + typedef ::std::list< ConnectedComponents > ConnectedComponentsType; + + + /// Create the range calculator + B2DConnectedRanges() : + maDisjunctAggregatesList(), + maTotalBounds() + { + } + + /** Add an additional range. + + This method integrates a new range into the connected + ranges lists. The method has a worst-case time complexity + of O(n^2), with n denoting the number of already added + ranges (typically, for well-behaved input, it is O(n) + though). + */ + void addRange( const B2DRange& rRange, + const UserData& rUserData ) + { + // check whether fast path is possible: if new range is + // outside accumulated total range, can add it as a + // separate component right away. + const bool bNotOutsideEverything( + maTotalBounds.overlaps( rRange ) ); + + // update own global bounds range + maTotalBounds.expand( rRange ); + + // assemble anything intersecting with rRange into + // this new connected component + ConnectedComponents aNewConnectedComponent; + + // as at least rRange will be a member of + // aNewConnectedComponent (will be added below), can + // preset the overall bounds here. + aNewConnectedComponent.maTotalBounds = rRange; + + + // STAGE 1: Search for intersecting maDisjunctAggregatesList entries + + + // if rRange is empty, it will intersect with no + // maDisjunctAggregatesList member. Thus, we can safe us + // the check. + // if rRange is outside all other rectangle, skip here, + // too + if( bNotOutsideEverything && + !rRange.isEmpty() ) + { + typename ConnectedComponentsType::iterator aCurrAggregate; + typename ConnectedComponentsType::iterator aLastAggregate; + + // flag, determining whether we touched one or more of + // the maDisjunctAggregatesList entries. _If_ we did, + // we have to repeat the intersection process, because + // these changes might have generated new + // intersections. + bool bSomeAggregatesChanged; + + // loop, until bSomeAggregatesChanged stays false + do + { + // only continue loop if 'intersects' branch below was hit + bSomeAggregatesChanged = false; + + // iterate over all current members of maDisjunctAggregatesList + for( aCurrAggregate=maDisjunctAggregatesList.begin(), + aLastAggregate=maDisjunctAggregatesList.end(); + aCurrAggregate != aLastAggregate; ) + { + // first check if current component's bounds + // are empty. This ensures that distinct empty + // components are not merged into one + // aggregate. As a matter of fact, they have + // no position and size. + + if( !aCurrAggregate->maTotalBounds.isEmpty() && + aCurrAggregate->maTotalBounds.overlaps( + aNewConnectedComponent.maTotalBounds ) ) + { + // union the intersecting + // maDisjunctAggregatesList element into + // aNewConnectedComponent + + // calc union bounding box + aNewConnectedComponent.maTotalBounds.expand( aCurrAggregate->maTotalBounds ); + + // extract all aCurrAggregate components + // to aNewConnectedComponent + aNewConnectedComponent.maComponentList.splice( + aNewConnectedComponent.maComponentList.end(), + aCurrAggregate->maComponentList ); + + // remove and delete aCurrAggregate entry + // from list (we've gutted it's content + // above). list::erase() will update our + // iterator with the predecessor here. + aCurrAggregate = maDisjunctAggregatesList.erase( aCurrAggregate ); + + // at least one aggregate changed, need to rescan everything + bSomeAggregatesChanged = true; + } + else + { + ++aCurrAggregate; + } + } + } + while( bSomeAggregatesChanged ); + } + + + // STAGE 2: Add newly generated connected component list element + + + // add new component to the end of the component list + aNewConnectedComponent.maComponentList.push_back( + ComponentType( rRange, rUserData ) ); + + // do some consistency checks (aka post conditions) + OSL_ENSURE( !aNewConnectedComponent.maComponentList.empty(), + "B2DConnectedRanges::addRange(): empty aggregate list" ); + OSL_ENSURE( !aNewConnectedComponent.maTotalBounds.isEmpty() || + aNewConnectedComponent.maComponentList.size() == 1, + "B2DConnectedRanges::addRange(): empty ranges must be solitary"); + + // add aNewConnectedComponent as a new entry to + // maDisjunctAggregatesList + maDisjunctAggregatesList.push_back( aNewConnectedComponent ); + } + + /** Apply a functor to each of the disjunct component + aggregates. + + @param aFunctor + Functor to apply. Must provide an operator( const ConnectedComponents& ). + + @return a copy of the functor, as applied to all aggregates. + */ + template< typename UnaryFunctor > UnaryFunctor forEachAggregate( UnaryFunctor aFunctor ) const + { + return ::std::for_each( maDisjunctAggregatesList.begin(), + maDisjunctAggregatesList.end(), + aFunctor ); + } + + private: + B2DConnectedRanges(const B2DConnectedRanges&) = delete; + B2DConnectedRanges& operator=( const B2DConnectedRanges& ) = delete; + + /** Current list of disjunct sets of connected components + + Each entry corresponds to one of the top-level rectangles + in the drawing above. + */ + ConnectedComponentsType maDisjunctAggregatesList; + + /** Global bound rect over all added ranges. + */ + B2DRange maTotalBounds; + }; +} + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |