tracks_cleaner.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004-2018 Jean-Pierre Charras, jp.charras at wanadoo.fr
 * Copyright (C) 2011 Wayne Stambaugh <[email protected]>
 * Copyright The KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */
 
#include "tracks_cleaner.h"
 
#include <atomic>
#include <bit>
 
#include <board_commit.h>
#include <cleanup_item.h>
#include <connectivity/connectivity_algo.h>
#include <connectivity/connectivity_data.h>
#include <drc/drc_rtree.h>
#include <reporter.h>
#include <thread_pool.h>
#include <lset.h>
#include <pad.h>
#include <pcb_track.h>
#include <tool/tool_manager.h>
#include <tools/pcb_actions.h>
#include <tools/global_edit_tool.h>
 
 
TRACKS_CLEANER::TRACKS_CLEANER( BOARD* aPcb, BOARD_COMMIT& aCommit ) :
        m_brd( aPcb ),
        m_commit( aCommit ),
        m_dryRun( true ),
        m_itemsList( nullptr ),
        m_reporter( nullptr ),
        m_filter( nullptr )
{
}
 
 
/* Main cleaning function.
 *  Delete
 * - Redundant points on tracks (merge aligned segments)
 * - vias on pad
 * - null length segments
 */
void TRACKS_CLEANER::CleanupBoard( bool aDryRun,
                                   std::vector<std::shared_ptr<CLEANUP_ITEM> >* aItemsList,
                                   bool aRemoveMisConnected, bool aCleanVias, bool aMergeSegments,
                                   bool aDeleteUnconnected, bool aDeleteTracksinPad,
                                   bool aDeleteDanglingVias, REPORTER* aReporter )
{
    m_reporter = aReporter;
    bool has_deleted = false;
 
    m_dryRun = aDryRun;
    m_itemsList = aItemsList;
 
    if( m_reporter )
    {
        if( aDryRun )
            m_reporter->Report( _( "Checking null tracks and vias..." ) );
        else
            m_reporter->Report( _( "Removing null tracks and vias..." ) );
 
        wxSafeYield();      // Timeslice to update UI
    }
 
    bool removeNullSegments = aMergeSegments || aRemoveMisConnected;
    cleanup( aCleanVias, removeNullSegments, aMergeSegments /* dup segments*/, aMergeSegments );
 
    if( m_reporter )
    {
        if( aDryRun )
            m_reporter->Report( _( "Checking redundant tracks..." ) );
        else
            m_reporter->Report( _( "Removing redundant tracks..." ) );
 
        wxSafeYield();      // Timeslice to update UI
    }
 
    // If we didn't remove duplicates above, do it now
    if( !aMergeSegments )
        cleanup( false, false, true, false );
 
    if( aRemoveMisConnected )
    {
        if( m_reporter )
        {
            if( aDryRun )
                m_reporter->Report( _( "Checking shorting tracks..." ) );
            else
                m_reporter->Report( _( "Removing shorting tracks..." ) );
 
            wxSafeYield();      // Timeslice to update UI
        }
 
        removeShortingTrackSegments();
    }
 
    if( aDeleteTracksinPad )
    {
        if( m_reporter )
        {
            if( aDryRun )
                m_reporter->Report( _( "Checking tracks in pads..." ) );
            else
                m_reporter->Report( _( "Removing tracks in pads..." ) );
 
            wxSafeYield();      // Timeslice to update UI
        }
 
        deleteTracksInPads();
    }
 
    if( aDeleteUnconnected || aDeleteDanglingVias )
    {
        if( m_reporter )
        {
            if( aDryRun )
            {
                m_reporter->Report( _( "Checking dangling tracks and vias..." ) );
            }
            else
            {
                if( aDeleteUnconnected )
                    m_reporter->Report( _( "Removing dangling tracks..." ) );
 
                if( aDeleteDanglingVias )
                    m_reporter->Report( _( "Removing dangling vias..." ) );
            }
 
            wxSafeYield();      // Timeslice to update UI
        }
 
        has_deleted = deleteDanglingTracks( aDeleteUnconnected, aDeleteDanglingVias );
    }
 
    if( has_deleted && aMergeSegments )
    {
        if( m_reporter )
        {
            if( aDryRun )
                m_reporter->Report( _( "Checking collinear tracks..." ) );
            else
                m_reporter->Report( _( "Merging collinear tracks..." ) );
 
            wxSafeYield();      // Timeslice to update UI
        }
 
        cleanup( false, false, false, true );
    }
}
 
 
bool TRACKS_CLEANER::filterItem( BOARD_CONNECTED_ITEM* aItem )
{
    if( !m_filter )
        return false;
 
    return (m_filter)( aItem );
}
 
 
void TRACKS_CLEANER::removeShortingTrackSegments()
{
    std::shared_ptr<CONNECTIVITY_DATA> connectivity = m_brd->GetConnectivity();
 
    std::set<BOARD_ITEM *> toRemove;
 
    for( PCB_TRACK* segment : m_brd->Tracks() )
    {
        if( segment->IsLocked() || filterItem( segment ) )
            continue;
 
        for( PAD* testedPad : connectivity->GetConnectedPads( segment ) )
        {
            if( segment->GetNetCode() != testedPad->GetNetCode() )
            {
                std::shared_ptr<CLEANUP_ITEM> item;
 
                if( segment->Type() == PCB_VIA_T )
                    item = std::make_shared<CLEANUP_ITEM>( CLEANUP_SHORTING_VIA );
                else
                    item = std::make_shared<CLEANUP_ITEM>( CLEANUP_SHORTING_TRACK );
 
                item->SetItems( segment );
                m_itemsList->push_back( std::move( item ) );
 
                toRemove.insert( segment );
            }
        }
 
        for( PCB_TRACK* testedTrack : connectivity->GetConnectedTracks( segment ) )
        {
            if( segment->GetNetCode() != testedTrack->GetNetCode() )
            {
                std::shared_ptr<CLEANUP_ITEM> item;
 
                if( segment->Type() == PCB_VIA_T )
                    item = std::make_shared<CLEANUP_ITEM>( CLEANUP_SHORTING_VIA );
                else
                    item = std::make_shared<CLEANUP_ITEM>( CLEANUP_SHORTING_TRACK );
 
                item->SetItems( segment );
                m_itemsList->push_back( std::move( item ) );
 
                toRemove.insert( segment );
            }
        }
    }
 
    if( !m_dryRun )
        removeItems( toRemove );
}
 
 
bool TRACKS_CLEANER::testTrackEndpointIsNode( PCB_TRACK* aTrack, bool aTstStart, bool aTstEnd )
{
    if( !( aTstStart && aTstEnd ) )
        return false;
 
    // A node is a point where more than 2 items are connected.  However, we elide tracks that are
    // collinear with the track being tested.
    const std::list<CN_ITEM*>& items =
                m_brd->GetConnectivity()->GetConnectivityAlgo()->ItemEntry( aTrack ).GetItems();
 
    if( items.empty() )
        return false;
 
    int itemcount = 0;
 
    for( CN_ITEM* item : items )
    {
        if( !item->Valid() || item->Parent() == aTrack || item->Parent()->HasFlag( IS_DELETED ) )
            continue;
 
        if( item->Parent()->Type() == PCB_TRACE_T &&
            static_cast<PCB_TRACK*>( item->Parent() )->ApproxCollinear( aTrack ) )
        {
            continue;
        }
 
        for( const std::shared_ptr<CN_ANCHOR>& anchor : item->Anchors() )
        {
            if( ( aTstStart && anchor->Pos() == aTrack->GetStart() )
                && ( aTstEnd && anchor->Pos() == aTrack->GetEnd() ) )
            {
                itemcount++;
                break;
            }
        }
    }
 
    return itemcount > 1;
}
 
 
bool TRACKS_CLEANER::deleteDanglingTracks( bool aTrack, bool aVia )
{
    bool item_erased = false;
    bool modified = false;
 
    if( !aTrack && !aVia )
        return false;
 
    do // Iterate when at least one track is deleted
    {
        item_erased = false;
        // Ensure the connectivity is up to date, especially after removing a dangling segment
        m_brd->BuildConnectivity();
 
        // Keep a duplicate deque to all deleting in the primary
        std::deque<PCB_TRACK*> temp_tracks( m_brd->Tracks() );
 
        for( PCB_TRACK* track : temp_tracks )
        {
            if( track->HasFlag( IS_DELETED ) || track->IsLocked() || filterItem( track ) )
                continue;
 
            if( !aVia && track->Type() == PCB_VIA_T )
                continue;
 
            if( !aTrack && ( track->Type() == PCB_TRACE_T || track->Type() == PCB_ARC_T ) )
                continue;
 
            // Test if a track (or a via) endpoint is not connected to another track or zone.
            if( m_brd->GetConnectivity()->TestTrackEndpointDangling( track, false ) )
            {
                std::shared_ptr<CLEANUP_ITEM> item;
 
                if( track->Type() == PCB_VIA_T )
                    item = std::make_shared<CLEANUP_ITEM>( CLEANUP_DANGLING_VIA );
                else
                    item = std::make_shared<CLEANUP_ITEM>( CLEANUP_DANGLING_TRACK );
 
                item->SetItems( track );
                m_itemsList->push_back( std::move( item ) );
                track->SetFlags( IS_DELETED );
 
                // keep iterating, because a track connected to the deleted track
                // now perhaps is not connected and should be deleted
                item_erased = true;
 
                if( !m_dryRun )
                {
                    m_brd->Remove( track );
                    m_commit.Removed( track );
                    modified = true;
                }
            }
        }
    } while( item_erased ); // A segment was erased: test for some new dangling segments
 
    return modified;
}
 
 
void TRACKS_CLEANER::deleteTracksInPads()
{
    std::set<BOARD_ITEM*> toRemove;
 
    // Delete tracks that start and end on the same pad
    std::shared_ptr<CONNECTIVITY_DATA> connectivity = m_brd->GetConnectivity();
 
    for( PCB_TRACK* track : m_brd->Tracks() )
    {
        if( track->IsLocked() || filterItem( track ) )
            continue;
 
        if( track->Type() == PCB_VIA_T )
            continue;
 
        // Mark track if connected to pads
        for( PAD* pad : connectivity->GetConnectedPads( track ) )
        {
            if( pad->HitTest( track->GetStart() ) && pad->HitTest( track->GetEnd() ) )
            {
                SHAPE_POLY_SET poly;
                track->TransformShapeToPolygon( poly, track->GetLayer(), 0, track->GetMaxError(),
                                                ERROR_INSIDE );
 
                poly.BooleanSubtract( *pad->GetEffectivePolygon( track->GetLayer(), ERROR_INSIDE ) );
 
                if( poly.IsEmpty() )
                {
                    auto item = std::make_shared<CLEANUP_ITEM>( CLEANUP_TRACK_IN_PAD );
                    item->SetItems( track );
                    m_itemsList->push_back( std::move( item ) );
 
                    toRemove.insert( track );
                    track->SetFlags( IS_DELETED );
                }
            }
        }
    }
 
    if( !m_dryRun )
        removeItems( toRemove );
}
 

void TRACKS_CLEANER::cleanup( bool aDeleteDuplicateVias, bool aDeleteNullSegments,
                              bool aDeleteDuplicateSegments, bool aMergeSegments )
{
    DRC_RTREE rtree;
 
    for( PCB_TRACK* track : m_brd->Tracks() )
    {
        track->ClearFlags( IS_DELETED | SKIP_STRUCT );
        rtree.Insert( track, track->GetLayer() );
    }
 
    std::set<BOARD_ITEM*> toRemove;
 
    for( PCB_TRACK* track : m_brd->Tracks() )
    {
        if( track->HasFlag( IS_DELETED ) || track->IsLocked() || filterItem( track ) )
            continue;
 
        if( aDeleteDuplicateVias && track->Type() == PCB_VIA_T )
        {
            PCB_VIA* via = static_cast<PCB_VIA*>( track );
 
            if( via->GetStart() != via->GetEnd() )
                via->SetEnd( via->GetStart() );
 
            rtree.QueryColliding( via, via->GetLayer(), via->GetLayer(),
                    // Filter:
                    [&]( BOARD_ITEM* aItem ) -> bool
                    {
                        return aItem->Type() == PCB_VIA_T
                                  && !aItem->HasFlag( SKIP_STRUCT )
                                  && !aItem->HasFlag( IS_DELETED );
                    },
                    // Visitor:
                    [&]( BOARD_ITEM* aItem ) -> bool
                    {
                        PCB_VIA* other = static_cast<PCB_VIA*>( aItem );
 
                        if( via->GetPosition() == other->GetPosition()
                                && via->GetViaType() == other->GetViaType()
                                && via->GetLayerSet() == other->GetLayerSet() )
                        {
                            auto item = std::make_shared<CLEANUP_ITEM>( CLEANUP_REDUNDANT_VIA );
                            item->SetItems( via );
                            m_itemsList->push_back( std::move( item ) );
 
                            via->SetFlags( IS_DELETED );
                            toRemove.insert( via );
                        }
 
                        return true;
                    } );
 
            // To delete through Via on THT pads at same location
            // Examine the list of connected pads: if a through pad is found, the via is redundant
            for( PAD* pad : m_brd->GetConnectivity()->GetConnectedPads( via ) )
            {
                const LSET all_cu = LSET::AllCuMask( m_brd->GetCopperLayerCount() );
 
                if( ( pad->GetLayerSet() & all_cu ) == all_cu )
                {
                    auto item = std::make_shared<CLEANUP_ITEM>( CLEANUP_REDUNDANT_VIA );
                    item->SetItems( via, pad );
                    m_itemsList->push_back( std::move( item ) );
 
                    via->SetFlags( IS_DELETED );
                    toRemove.insert( via );
                    break;
                }
            }
 
            via->SetFlags( SKIP_STRUCT );
        }
 
        if( aDeleteNullSegments && track->Type() != PCB_VIA_T )
        {
            if( track->IsNull() )
            {
                auto item = std::make_shared<CLEANUP_ITEM>( CLEANUP_ZERO_LENGTH_TRACK );
                item->SetItems( track );
                m_itemsList->push_back( std::move( item ) );
 
                track->SetFlags( IS_DELETED );
                toRemove.insert( track );
            }
        }
 
        if( aDeleteDuplicateSegments && track->Type() == PCB_TRACE_T && !track->IsNull() )
        {
            rtree.QueryColliding( track, track->GetLayer(), track->GetLayer(),
                    // Filter:
                    [&]( BOARD_ITEM* aItem ) -> bool
                    {
                        return aItem->Type() == PCB_TRACE_T
                                  && !aItem->HasFlag( SKIP_STRUCT )
                                  && !aItem->HasFlag( IS_DELETED )
                                  && !static_cast<PCB_TRACK*>( aItem )->IsNull();
                    },
                    // Visitor:
                    [&]( BOARD_ITEM* aItem ) -> bool
                    {
                        PCB_TRACK* other = static_cast<PCB_TRACK*>( aItem );
 
                        if( track->IsPointOnEnds( other->GetStart() )
                                && track->IsPointOnEnds( other->GetEnd() )
                                && track->GetWidth() == other->GetWidth()
                                && track->GetLayer() == other->GetLayer() )
                        {
                            auto item = std::make_shared<CLEANUP_ITEM>( CLEANUP_DUPLICATE_TRACK );
                            item->SetItems( track );
                            m_itemsList->push_back( std::move( item ) );
 
                            track->SetFlags( IS_DELETED );
                            toRemove.insert( track );
                        }
 
                        return true;
                    } );
 
            track->SetFlags( SKIP_STRUCT );
        }
    }
 
    if( !m_dryRun )
        removeItems( toRemove );
 
 
 
 
    auto mergeSegments = [&]( std::shared_ptr<CN_CONNECTIVITY_ALGO> connectivity ) -> bool
    {
        auto track_loop = [&]( int aStart, int aEnd ) -> std::vector<std::pair<PCB_TRACK*, PCB_TRACK*>>
        {
            std::vector<std::pair<PCB_TRACK*, PCB_TRACK*>> tracks;
 
            for( int ii = aStart; ii < aEnd; ++ii )
            {
                PCB_TRACK* segment = m_brd->Tracks()[ii];
 
                // one can merge only collinear segments, not vias or arcs.
                if( segment->Type() != PCB_TRACE_T )
                    continue;
 
                if( segment->HasFlag( IS_DELETED ) ) // already taken into account
                    continue;
 
                if( filterItem( segment ) )
                    continue;
 
                // for each end of the segment:
                auto& cnItems = connectivity->ItemEntry( segment ).GetItems();
 
                for( CN_ITEM* citem : cnItems )
                {
                    // Do not merge an end which has different width tracks attached -- it's a
                    // common use-case for necking-down a track between pads.
                    std::vector<PCB_TRACK*> sameWidthCandidates;
                    std::vector<PCB_TRACK*> differentWidthCandidates;
 
                    for( CN_ITEM* connected : citem->ConnectedItems() )
                    {
                        if( !connected->Valid() )
                            continue;
 
                        BOARD_CONNECTED_ITEM* candidate = connected->Parent();
 
                        if( candidate->Type() == PCB_TRACE_T && !candidate->HasFlag( IS_DELETED )
                            && !filterItem( candidate ) )
                        {
                            PCB_TRACK* candidateSegment = static_cast<PCB_TRACK*>( candidate );
 
                            if( candidateSegment->GetWidth() == segment->GetWidth() )
                            {
                                sameWidthCandidates.push_back( candidateSegment );
                            }
                            else
                            {
                                differentWidthCandidates.push_back( candidateSegment );
                                break;
                            }
                        }
                    }
 
                    if( !differentWidthCandidates.empty() )
                        continue;
 
                    for( PCB_TRACK* candidate : sameWidthCandidates )
                    {
                        if( candidate < segment ) // avoid duplicate merges
                            continue;
 
                        if( segment->ApproxCollinear( *candidate )
                            && testMergeCollinearSegments( segment, candidate ) )
                        {
                            tracks.emplace_back( segment, candidate );
                            break;
                        }
                    }
                }
            }
 
            return tracks;
        };
 
        // The idea here is to parallelize the loop that does not modify the connectivity
        // and extract all of the pairs of segments that might be merged.  Then, perform
        // the actual merge in the main loop.
        thread_pool& tp = GetKiCadThreadPool();
        auto merge_returns = tp.submit_blocks( 0, m_brd->Tracks().size(), track_loop );
        bool retval = false;
 
        for( size_t ii = 0; ii < merge_returns.size(); ++ii )
        {
            std::future<std::vector<std::pair<PCB_TRACK*, PCB_TRACK*>>>& ret = merge_returns[ii];
 
            if( ret.valid() )
            {
                for( auto& [seg1, seg2] : ret.get() )
                {
                    retval = true;
 
                    if( seg1->HasFlag( IS_DELETED ) || seg2->HasFlag( IS_DELETED ) )
                        continue;
 
                    mergeCollinearSegments( seg1, seg2 );
                }
            }
        }
 
        return retval;
    };
 
    if( aMergeSegments )
    {
        do
        {
            while( !m_brd->BuildConnectivity() )
                wxSafeYield();
 
            // BuildConnectivity adds items but doesn't establish connections between them.
            // RecalculateRatsnest triggers searchConnections which actually finds and links
            // connected items in the connectivity graph.
            m_brd->GetConnectivity()->RecalculateRatsnest();
 
            std::lock_guard lock( m_mutex );
            m_connectedItemsCache.clear();
        } while( mergeSegments( m_brd->GetConnectivity()->GetConnectivityAlgo() ) );
    }
 
    for( PCB_TRACK* track : m_brd->Tracks() )
        track->ClearFlags( IS_DELETED | SKIP_STRUCT );
}
 
 
const std::vector<BOARD_CONNECTED_ITEM*>& TRACKS_CLEANER::getConnectedItems( PCB_TRACK* aTrack )
{
    const std::shared_ptr<CONNECTIVITY_DATA>& connectivity = m_brd->GetConnectivity();
    std::lock_guard                           lock( m_mutex );
 
    if( !m_connectedItemsCache.contains( aTrack ) )
        m_connectedItemsCache[aTrack] = connectivity->GetConnectedItems( aTrack );
 
    return m_connectedItemsCache.at( aTrack );
}
 
 
bool TRACKS_CLEANER::testMergeCollinearSegments( PCB_TRACK* aSeg1, PCB_TRACK* aSeg2, PCB_TRACK* aDummySeg )
{
    if( aSeg1->IsLocked() || aSeg2->IsLocked() )
        return false;
 
    // Collect the unique points where the two tracks are connected to other items
    const unsigned p1s = 1 << 0;
    const unsigned p1e = 1 << 1;
    const unsigned p2s = 1 << 2;
    const unsigned p2e = 1 << 3;
    std::vector<VECTOR2I> pts = { aSeg1->GetStart(), aSeg1->GetEnd(), aSeg2->GetStart(), aSeg2->GetEnd() };
    std::atomic<unsigned> flags = 0;
 
    auto collectPtsSeg1 =
            [&]( BOARD_CONNECTED_ITEM* citem )
            {
                if( std::popcount( flags.load() ) > 2 )
                    return;
 
                if( citem->Type() == PCB_TRACE_T || citem->Type() == PCB_ARC_T
                        || citem->Type() == PCB_VIA_T )
                {
                    PCB_TRACK* track = static_cast<PCB_TRACK*>( citem );
 
                    if( track->IsPointOnEnds( aSeg1->GetStart() ) )
                        flags |= p1s;
 
                    if( track->IsPointOnEnds( aSeg1->GetEnd() ) )
                        flags |= p1e;
                }
                else
                {
                    if( !( flags & p1s ) && citem->HitTest( aSeg1->GetStart(), ( aSeg1->GetWidth() + 1 ) / 2 ) )
                        flags |= p1s;
 
                    if( !( flags & p1e ) && citem->HitTest( aSeg1->GetEnd(), ( aSeg1->GetWidth() + 1 ) / 2 ) )
                        flags |= p1e;
                }
            };
 
    auto collectPtsSeg2 =
            [&]( BOARD_CONNECTED_ITEM* citem )
            {
                if( std::popcount( flags.load() ) > 2 )
                    return;
 
                if( citem->Type() == PCB_TRACE_T || citem->Type() == PCB_ARC_T
                        || citem->Type() == PCB_VIA_T )
                {
                    PCB_TRACK* track = static_cast<PCB_TRACK*>( citem );
 
                    if( track->IsPointOnEnds( aSeg2->GetStart() ) )
                        flags |= p2s;
 
                    if( track->IsPointOnEnds( aSeg2->GetEnd() ) )
                        flags |= p2e;
                }
                else
                {
                    if( !( flags & p2s ) && citem->HitTest( aSeg2->GetStart(), ( aSeg2->GetWidth() + 1 ) / 2 ) )
                        flags |= p2s;
 
                    if( !( flags & p2e ) && citem->HitTest( aSeg2->GetEnd(), ( aSeg2->GetWidth() + 1 ) / 2 ) )
                        flags |= p2e;
                }
            };
 
    for( BOARD_CONNECTED_ITEM* item : getConnectedItems( aSeg1 ) )
    {
        if( item->HasFlag( IS_DELETED ) )
            continue;
 
        if( item != aSeg1 && item != aSeg2 )
            collectPtsSeg1( item );
    }
 
    for( BOARD_CONNECTED_ITEM* item : getConnectedItems( aSeg2 ) )
    {
        if( item->HasFlag( IS_DELETED ) )
            continue;
 
        if( item != aSeg1 && item != aSeg2 )
            collectPtsSeg2( item );
    }
 
    // This means there is a node in the center
    if( std::popcount( flags.load() ) > 2 )
        return false;
 
    // Verify the removed point after merging is not a node.
    // If it is a node (i.e. if more than one other item is connected, the segments cannot be merged
 
    PCB_TRACK dummy_seg( *aSeg1 );
 
    if( !aDummySeg )
        aDummySeg = &dummy_seg;
 
    // Calculate the new ends of the segment to merge, and store them to dummy_seg:
    int min_x = std::min( aSeg1->GetStart().x,
            std::min( aSeg1->GetEnd().x, std::min( aSeg2->GetStart().x, aSeg2->GetEnd().x ) ) );
    int min_y = std::min( aSeg1->GetStart().y,
            std::min( aSeg1->GetEnd().y, std::min( aSeg2->GetStart().y, aSeg2->GetEnd().y ) ) );
    int max_x = std::max( aSeg1->GetStart().x,
            std::max( aSeg1->GetEnd().x, std::max( aSeg2->GetStart().x, aSeg2->GetEnd().x ) ) );
    int max_y = std::max( aSeg1->GetStart().y,
            std::max( aSeg1->GetEnd().y, std::max( aSeg2->GetStart().y, aSeg2->GetEnd().y ) ) );
 
    if( ( aSeg1->GetStart().x > aSeg1->GetEnd().x )
            == ( aSeg1->GetStart().y > aSeg1->GetEnd().y ) )
    {
        aDummySeg->SetStart( VECTOR2I( min_x, min_y ) );
        aDummySeg->SetEnd( VECTOR2I( max_x, max_y ) );
    }
    else
    {
        aDummySeg->SetStart( VECTOR2I( min_x, max_y ) );
        aDummySeg->SetEnd( VECTOR2I( max_x, min_y ) );
    }
 
    // The new ends of the segment must be connected to all of the same points as the original
    // segments.  If not, the segments cannot be merged.
    for( unsigned i = 0; i < 4; ++i )
    {
        if( ( flags & ( 1 << i ) ) && !aDummySeg->IsPointOnEnds( pts[i] ) )
            return false;
    }
 
    // Now find the removed end(s) and stop merging if it is a node:
    return !testTrackEndpointIsNode( aSeg1, aDummySeg->IsPointOnEnds( aSeg1->GetStart() ),
                                aDummySeg->IsPointOnEnds( aSeg1->GetEnd() ) );
}
 
bool TRACKS_CLEANER::mergeCollinearSegments( PCB_TRACK* aSeg1, PCB_TRACK* aSeg2 )
{
    PCB_TRACK dummy_seg( *aSeg1 );
 
    if( !testMergeCollinearSegments( aSeg1, aSeg2, &dummy_seg ) )
        return false;
 
    std::shared_ptr<CLEANUP_ITEM> item = std::make_shared<CLEANUP_ITEM>( CLEANUP_MERGE_TRACKS );
    item->SetItems( aSeg1, aSeg2 );
    m_itemsList->push_back( std::move( item ) );
 
    aSeg2->SetFlags( IS_DELETED );
 
    if( !m_dryRun )
    {
        m_commit.Modify( aSeg1 );
 
        *aSeg1 = dummy_seg;
 
        m_brd->GetConnectivity()->Update( aSeg1 );
 
        // Merge successful, seg2 has to go away
        m_brd->Remove( aSeg2 );
        m_commit.Removed( aSeg2 );
    }
 
    return true;
}
 
 
void TRACKS_CLEANER::removeItems( std::set<BOARD_ITEM*>& aItems )
{
    for( BOARD_ITEM* item : aItems )
    {
        m_brd->Remove( item );
        m_commit.Removed( item );
    }
}