connectivity_algo.cpp

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/*
 * This program source code file is part of KICAD, a free EDA CAD application.
 *
 * Copyright (C) 2016-2018 CERN
 * Copyright (C) 2020-2023 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * @author Tomasz Wlostowski <[email protected]>
 *
 * 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 <algorithm>
#include <future>
#include <mutex>
 
#include <connectivity/connectivity_algo.h>
#include <progress_reporter.h>
#include <geometry/geometry_utils.h>
#include <board_commit.h>
#include <core/thread_pool.h>
#include <pcb_shape.h>
 
#include <wx/log.h>
 
#ifdef PROFILE
#include <core/profile.h>
#endif
 
 
bool CN_CONNECTIVITY_ALGO::Remove( BOARD_ITEM* aItem )
{
 markItemNetAsDirty( aItem );
 
 switch( aItem->Type() )
 {
 case PCB_FOOTPRINT_T:
 for( PAD* pad : static_cast<FOOTPRINT*>( aItem )->Pads() )
 {
 m_itemMap[pad].MarkItemsAsInvalid();
 m_itemMap.erase( pad );
 }
 
 m_itemList.SetDirty( true );
 break;
 
 case PCB_PAD_T:
 case PCB_TRACE_T:
 case PCB_ARC_T:
 case PCB_VIA_T:
 case PCB_ZONE_T:
 case PCB_SHAPE_T:
 m_itemMap[aItem].MarkItemsAsInvalid();
 m_itemMap.erase ( aItem );
 m_itemList.SetDirty( true );
 break;
 
 default:
 return false;
 }
 
 // Once we delete an item, it may connect between lists, so mark both as potentially invalid
 m_itemList.SetHasInvalid( true );
 
 return true;
}
 
 
void CN_CONNECTIVITY_ALGO::markItemNetAsDirty( const BOARD_ITEM* aItem )
{
 if( aItem->IsConnected() )
 {
 const BOARD_CONNECTED_ITEM* citem = static_cast<const BOARD_CONNECTED_ITEM*>( aItem );
 MarkNetAsDirty( citem->GetNetCode() );
 }
 else
 {
 if( aItem->Type() == PCB_FOOTPRINT_T )
 {
 const FOOTPRINT* footprint = static_cast<const FOOTPRINT*>( aItem );
 
 for( PAD* pad : footprint->Pads() )
 MarkNetAsDirty( pad->GetNetCode() );
 }
 }
}
 
 
bool CN_CONNECTIVITY_ALGO::Add( BOARD_ITEM* aItem )
{
 if( !aItem->IsOnCopperLayer() )
 return false;
 
 auto alreadyAdded =
 [this]( BOARD_ITEM* item )
 {
 auto it = m_itemMap.find( item );
 
 if( it == m_itemMap.end() )
 return false;
 
 // Don't be fooled by an empty ITEM_MAP_ENTRY auto-created by operator[].
 return !it->second.GetItems().empty();
 };
 
 switch( aItem->Type() )
 {
 case PCB_NETINFO_T:
 MarkNetAsDirty( static_cast<NETINFO_ITEM*>( aItem )->GetNetCode() );
 break;
 
 case PCB_FOOTPRINT_T:
 {
 if( static_cast<FOOTPRINT*>( aItem )->GetAttributes() & FP_JUST_ADDED )
 return false;
 
 for( PAD* pad : static_cast<FOOTPRINT*>( aItem )->Pads() )
 {
 if( alreadyAdded( pad ) )
 return false;
 
 add( m_itemList, pad );
 }
 
 break;
 }
 
 case PCB_PAD_T:
 {
 if( FOOTPRINT* fp = aItem->GetParentFootprint() )
 {
 if( fp->GetAttributes() & FP_JUST_ADDED )
 return false;
 }
 
 if( alreadyAdded( aItem ) )
 return false;
 
 add( m_itemList, static_cast<PAD*>( aItem ) );
 break;
 }
 
 case PCB_TRACE_T:
 if( alreadyAdded( aItem ) )
 return false;
 
 add( m_itemList, static_cast<PCB_TRACK*>( aItem ) );
 break;
 
 case PCB_ARC_T:
 if( alreadyAdded( aItem ) )
 return false;
 
 add( m_itemList, static_cast<PCB_ARC*>( aItem ) );
 break;
 
 case PCB_VIA_T:
 if( alreadyAdded( aItem ) )
 return false;
 
 add( m_itemList, static_cast<PCB_VIA*>( aItem ) );
 break;
 
 case PCB_SHAPE_T:
 if( alreadyAdded( aItem ) )
 return false;
 
 if( !IsCopperLayer( aItem->GetLayer() ) )
 return false;
 
 add( m_itemList, static_cast<PCB_SHAPE*>( aItem ) );
 break;
 
 case PCB_ZONE_T:
 {
 ZONE* zone = static_cast<ZONE*>( aItem );
 
 if( alreadyAdded( aItem ) )
 return false;
 
 m_itemMap[zone] = ITEM_MAP_ENTRY();
 
 for( PCB_LAYER_ID layer : zone->GetLayerSet().Seq() )
 {
 for( CN_ITEM* zitem : m_itemList.Add( zone, layer ) )
 m_itemMap[zone].Link( zitem );
 }
 }
 break;
 
 default:
 return false;
 }
 
 markItemNetAsDirty( aItem );
 
 return true;
}
 
 
void CN_CONNECTIVITY_ALGO::searchConnections()
{
#ifdef PROFILE
 PROF_TIMER garbage_collection( "garbage-collection" );
#endif
 std::vector<CN_ITEM*> garbage;
 garbage.reserve( 1024 );
 
 m_itemList.RemoveInvalidItems( garbage );
 
 for( CN_ITEM* item : garbage )
 delete item;
 
#ifdef PROFILE
 garbage_collection.Show();
 PROF_TIMER search_basic( "search-basic" );
#endif
 
 thread_pool& tp = GetKiCadThreadPool();
 std::vector<CN_ITEM*> dirtyItems;
 std::copy_if( m_itemList.begin(), m_itemList.end(), std::back_inserter( dirtyItems ),
 [] ( CN_ITEM* aItem )
 {
 return aItem->Dirty();
 } );
 
 if( m_progressReporter )
 {
 m_progressReporter->SetMaxProgress( dirtyItems.size() );
 
 if( !m_progressReporter->KeepRefreshing() )
 return;
 }
 
 if( m_itemList.IsDirty() )
 {
 
 std::vector<std::future<size_t>> returns( dirtyItems.size() );
 
 auto conn_lambda =
 [&dirtyItems]( size_t aItem, CN_LIST* aItemList,
 PROGRESS_REPORTER* aReporter) -> size_t
 {
 if( aReporter && aReporter->IsCancelled() )
 return 0;
 
 CN_VISITOR visitor( dirtyItems[aItem] );
 aItemList->FindNearby( dirtyItems[aItem], visitor );
 
 if( aReporter )
 aReporter->AdvanceProgress();
 
 return 1;
 };
 
 for( size_t ii = 0; ii < dirtyItems.size(); ++ii )
 returns[ii] = tp.submit( conn_lambda, ii, &m_itemList, m_progressReporter );
 
 for( const std::future<size_t>& ret : returns )
 {
 // Here we balance returns with a 250ms timeout to allow UI updating
 std::future_status status = ret.wait_for( std::chrono::milliseconds( 250 ) );
 
 while( status != std::future_status::ready )
 {
 if( m_progressReporter )
 m_progressReporter->KeepRefreshing();
 
 status = ret.wait_for( std::chrono::milliseconds( 250 ) );
 }
 }
 
 if( m_progressReporter )
 m_progressReporter->KeepRefreshing();
 }
 
#ifdef PROFILE
 search_basic.Show();
#endif
 
 m_itemList.ClearDirtyFlags();
}
 
 
const CN_CONNECTIVITY_ALGO::CLUSTERS CN_CONNECTIVITY_ALGO::SearchClusters( CLUSTER_SEARCH_MODE aMode )
{
 if( aMode == CSM_PROPAGATE )
 {
 return SearchClusters( aMode,
 { PCB_TRACE_T, PCB_ARC_T, PCB_PAD_T, PCB_VIA_T, PCB_FOOTPRINT_T,
 PCB_SHAPE_T },
 -1 );
 }
 else
 {
 return SearchClusters( aMode,
 { PCB_TRACE_T, PCB_ARC_T, PCB_PAD_T, PCB_VIA_T, PCB_ZONE_T,
 PCB_FOOTPRINT_T, PCB_SHAPE_T },
 -1 );
 }
}
 
 
const CN_CONNECTIVITY_ALGO::CLUSTERS
CN_CONNECTIVITY_ALGO::SearchClusters( CLUSTER_SEARCH_MODE aMode,
 const std::initializer_list<KICAD_T>& aTypes,
 int aSingleNet, CN_ITEM* rootItem )
{
 bool withinAnyNet = ( aMode != CSM_PROPAGATE );
 
 std::deque<CN_ITEM*> Q;
 std::set<CN_ITEM*> item_set;
 
 CLUSTERS clusters;
 
 if( m_itemList.IsDirty() )
 searchConnections();
 
 auto addToSearchList =
 [&item_set, withinAnyNet, aSingleNet, &aTypes, rootItem ]( CN_ITEM *aItem )
 {
 if( withinAnyNet && aItem->Net() <= 0 )
 return;
 
 if( !aItem->Valid() )
 return;
 
 if( aSingleNet >=0 && aItem->Net() != aSingleNet )
 return;
 
 bool found = false;
 
 for( KICAD_T type : aTypes )
 {
 if( aItem->Parent()->Type() == type )
 {
 found = true;
 break;
 }
 }
 
 if( !found && aItem != rootItem )
 return;
 
 aItem->SetVisited( false );
 
 item_set.insert( aItem );
 };
 
 std::for_each( m_itemList.begin(), m_itemList.end(), addToSearchList );
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return CLUSTERS();
 
 while( !item_set.empty() )
 {
 std::shared_ptr<CN_CLUSTER> cluster = std::make_shared<CN_CLUSTER>();
 CN_ITEM* root;
 auto it = item_set.begin();
 
 while( it != item_set.end() && (*it)->Visited() )
 it = item_set.erase( item_set.begin() );
 
 if( it == item_set.end() )
 break;
 
 root = *it;
 root->SetVisited( true );
 
 Q.clear();
 Q.push_back( root );
 
 while( Q.size() )
 {
 CN_ITEM* current = Q.front();
 
 Q.pop_front();
 cluster->Add( current );
 
 for( CN_ITEM* n : current->ConnectedItems() )
 {
 if( withinAnyNet && n->Net() != root->Net() )
 continue;
 
 if( !n->Visited() && n->Valid() )
 {
 n->SetVisited( true );
 Q.push_back( n );
 }
 }
 }
 
 clusters.push_back( cluster );
 }
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return CLUSTERS();
 
 std::sort( clusters.begin(), clusters.end(),
 []( const std::shared_ptr<CN_CLUSTER>& a, const std::shared_ptr<CN_CLUSTER>& b )
 {
 return a->OriginNet() < b->OriginNet();
 } );
 
 return clusters;
}
 
 
void CN_CONNECTIVITY_ALGO::Build( BOARD* aBoard, PROGRESS_REPORTER* aReporter )
{
 // Generate CN_ZONE_LAYERs for each island on each layer of each zone
 //
 std::vector<CN_ZONE_LAYER*> zitems;
 
 for( ZONE* zone : aBoard->Zones() )
 {
 if( zone->IsOnCopperLayer() )
 {
 m_itemMap[zone] = ITEM_MAP_ENTRY();
 markItemNetAsDirty( zone );
 
 for( PCB_LAYER_ID layer : zone->GetLayerSet().Seq() )
 {
 if( IsCopperLayer( layer ) )
 {
 for( int j = 0; j < zone->GetFilledPolysList( layer )->OutlineCount(); j++ )
 zitems.push_back( new CN_ZONE_LAYER( zone, layer, j ) );
 }
 }
 }
 }
 
 // Setup progress metrics
 //
 int progressDelta = 50;
 double size = 0.0;
 
 size += zitems.size(); // Once for building RTrees
 size += zitems.size(); // Once for adding to connectivity
 size += aBoard->Tracks().size();
 size += aBoard->Drawings().size();
 
 for( FOOTPRINT* footprint : aBoard->Footprints() )
 size += footprint->Pads().size();
 
 size *= 1.5; // Our caller gets the other third of the progress bar
 
 progressDelta = std::max( progressDelta, (int) size / 4 );
 
 auto report =
 [&]( int progress )
 {
 if( aReporter && ( progress % progressDelta ) == 0 )
 {
 aReporter->SetCurrentProgress( progress / size );
 aReporter->KeepRefreshing( false );
 }
 };
 
 // Generate RTrees for CN_ZONE_LAYER items (in parallel)
 //
 thread_pool& tp = GetKiCadThreadPool();
 std::vector<std::future<size_t>> returns( zitems.size() );
 
 auto cache_zones =
 [aReporter]( CN_ZONE_LAYER* aZoneLayer ) -> size_t
 {
 if( aReporter && aReporter->IsCancelled() )
 return 0;
 
 aZoneLayer->BuildRTree();
 
 if( aReporter )
 aReporter->AdvanceProgress();
 
 return 1;
 };
 
 for( size_t ii = 0; ii < zitems.size(); ++ii )
 returns[ii] = tp.submit( cache_zones, zitems[ii] );
 
 for( const std::future<size_t>& ret : returns )
 {
 std::future_status status = ret.wait_for( std::chrono::milliseconds( 250 ) );
 
 while( status != std::future_status::ready )
 {
 if( aReporter )
 aReporter->KeepRefreshing();
 
 status = ret.wait_for( std::chrono::milliseconds( 250 ) );
 }
 
 }
 
 // Add CN_ZONE_LAYERS, tracks, and pads to connectivity
 //
 int ii = zitems.size();
 
 for( CN_ZONE_LAYER* zitem : zitems )
 {
 m_itemList.Add( zitem );
 m_itemMap[ zitem->Parent() ].Link( zitem );
 report( ++ii );
 }
 
 for( PCB_TRACK* tv : aBoard->Tracks() )
 {
 Add( tv );
 report( ++ii );
 }
 
 for( FOOTPRINT* footprint : aBoard->Footprints() )
 {
 for( PAD* pad : footprint->Pads() )
 {
 Add( pad );
 report( ++ii );
 }
 }
 
 for( BOARD_ITEM* drawing : aBoard->Drawings() )
 {
 if( PCB_SHAPE* shape = dynamic_cast<PCB_SHAPE*>( drawing ) )
 {
 if( shape->IsOnCopperLayer() )
 Add( shape );
 }
 
 report( ++ii );
 }
 
 if( aReporter )
 {
 aReporter->SetCurrentProgress( (double) ii / (double) size );
 aReporter->KeepRefreshing( false );
 }
}
 
 
void CN_CONNECTIVITY_ALGO::LocalBuild( const std::vector<BOARD_ITEM*>& aItems )
{
 for( BOARD_ITEM* item : aItems )
 {
 switch( item->Type() )
 {
 case PCB_TRACE_T:
 case PCB_ARC_T:
 case PCB_VIA_T:
 case PCB_PAD_T:
 case PCB_FOOTPRINT_T:
 case PCB_SHAPE_T:
 Add( item );
 break;
 
 default:
 break;
 }
 }
}
 
 
void CN_CONNECTIVITY_ALGO::propagateConnections( BOARD_COMMIT* aCommit )
{
 for( const std::shared_ptr<CN_CLUSTER>& cluster : m_connClusters )
 {
 if( cluster->IsConflicting() )
 {
 // Conflicting pads in cluster: we don't know the user's intent so best to do
 // nothing.
 wxLogTrace( wxT( "CN" ), wxT( "Conflicting pads in cluster %p; skipping propagation" ),
 cluster.get() );
 }
 else if( cluster->HasValidNet() )
 {
 // Propagate from the origin (will be a pad if there are any, or another item if
 // there are no pads).
 int n_changed = 0;
 
 for( CN_ITEM* item : *cluster )
 {
 if( item->Valid() && item->CanChangeNet()
 && item->Parent()->GetNetCode() != cluster->OriginNet() )
 {
 MarkNetAsDirty( item->Parent()->GetNetCode() );
 MarkNetAsDirty( cluster->OriginNet() );
 
 if( aCommit )
 aCommit->Modify( item->Parent() );
 
 item->Parent()->SetNetCode( cluster->OriginNet() );
 n_changed++;
 }
 }
 
 if( n_changed )
 {
 wxLogTrace( wxT( "CN" ), wxT( "Cluster %p: net: %d %s" ),
 cluster.get(),
 cluster->OriginNet(),
 (const char*) cluster->OriginNetName().c_str() );
 }
 else
 {
 wxLogTrace( wxT( "CN" ), wxT( "Cluster %p: no changeable items to propagate to" ),
 cluster.get() );
 }
 }
 else
 {
 wxLogTrace( wxT( "CN" ), wxT( "Cluster %p: connected to unused net" ),
 cluster.get() );
 }
 }
}
 
 
void CN_CONNECTIVITY_ALGO::PropagateNets( BOARD_COMMIT* aCommit )
{
 m_connClusters = SearchClusters( CSM_PROPAGATE );
 propagateConnections( aCommit );
}
 
 
void CN_CONNECTIVITY_ALGO::FillIsolatedIslandsMap(
 std::map<ZONE*, std::map<PCB_LAYER_ID, ISOLATED_ISLANDS>>& aMap,
 bool aConnectivityAlreadyRebuilt )
{
 int progressDelta = 50;
 int ii = 0;
 
 progressDelta = std::max( progressDelta, (int) aMap.size() / 4 );
 
 if( !aConnectivityAlreadyRebuilt )
 {
 for( const auto& [ zone, islands ] : aMap )
 {
 Remove( zone );
 Add( zone );
 ii++;
 
 if( m_progressReporter && ( ii % progressDelta ) == 0 )
 {
 m_progressReporter->SetCurrentProgress( (double) ii / (double) aMap.size() );
 m_progressReporter->KeepRefreshing( false );
 }
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return;
 }
 }
 
 m_connClusters = SearchClusters( CSM_CONNECTIVITY_CHECK );
 
 for( auto& [ zone, zoneIslands ] : aMap )
 {
 for( auto& [ layer, layerIslands ] : zoneIslands )
 {
 if( zone->GetFilledPolysList( layer )->IsEmpty() )
 continue;
 
 for( const std::shared_ptr<CN_CLUSTER>& cluster : m_connClusters )
 {
 for( CN_ITEM* item : *cluster )
 {
 if( item->Parent() == zone && item->Layer() == layer )
 {
 CN_ZONE_LAYER* z = static_cast<CN_ZONE_LAYER*>( item );
 
 if( cluster->IsOrphaned() )
 layerIslands.m_IsolatedOutlines.push_back( z->SubpolyIndex() );
 else if( z->HasSingleConnection() )
 layerIslands.m_SingleConnectionOutlines.push_back( z->SubpolyIndex() );
 }
 }
 }
 }
 }
}
 
 
const CN_CONNECTIVITY_ALGO::CLUSTERS& CN_CONNECTIVITY_ALGO::GetClusters()
{
 m_ratsnestClusters = SearchClusters( CSM_RATSNEST );
 return m_ratsnestClusters;
}
 
 
void CN_CONNECTIVITY_ALGO::MarkNetAsDirty( int aNet )
{
 if( aNet < 0 )
 return;
 
 if( (int) m_dirtyNets.size() <= aNet )
 {
 int lastNet = m_dirtyNets.size() - 1;
 
 if( lastNet < 0 )
 lastNet = 0;
 
 m_dirtyNets.resize( aNet + 1 );
 
 for( int i = lastNet; i < aNet + 1; i++ )
 m_dirtyNets[i] = true;
 }
 
 m_dirtyNets[aNet] = true;
}
 
 
void CN_VISITOR::checkZoneItemConnection( CN_ZONE_LAYER* aZoneLayer, CN_ITEM* aItem )
{
 PCB_LAYER_ID layer = aZoneLayer->GetLayer();
 BOARD_CONNECTED_ITEM* item = aItem->Parent();
 
 if( !item->IsOnLayer( layer ) )
 return;
 
 auto connect =
 [&]()
 {
 aZoneLayer->Connect( aItem );
 aItem->Connect( aZoneLayer );
 };
 
 // Try quick checks first...
 if( item->Type() == PCB_PAD_T )
 {
 PAD* pad = static_cast<PAD*>( item );
 
 if( pad->ConditionallyFlashed( layer )
 && pad->GetZoneLayerOverride( layer ) == ZLO_FORCE_NO_ZONE_CONNECTION )
 {
 return;
 }
 }
 else if( item->Type() == PCB_VIA_T )
 {
 PCB_VIA* via = static_cast<PCB_VIA*>( item );
 
 if( via->ConditionallyFlashed( layer )
 && via->GetZoneLayerOverride( layer ) == ZLO_FORCE_NO_ZONE_CONNECTION )
 {
 return;
 }
 }
 
 for( int i = 0; i < aItem->AnchorCount(); ++i )
 {
 if( aZoneLayer->ContainsPoint( aItem->GetAnchor( i ) ) )
 {
 connect();
 return;
 }
 }
 
 if( item->Type() == PCB_VIA_T || item->Type() == PCB_PAD_T )
 {
 // As long as the pad/via crosses the zone layer, check for the full effective shape
 // We check for the overlapping layers above
 if( aZoneLayer->Collide( item->GetEffectiveShape( layer, FLASHING::ALWAYS_FLASHED ).get() ) )
 connect();
 
 return;
 }
 
 if( aZoneLayer->Collide( item->GetEffectiveShape( layer ).get() ) )
 connect();
}
 
void CN_VISITOR::checkZoneZoneConnection( CN_ZONE_LAYER* aZoneLayerA, CN_ZONE_LAYER* aZoneLayerB )
{
 const ZONE* zoneA = static_cast<const ZONE*>( aZoneLayerA->Parent() );
 const ZONE* zoneB = static_cast<const ZONE*>( aZoneLayerB->Parent() );
 
 const BOX2I& boxA = aZoneLayerA->BBox();
 const BOX2I& boxB = aZoneLayerB->BBox();
 
 PCB_LAYER_ID layer = aZoneLayerA->GetLayer();
 
 if( aZoneLayerB->GetLayer() != layer )
 return;
 
 if( !boxA.Intersects( boxB ) )
 return;
 
 const SHAPE_LINE_CHAIN& outline =
 zoneA->GetFilledPolysList( layer )->COutline( aZoneLayerA->SubpolyIndex() );
 
 for( int i = 0; i < outline.PointCount(); i++ )
 {
 if( !boxB.Contains( outline.CPoint( i ) ) )
 continue;
 
 if( aZoneLayerB->ContainsPoint( outline.CPoint( i ) ) )
 {
 aZoneLayerA->Connect( aZoneLayerB );
 aZoneLayerB->Connect( aZoneLayerA );
 return;
 }
 }
 
 const SHAPE_LINE_CHAIN& outline2 =
 zoneB->GetFilledPolysList( layer )->COutline( aZoneLayerB->SubpolyIndex() );
 
 for( int i = 0; i < outline2.PointCount(); i++ )
 {
 if( !boxA.Contains( outline2.CPoint( i ) ) )
 continue;
 
 if( aZoneLayerA->ContainsPoint( outline2.CPoint( i ) ) )
 {
 aZoneLayerA->Connect( aZoneLayerB );
 aZoneLayerB->Connect( aZoneLayerA );
 return;
 }
 }
}
 
 
bool CN_VISITOR::operator()( CN_ITEM* aCandidate )
{
 const BOARD_CONNECTED_ITEM* parentA = aCandidate->Parent();
 const BOARD_CONNECTED_ITEM* parentB = m_item->Parent();
 
 if( !aCandidate->Valid() || !m_item->Valid() )
 return true;
 
 if( parentA == parentB )
 return true;
 
 // Don't connect items in different nets that can't be changed
 if( !aCandidate->CanChangeNet() && !m_item->CanChangeNet() && aCandidate->Net() != m_item->Net() )
 return true;
 
 // If both m_item and aCandidate are marked dirty, they will both be searched
 // Since we are reciprocal in our connection, we arbitrarily pick one of the connections
 // to conduct the expensive search
 if( aCandidate->Dirty() && aCandidate < m_item )
 return true;
 
 // We should handle zone-zone connection separately
 if ( parentA->Type() == PCB_ZONE_T && parentB->Type() == PCB_ZONE_T )
 {
 checkZoneZoneConnection( static_cast<CN_ZONE_LAYER*>( m_item ),
 static_cast<CN_ZONE_LAYER*>( aCandidate ) );
 return true;
 }
 
 if( parentA->Type() == PCB_ZONE_T )
 {
 checkZoneItemConnection( static_cast<CN_ZONE_LAYER*>( aCandidate ), m_item );
 return true;
 }
 
 if( parentB->Type() == PCB_ZONE_T )
 {
 checkZoneItemConnection( static_cast<CN_ZONE_LAYER*>( m_item ), aCandidate );
 return true;
 }
 
 LSET commonLayers = parentA->GetLayerSet() & parentB->GetLayerSet();
 
 for( PCB_LAYER_ID layer : commonLayers.Seq() )
 {
 FLASHING flashingA = FLASHING::NEVER_FLASHED;
 FLASHING flashingB = FLASHING::NEVER_FLASHED;
 
 if( parentA->Type() == PCB_PAD_T )
 {
 if( !static_cast<const PAD*>( parentA )->ConditionallyFlashed( layer ) )
 flashingA = FLASHING::ALWAYS_FLASHED;
 }
 else if( parentA->Type() == PCB_VIA_T )
 {
 if( !static_cast<const PCB_VIA*>( parentA )->ConditionallyFlashed( layer ) )
 flashingA = FLASHING::ALWAYS_FLASHED;
 }
 
 if( parentB->Type() == PCB_PAD_T )
 {
 if( !static_cast<const PAD*>( parentB )->ConditionallyFlashed( layer ) )
 flashingB = FLASHING::ALWAYS_FLASHED;
 }
 else if( parentB->Type() == PCB_VIA_T )
 {
 if( !static_cast<const PCB_VIA*>( parentB )->ConditionallyFlashed( layer ) )
 flashingB = FLASHING::ALWAYS_FLASHED;
 }
 
 if( parentA->GetEffectiveShape( layer, flashingA )->Collide(
 parentB->GetEffectiveShape( layer, flashingB ).get() ) )
 {
 m_item->Connect( aCandidate );
 aCandidate->Connect( m_item );
 return true;
 }
 }
 
 return true;
};
 
 
void CN_CONNECTIVITY_ALGO::Clear()
{
 m_ratsnestClusters.clear();
 m_connClusters.clear();
 m_itemMap.clear();
 m_itemList.Clear();
 
}
 
void CN_CONNECTIVITY_ALGO::SetProgressReporter( PROGRESS_REPORTER* aReporter )
{
 m_progressReporter = aReporter;
}