kicad/eeschema/sch_screen.cpp

/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2013 Jean-Pierre Charras, jp.charras at wanadoo.fr
 * Copyright (C) 2012 SoftPLC Corporation, Dick Hollenbeck <dick@softplc.com>
 * Copyright (C) 2008 Wayne Stambaugh <stambaughw@gmail.com>
 * Copyright (C) 1992-2022 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 <wx/filefn.h>

#include <eda_item.h>
#include <id.h>
#include <string_utils.h>
#include <kiway.h>
#include <plotters/plotter.h>
#include <project.h>
#include <reporter.h>
#include <sch_draw_panel.h>
#include <sch_edit_frame.h>
#include <sch_item.h>

#include <symbol_library.h>
#include <connection_graph.h>
#include <lib_item.h>
#include <lib_pin.h>
#include <lib_shape.h>
#include <sch_symbol.h>
#include <sch_junction.h>
#include <sch_line.h>
#include <sch_marker.h>
#include <sch_sheet.h>
#include <sch_sheet_pin.h>
#include <sch_text.h>
#include <schematic.h>
#include <symbol_lib_table.h>
#include <tool/common_tools.h>
#include <sim/sim_model.h> // For V6 to V7 simulation model migration.
#include <sim/sim_value.h> //
#include <locale_io.h>

#include <algorithm>

// TODO(JE) Debugging only
#include <profile.h>
#include "sch_bus_entry.h"
#include "sim/sim_model_ideal.h"

SCH_SCREEN::SCH_SCREEN( EDA_ITEM* aParent ) :
    BASE_SCREEN( aParent, SCH_SCREEN_T ),
    m_fileFormatVersionAtLoad( 0 ),
    m_paper( wxT( "A4" ) ),
    m_isReadOnly( false ),
    m_fileExists( false )
{
    m_modification_sync = 0;
    m_refCount = 0;
    m_zoomInitialized = false;
    m_LastZoomLevel = 1.0;

    // Suitable for schematic only. For symbol_editor and viewlib, must be set to true
    m_Center = false;

    InitDataPoints( m_paper.GetSizeIU( schIUScale.IU_PER_MILS ) );
}


SCH_SCREEN::~SCH_SCREEN()
{
    clearLibSymbols();
    FreeDrawList();
}


SCHEMATIC* SCH_SCREEN::Schematic() const
{
    wxCHECK_MSG( GetParent() && GetParent()->Type() == SCHEMATIC_T, nullptr,
                 wxT( "SCH_SCREEN must have a SCHEMATIC parent!" ) );

    return static_cast<SCHEMATIC*>( GetParent() );
}


void SCH_SCREEN::clearLibSymbols()
{
    for( const std::pair<const wxString, LIB_SYMBOL*>& libSymbol : m_libSymbols )
        delete libSymbol.second;

    m_libSymbols.clear();
}


void SCH_SCREEN::SetFileName( const wxString& aFileName )
{
    wxASSERT( aFileName.IsEmpty() || wxIsAbsolutePath( aFileName ) );

    m_fileName = aFileName;
}


void SCH_SCREEN::IncRefCount()
{
    m_refCount++;
}


void SCH_SCREEN::DecRefCount()
{
    wxCHECK_RET( m_refCount != 0, wxT( "Screen reference count already zero.  Bad programmer!" ) );
    m_refCount--;
}


bool SCH_SCREEN::HasItems( KICAD_T aItemType ) const
{
    EE_RTREE::EE_TYPE sheets = m_rtree.OfType( aItemType );

    return sheets.begin() != sheets.end();
}


bool SCH_SCREEN::ClassOf( const EDA_ITEM* aItem )
{
    return aItem && SCH_SCREEN_T == aItem->Type();
}


void SCH_SCREEN::Append( SCH_ITEM* aItem )
{
    if( aItem->Type() != SCH_SHEET_PIN_T && aItem->Type() != SCH_FIELD_T )
    {
        // Ensure the item can reach the SCHEMATIC through this screen
        aItem->SetParent( this );

        if( aItem->Type() == SCH_SYMBOL_T )
        {
            SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( aItem );

            if( symbol->GetLibSymbolRef() )
            {
                symbol->GetLibSymbolRef()->GetDrawItems().sort();

                auto it = m_libSymbols.find( symbol->GetSchSymbolLibraryName() );

                if( it == m_libSymbols.end() || !it->second )
                {
                    m_libSymbols[symbol->GetSchSymbolLibraryName()] =
                            new LIB_SYMBOL( *symbol->GetLibSymbolRef() );
                }
                else
                {
                    // The original library symbol may have changed since the last time
                    // it was added to the schematic.  If it has changed, then a new name
                    // must be created for the library symbol list to prevent all of the
                    // other schematic symbols referencing that library symbol from changing.
                    LIB_SYMBOL* foundSymbol = it->second;

                    foundSymbol->GetDrawItems().sort();

                    if( *foundSymbol != *symbol->GetLibSymbolRef() )
                    {
                        int cnt = 1;
                        wxString newName;

                        newName.Printf( "%s_%d", symbol->GetLibId().GetUniStringLibItemName(),
                                        cnt );

                        while( m_libSymbols.find( newName ) != m_libSymbols.end() )
                        {
                            cnt += 1;
                            newName.Printf( "%s_%d", symbol->GetLibId().GetUniStringLibItemName(),
                                            cnt );
                        }

                        // Update the schematic symbol library link as this symbol only exists
                        // in the schematic.
                        symbol->SetSchSymbolLibraryName( newName );

                        LIB_SYMBOL* newLibSymbol = new LIB_SYMBOL( *symbol->GetLibSymbolRef() );
                        LIB_ID newLibId( wxEmptyString, newName );

                        newLibSymbol->SetLibId( newLibId );
                        newLibSymbol->SetName( newName );
                        symbol->SetLibSymbol( newLibSymbol->Flatten().release() );
                        m_libSymbols[newName] = newLibSymbol;
                    }
                }
            }
        }

        m_rtree.insert( aItem );
        --m_modification_sync;
    }
}


void SCH_SCREEN::Append( SCH_SCREEN* aScreen )
{
    wxCHECK_RET( aScreen, "Invalid screen object." );

    // No need to descend the hierarchy.  Once the top level screen is copied, all of its
    // children are copied as well.
    for( SCH_ITEM* aItem : aScreen->m_rtree )
        Append( aItem );

    aScreen->Clear( false );
}


void SCH_SCREEN::Clear( bool aFree )
{
    if( aFree )
    {
        FreeDrawList();
        clearLibSymbols();
    }
    else
    {
        m_rtree.clear();
    }

    // Clear the project settings
    m_virtualPageNumber = m_pageCount = 1;

    m_titles.Clear();
}


void SCH_SCREEN::FreeDrawList()
{
    // We don't know which order we will encounter dependent items (e.g. pins or fields), so
    // we store the items to be deleted until we've fully cleared the tree before deleting
    std::vector<SCH_ITEM*> delete_list;

    std::copy_if( m_rtree.begin(), m_rtree.end(), std::back_inserter( delete_list ),
            []( SCH_ITEM* aItem )
            {
                return ( aItem->Type() != SCH_SHEET_PIN_T && aItem->Type() != SCH_FIELD_T );
            } );

    m_rtree.clear();

    for( SCH_ITEM* item : delete_list )
        delete item;
}


void SCH_SCREEN::Update( SCH_ITEM* aItem )
{
    if( Remove( aItem ) )
        Append( aItem );
}


bool SCH_SCREEN::Remove( SCH_ITEM* aItem )
{
    bool retv = m_rtree.remove( aItem );

    // Check if the library symbol for the removed schematic symbol is still required.
    if( retv && aItem->Type() == SCH_SYMBOL_T )
    {
        SCH_SYMBOL* removedSymbol = static_cast<SCH_SYMBOL*>( aItem );

        bool removeUnusedLibSymbol = true;

        for( SCH_ITEM* item : Items().OfType( SCH_SYMBOL_T ) )
        {
            SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );

            if( removedSymbol->GetSchSymbolLibraryName() == symbol->GetSchSymbolLibraryName() )
            {
                removeUnusedLibSymbol = false;
                break;
            }
        }

        if( removeUnusedLibSymbol )
        {
            auto it = m_libSymbols.find( removedSymbol->GetSchSymbolLibraryName() );

            if( it != m_libSymbols.end() )
            {
                delete it->second;
                m_libSymbols.erase( it );
            }
        }
    }

    return retv;
}


void SCH_SCREEN::DeleteItem( SCH_ITEM* aItem )
{
    wxCHECK_RET( aItem, wxT( "Cannot delete invalid item from screen." ) );

    // Markers are not saved in the file, no need to flag as modified.
    // TODO: Maybe we should have a listing somewhere of items that aren't saved?
    if( aItem->Type() != SCH_MARKER_T )
        SetContentModified();

    Remove( aItem );

    if( aItem->Type() == SCH_SHEET_PIN_T )
    {
        // This structure is attached to a sheet, get the parent sheet object.
        SCH_SHEET_PIN* sheetPin = (SCH_SHEET_PIN*) aItem;
        SCH_SHEET* sheet = sheetPin->GetParent();
        wxCHECK_RET( sheet, wxT( "Sheet pin parent not properly set, bad programmer!" ) );
        sheet->RemovePin( sheetPin );
        return;
    }

    delete aItem;
}


bool SCH_SCREEN::CheckIfOnDrawList( const SCH_ITEM* aItem ) const
{
    return m_rtree.contains( aItem, true );
}


SCH_ITEM* SCH_SCREEN::GetItem( const VECTOR2I& aPosition, int aAccuracy, KICAD_T aType ) const
{
    BOX2I bbox;
    bbox.SetOrigin( aPosition );
    bbox.Inflate( aAccuracy );

    for( SCH_ITEM* item : Items().Overlapping( aType, bbox ) )
    {
        if( item->HitTest( aPosition, aAccuracy ) )
            return item;
    }

    return nullptr;
}


std::set<SCH_ITEM*> SCH_SCREEN::MarkConnections( SCH_LINE* aSegment, bool aSecondPass )
{
#define PROCESSED CANDIDATE     // Don't use SKIP_STRUCT; IsConnected() returns false if it's set.

    std::set<SCH_ITEM*>   retval;
    std::stack<SCH_LINE*> to_search;

    wxCHECK_MSG( aSegment && aSegment->Type() == SCH_LINE_T, retval, wxT( "Invalid pointer." ) );

    to_search.push( aSegment );

    while( !to_search.empty() )
    {
        SCH_ITEM* item = to_search.top();
        to_search.pop();

        if( item->HasFlag( PROCESSED ) )
            continue;

        item->SetFlags( PROCESSED );

        for( SCH_ITEM* candidate : Items().Overlapping( SCH_LINE_T, item->GetBoundingBox() ) )
        {
            SCH_LINE* line = static_cast<SCH_LINE*>( candidate );

            if( line->HasFlag( PROCESSED ) )
                continue;

            // Skip connecting lines on different layers (e.g. buses)
            if( item->GetLayer() != line->GetLayer() )
                continue;

            for( VECTOR2I pt : { line->GetStartPoint(), line->GetEndPoint() } )
            {
                if( item->IsConnected( pt ) )
                {
                    SCH_ITEM* junction = GetItem( pt, 0, SCH_JUNCTION_T );
                    SCH_ITEM*      pin = GetItem( pt, 0, SCH_PIN_T );

                    if( item->IsSelected() && aSecondPass )
                    {
                        if( junction )
                            retval.insert( junction );

                        retval.insert( line );
                        to_search.push( line );
                    }
                    else if( !junction && !pin )
                    {
                        retval.insert( line );
                        to_search.push( line );
                    }

                    break;
                }
            }
        }
    }

    for( SCH_ITEM* item : Items() )
        item->ClearTempFlags();

    return retval;
}


bool SCH_SCREEN::IsJunction( const VECTOR2I& aPosition ) const
{
    bool hasExplicitJunction;
    bool hasBusEntry;
    bool isJunction = doIsJunction( aPosition, false, &hasExplicitJunction, &hasBusEntry );

    return isJunction;
}


bool SCH_SCREEN::IsExplicitJunction( const VECTOR2I& aPosition ) const
{
    bool hasExplicitJunction;
    bool hasBusEntry;
    bool isJunction = doIsJunction( aPosition, false, &hasExplicitJunction, &hasBusEntry );

    return isJunction && !hasBusEntry;
}


bool SCH_SCREEN::IsExplicitJunctionNeeded( const VECTOR2I& aPosition ) const
{
    bool hasExplicitJunction;
    bool hasBusEntry;
    bool isJunction = doIsJunction( aPosition, false, &hasExplicitJunction, &hasBusEntry );

    return isJunction && !hasBusEntry && !hasExplicitJunction;
}

TEXT_SPIN_STYLE SCH_SCREEN::GetLabelOrientationForPoint( const VECTOR2I&       aPosition,
                                                         TEXT_SPIN_STYLE       aDefaultOrientation,
                                                         const SCH_SHEET_PATH* aSheet ) const
{
    auto ret = aDefaultOrientation;
    for( SCH_ITEM* item : Items().Overlapping( aPosition ) )
    {
        if( item->GetEditFlags() & STRUCT_DELETED )
            continue;

        switch( item->Type() )
        {
        case SCH_BUS_WIRE_ENTRY_T:
        {
            auto busEntry = static_cast<const SCH_BUS_WIRE_ENTRY*>( item );
            if( busEntry->m_connected_bus_item )
            {
                // bus connected, take the bus direction into consideration ony if it is
                // vertical or horizontal
                auto bus = static_cast<const SCH_LINE*>( busEntry->m_connected_bus_item );
                if( bus->Angle().AsDegrees() == 90.0 )
                {
                    // bus is vertical -> label shall be horizontal and
                    // shall be placed to the side where the bus entry is
                    if( aPosition.x < bus->GetPosition().x )
                        ret = TEXT_SPIN_STYLE::LEFT;
                    else if( aPosition.x > bus->GetPosition().x )
                        ret = TEXT_SPIN_STYLE::RIGHT;
                }
                else if( bus->Angle().AsDegrees() == 0.0 )
                {
                    // bus is horizontal -> label shall be vertical and
                    // shall be placed to the side where the bus entry is
                    if( aPosition.y < bus->GetPosition().y )
                        ret = TEXT_SPIN_STYLE::UP;
                    else if( aPosition.y > bus->GetPosition().y )
                        ret = TEXT_SPIN_STYLE::BOTTOM;
                }
            }
        }
        break;

        case SCH_LINE_T:
        {
            auto line = static_cast<const SCH_LINE*>( item );
            // line angles goes between -90 and 90 degrees, but normalize
            auto angle = line->Angle().Normalize90().AsDegrees();

            if( -45 < angle && angle <= 45 )
            {
                if( line->GetStartPoint().x <= line->GetEndPoint().x )
                {
                    ret = line->GetEndPoint() == aPosition ? TEXT_SPIN_STYLE::RIGHT
                                                           : TEXT_SPIN_STYLE::LEFT;
                }
                else
                {
                    ret = line->GetEndPoint() == aPosition ? TEXT_SPIN_STYLE::LEFT
                                                           : TEXT_SPIN_STYLE::RIGHT;
                }
            }
            else
            {
                if( line->GetStartPoint().y <= line->GetEndPoint().y )
                {
                    ret = line->GetEndPoint() == aPosition ? TEXT_SPIN_STYLE::BOTTOM
                                                           : TEXT_SPIN_STYLE::UP;
                }
                else
                {
                    ret = line->GetEndPoint() == aPosition ? TEXT_SPIN_STYLE::UP
                                                           : TEXT_SPIN_STYLE::BOTTOM;
                }
            }
        }
        break;

        case SCH_SYMBOL_T:
        {
            SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );

            for( SCH_PIN* pin : symbol->GetPins( aSheet ) )
            {
                if( pin->GetPosition() == aPosition )
                {
                    if( pin->GetOrientation() == PIN_RIGHT )
                    {
                        ret = TEXT_SPIN_STYLE::LEFT;
                    }
                    else if( pin->GetOrientation() == PIN_LEFT )
                    {
                        ret = TEXT_SPIN_STYLE::RIGHT;
                    }
                    else if( pin->GetOrientation() == PIN_UP )
                    {
                        ret = TEXT_SPIN_STYLE::BOTTOM;
                    }
                    else if( pin->GetOrientation() == PIN_DOWN )
                    {
                        ret = TEXT_SPIN_STYLE::UP;
                    }

                    switch( static_cast<SYMBOL_ORIENTATION_T>(
                            symbol->GetOrientation() & ( ~( SYM_MIRROR_X | SYM_MIRROR_Y ) ) ) )
                    {
                    case SYM_ROTATE_CLOCKWISE:
                    case SYM_ORIENT_90:
                        if( ret == TEXT_SPIN_STYLE::UP )
                            ret = TEXT_SPIN_STYLE::LEFT;
                        else if( ret == TEXT_SPIN_STYLE::BOTTOM )
                            ret = TEXT_SPIN_STYLE::RIGHT;
                        else if( ret == TEXT_SPIN_STYLE::LEFT )
                            ret = TEXT_SPIN_STYLE::BOTTOM;
                        else if( ret == TEXT_SPIN_STYLE::RIGHT )
                            ret = TEXT_SPIN_STYLE::UP;

                        if( symbol->GetOrientation() & SYM_MIRROR_X )
                        {
                            if( ret == TEXT_SPIN_STYLE::UP )
                                ret = TEXT_SPIN_STYLE::BOTTOM;
                            else if( ret == TEXT_SPIN_STYLE::BOTTOM )
                                ret = TEXT_SPIN_STYLE::UP;
                        }

                        if( symbol->GetOrientation() & SYM_MIRROR_Y )
                        {
                            if( ret == TEXT_SPIN_STYLE::LEFT )
                                ret = TEXT_SPIN_STYLE::RIGHT;
                            else if( ret == TEXT_SPIN_STYLE::RIGHT )
                                ret = TEXT_SPIN_STYLE::LEFT;
                        }
                        break;
                    case SYM_ROTATE_COUNTERCLOCKWISE:
                    case SYM_ORIENT_270:
                        if( ret == TEXT_SPIN_STYLE::UP )
                            ret = TEXT_SPIN_STYLE::RIGHT;
                        else if( ret == TEXT_SPIN_STYLE::BOTTOM )
                            ret = TEXT_SPIN_STYLE::LEFT;
                        else if( ret == TEXT_SPIN_STYLE::LEFT )
                            ret = TEXT_SPIN_STYLE::UP;
                        else if( ret == TEXT_SPIN_STYLE::RIGHT )
                            ret = TEXT_SPIN_STYLE::BOTTOM;

                        if( symbol->GetOrientation() & SYM_MIRROR_X )
                        {
                            if( ret == TEXT_SPIN_STYLE::UP )
                                ret = TEXT_SPIN_STYLE::BOTTOM;
                            else if( ret == TEXT_SPIN_STYLE::BOTTOM )
                                ret = TEXT_SPIN_STYLE::UP;
                        }

                        if( symbol->GetOrientation() & SYM_MIRROR_Y )
                        {
                            if( ret == TEXT_SPIN_STYLE::LEFT )
                                ret = TEXT_SPIN_STYLE::RIGHT;
                            else if( ret == TEXT_SPIN_STYLE::RIGHT )
                                ret = TEXT_SPIN_STYLE::LEFT;
                        }
                        break;
                    case SYM_ORIENT_180:
                        if( ret == TEXT_SPIN_STYLE::UP )
                            ret = TEXT_SPIN_STYLE::BOTTOM;
                        else if( ret == TEXT_SPIN_STYLE::BOTTOM )
                            ret = TEXT_SPIN_STYLE::UP;
                        else if( ret == TEXT_SPIN_STYLE::LEFT )
                            ret = TEXT_SPIN_STYLE::RIGHT;
                        else if( ret == TEXT_SPIN_STYLE::RIGHT )
                            ret = TEXT_SPIN_STYLE::LEFT;

                        if( symbol->GetOrientation() & SYM_MIRROR_X )
                        {
                            if( ret == TEXT_SPIN_STYLE::UP )
                                ret = TEXT_SPIN_STYLE::BOTTOM;
                            else if( ret == TEXT_SPIN_STYLE::BOTTOM )
                                ret = TEXT_SPIN_STYLE::UP;
                        }

                        if( symbol->GetOrientation() & SYM_MIRROR_Y )
                        {
                            if( ret == TEXT_SPIN_STYLE::LEFT )
                                ret = TEXT_SPIN_STYLE::RIGHT;
                            else if( ret == TEXT_SPIN_STYLE::RIGHT )
                                ret = TEXT_SPIN_STYLE::LEFT;
                        }
                        break;
                    case SYM_ORIENT_0:
                    case SYM_NORMAL:
                    default:
                        if( symbol->GetOrientation() & SYM_MIRROR_X )
                        {
                            if( ret == TEXT_SPIN_STYLE::UP )
                                ret = TEXT_SPIN_STYLE::BOTTOM;
                            else if( ret == TEXT_SPIN_STYLE::BOTTOM )
                                ret = TEXT_SPIN_STYLE::UP;
                        }

                        if( symbol->GetOrientation() & SYM_MIRROR_Y )
                        {
                            if( ret == TEXT_SPIN_STYLE::LEFT )
                                ret = TEXT_SPIN_STYLE::RIGHT;
                            else if( ret == TEXT_SPIN_STYLE::RIGHT )
                                ret = TEXT_SPIN_STYLE::LEFT;
                        }
                        break;
                    }

                    break;
                }
            }
        }
        break;
        default: break;
        }
    }
    return ret;
}


bool SCH_SCREEN::IsExplicitJunctionAllowed( const VECTOR2I& aPosition ) const
{
    bool hasExplicitJunction;
    bool hasBusEntry;
    bool isJunction = doIsJunction( aPosition, true, &hasExplicitJunction, &hasBusEntry );

    return isJunction && !hasBusEntry;
}



bool SCH_SCREEN::doIsJunction( const VECTOR2I& aPosition, bool aBreakCrossings,
                             bool* aHasExplicitJunctionDot, bool* aHasBusEntry ) const
{
    enum layers { WIRES = 0, BUSES };

    *aHasExplicitJunctionDot = false;
    *aHasBusEntry = false;

    bool                          breakLines[ 2 ] = { false };
    std::unordered_set<int>       exitAngles[ 2 ];
    std::vector<const SCH_LINE*>  midPointLines[ 2 ];

    // A pin at 90° still shouldn't match a line at 90° so just give pins unique numbers
    int                           uniqueAngle = 10000;

    for( const SCH_ITEM* item : Items().Overlapping( aPosition ) )
    {
        if( item->GetEditFlags() & STRUCT_DELETED )
            continue;

        switch( item->Type() )
        {
        case SCH_JUNCTION_T:
            if( item->HitTest( aPosition, -1 ) )
                *aHasExplicitJunctionDot = true;

            break;

        case SCH_LINE_T:
        {
            const SCH_LINE* line = static_cast<const SCH_LINE*>( item );
            int             layer;

            if( line->GetStartPoint() == line->GetEndPoint() )
                break;
            else if( line->GetLayer() == LAYER_WIRE )
                layer = WIRES;
            else if( line->GetLayer() == LAYER_BUS )
                layer = BUSES;
            else
                break;

            if( line->IsConnected( aPosition ) )
            {
                breakLines[ layer ] = true;
                exitAngles[ layer ].insert( line->GetAngleFrom( aPosition ) );
            }
            else if( line->HitTest( aPosition, -1 ) )
            {
                if( aBreakCrossings )
                    breakLines[ layer ] = true;

                // Defer any line midpoints until we know whether or not we're breaking them
                midPointLines[ layer ].push_back( line );
            }
        }
            break;

        case SCH_BUS_WIRE_ENTRY_T:
            if( item->IsConnected( aPosition ) )
            {
                breakLines[ BUSES ] = true;
                exitAngles[ BUSES ].insert( uniqueAngle++ );
                breakLines[ WIRES ] = true;
                exitAngles[ WIRES ].insert( uniqueAngle++ );
                *aHasBusEntry = true;
            }

            break;

        case SCH_SYMBOL_T:
        case SCH_SHEET_T:
            if( item->IsConnected( aPosition ) )
            {
                breakLines[ WIRES ] = true;
                exitAngles[ WIRES ].insert( uniqueAngle++ );
            }

            break;

        default:
            break;
        }
    }

    for( int layer : { WIRES, BUSES } )
    {
        if( breakLines[ layer ] )
        {
            for( const SCH_LINE* line : midPointLines[ layer ] )
            {
                exitAngles[ layer ].insert( line->GetAngleFrom( aPosition ) );
                exitAngles[ layer ].insert( line->GetReverseAngleFrom( aPosition ) );
            }
        }
    }

    return exitAngles[ WIRES ].size() >= 3 || exitAngles[ BUSES ].size() >= 3;
}


bool SCH_SCREEN::IsTerminalPoint( const VECTOR2I& aPosition, int aLayer ) const
{
    wxCHECK_MSG( aLayer == LAYER_NOTES || aLayer == LAYER_BUS || aLayer == LAYER_WIRE, false,
                 wxT( "Invalid layer type passed to SCH_SCREEN::IsTerminalPoint()." ) );

    SCH_SHEET_PIN* sheetPin;
    SCH_LABEL_BASE* label;

    switch( aLayer )
    {
    case LAYER_BUS:
        if( GetBus( aPosition ) )
            return true;

        sheetPin = GetSheetPin( aPosition );

        if( sheetPin && sheetPin->IsConnected( aPosition ) )
            return true;

        label = GetLabel( aPosition );

        if( label && label->IsConnected( aPosition ) )
            return true;

        break;

    case LAYER_NOTES:
        if( GetLine( aPosition ) )
            return true;

        break;

    case LAYER_WIRE:
        if( GetItem( aPosition, 1, SCH_BUS_WIRE_ENTRY_T) )
            return true;

        if( GetItem( aPosition, 1, SCH_JUNCTION_T ) )
            return true;

        if( GetPin( aPosition, nullptr, true ) )
            return true;

        if( GetWire( aPosition ) )
            return true;

        label = GetLabel( aPosition, 1 );

        if( label && label->IsConnected( aPosition ) )
            return true;

        sheetPin = GetSheetPin( aPosition );

        if( sheetPin && sheetPin->IsConnected( aPosition ) )
            return true;

        break;

    default:
        break;
    }

    return false;
}


void SCH_SCREEN::UpdateSymbolLinks( REPORTER* aReporter )
{
    wxCHECK_RET( Schematic(), "Cannot call SCH_SCREEN::UpdateSymbolLinks with no SCHEMATIC" );

    wxString msg;
    std::unique_ptr< LIB_SYMBOL > libSymbol;
    std::vector<SCH_SYMBOL*> symbols;
    SYMBOL_LIB_TABLE* libs = Schematic()->Prj().SchSymbolLibTable();

    // This will be a nullptr if an s-expression schematic is loaded.
    SYMBOL_LIBS* legacyLibs = Schematic()->Prj().SchLibs();

    for( SCH_ITEM* item : Items().OfType( SCH_SYMBOL_T ) )
        symbols.push_back( static_cast<SCH_SYMBOL*>( item ) );

    // Remove them from the R tree.  There bounding box size may change.
    for( SCH_SYMBOL* symbol : symbols )
        Remove( symbol );

    // Clear all existing symbol links.
    clearLibSymbols();

    for( SCH_SYMBOL* symbol : symbols )
    {
        LIB_SYMBOL* tmp = nullptr;
        libSymbol.reset();

        // If the symbol is already in the internal library, map the symbol to it.
        auto it = m_libSymbols.find( symbol->GetSchSymbolLibraryName() );

        if( ( it != m_libSymbols.end() ) )
        {
            if( aReporter )
            {
                msg.Printf( _( "Setting schematic symbol '%s %s' library identifier to '%s'." ),
                            symbol->GetField( REFERENCE_FIELD )->GetText(),
                            symbol->GetField( VALUE_FIELD )->GetText(),
                            UnescapeString( symbol->GetLibId().Format() ) );
                aReporter->ReportTail( msg, RPT_SEVERITY_INFO );
            }

            // Internal library symbols are already flattened so just make a copy.
            symbol->SetLibSymbol( new LIB_SYMBOL( *it->second ) );
            continue;
        }

        if( !symbol->GetLibId().IsValid() )
        {
            if( aReporter )
            {
                msg.Printf( _( "Schematic symbol reference '%s' library identifier is not valid. "
                               "Unable to link library symbol." ),
                            UnescapeString( symbol->GetLibId().Format() ) );
                aReporter->ReportTail( msg, RPT_SEVERITY_WARNING );
            }

            continue;
        }

        // LIB_TABLE_BASE::LoadSymbol() throws an IO_ERROR if the library nickname
        // is not found in the table so check if the library still exists in the table
        // before attempting to load the symbol.
        if( !libs->HasLibrary( symbol->GetLibId().GetLibNickname() ) && !legacyLibs )
        {
            if( aReporter )
            {
                msg.Printf( _( "Symbol library '%s' not found and no fallback cache library "
                               "available.  Unable to link library symbol." ),
                            symbol->GetLibId().GetLibNickname().wx_str() );
                aReporter->ReportTail( msg, RPT_SEVERITY_WARNING );
            }

            continue;
        }

        if( libs->HasLibrary( symbol->GetLibId().GetLibNickname() ) )
        {
            try
            {
                tmp = libs->LoadSymbol( symbol->GetLibId() );
            }
            catch( const IO_ERROR& ioe )
            {
                if( aReporter )
                {
                    msg.Printf( _( "I/O error %s resolving library symbol %s" ), ioe.What(),
                                UnescapeString( symbol->GetLibId().Format() ) );
                    aReporter->ReportTail( msg, RPT_SEVERITY_ERROR );
                }
            }
        }

        if( !tmp && legacyLibs && legacyLibs->GetLibraryCount() )
        {
            SYMBOL_LIB& legacyCacheLib = legacyLibs->back();

            // It better be the cache library.
            wxCHECK2( legacyCacheLib.IsCache(), continue );

            wxString id = symbol->GetLibId().Format();

            id.Replace( ':', '_' );

            if( aReporter )
            {
                msg.Printf( _( "Falling back to cache to set symbol '%s:%s' link '%s'." ),
                            symbol->GetField( REFERENCE_FIELD )->GetText(),
                            symbol->GetField( VALUE_FIELD )->GetText(),
                            UnescapeString( id ) );
                aReporter->ReportTail( msg, RPT_SEVERITY_WARNING );
            }

            tmp = legacyCacheLib.FindSymbol( id );
        }

        if( tmp )
        {
            // We want a full symbol not just the top level child symbol.
            libSymbol = tmp->Flatten();
            libSymbol->SetParent();

            m_libSymbols.insert( { symbol->GetSchSymbolLibraryName(),
                                   new LIB_SYMBOL( *libSymbol.get() ) } );

            if( aReporter )
            {
                msg.Printf( _( "Setting schematic symbol '%s %s' library identifier to '%s'." ),
                            symbol->GetField( REFERENCE_FIELD )->GetText(),
                            symbol->GetField( VALUE_FIELD )->GetText(),
                            UnescapeString( symbol->GetLibId().Format() ) );
                aReporter->ReportTail( msg, RPT_SEVERITY_INFO );
            }
        }
        else
        {
            if( aReporter )
            {
                msg.Printf( _( "No library symbol found for schematic symbol '%s %s'." ),
                            symbol->GetField( REFERENCE_FIELD )->GetText(),
                            symbol->GetField( VALUE_FIELD )->GetText() );
                aReporter->ReportTail( msg, RPT_SEVERITY_ERROR );
            }
        }

        symbol->SetLibSymbol( libSymbol.release() );
    }

    // Changing the symbol may adjust the bbox of the symbol.  This re-inserts the
    // item with the new bbox
    for( SCH_SYMBOL* symbol : symbols )
        Append( symbol );
}


void SCH_SCREEN::UpdateLocalLibSymbolLinks()
{
    std::vector<SCH_SYMBOL*> symbols;

    for( SCH_ITEM* item : Items().OfType( SCH_SYMBOL_T ) )
        symbols.push_back( static_cast<SCH_SYMBOL*>( item ) );

    for( SCH_SYMBOL* symbol : symbols )
    {
        // Changing the symbol may adjust the bbox of the symbol; remove and reinsert it afterwards.
        m_rtree.remove( symbol );

        auto it = m_libSymbols.find( symbol->GetSchSymbolLibraryName() );

        LIB_SYMBOL* libSymbol = nullptr;

        if( it != m_libSymbols.end() )
            libSymbol = new LIB_SYMBOL( *it->second );

        symbol->SetLibSymbol( libSymbol );

        m_rtree.insert( symbol );
    }
}


void SCH_SCREEN::SetConnectivityDirty()
{
    for( SCH_ITEM* item : Items() )
        item->SetConnectivityDirty( true );
}


void SCH_SCREEN::Print( const RENDER_SETTINGS* aSettings )
{
    // Ensure links are up to date, even if a library was reloaded for some reason:
    std::vector<SCH_ITEM*> junctions;
    std::vector<SCH_ITEM*> bitmaps;
    std::vector<SCH_ITEM*> other;

    for( SCH_ITEM* item : Items() )
    {
        if( item->IsMoving() || item->IsResized() )
            continue;

        if( item->Type() == SCH_JUNCTION_T )
            junctions.push_back( item );
        else if( item->Type() == SCH_BITMAP_T )
            bitmaps.push_back( item );
        else
            other.push_back( item );
    }

    /// Sort to ensure plot-order consistency with screen drawing
    std::stable_sort( other.begin(), other.end(),
               []( const SCH_ITEM* a, const SCH_ITEM* b )
               {
                    if( a->Type() == b->Type() )
                        return a->GetLayer() > b->GetLayer();

                    return a->Type() < b->Type();
               } );

    for( SCH_ITEM* item : bitmaps )
        item->Print( aSettings, VECTOR2I( 0, 0 ) );

    for( SCH_ITEM* item : other )
        item->PrintBackground( aSettings, VECTOR2I( 0, 0 ) );

    for( SCH_ITEM* item : other )
        item->Print( aSettings, VECTOR2I( 0, 0 ) );

    for( SCH_ITEM* item : junctions )
        item->Print( aSettings, VECTOR2I( 0, 0 ) );
}


void SCH_SCREEN::Plot( PLOTTER* aPlotter ) const
{
    // Ensure links are up to date, even if a library was reloaded for some reason:
    std::vector<SCH_ITEM*>   junctions;
    std::vector<SCH_ITEM*>   bitmaps;
    std::vector<SCH_SYMBOL*> symbols;
    std::vector<SCH_ITEM*>   other;

    for( SCH_ITEM* item : Items() )
    {
        if( item->IsMoving() || item->IsResized() )
            continue;

        if( item->Type() == SCH_JUNCTION_T )
            junctions.push_back( item );
        else if( item->Type() == SCH_BITMAP_T )
            bitmaps.push_back( item );
        else
            other.push_back( item );

        // Where the symbols overlap each other, we need to plot the text items a second
        // time to get them on top of the overlapping element.  This collection is in addition
        // to the symbols already collected in `other`
        if( item->Type() == SCH_SYMBOL_T )
        {
            for( SCH_ITEM* sym : m_rtree.Overlapping( SCH_SYMBOL_T, item->GetBoundingBox() ) )
            {
                if( sym != item )
                {
                    symbols.push_back( static_cast<SCH_SYMBOL*>( item ) );
                    break;
                }
            }
        }
    }

    /// Sort to ensure plot-order consistency with screen drawing
    std::sort( other.begin(), other.end(),
               []( const SCH_ITEM* a, const SCH_ITEM* b )
               {
                    if( a->Type() == b->Type() )
                        return a->GetLayer() > b->GetLayer();

                    return a->Type() > b->Type();
                } );

    int defaultPenWidth = aPlotter->RenderSettings()->GetDefaultPenWidth();
    constexpr bool background = true;

    // Bitmaps are drawn first to ensure they are in the background
    // This is particularly important for the wxPostscriptDC (used in *nix printers) as
    // the bitmap PS command clears the screen
    for( const SCH_ITEM* item : bitmaps )
    {
        aPlotter->SetCurrentLineWidth( std::max( item->GetPenWidth(), defaultPenWidth ) );
        item->Plot( aPlotter, background );
    }

    for( const SCH_ITEM* item : other )
    {
        aPlotter->SetCurrentLineWidth( std::max( item->GetPenWidth(), defaultPenWidth ) );
        item->Plot( aPlotter, background );
    }

    for( const SCH_ITEM* item : other )
    {
        aPlotter->SetCurrentLineWidth( std::max( item->GetPenWidth(), defaultPenWidth ) );
        item->Plot( aPlotter, !background );
    }

    // After plotting the symbols as a group above (in `other`), we need to overplot the pins
    // and symbols to ensure that they are always visible
    for( const SCH_SYMBOL* sym :symbols )
    {
        aPlotter->SetCurrentLineWidth( std::max( sym->GetPenWidth(), defaultPenWidth ) );

        for( SCH_FIELD field : sym->GetFields() )
            field.Plot( aPlotter, false );

        sym->PlotPins( aPlotter );
    }

    for( const SCH_ITEM* item : junctions )
    {
        aPlotter->SetCurrentLineWidth( std::max( item->GetPenWidth(), defaultPenWidth ) );
        item->Plot( aPlotter, !background );
    }
}


void SCH_SCREEN::ClearDrawingState()
{
    for( SCH_ITEM* item : Items() )
        item->ClearTempFlags();
}


LIB_PIN* SCH_SCREEN::GetPin( const VECTOR2I& aPosition, SCH_SYMBOL** aSymbol,
                             bool aEndPointOnly ) const
{
    SCH_SYMBOL*  candidate = nullptr;
    LIB_PIN*     pin = nullptr;

    for( SCH_ITEM* item : Items().Overlapping( SCH_SYMBOL_T, aPosition ) )
    {
        candidate = static_cast<SCH_SYMBOL*>( item );

        if( aEndPointOnly )
        {
            pin = nullptr;

            if( !candidate->GetLibSymbolRef() )
                continue;

            for( pin = candidate->GetLibSymbolRef()->GetNextPin(); pin;
                 pin = candidate->GetLibSymbolRef()->GetNextPin( pin ) )
            {
                // Skip items not used for this part.
                if( candidate->GetUnit() && pin->GetUnit() &&
                    ( pin->GetUnit() != candidate->GetUnit() ) )
                    continue;

                if( candidate->GetConvert() && pin->GetConvert() &&
                    ( pin->GetConvert() != candidate->GetConvert() ) )
                    continue;

                if( candidate->GetPinPhysicalPosition( pin ) == aPosition )
                    break;
            }

            if( pin )
                break;
        }
        else
        {
            pin = (LIB_PIN*) candidate->GetDrawItem( aPosition, LIB_PIN_T );

            if( pin )
                break;
        }
    }

    if( pin && aSymbol )
        *aSymbol = candidate;

    return pin;
}


SCH_SHEET_PIN* SCH_SCREEN::GetSheetPin( const VECTOR2I& aPosition ) const
{
    SCH_SHEET_PIN* sheetPin = nullptr;

    for( SCH_ITEM* item : Items().Overlapping( SCH_SHEET_T, aPosition ) )
    {
        SCH_SHEET* sheet = static_cast<SCH_SHEET*>( item );

        sheetPin = sheet->GetPin( aPosition );

        if( sheetPin )
            break;
    }

    return sheetPin;
}


size_t SCH_SCREEN::CountConnectedItems( const VECTOR2I& aPos, bool aTestJunctions ) const
{
    size_t count = 0;

    for( const SCH_ITEM* item : Items().Overlapping( aPos ) )
    {
        if( ( item->Type() != SCH_JUNCTION_T || aTestJunctions ) && item->IsConnected( aPos ) )
            count++;
    }

    return count;
}


void SCH_SCREEN::ClearAnnotation( SCH_SHEET_PATH* aSheetPath, bool aResetPrefix )
{

    for( SCH_ITEM* item : Items().OfType( SCH_SYMBOL_T ) )
    {
        SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );

        symbol->ClearAnnotation( aSheetPath, aResetPrefix );
    }
}


void SCH_SCREEN::EnsureAlternateReferencesExist()
{
    if( GetClientSheetPaths().size() <= 1 ) // No need for alternate reference
        return;

    for( SCH_ITEM* item : Items().OfType( SCH_SYMBOL_T ) )
    {
        SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );

        // Add (when not existing) all sheet path entries
        for( const SCH_SHEET_PATH& sheet : GetClientSheetPaths() )
            symbol->AddSheetPathReferenceEntryIfMissing( sheet.Path() );
    }
}


void SCH_SCREEN::GetHierarchicalItems( std::vector<SCH_ITEM*>* aItems ) const
{
    for( SCH_ITEM* item : Items() )
    {
        if( item->IsType( { SCH_SYMBOL_T, SCH_SHEET_T, SCH_LABEL_LOCATE_ANY_T } ) )
            aItems->push_back( item );
    }
}


void SCH_SCREEN::GetSheets( std::vector<SCH_ITEM*>* aItems ) const
{
    for( SCH_ITEM* item : Items().OfType( SCH_SHEET_T ) )
        aItems->push_back( item );

    std::sort( aItems->begin(), aItems->end(),
            []( EDA_ITEM* a, EDA_ITEM* b ) -> bool
            {
                if( a->GetPosition().x == b->GetPosition().x )
                {
                    // Ensure deterministic sort
                    if( a->GetPosition().y == b->GetPosition().y )
                        return a->m_Uuid < b->m_Uuid;

                    return a->GetPosition().y < b->GetPosition().y;
                }
                else
                {
                    return a->GetPosition().x < b->GetPosition().x;
                }
            } );
}


void SCH_SCREEN::TestDanglingEnds( const SCH_SHEET_PATH* aPath,
                                   std::function<void( SCH_ITEM* )>* aChangedHandler ) const
{
    std::vector<DANGLING_END_ITEM> endPoints;

    for( SCH_ITEM* item : Items() )
    {
        if( item->IsConnectable() )
        {
            endPoints.clear();

            for( SCH_ITEM* overlapping : Items().Overlapping( item->GetBoundingBox() ) )
                overlapping->GetEndPoints( endPoints );

            if( item->UpdateDanglingState( endPoints, aPath ) )
            {
                if( aChangedHandler )
                    (*aChangedHandler)( item );
            }
        }
    }
}


SCH_LINE* SCH_SCREEN::GetLine( const VECTOR2I& aPosition, int aAccuracy, int aLayer,
                               SCH_LINE_TEST_T aSearchType ) const
{
    // an accuracy of 0 had problems with rounding errors; use at least 1
    aAccuracy = std::max( aAccuracy, 1 );

    for( SCH_ITEM* item : Items().Overlapping( aPosition, aAccuracy ) )
    {
        if( item->Type() != SCH_LINE_T )
            continue;

        if( item->GetLayer() != aLayer )
            continue;

        if( !item->HitTest( aPosition, aAccuracy ) )
            continue;

        switch( aSearchType )
        {
        case ENTIRE_LENGTH_T:
            return (SCH_LINE*) item;

        case EXCLUDE_END_POINTS_T:
            if( !( (SCH_LINE*) item )->IsEndPoint( aPosition ) )
                return (SCH_LINE*) item;
            break;

        case END_POINTS_ONLY_T:
            if( ( (SCH_LINE*) item )->IsEndPoint( aPosition ) )
                return (SCH_LINE*) item;
        }
    }

    return nullptr;
}


SCH_LABEL_BASE* SCH_SCREEN::GetLabel( const VECTOR2I& aPosition, int aAccuracy ) const
{
    for( SCH_ITEM* item : Items().Overlapping( aPosition, aAccuracy ) )
    {
        switch( item->Type() )
        {
        case SCH_LABEL_T:
        case SCH_GLOBAL_LABEL_T:
        case SCH_HIER_LABEL_T:
        case SCH_DIRECTIVE_LABEL_T:
            if( item->HitTest( aPosition, aAccuracy ) )
                return static_cast<SCH_LABEL_BASE*>( item );

            break;

        default:
            ;
        }
    }

    return nullptr;
}


void SCH_SCREEN::AddLibSymbol( LIB_SYMBOL* aLibSymbol )
{
    wxCHECK( aLibSymbol, /* void */ );

    wxString libSymbolName = aLibSymbol->GetLibId().Format().wx_str();

    auto it = m_libSymbols.find( libSymbolName );

    if( it != m_libSymbols.end() )
    {
        delete it->second;
        m_libSymbols.erase( it );
    }

    m_libSymbols[libSymbolName] = aLibSymbol;
}


void SCH_SCREEN::AddBusAlias( std::shared_ptr<BUS_ALIAS> aAlias )
{
    m_aliases.insert( aAlias );
}


void SCH_SCREEN::SetLegacySymbolInstanceData()
{
    for( SCH_ITEM* item : Items().OfType( SCH_SYMBOL_T ) )
    {
        SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );

        // Add missing value and footprint instance data for legacy schematics.
        for( const SYMBOL_INSTANCE_REFERENCE& instance : symbol->GetInstanceReferences() )
        {
            symbol->AddHierarchicalReference( instance.m_Path, instance.m_Reference,
                                              instance.m_Unit );
        }
    }
}


#if defined(DEBUG)
void SCH_SCREEN::Show( int nestLevel, std::ostream& os ) const
{
    // for now, make it look like XML, expand on this later.
    NestedSpace( nestLevel, os ) << '<' << GetClass().Lower().mb_str() << ">\n";

    for( const SCH_ITEM* item : Items() )
        item->Show( nestLevel + 1, os );

    NestedSpace( nestLevel, os ) << "</" << GetClass().Lower().mb_str() << ">\n";
}
#endif


SCH_SCREENS::SCH_SCREENS( SCH_SHEET* aSheet )
{
    m_index = 0;
    buildScreenList( aSheet );
}


SCH_SCREENS::~SCH_SCREENS()
{
}


SCH_SCREEN* SCH_SCREENS::GetFirst()
{
    m_index = 0;

    if( m_screens.size() > 0 )
        return m_screens[0];

    return nullptr;
}


SCH_SCREEN* SCH_SCREENS::GetNext()
{
    if( m_index < m_screens.size() )
        m_index++;

    return GetScreen( m_index );
}


SCH_SCREEN* SCH_SCREENS::GetScreen( unsigned int aIndex ) const
{
    if( aIndex < m_screens.size() )
        return m_screens[ aIndex ];

    return nullptr;
}


SCH_SHEET* SCH_SCREENS::GetSheet( unsigned int aIndex ) const
{
    if( aIndex < m_sheets.size() )
        return m_sheets[ aIndex ];

    return nullptr;
}


void SCH_SCREENS::addScreenToList( SCH_SCREEN* aScreen, SCH_SHEET* aSheet )
{
    if( aScreen == nullptr )
        return;

    for( const SCH_SCREEN* screen : m_screens )
    {
        if( screen == aScreen )
            return;
    }

    m_screens.push_back( aScreen );
    m_sheets.push_back( aSheet );
}


void SCH_SCREENS::buildScreenList( SCH_SHEET* aSheet )
{
    if( aSheet && aSheet->Type() == SCH_SHEET_T )
    {
        SCH_SCREEN* screen = aSheet->GetScreen();

        wxCHECK_RET( screen, "No screen for aSheet" );

        addScreenToList( screen, aSheet );

        for( SCH_ITEM* item : screen->Items().OfType( SCH_SHEET_T ) )
            buildScreenList( static_cast<SCH_SHEET*>( item ) );
    }
}


void SCH_SCREENS::ClearAnnotationOfNewSheetPaths( SCH_SHEET_LIST& aInitialSheetPathList )
{
    SCH_SCREEN* first = GetFirst();

    if( !first )
        return;

    SCHEMATIC* sch = first->Schematic();

    wxCHECK_RET( sch, "Null schematic in SCH_SCREENS::ClearAnnotationOfNewSheetPaths" );

    // Clear the annotation for symbols inside new sheetpaths not already in aInitialSheetList
    SCH_SCREENS screensList( sch->Root() );     // The list of screens, shared by sheet paths
    screensList.BuildClientSheetPathList();     // build the shared by sheet paths, by screen

    // Search for new sheet paths, not existing in aInitialSheetPathList
    // and existing in sheetpathList
    for( SCH_SHEET_PATH& sheetpath : sch->GetSheets() )
    {
        bool path_exists = false;

        for( const SCH_SHEET_PATH& existing_sheetpath: aInitialSheetPathList )
        {
            if( existing_sheetpath.Path() == sheetpath.Path() )
            {
                path_exists = true;
                break;
            }
        }

        if( !path_exists )
        {
            // A new sheet path is found: clear the annotation corresponding to this new path:
            SCH_SCREEN* curr_screen = sheetpath.LastScreen();

            // Clear annotation and create the AR for this path, if not exists,
            // when the screen is shared by sheet paths.
            // Otherwise ClearAnnotation do nothing, because the F1 field is used as
            // reference default value and takes the latest displayed value
            curr_screen->EnsureAlternateReferencesExist();
            curr_screen->ClearAnnotation( &sheetpath, false );
        }
    }
}


int SCH_SCREENS::ReplaceDuplicateTimeStamps()
{
    std::vector<SCH_ITEM*> items;
    int count = 0;

    auto timestamp_cmp = []( const EDA_ITEM* a, const EDA_ITEM* b ) -> bool
                         {
                             return a->m_Uuid < b->m_Uuid;
                         };

    std::set<EDA_ITEM*, decltype( timestamp_cmp )> unique_stamps( timestamp_cmp );

    for( SCH_SCREEN* screen : m_screens )
        screen->GetHierarchicalItems( &items );

    if( items.size() < 2 )
        return 0;

    for( EDA_ITEM* item : items )
    {
        if( !unique_stamps.insert( item ).second )
        {
            // Reset to fully random UUID.  This may lose reference, but better to be
            // deterministic about it rather than to have duplicate UUIDs with random
            // side-effects.
            const_cast<KIID&>( item->m_Uuid ) = KIID();
            count++;

            // @todo If the item is a sheet, we need to decend the heirarchy from the sheet
            //       and repace all instances of the changed UUID in sheet paths.  Otherwise,
            //       all instance paths with the sheet's UUID will get clobbered.
        }
    }

    return count;
}


void SCH_SCREENS::ClearEditFlags()
{
    for( SCH_SCREEN* screen = GetFirst(); screen; screen = GetNext() )
    {
        for( SCH_ITEM* item : screen->Items() )
            item->ClearEditFlags();
    }
}


void SCH_SCREENS::DeleteMarker( SCH_MARKER* aMarker )
{
    for( SCH_SCREEN* screen = GetFirst(); screen; screen = GetNext() )
    {
        for( SCH_ITEM* item : screen->Items().OfType( SCH_MARKER_T ) )
        {
            if( item == aMarker )
            {
                screen->DeleteItem( item );
                return;
            }
        }
    }
}


void SCH_SCREENS::DeleteMarkers( enum MARKER_BASE::TYPEMARKER aMarkerType, int aErrorCode,
                                 bool aIncludeExclusions )
{
    for( SCH_SCREEN* screen = GetFirst(); screen; screen = GetNext() )
    {
        std::vector<SCH_ITEM*> markers;

        for( SCH_ITEM* item : screen->Items().OfType( SCH_MARKER_T ) )
        {
            SCH_MARKER* marker = static_cast<SCH_MARKER*>( item );
            std::shared_ptr<RC_ITEM>rcItem = marker->GetRCItem();

            if( marker->GetMarkerType() == aMarkerType
                    && ( aErrorCode == ERCE_UNSPECIFIED || rcItem->GetErrorCode() == aErrorCode )
                    && ( !marker->IsExcluded() || aIncludeExclusions ) )
            {
                markers.push_back( item );
            }
        }

        for( SCH_ITEM* marker : markers )
            screen->DeleteItem( marker );
    }
}


void SCH_SCREENS::DeleteAllMarkers( enum MARKER_BASE::TYPEMARKER aMarkerType,
                                    bool aIncludeExclusions )
{
    DeleteMarkers( aMarkerType, ERCE_UNSPECIFIED, aIncludeExclusions );
}


void SCH_SCREENS::UpdateSymbolLinks( REPORTER* aReporter )
{
    for( SCH_SCREEN* screen = GetFirst(); screen; screen = GetNext() )
        screen->UpdateSymbolLinks( aReporter );

    SCH_SCREEN* first = GetFirst();

    if( !first )
        return;

    SCHEMATIC* sch = first->Schematic();

    wxCHECK_RET( sch, "Null schematic in SCH_SCREENS::UpdateSymbolLinks" );

    SCH_SHEET_LIST sheets = sch->GetSheets();

    // All of the library symbols have been replaced with copies so the connection graph
    // pointers are stale.
    if( sch->ConnectionGraph() )
        sch->ConnectionGraph()->Recalculate( sheets, true );
}


bool SCH_SCREENS::HasNoFullyDefinedLibIds()
{
    bool has_symbols = false;

    for( SCH_SCREEN* screen = GetFirst(); screen; screen = GetNext() )
    {
        for( SCH_ITEM* item : screen->Items().OfType( SCH_SYMBOL_T ) )
        {
            SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );
            has_symbols = true;

            if( !symbol->GetLibId().GetLibNickname().empty() )
                return false;
        }
    }

    // return true (i.e. has no fully defined symbol) only if at least one symbol is found
    return has_symbols ? true : false;
}


size_t SCH_SCREENS::GetLibNicknames( wxArrayString& aLibNicknames )
{
    for( SCH_SCREEN* screen = GetFirst(); screen; screen = GetNext() )
    {
        for( SCH_ITEM* item : screen->Items().OfType( SCH_SYMBOL_T ) )
        {
            SCH_SYMBOL* symbol   = static_cast<SCH_SYMBOL*>( item );
            const UTF8& nickname = symbol->GetLibId().GetLibNickname();

            if( !nickname.empty() && ( aLibNicknames.Index( nickname ) == wxNOT_FOUND ) )
                aLibNicknames.Add( nickname );
        }
    }

    return aLibNicknames.GetCount();
}


int SCH_SCREENS::ChangeSymbolLibNickname( const wxString& aFrom, const wxString& aTo )
{
    SCH_SCREEN* screen;
    int cnt = 0;

    for( screen = GetFirst(); screen; screen = GetNext() )
    {
        for( SCH_ITEM* item : screen->Items().OfType( SCH_SYMBOL_T ) )
        {
            SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );

            if( symbol->GetLibId().GetLibNickname() != aFrom )
                continue;

            LIB_ID id = symbol->GetLibId();
            id.SetLibNickname( aTo );
            symbol->SetLibId( id );
            cnt++;
        }
    }

    return cnt;
}


bool SCH_SCREENS::HasSchematic( const wxString& aSchematicFileName )
{
    for( const SCH_SCREEN* screen = GetFirst(); screen; screen = GetNext() )
    {
        if( screen->GetFileName() == aSchematicFileName )
            return true;
    }

    return false;
}


bool SCH_SCREENS::CanCauseCaseSensitivityIssue( const wxString& aSchematicFileName ) const
{
    wxString   lhsLower;
    wxString   rhsLower;
    wxFileName lhs;
    wxFileName rhs = aSchematicFileName;

    wxCHECK( rhs.IsAbsolute(), false );

    for( const SCH_SCREEN* screen : m_screens )
    {
        lhs = screen->GetFileName();

        if( lhs.GetPath() != rhs.GetPath() )
            continue;

        lhsLower = lhs.GetFullName().Lower();
        rhsLower = rhs.GetFullName().Lower();

        if( lhsLower == rhsLower && lhs.GetFullName() != rhs.GetFullName() )
            return true;
    }

    return false;
}


void SCH_SCREENS::BuildClientSheetPathList()
{
    SCH_SCREEN* first = GetFirst();

    if( !first )
        return;

    SCHEMATIC* sch = first->Schematic();

    wxCHECK_RET( sch, "Null schematic in SCH_SCREENS::BuildClientSheetPathList" );

    for( SCH_SCREEN* curr_screen = GetFirst(); curr_screen; curr_screen = GetNext() )
        curr_screen->GetClientSheetPaths().clear();

    for( SCH_SHEET_PATH& sheetpath : sch->GetSheets() )
    {
        SCH_SCREEN* used_screen = sheetpath.LastScreen();

        // Search for the used_screen in list and add this unique sheet path:
        for( SCH_SCREEN* curr_screen = GetFirst(); curr_screen; curr_screen = GetNext() )
        {
            if( used_screen == curr_screen )
            {
                curr_screen->GetClientSheetPaths().push_back( sheetpath );
                break;
            }
        }
    }
}


void SCH_SCREENS::SetLegacySymbolInstanceData()
{
    for( SCH_SCREEN* screen = GetFirst(); screen; screen = GetNext() )
        screen->SetLegacySymbolInstanceData();
}


void SCH_SCREEN::MigrateSimModels()
{
    LOCALE_IO toggle;

    // V6 schematics may specify model names in Value fields, which we don't do in V7.
    // Migrate by adding an equivalent model for these symbols.

    for( SCH_ITEM* item : Items().OfType( SCH_SYMBOL_T ) )
    {
        SCH_SYMBOL* symbol = static_cast<SCH_SYMBOL*>( item );
        migrateSimModel( *symbol );
    }
}


void SCH_SCREEN::migrateSimModel( SCH_SYMBOL& aSymbol )
{
    if( aSymbol.FindField( SIM_MODEL::DEVICE_TYPE_FIELD )
        || aSymbol.FindField( SIM_MODEL::TYPE_FIELD )
        || aSymbol.FindField( SIM_MODEL::PINS_FIELD )
        || aSymbol.FindField( SIM_MODEL::PARAMS_FIELD ) )
    {
        // Has a V7 model field -- skip.
        return;
    }

    wxString prefix = aSymbol.GetPrefix();
    wxString value = aSymbol.GetValueFieldText( true );

    wxString spiceType;
    wxString spiceModel;
    wxString spiceLib;
    wxString pinMap;

    if( aSymbol.FindField( wxT( "Spice_Primitive" ) )
        || aSymbol.FindField( wxT( "Spice_Node_Sequence" ) )
        || aSymbol.FindField( wxT( "Spice_Model" ) )
        || aSymbol.FindField( wxT( "Spice_Netlist_Enabled" ) )
        || aSymbol.FindField( wxT( "Spice_Lib_File" ) ) )
    {
        if( SCH_FIELD* primitiveField = aSymbol.FindField( wxT( "Spice_Primitive" ) ) )
        {
            spiceType = primitiveField->GetText();
            aSymbol.RemoveField( wxT( "Spice_Primitive" ) );
        }

        if( SCH_FIELD* nodeSequenceField = aSymbol.FindField( wxT( "Spice_Node_Sequence" ) ) )
        {
            const wxString  delimiters( "{:,; }" );
            const wxString& nodeSequence = nodeSequenceField->GetText();

            if( nodeSequence != "" )
            {
                wxStringTokenizer tkz( nodeSequence, delimiters );

                for( long modelPinNumber = 1; tkz.HasMoreTokens(); ++modelPinNumber )
                {
                    long symbolPinNumber = 1;
                    tkz.GetNextToken().ToLong( &symbolPinNumber );

                    if( modelPinNumber != 1 )
                        pinMap.Append( " " );

                    pinMap.Append( wxString::Format( "%ld=%ld", symbolPinNumber, modelPinNumber ) );
                }
            }

            aSymbol.RemoveField( wxT( "Spice_Node_Sequence" ) );
        }

        if( SCH_FIELD* modelField = aSymbol.FindField( wxT( "Spice_Model" ) ) )
        {
            spiceModel = modelField->GetText();
            aSymbol.RemoveField( wxT( "Spice_Model" ) );
        }
        else
        {
            spiceModel = aSymbol.FindField( wxT( "Value" ) )->GetText();
        }

        if( SCH_FIELD* netlistEnabledField = aSymbol.FindField( wxT( "Spice_Netlist_Enabled" ) ) )
        {
            wxString netlistEnabled = netlistEnabledField->GetText().Lower();

            if( netlistEnabled.StartsWith( wxT( "0" ) )
                || netlistEnabled.StartsWith( wxT( "n" ) )
                || netlistEnabled.StartsWith( wxT( "f" ) ) )
            {
                SCH_FIELD enableField( VECTOR2I( 0, 0 ), aSymbol.GetFieldCount(), &aSymbol,
                                       SIM_MODEL::ENABLE_FIELD );
            }
        }

        if( SCH_FIELD* libFileField = aSymbol.FindField( wxT( "Spice_Lib_File" ) ) )
        {
            spiceLib = libFileField->GetText();
            aSymbol.RemoveField( wxT( "Spice_Lib_File" ) );
        }
    }
    else if( prefix == wxT( "V" ) || prefix == wxT( "I" ) )
    {
        spiceModel = value;
    }
    else
    {
        // Auto convert some legacy fields used in the middle of 7.0 development...

        if( SCH_FIELD* legacyDevice = aSymbol.FindField( wxT( "Sim_Type" ) ) )
        {
            legacyDevice->SetName( SIM_MODEL::TYPE_FIELD );
        }

        if( SCH_FIELD* legacyDevice = aSymbol.FindField( wxT( "Sim_Device" ) ) )
        {
            legacyDevice->SetName( SIM_MODEL::DEVICE_TYPE_FIELD );
        }

        if( SCH_FIELD* legacyPins = aSymbol.FindField( wxT( "Sim_Pins" ) ) )
        {
            // Migrate pins from array of indexes to name-value-pairs
            wxArrayString pinIndexes;
            wxString      pins;

            wxStringSplit( legacyPins->GetText(), pinIndexes, ' ' );

            if( SIM_MODEL_IDEAL::InferSimParams( prefix, value ).length() )
            {
                if( pinIndexes[0] == wxT( "2" ) )
                    pins = "1=- 2=+";
                else
                    pins = "1=+ 2=-";
            }
            else
            {
                for( unsigned ii = 0; ii < pinIndexes.size(); ++ii )
                {
                    if( ii > 0 )
                        pins.Append( wxS( " " ) );

                    pins.Append( wxString::Format( wxT( "%u=%s" ), ii + 1, pinIndexes[ ii ] ) );
                }
            }

            legacyPins->SetName( SIM_MODEL::PINS_FIELD );
            legacyPins->SetText( pins );
        }

        if( SCH_FIELD* legacyPins = aSymbol.FindField( wxT( "Sim_Params" ) ) )
        {
            legacyPins->SetName( SIM_MODEL::PARAMS_FIELD );
        }

        return;
    }

    // Insert a plaintext model as a substitute.

    SCH_FIELD deviceTypeField( VECTOR2I( 0, 0 ), aSymbol.GetFieldCount(), &aSymbol,
                               SIM_MODEL::DEVICE_TYPE_FIELD );
    deviceTypeField.SetText( SIM_MODEL::DeviceInfo( SIM_MODEL::DEVICE_T::SPICE ).fieldValue );
    aSymbol.AddField( deviceTypeField );

    SCH_FIELD paramsField( VECTOR2I( 0, 0 ), aSymbol.GetFieldCount(), &aSymbol,
                           SIM_MODEL::PARAMS_FIELD );
    paramsField.SetText( wxString::Format( "type=\"%s\" model=\"%s\" lib=\"%s\"",
                                           spiceType, spiceModel, spiceLib ) );
    aSymbol.AddField( paramsField );

    // Legacy models by default get linear pin mapping.
    if( pinMap != "" )
    {
        SCH_FIELD pinsField( VECTOR2I( 0, 0 ), aSymbol.GetFieldCount(), &aSymbol,
                             SIM_MODEL::PINS_FIELD );

        pinsField.SetText( pinMap );
        aSymbol.AddField( pinsField );
    }
    else
    {
        wxString pins;

        for( unsigned ii = 0; ii < aSymbol.GetLibPins().size(); ++ii )
        {
            if( ii > 0 )
                pins.Append( wxS( " " ) );

            pins.Append( wxString::Format( wxT( "%u=%u" ), ii + 1, ii + 1 ) );
        }

        SCH_FIELD pinsField( VECTOR2I( 0, 0 ), aSymbol.GetFieldCount(), &aSymbol,
                             SIM_MODEL::PINS_FIELD );
        pinsField.SetText( pins );
        aSymbol.AddField( pinsField );
    }
}