pcb_grid_helper.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2014 CERN
 * Copyright (C) 2018-2023 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 "pcb_grid_helper.h"
 
#include <functional>
 
#include <advanced_config.h>
#include <pcb_dimension.h>
#include <pcb_shape.h>
#include <footprint.h>
#include <pad.h>
#include <pcb_group.h>
#include <pcb_track.h>
#include <zone.h>
#include <gal/graphics_abstraction_layer.h>
#include <geometry/intersection.h>
#include <geometry/nearest.h>
#include <geometry/oval.h>
#include <geometry/shape_circle.h>
#include <geometry/shape_line_chain.h>
#include <geometry/shape_rect.h>
#include <geometry/shape_segment.h>
#include <geometry/shape_simple.h>
#include <geometry/shape_utils.h>
#include <macros.h>
#include <math/util.h> // for KiROUND
#include <gal/painter.h>
#include <pcbnew_settings.h>
#include <tool/tool_manager.h>
#include <tools/pcb_tool_base.h>
#include <view/view.h>
 
namespace
{
 
std::optional<INTERSECTABLE_GEOM> GetBoardIntersectable( const BOARD_ITEM& aItem )
{
 switch( aItem.Type() )
 {
 case PCB_SHAPE_T:
 {
 const PCB_SHAPE& shape = static_cast<const PCB_SHAPE&>( aItem );
 
 switch( shape.GetShape() )
 {
 case SHAPE_T::SEGMENT: return SEG{ shape.GetStart(), shape.GetEnd() };
 
 case SHAPE_T::CIRCLE: return CIRCLE{ shape.GetCenter(), shape.GetRadius() };
 
 case SHAPE_T::ARC:
 return SHAPE_ARC{ shape.GetStart(), shape.GetArcMid(), shape.GetEnd(), 0 };
 
 case SHAPE_T::RECTANGLE: return BOX2I::ByCorners( shape.GetStart(), shape.GetEnd() );
 
 default: break;
 }
 
 break;
 }
 
 case PCB_TRACE_T:
 {
 const PCB_TRACK& track = static_cast<const PCB_TRACK&>( aItem );
 
 return SEG{ track.GetStart(), track.GetEnd() };
 }
 
 case PCB_ARC_T:
 {
 const PCB_ARC& arc = static_cast<const PCB_ARC&>( aItem );
 
 return SHAPE_ARC{ arc.GetStart(), arc.GetMid(), arc.GetEnd(), 0 };
 }
 
 default: break;
 }
 
 return std::nullopt;
}
 
std::optional<int64_t> FindSquareDistanceToItem( const BOARD_ITEM& item, const VECTOR2I& aPos )
{
 std::optional<INTERSECTABLE_GEOM> intersectable = GetBoardIntersectable( item );
 std::optional<NEARABLE_GEOM> nearable;
 
 if( intersectable )
 {
 // Exploit the intersectable as a nearable
 std::visit(
 [&]( auto& geom )
 {
 nearable = NEARABLE_GEOM( std::move( geom ) );
 },
 *intersectable );
 }
 
 // Whatever the item is, we don't have a nearable for it
 if( !nearable )
 return std::nullopt;
 
 const VECTOR2I nearestPt = GetNearestPoint( *nearable, aPos );
 return nearestPt.SquaredDistance( aPos );
}
 
} // namespace
 
PCB_GRID_HELPER::PCB_GRID_HELPER( TOOL_MANAGER* aToolMgr, MAGNETIC_SETTINGS* aMagneticSettings ) :
 GRID_HELPER( aToolMgr, LAYER_ANCHOR ), m_magneticSettings( aMagneticSettings )
{
 KIGFX::VIEW* view = m_toolMgr->GetView();
 KIGFX::RENDER_SETTINGS* settings = view->GetPainter()->GetSettings();
 KIGFX::COLOR4D auxItemsColor = settings->GetLayerColor( LAYER_AUX_ITEMS );
 
 m_viewAxis.SetSize( 20000 );
 m_viewAxis.SetStyle( KIGFX::ORIGIN_VIEWITEM::CROSS );
 m_viewAxis.SetColor( auxItemsColor.WithAlpha( 0.4 ) );
 m_viewAxis.SetDrawAtZero( true );
 view->Add( &m_viewAxis );
 view->SetVisible( &m_viewAxis, false );
 
 m_viewSnapPoint.SetSize( 10 );
 m_viewSnapPoint.SetStyle( KIGFX::ORIGIN_VIEWITEM::CIRCLE_CROSS );
 m_viewSnapPoint.SetColor( auxItemsColor );
 m_viewSnapPoint.SetDrawAtZero( true );
 view->Add( &m_viewSnapPoint );
 view->SetVisible( &m_viewSnapPoint, false );
}
 
 
PCB_GRID_HELPER::~PCB_GRID_HELPER()
{
 KIGFX::VIEW* view = m_toolMgr->GetView();
 
 view->Remove( &m_viewAxis );
 view->Remove( &m_viewSnapPoint );
}
 
 
void PCB_GRID_HELPER::AddConstructionItems( std::vector<BOARD_ITEM*> aItems, bool aExtensionOnly,
 bool aIsPersistent )
{
 if( !ADVANCED_CFG::GetCfg().m_EnableExtensionSnaps )
 {
 return;
 }
 
 // For all the elements that get drawn construction geometry,
 // add something suitable to the construction helper.
 // This can be nothing.
 CONSTRUCTION_MANAGER::CONSTRUCTION_ITEM_BATCH constructionItemsBatch;
 
 std::vector<VECTOR2I> referenceOnlyPoints;
 
 for( BOARD_ITEM* item : aItems )
 {
 std::vector<KIGFX::CONSTRUCTION_GEOM::DRAWABLE> constructionDrawables;
 
 if( item->Type() == PCB_SHAPE_T )
 {
 PCB_SHAPE& shape = static_cast<PCB_SHAPE&>( *item );
 
 switch( shape.GetShape() )
 {
 case SHAPE_T::SEGMENT:
 {
 if( !aExtensionOnly )
 {
 constructionDrawables.emplace_back( LINE{ shape.GetStart(), shape.GetEnd() } );
 }
 else
 {
 // Two rays, extending from the segment ends
 const VECTOR2I segVec = shape.GetEnd() - shape.GetStart();
 constructionDrawables.emplace_back(
 HALF_LINE{ shape.GetStart(), shape.GetStart() - segVec } );
 constructionDrawables.emplace_back(
 HALF_LINE{ shape.GetEnd(), shape.GetEnd() + segVec } );
 }
 
 if( aIsPersistent )
 {
 // include the original endpoints as construction items
 // (this allows H/V snapping)
 constructionDrawables.emplace_back( shape.GetStart() );
 constructionDrawables.emplace_back( shape.GetEnd() );
 
 // But mark them as references, so they don't get snapped to themsevles
 referenceOnlyPoints.emplace_back( shape.GetStart() );
 referenceOnlyPoints.emplace_back( shape.GetEnd() );
 }
 break;
 }
 case SHAPE_T::ARC:
 {
 if( !aExtensionOnly )
 {
 constructionDrawables.push_back(
 CIRCLE{ shape.GetCenter(), shape.GetRadius() } );
 }
 else
 {
 // The rest of the circle is the arc through the opposite point to the midpoint
 const VECTOR2I oppositeMid =
 shape.GetCenter() + ( shape.GetCenter() - shape.GetArcMid() );
 constructionDrawables.push_back(
 SHAPE_ARC{ shape.GetStart(), oppositeMid, shape.GetEnd(), 0 } );
 }
 constructionDrawables.push_back( shape.GetCenter() );
 
 if( aIsPersistent )
 {
 // include the original endpoints as construction items
 // (this allows H/V snapping)
 constructionDrawables.emplace_back( shape.GetStart() );
 constructionDrawables.emplace_back( shape.GetEnd() );
 
 // But mark them as references, so they don't get snapped to themselves
 referenceOnlyPoints.emplace_back( shape.GetStart() );
 referenceOnlyPoints.emplace_back( shape.GetEnd() );
 }
 
 break;
 }
 case SHAPE_T::CIRCLE:
 case SHAPE_T::RECTANGLE:
 {
 constructionDrawables.push_back( shape.GetCenter() );
 break;
 }
 default:
 // This shape doesn't have any construction geometry to draw
 break;
 }
 }
 
 // At this point, constructionDrawables can be empty, which is fine
 // (it means there's no additional construction geometry to draw, but
 // the item is still going to be proposed for activation)
 constructionItemsBatch.emplace_back( CONSTRUCTION_MANAGER::CONSTRUCTION_ITEM{
 CONSTRUCTION_MANAGER::SOURCE::FROM_ITEMS,
 item,
 std::move( constructionDrawables ),
 } );
 }
 
 if( referenceOnlyPoints.size() )
 {
 getSnapManager().SetReferenceOnlyPoints( std::move( referenceOnlyPoints ) );
 }
 
 // Let the manager handle it
 getSnapManager().GetConstructionManager().ProposeConstructionItems(
 std::move( constructionItemsBatch ), aIsPersistent );
}
 
 
VECTOR2I PCB_GRID_HELPER::AlignToSegment( const VECTOR2I& aPoint, const SEG& aSeg )
{
 const int c_gridSnapEpsilon_sq = 4;
 
 VECTOR2I aligned = Align( aPoint );
 
 if( !m_enableSnap )
 return aligned;
 
 std::vector<VECTOR2I> points;
 
 const SEG testSegments[] = { SEG( aligned, aligned + VECTOR2( 1, 0 ) ),
 SEG( aligned, aligned + VECTOR2( 0, 1 ) ),
 SEG( aligned, aligned + VECTOR2( 1, 1 ) ),
 SEG( aligned, aligned + VECTOR2( 1, -1 ) ) };
 
 for( const SEG& seg : testSegments )
 {
 OPT_VECTOR2I vec = aSeg.IntersectLines( seg );
 
 if( vec && aSeg.SquaredDistance( *vec ) <= c_gridSnapEpsilon_sq )
 points.push_back( *vec );
 }
 
 VECTOR2I nearest = aligned;
 SEG::ecoord min_d_sq = VECTOR2I::ECOORD_MAX;
 
 // Snap by distance between pointer and endpoints
 for( const VECTOR2I& pt : { aSeg.A, aSeg.B } )
 {
 SEG::ecoord d_sq = ( pt - aPoint ).SquaredEuclideanNorm();
 
 if( d_sq < min_d_sq )
 {
 min_d_sq = d_sq;
 nearest = pt;
 }
 }
 
 // Snap by distance between aligned cursor and intersections
 for( const VECTOR2I& pt : points )
 {
 SEG::ecoord d_sq = ( pt - aligned ).SquaredEuclideanNorm();
 
 if( d_sq < min_d_sq )
 {
 min_d_sq = d_sq;
 nearest = pt;
 }
 }
 
 return nearest;
}
 
 
VECTOR2I PCB_GRID_HELPER::AlignToArc( const VECTOR2I& aPoint, const SHAPE_ARC& aArc )
{
 VECTOR2I aligned = Align( aPoint );
 
 if( !m_enableSnap )
 return aligned;
 
 std::vector<VECTOR2I> points;
 
 aArc.IntersectLine( SEG( aligned, aligned + VECTOR2( 1, 0 ) ), &points );
 aArc.IntersectLine( SEG( aligned, aligned + VECTOR2( 0, 1 ) ), &points );
 aArc.IntersectLine( SEG( aligned, aligned + VECTOR2( 1, 1 ) ), &points );
 aArc.IntersectLine( SEG( aligned, aligned + VECTOR2( 1, -1 ) ), &points );
 
 VECTOR2I nearest = aligned;
 SEG::ecoord min_d_sq = VECTOR2I::ECOORD_MAX;
 
 // Snap by distance between pointer and endpoints
 for( const VECTOR2I& pt : { aArc.GetP0(), aArc.GetP1() } )
 {
 SEG::ecoord d_sq = ( pt - aPoint ).SquaredEuclideanNorm();
 
 if( d_sq < min_d_sq )
 {
 min_d_sq = d_sq;
 nearest = pt;
 }
 }
 
 // Snap by distance between aligned cursor and intersections
 for( const VECTOR2I& pt : points )
 {
 SEG::ecoord d_sq = ( pt - aligned ).SquaredEuclideanNorm();
 
 if( d_sq < min_d_sq )
 {
 min_d_sq = d_sq;
 nearest = pt;
 }
 }
 
 return nearest;
}
 
 
VECTOR2I PCB_GRID_HELPER::AlignToNearestPad( const VECTOR2I& aMousePos, std::deque<PAD*>& aPads )
{
 clearAnchors();
 
 for( BOARD_ITEM* item : aPads )
 computeAnchors( item, aMousePos, true, nullptr );
 
 double minDist = std::numeric_limits<double>::max();
 ANCHOR* nearestOrigin = nullptr;
 
 for( ANCHOR& a : m_anchors )
 {
 if( ( ORIGIN & a.flags ) != ORIGIN )
 continue;
 
 bool hitAny = true;
 for( EDA_ITEM* item : m_snapItem->items )
 {
 hitAny = hitAny && item->HitTest( aMousePos );
 }
 
 if( !hitAny )
 continue;
 
 double dist = a.Distance( aMousePos );
 
 if( dist < minDist )
 {
 minDist = dist;
 nearestOrigin = &a;
 }
 }
 
 return nearestOrigin ? nearestOrigin->pos : aMousePos;
}
 
 
VECTOR2I PCB_GRID_HELPER::BestDragOrigin( const VECTOR2I &aMousePos,
 std::vector<BOARD_ITEM*>& aItems,
 GRID_HELPER_GRIDS aGrid,
 const PCB_SELECTION_FILTER_OPTIONS* aSelectionFilter )
{
 clearAnchors();
 
 computeAnchors( aItems, aMousePos, true, aSelectionFilter, nullptr, true );
 
 double lineSnapMinCornerDistance = m_toolMgr->GetView()->ToWorld( 50 );
 
 ANCHOR* nearestOutline = nearestAnchor( aMousePos, OUTLINE );
 ANCHOR* nearestCorner = nearestAnchor( aMousePos, CORNER );
 ANCHOR* nearestOrigin = nearestAnchor( aMousePos, ORIGIN );
 ANCHOR* best = nullptr;
 double minDist = std::numeric_limits<double>::max();
 
 if( nearestOrigin )
 {
 minDist = nearestOrigin->Distance( aMousePos );
 best = nearestOrigin;
 }
 
 if( nearestCorner )
 {
 double dist = nearestCorner->Distance( aMousePos );
 
 if( dist < minDist )
 {
 minDist = dist;
 best = nearestCorner;
 }
 }
 
 if( nearestOutline )
 {
 double dist = nearestOutline->Distance( aMousePos );
 
 if( minDist > lineSnapMinCornerDistance && dist < minDist )
 best = nearestOutline;
 }
 
 return best ? best->pos : aMousePos;
}
 
 
VECTOR2I PCB_GRID_HELPER::BestSnapAnchor( const VECTOR2I& aOrigin, BOARD_ITEM* aReferenceItem,
 GRID_HELPER_GRIDS aGrid )
{
 LSET layers;
 std::vector<BOARD_ITEM*> item;
 
 if( aReferenceItem )
 {
 layers = aReferenceItem->GetLayerSet();
 item.push_back( aReferenceItem );
 }
 else
 {
 layers = LSET::AllLayersMask();
 }
 
 return BestSnapAnchor( aOrigin, layers, aGrid, item );
}
 
 
VECTOR2I PCB_GRID_HELPER::BestSnapAnchor( const VECTOR2I& aOrigin, const LSET& aLayers,
 GRID_HELPER_GRIDS aGrid,
 const std::vector<BOARD_ITEM*>& aSkip )
{
 // Tuning constant: snap radius in screen space
 const int snapSize = 25;
 
 // Snapping distance is in screen space, clamped to the current grid to ensure that the grid
 // points that are visible can always be snapped to.
 // see https://gitlab.com/kicad/code/kicad/-/issues/5638
 // see https://gitlab.com/kicad/code/kicad/-/issues/7125
 // see https://gitlab.com/kicad/code/kicad/-/issues/12303
 double snapScale = m_toolMgr->GetView()->ToWorld( snapSize );
 // warning: GetVisibleGrid().x sometimes returns a value > INT_MAX. Intermediate calculation
 // needs double.
 int snapRange = KiROUND( m_enableGrid ? std::min( snapScale, GetVisibleGrid().x ) : snapScale );
 
 //Respect limits of coordinates representation
 const BOX2I visibilityHorizon =
 BOX2ISafe( VECTOR2D( aOrigin ) - snapRange / 2.0, VECTOR2D( snapRange, snapRange ) );
 
 clearAnchors();
 
 const std::vector<BOARD_ITEM*> visibleItems = queryVisible( visibilityHorizon, aSkip );
 computeAnchors( visibleItems, aOrigin, false, nullptr, &aLayers, false );
 
 ANCHOR* nearest = nearestAnchor( aOrigin, SNAPPABLE );
 VECTOR2I nearestGrid = Align( aOrigin, aGrid );
 
 if( KIGFX::ANCHOR_DEBUG* ad = enableAndGetAnchorDebug(); ad )
 {
 ad->ClearAnchors();
 for( const ANCHOR& anchor : m_anchors )
 ad->AddAnchor( anchor.pos );
 
 ad->SetNearest( nearest ? OPT_VECTOR2I{ nearest->pos } : std::nullopt );
 m_toolMgr->GetView()->Update( ad, KIGFX::GEOMETRY );
 }
 
 // The distance to the nearest snap point, if any
 std::optional<int> snapDist;
 if( nearest )
 snapDist = nearest->Distance( aOrigin );
 
 showConstructionGeometry( m_enableSnap );
 
 SNAP_MANAGER& snapManager = getSnapManager();
 SNAP_LINE_MANAGER& snapLineManager = snapManager.GetSnapLineManager();
 
 const auto ptIsReferenceOnly = [&]( const VECTOR2I& aPt )
 {
 const std::vector<VECTOR2I>& referenceOnlyPoints = snapManager.GetReferenceOnlyPoints();
 return std::find( referenceOnlyPoints.begin(), referenceOnlyPoints.end(), aPt )
 != referenceOnlyPoints.end();
 };
 
 const auto proposeConstructionForItems = [&]( const std::vector<EDA_ITEM*>& aItems )
 {
 // Add any involved item as a temporary construction item
 // (de-duplication with existing construction items is handled later)
 std::vector<BOARD_ITEM*> items;
 
 for( EDA_ITEM* item : aItems )
 {
 BOARD_ITEM* boardItem = static_cast<BOARD_ITEM*>( item );
 
 // Null items are allowed to arrive here as they represent geometry that isn't
 // specifically tied to a board item. For example snap lines from some
 // other anchor.
 // But they don't produce new construction items.
 if( boardItem )
 {
 if( m_magneticSettings->allLayers
 || ( ( aLayers & boardItem->GetLayerSet() ).any() ) )
 {
 items.push_back( boardItem );
 }
 }
 }
 
 // Temporary construction items are not persistent and don't
 // overlay the items themselves (as the items will not be moved)
 AddConstructionItems( items, true, false );
 };
 
 bool snapValid = false;
 
 if( m_enableSnap )
 {
 // Existing snap lines need priority over new snaps
 if( m_enableSnapLine )
 {
 OPT_VECTOR2I snapLineSnap = snapLineManager.GetNearestSnapLinePoint(
 aOrigin, nearestGrid, snapDist, snapRange );
 
 // We found a better snap point that the nearest one
 if( snapLineSnap && m_skipPoint != *snapLineSnap )
 {
 snapLineManager.SetSnapLineEnd( *snapLineSnap );
 snapValid = true;
 
 // Don't show a snap point if we're snapping to a grid rather than an anchor
 m_toolMgr->GetView()->SetVisible( &m_viewSnapPoint, false );
 m_viewSnapPoint.SetSnapTypes( POINT_TYPE::PT_NONE );
 
 // Only return the snap line end as a snap if it's not a reference point
 // (we don't snap to reference points, but we can use them to update the snap line,
 // without actually snapping)
 if( !ptIsReferenceOnly( *snapLineSnap ) )
 {
 return *snapLineSnap;
 }
 }
 }
 
 // If there's a snap anchor within range, use it if we can
 if( nearest && nearest->Distance( aOrigin ) <= snapRange )
 {
 const bool anchorIsConstructed = nearest->flags & ANCHOR_FLAGS::CONSTRUCTED;
 
 // If the nearest anchor is a reference point, we don't snap to it,
 // but we can update the snap line origin
 if( ptIsReferenceOnly( nearest->pos ) )
 {
 // We can set the snap line origin, but don't mess with the
 // accepted snap point
 snapLineManager.SetSnapLineOrigin( nearest->pos );
 }
 else
 {
 // 'Intrinsic' points of items can trigger adding construction geometry
 // for _that_ item by proximity. E.g. just mousing over the intersection
 // of an item doesn't add a construction item for the second item).
 // This is to make construction items less intrusive and more
 // a result of user intent.
 if( !anchorIsConstructed )
 {
 proposeConstructionForItems( nearest->items );
 }
 
 const auto shouldAcceptAnchor = [&]( const ANCHOR& aAnchor )
 {
 // If no extension snaps are enabled, don't inhibit
 static const bool haveExtensions =
 ADVANCED_CFG::GetCfg().m_EnableExtensionSnaps;
 if( !haveExtensions )
 return true;
 
 // Check that any involved real items are 'active'
 // (i.e. the user has moused over a key point previously)
 // If any are not real (e.g. snap lines), they are allowed to be involved
 //
 // This is an area most likely to be controversial/need tuning,
 // as some users will think it's fiddly; without 'activation', others will
 // think the snaps are intrusive.
 bool allRealAreInvolved =
 snapManager.GetConstructionManager().InvolvesAllGivenRealItems(
 aAnchor.items );
 return allRealAreInvolved;
 };
 
 if( shouldAcceptAnchor( *nearest ) )
 {
 m_snapItem = *nearest;
 
 // Set the snap line origin or end as needed
 snapLineManager.SetSnappedAnchor( m_snapItem->pos );
 // Show the correct snap point marker
 updateSnapPoint( { m_snapItem->pos, m_snapItem->pointTypes } );
 
 return m_snapItem->pos;
 }
 }
 
 snapValid = true;
 }
 else
 {
 static const bool canActivateByHitTest =
 ADVANCED_CFG::GetCfg().m_ExtensionSnapActivateOnHover;
 if( canActivateByHitTest )
 {
 // An exact hit on an item, even if not near a snap point
 // If it's tool hard to hit by hover, this can be increased
 // to make it non-exact.
 const int hoverAccuracy = 0;
 for( BOARD_ITEM* item : visibleItems )
 {
 if( item->HitTest( aOrigin, hoverAccuracy ) )
 {
 proposeConstructionForItems( { item } );
 snapValid = true;
 break;
 }
 }
 }
 }
 
 // If we got here, we didn't snap to an anchor or snap line
 
 // If we're snapping to a grid, on-element snaps would be too intrusive
 // but they're useful when there isn't a grid to snap to
 if( !m_enableGrid )
 {
 OPT_VECTOR2I nearestPointOnAnElement =
 GetNearestPoint( m_pointOnLineCandidates, aOrigin );
 
 // Got any nearest point - snap if in range
 if( nearestPointOnAnElement
 && nearestPointOnAnElement->Distance( aOrigin ) <= snapRange )
 {
 updateSnapPoint( { *nearestPointOnAnElement, POINT_TYPE::PT_ON_ELEMENT } );
 
 // Clear the snap end, but keep the origin so touching another line
 // doesn't kill a snap line
 snapLineManager.SetSnapLineEnd( std::nullopt );
 return *nearestPointOnAnElement;
 }
 }
 }
 
 // Completely failed to find any snap point, so snap to the grid
 
 m_snapItem = std::nullopt;
 
 if( !snapValid )
 {
 snapLineManager.ClearSnapLine();
 snapManager.GetConstructionManager().CancelProposal();
 }
 else
 {
 snapLineManager.SetSnapLineEnd( std::nullopt );
 }
 
 m_toolMgr->GetView()->SetVisible( &m_viewSnapPoint, false );
 
 return nearestGrid;
}
 
 
BOARD_ITEM* PCB_GRID_HELPER::GetSnapped() const
{
 if( !m_snapItem )
 return nullptr;
 
 // The snap anchor doesn't have an item associated with it
 // (odd, could it be entirely made of construction geometry?)
 if( m_snapItem->items.empty() )
 return nullptr;
 
 return static_cast<BOARD_ITEM*>( m_snapItem->items[0] );
}
 
 
GRID_HELPER_GRIDS PCB_GRID_HELPER::GetItemGrid( const EDA_ITEM* aItem ) const
{
 if( !aItem )
 return GRID_CURRENT;
 
 switch( aItem->Type() )
 {
 case PCB_FOOTPRINT_T:
 case PCB_PAD_T:
 return GRID_CONNECTABLE;
 
 case PCB_TEXT_T:
 case PCB_FIELD_T:
 return GRID_TEXT;
 
 case PCB_SHAPE_T:
 case PCB_DIMENSION_T:
 case PCB_REFERENCE_IMAGE_T:
 case PCB_TEXTBOX_T:
 return GRID_GRAPHICS;
 
 case PCB_TRACE_T:
 case PCB_ARC_T:
 return GRID_WIRES;
 
 case PCB_VIA_T:
 return GRID_VIAS;
 
 default:
 return GRID_CURRENT;
 }
}
 
 
VECTOR2D PCB_GRID_HELPER::GetGridSize( GRID_HELPER_GRIDS aGrid ) const
{
 const GRID_SETTINGS& grid = m_toolMgr->GetSettings()->m_Window.grid;
 int idx = -1;
 
 VECTOR2D g = m_toolMgr->GetView()->GetGAL()->GetGridSize();
 
 if( !grid.overrides_enabled )
 return g;
 
 switch( aGrid )
 {
 case GRID_CONNECTABLE:
 if( grid.override_connected )
 idx = grid.override_connected_idx;
 
 break;
 
 case GRID_WIRES:
 if( grid.override_wires )
 idx = grid.override_wires_idx;
 
 break;
 
 case GRID_VIAS:
 if( grid.override_vias )
 idx = grid.override_vias_idx;
 
 break;
 
 case GRID_TEXT:
 if( grid.override_text )
 idx = grid.override_text_idx;
 
 break;
 
 case GRID_GRAPHICS:
 if( grid.override_graphics )
 idx = grid.override_graphics_idx;
 
 break;
 
 default:
 break;
 }
 
 if( idx >= 0 && idx < (int) grid.grids.size() )
 g = grid.grids[idx].ToDouble( pcbIUScale );
 
 return g;
}
 
 
std::vector<BOARD_ITEM*>
PCB_GRID_HELPER::queryVisible( const BOX2I& aArea, const std::vector<BOARD_ITEM*>& aSkip ) const
{
 std::set<BOARD_ITEM*> items;
 std::vector<KIGFX::VIEW::LAYER_ITEM_PAIR> selectedItems;
 
 PCB_TOOL_BASE* currentTool = static_cast<PCB_TOOL_BASE*>( m_toolMgr->GetCurrentTool() );
 KIGFX::VIEW* view = m_toolMgr->GetView();
 RENDER_SETTINGS* settings = view->GetPainter()->GetSettings();
 const std::set<int>& activeLayers = settings->GetHighContrastLayers();
 bool isHighContrast = settings->GetHighContrast();
 
 view->Query( aArea, selectedItems );
 
 for( const auto& [ viewItem, layer ] : selectedItems )
 {
 BOARD_ITEM* boardItem = static_cast<BOARD_ITEM*>( viewItem );
 
 if( currentTool->IsFootprintEditor() )
 {
 // If we are in the footprint editor, don't use the footprint itself
 if( boardItem->Type() == PCB_FOOTPRINT_T )
 continue;
 }
 else
 {
 // If we are not in the footprint editor, don't use footprint-editor-private items
 if( FOOTPRINT* parentFP = boardItem->GetParentFootprint() )
 {
 if( IsPcbLayer( layer ) && parentFP->GetPrivateLayers().test( layer ) )
 continue;
 }
 }
 
 // The boardItem must be visible and on an active layer
 if( view->IsVisible( boardItem )
 && ( !isHighContrast || activeLayers.count( layer ) )
 && boardItem->ViewGetLOD( layer, view ) < view->GetScale() )
 {
 items.insert ( boardItem );
 }
 }
 
 std::function<void( BOARD_ITEM* )> skipItem =
 [&]( BOARD_ITEM* aItem )
 {
 items.erase( aItem );
 
 aItem->RunOnDescendants(
 [&]( BOARD_ITEM* aChild )
 {
 skipItem( aChild );
 } );
 };
 
 for( BOARD_ITEM* item : aSkip )
 skipItem( item );
 
 return {items.begin(), items.end()};
}
 
 
struct PCB_INTERSECTABLE
{
 BOARD_ITEM* Item;
 INTERSECTABLE_GEOM Geometry;
 
 // Clang wants this constructor
 PCB_INTERSECTABLE( BOARD_ITEM* aItem, INTERSECTABLE_GEOM aSeg ) :
 Item( aItem ), Geometry( std::move( aSeg ) )
 {
 }
};
 
 
void PCB_GRID_HELPER::computeAnchors( const std::vector<BOARD_ITEM*>& aItems,
 const VECTOR2I& aRefPos, bool aFrom,
 const PCB_SELECTION_FILTER_OPTIONS* aSelectionFilter,
 const LSET* aMatchLayers, bool aForDrag )
{
 std::vector<PCB_INTERSECTABLE> intersectables;
 
 // These could come from a more granular snap mode filter
 // But when looking for drag points, we don't want construction geometry
 const bool computeIntersections = !aForDrag;
 const bool computePointsOnElements = !aForDrag;
 const bool excludeGraphics = aSelectionFilter && !aSelectionFilter->graphics;
 const bool excludeTracks = aSelectionFilter && !aSelectionFilter->tracks;
 
 const auto itemIsSnappable = [&]( const BOARD_ITEM& aItem )
 {
 // If we are filtering by layers, check if the item matches
 if( aMatchLayers )
 {
 return m_magneticSettings->allLayers
 || ( ( *aMatchLayers & aItem.GetLayerSet() ).any() );
 }
 return true;
 };
 
 const auto processItem = [&]( BOARD_ITEM& item )
 {
 // Don't even process the item if it doesn't match the layers
 if( !itemIsSnappable( item ) )
 {
 return;
 }
 
 // First, add all the key points of the item itself
 computeAnchors( &item, aRefPos, aFrom, aSelectionFilter );
 
 // If we are computing intersections, construct the relevant intersectables
 // Points on elements also use the intersectables.
 if( computeIntersections || computePointsOnElements )
 {
 std::optional<INTERSECTABLE_GEOM> intersectableGeom;
 if( !excludeGraphics && item.Type() == PCB_SHAPE_T )
 {
 intersectableGeom = GetBoardIntersectable( item );
 }
 else if( !excludeTracks && ( item.Type() == PCB_TRACE_T || item.Type() == PCB_ARC_T ) )
 {
 intersectableGeom = GetBoardIntersectable( item );
 }
 
 if( intersectableGeom )
 {
 intersectables.emplace_back( &item, *intersectableGeom );
 }
 }
 };
 
 for( BOARD_ITEM* item : aItems )
 {
 processItem( *item );
 }
 
 for( const CONSTRUCTION_MANAGER::CONSTRUCTION_ITEM_BATCH& batch :
 getSnapManager().GetConstructionItems() )
 {
 for( const CONSTRUCTION_MANAGER::CONSTRUCTION_ITEM& constructionItem : batch )
 {
 BOARD_ITEM* involvedItem = static_cast<BOARD_ITEM*>( constructionItem.Item );
 
 
 for( const KIGFX::CONSTRUCTION_GEOM::DRAWABLE& drawable :
 constructionItem.Constructions )
 {
 std::visit(
 [&]( const auto& visited )
 {
 using ItemType = std::decay_t<decltype( visited )>;
 
 if constexpr( std::is_same_v<ItemType, LINE>
 || std::is_same_v<ItemType, CIRCLE>
 || std::is_same_v<ItemType, HALF_LINE>
 || std::is_same_v<ItemType, SHAPE_ARC> )
 {
 intersectables.emplace_back( involvedItem, visited );
 }
 else if constexpr( std::is_same_v<ItemType, VECTOR2I> )
 {
 // Add any free-floating points as snap points.
 addAnchor( visited, SNAPPABLE | CONSTRUCTED, involvedItem,
 POINT_TYPE::PT_NONE );
 }
 },
 drawable );
 }
 }
 }
 
 // Now, add all the intersections between the items
 // This is obviously quadratic, so performance may be a concern for large selections
 // But, so far up to ~20k comparisons seems not to be an issue with run times in the ms range
 // and it's usually only a handful of items.
 
 if( computeIntersections )
 {
 for( std::size_t ii = 0; ii < intersectables.size(); ++ii )
 {
 const PCB_INTERSECTABLE& intersectableA = intersectables[ii];
 
 for( std::size_t jj = ii + 1; jj < intersectables.size(); ++jj )
 {
 const PCB_INTERSECTABLE& intersectableB = intersectables[jj];
 
 // An item and its own extension will often have intersections (as they are on top of each other),
 // but they not useful points to snap to
 if( intersectableA.Item == intersectableB.Item )
 continue;
 
 std::vector<VECTOR2I> intersections;
 const INTERSECTION_VISITOR visitor{ intersectableA.Geometry, intersections };
 
 std::visit( visitor, intersectableB.Geometry );
 
 // For each intersection, add an intersection snap anchor
 for( const VECTOR2I& intersection : intersections )
 {
 std::vector<EDA_ITEM*> items = {
 intersectableA.Item,
 intersectableB.Item,
 };
 addAnchor( intersection, SNAPPABLE | CONSTRUCTED, std::move( items ),
 POINT_TYPE::PT_INTERSECTION );
 }
 }
 }
 }
 
 // The intersectables can also be used for fall-back snapping to "point on line"
 // snaps if no other snap is found
 m_pointOnLineCandidates.clear();
 if( computePointsOnElements )
 {
 // For the moment, it's trivial to make a NEARABLE from an INTERSECTABLE,
 // because all INTERSECTABLEs are also NEARABLEs.
 for( const PCB_INTERSECTABLE& intersectable : intersectables )
 {
 std::visit(
 [&]( const auto& geom )
 {
 NEARABLE_GEOM nearable( geom );
 m_pointOnLineCandidates.emplace_back( nearable );
 },
 intersectable.Geometry );
 }
 }
}
 
 
void PCB_GRID_HELPER::computeAnchors( BOARD_ITEM* aItem, const VECTOR2I& aRefPos, bool aFrom,
 const PCB_SELECTION_FILTER_OPTIONS* aSelectionFilter )
{
 KIGFX::VIEW* view = m_toolMgr->GetView();
 RENDER_SETTINGS* settings = view->GetPainter()->GetSettings();
 const std::set<int>& activeLayers = settings->GetHighContrastLayers();
 bool isHighContrast = settings->GetHighContrast();
 
 auto checkVisibility =
 [&]( BOARD_ITEM* item )
 {
 if( !view->IsVisible( item ) )
 return false;
 
 bool onActiveLayer = !isHighContrast;
 bool isLODVisible = false;
 
 for( PCB_LAYER_ID layer : item->GetLayerSet().Seq() )
 {
 if( !onActiveLayer && activeLayers.count( layer ) )
 onActiveLayer = true;
 
 if( !isLODVisible && item->ViewGetLOD( layer, view ) < view->GetScale() )
 isLODVisible = true;
 
 if( onActiveLayer && isLODVisible )
 return true;
 }
 
 return false;
 };
 
 // As defaults, these are probably reasonable to avoid spamming key points
 const KIGEOM::OVAL_KEY_POINT_FLAGS ovalKeyPointFlags =
 KIGEOM::OVAL_CENTER | KIGEOM::OVAL_CAP_TIPS | KIGEOM::OVAL_SIDE_MIDPOINTS
 | KIGEOM::OVAL_CARDINAL_EXTREMES;
 
 auto handlePadShape = [&]( PAD* aPad, PCB_LAYER_ID aLayer )
 {
 addAnchor( aPad->GetPosition(), ORIGIN | SNAPPABLE, aPad, POINT_TYPE::PT_CENTER );
 
 if( aFrom )
 return;
 
 switch( aPad->GetShape( aLayer ) )
 {
 case PAD_SHAPE::CIRCLE:
 {
 const CIRCLE circle( aPad->ShapePos( aLayer ), aPad->GetSizeX() / 2 );
 
 for( const TYPED_POINT2I& pt : KIGEOM::GetCircleKeyPoints( circle, false ) )
 {
 addAnchor( pt.m_point, OUTLINE | SNAPPABLE, aPad, pt.m_types );
 }
 
 break;
 }
 case PAD_SHAPE::OVAL:
 {
 const OVAL oval( aPad->GetSize( aLayer ), aPad->GetPosition(), aPad->GetOrientation() );
 
 for( const TYPED_POINT2I& pt : KIGEOM::GetOvalKeyPoints( oval, ovalKeyPointFlags ) )
 {
 addAnchor( pt.m_point, OUTLINE | SNAPPABLE, aPad, pt.m_types );
 }
 
 break;
 }
 case PAD_SHAPE::RECTANGLE:
 case PAD_SHAPE::TRAPEZOID:
 case PAD_SHAPE::ROUNDRECT:
 case PAD_SHAPE::CHAMFERED_RECT:
 {
 VECTOR2I half_size( aPad->GetSize( aLayer ) / 2 );
 VECTOR2I trap_delta( 0, 0 );
 
 if( aPad->GetShape( aLayer ) == PAD_SHAPE::TRAPEZOID )
 trap_delta = aPad->GetDelta( aLayer ) / 2;
 
 SHAPE_LINE_CHAIN corners;
 
 corners.Append( -half_size.x - trap_delta.y, half_size.y + trap_delta.x );
 corners.Append( half_size.x + trap_delta.y, half_size.y - trap_delta.x );
 corners.Append( half_size.x - trap_delta.y, -half_size.y + trap_delta.x );
 corners.Append( -half_size.x + trap_delta.y, -half_size.y - trap_delta.x );
 corners.SetClosed( true );
 
 corners.Rotate( aPad->GetOrientation() );
 corners.Move( aPad->ShapePos( aLayer ) );
 
 for( std::size_t ii = 0; ii < corners.GetSegmentCount(); ++ii )
 {
 const SEG& seg = corners.GetSegment( ii );
 addAnchor( seg.A, OUTLINE | SNAPPABLE, aPad, POINT_TYPE::PT_CORNER );
 addAnchor( seg.Center(), OUTLINE | SNAPPABLE, aPad, POINT_TYPE::PT_MID );
 
 if( ii == corners.GetSegmentCount() - 1 )
 addAnchor( seg.B, OUTLINE | SNAPPABLE, aPad, POINT_TYPE::PT_CORNER );
 }
 
 break;
 }
 
 default:
 {
 const auto& outline = aPad->GetEffectivePolygon( aLayer, ERROR_INSIDE );
 
 if( !outline->IsEmpty() )
 {
 for( const VECTOR2I& pt : outline->Outline( 0 ).CPoints() )
 addAnchor( pt, OUTLINE | SNAPPABLE, aPad );
 }
 
 break;
 }
 }
 
 if( aPad->HasHole() )
 {
 // Holes are at the pad centre (it's the shape that may be offset)
 const VECTOR2I hole_pos = aPad->GetPosition();
 const VECTOR2I hole_size = aPad->GetDrillSize();
 
 std::vector<TYPED_POINT2I> snap_pts;
 
 if( hole_size.x == hole_size.y )
 {
 // Circle
 const CIRCLE circle( hole_pos, hole_size.x / 2 );
 snap_pts = KIGEOM::GetCircleKeyPoints( circle, true );
 }
 else
 {
 // Oval
 
 // For now there's no way to have an off-angle hole, so this is the
 // same as the pad. In future, this may not be true:
 // https://gitlab.com/kicad/code/kicad/-/issues/4124
 const OVAL oval( hole_size, hole_pos, aPad->GetOrientation() );
 snap_pts = KIGEOM::GetOvalKeyPoints( oval, ovalKeyPointFlags );
 }
 
 for( const TYPED_POINT2I& snap_pt : snap_pts )
 addAnchor( snap_pt.m_point, OUTLINE | SNAPPABLE, aPad, snap_pt.m_types );
 }
 };
 
 auto handleShape =
 [&]( PCB_SHAPE* shape )
 {
 VECTOR2I start = shape->GetStart();
 VECTOR2I end = shape->GetEnd();
 
 switch( shape->GetShape() )
 {
 case SHAPE_T::CIRCLE:
 {
 const int r = ( start - end ).EuclideanNorm();
 
 addAnchor( start, ORIGIN | SNAPPABLE, shape, POINT_TYPE::PT_CENTER );
 
 addAnchor( start + VECTOR2I( -r, 0 ), OUTLINE | SNAPPABLE, shape,
 POINT_TYPE::PT_QUADRANT );
 addAnchor( start + VECTOR2I( r, 0 ), OUTLINE | SNAPPABLE, shape,
 POINT_TYPE::PT_QUADRANT );
 addAnchor( start + VECTOR2I( 0, -r ), OUTLINE | SNAPPABLE, shape,
 POINT_TYPE::PT_QUADRANT );
 addAnchor( start + VECTOR2I( 0, r ), OUTLINE | SNAPPABLE, shape,
 POINT_TYPE::PT_QUADRANT );
 break;
 }
 
 case SHAPE_T::ARC:
 addAnchor( shape->GetStart(), CORNER | SNAPPABLE, shape,
 POINT_TYPE::PT_END );
 addAnchor( shape->GetEnd(), CORNER | SNAPPABLE, shape,
 POINT_TYPE::PT_END );
 addAnchor( shape->GetArcMid(), CORNER | SNAPPABLE, shape,
 POINT_TYPE::PT_MID );
 addAnchor( shape->GetCenter(), ORIGIN | SNAPPABLE, shape,
 POINT_TYPE::PT_CENTER );
 break;
 
 case SHAPE_T::RECTANGLE:
 {
 VECTOR2I point2( end.x, start.y );
 VECTOR2I point3( start.x, end.y );
 SEG first( start, point2 );
 SEG second( point2, end );
 SEG third( end, point3 );
 SEG fourth( point3, start );
 
 const int snapFlags = CORNER | SNAPPABLE;
 
 addAnchor( shape->GetCenter(), snapFlags, shape, POINT_TYPE::PT_CENTER );
 
 addAnchor( first.A, snapFlags, shape, POINT_TYPE::PT_CORNER );
 addAnchor( first.Center(), snapFlags, shape, POINT_TYPE::PT_MID );
 addAnchor( second.A, snapFlags, shape, POINT_TYPE::PT_CORNER );
 addAnchor( second.Center(), snapFlags, shape, POINT_TYPE::PT_MID );
 addAnchor( third.A, snapFlags, shape, POINT_TYPE::PT_CORNER );
 addAnchor( third.Center(), snapFlags, shape, POINT_TYPE::PT_MID );
 addAnchor( fourth.A, snapFlags, shape, POINT_TYPE::PT_CORNER );
 addAnchor( fourth.Center(), snapFlags, shape, POINT_TYPE::PT_MID );
 break;
 }
 
 case SHAPE_T::SEGMENT:
 addAnchor( start, CORNER | SNAPPABLE, shape, POINT_TYPE::PT_END );
 addAnchor( end, CORNER | SNAPPABLE, shape, POINT_TYPE::PT_END );
 addAnchor( shape->GetCenter(), CORNER | SNAPPABLE, shape,
 POINT_TYPE::PT_MID );
 break;
 
 case SHAPE_T::POLY:
 {
 SHAPE_LINE_CHAIN lc;
 lc.SetClosed( true );
 std::vector<VECTOR2I> poly;
 shape->DupPolyPointsList( poly );
 
 for( const VECTOR2I& p : poly )
 {
 addAnchor( p, CORNER | SNAPPABLE, shape, POINT_TYPE::PT_CORNER );
 lc.Append( p );
 }
 
 addAnchor( lc.NearestPoint( aRefPos ), OUTLINE, aItem );
 break;
 }
 
 case SHAPE_T::BEZIER:
 addAnchor( start, CORNER | SNAPPABLE, shape, POINT_TYPE::PT_END );
 addAnchor( end, CORNER | SNAPPABLE, shape, POINT_TYPE::PT_END );
 KI_FALLTHROUGH;
 
 default:
 addAnchor( shape->GetPosition(), ORIGIN | SNAPPABLE, shape );
 break;
 }
 };
 
 switch( aItem->Type() )
 {
 case PCB_FOOTPRINT_T:
 {
 FOOTPRINT* footprint = static_cast<FOOTPRINT*>( aItem );
 
 for( PAD* pad : footprint->Pads() )
 {
 if( aFrom )
 {
 if( aSelectionFilter && !aSelectionFilter->pads )
 continue;
 }
 else
 {
 if( m_magneticSettings->pads != MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 continue;
 }
 
 if( !checkVisibility( pad ) )
 continue;
 
 if( !pad->GetBoundingBox().Contains( aRefPos ) )
 continue;
 
 pad->Padstack().ForEachUniqueLayer(
 [&]( PCB_LAYER_ID aLayer )
 {
 if( activeLayers.count( aLayer ) )
 handlePadShape( pad, aLayer );
 } );
 }
 
 if( aFrom && aSelectionFilter && !aSelectionFilter->footprints )
 break;
 
 // If the cursor is not over a pad, snap to the anchor (if visible) or the center
 // (if markedly different from the anchor).
 VECTOR2I position = footprint->GetPosition();
 VECTOR2I center = footprint->GetBoundingBox( false ).Centre();
 VECTOR2I grid( GetGrid() );
 
 if( view->IsLayerVisible( LAYER_ANCHOR ) )
 addAnchor( position, ORIGIN | SNAPPABLE, footprint, POINT_TYPE::PT_CENTER );
 
 if( ( center - position ).SquaredEuclideanNorm() > grid.SquaredEuclideanNorm() )
 addAnchor( center, ORIGIN | SNAPPABLE, footprint, POINT_TYPE::PT_CENTER );
 
 break;
 }
 
 case PCB_PAD_T:
 if( aFrom )
 {
 if( aSelectionFilter && !aSelectionFilter->pads )
 break;
 }
 else
 {
 if( m_magneticSettings->pads != MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 break;
 }
 
 if( checkVisibility( aItem ) )
 {
 PAD* pad = static_cast<PAD*>( aItem );
 
 pad->Padstack().ForEachUniqueLayer(
 [&]( PCB_LAYER_ID aLayer )
 {
 if( activeLayers.count( aLayer ) )
 handlePadShape( pad, aLayer );
 } );
 }
 
 break;
 
 case PCB_TEXTBOX_T:
 if( aFrom )
 {
 if( aSelectionFilter && !aSelectionFilter->text )
 break;
 }
 else
 {
 if( !m_magneticSettings->graphics )
 break;
 }
 
 if( checkVisibility( aItem ) )
 handleShape( static_cast<PCB_SHAPE*>( aItem ) );
 
 break;
 
 case PCB_SHAPE_T:
 if( aFrom )
 {
 if( aSelectionFilter && !aSelectionFilter->graphics )
 break;
 }
 else
 {
 if( !m_magneticSettings->graphics )
 break;
 }
 
 if( checkVisibility( aItem ) )
 handleShape( static_cast<PCB_SHAPE*>( aItem ) );
 
 break;
 
 case PCB_TRACE_T:
 case PCB_ARC_T:
 if( aFrom )
 {
 if( aSelectionFilter && !aSelectionFilter->tracks )
 break;
 }
 else
 {
 if( m_magneticSettings->tracks != MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 break;
 }
 
 if( checkVisibility( aItem ) )
 {
 PCB_TRACK* track = static_cast<PCB_TRACK*>( aItem );
 
 addAnchor( track->GetStart(), CORNER | SNAPPABLE, track, POINT_TYPE::PT_END );
 addAnchor( track->GetEnd(), CORNER | SNAPPABLE, track, POINT_TYPE::PT_END );
 addAnchor( track->GetCenter(), ORIGIN, track, POINT_TYPE::PT_MID );
 }
 
 break;
 
 case PCB_MARKER_T:
 case PCB_TARGET_T:
 addAnchor( aItem->GetPosition(), ORIGIN | CORNER | SNAPPABLE, aItem,
 POINT_TYPE::PT_CENTER );
 break;
 
 case PCB_VIA_T:
 if( aFrom )
 {
 if( aSelectionFilter && !aSelectionFilter->vias )
 break;
 }
 else
 {
 if( m_magneticSettings->tracks != MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 break;
 }
 
 if( checkVisibility( aItem ) )
 addAnchor( aItem->GetPosition(), ORIGIN | CORNER | SNAPPABLE, aItem,
 POINT_TYPE::PT_CENTER );
 
 break;
 
 case PCB_ZONE_T:
 if( aFrom && aSelectionFilter && !aSelectionFilter->zones )
 break;
 
 if( checkVisibility( aItem ) )
 {
 const SHAPE_POLY_SET* outline = static_cast<const ZONE*>( aItem )->Outline();
 
 SHAPE_LINE_CHAIN lc;
 lc.SetClosed( true );
 
 for( auto iter = outline->CIterateWithHoles(); iter; iter++ )
 {
 addAnchor( *iter, CORNER | SNAPPABLE, aItem, POINT_TYPE::PT_CORNER );
 lc.Append( *iter );
 }
 
 addAnchor( lc.NearestPoint( aRefPos ), OUTLINE, aItem );
 }
 
 break;
 
 case PCB_DIM_ALIGNED_T:
 case PCB_DIM_ORTHOGONAL_T:
 if( aFrom && aSelectionFilter && !aSelectionFilter->dimensions )
 break;
 
 if( checkVisibility( aItem ) )
 {
 const PCB_DIM_ALIGNED* dim = static_cast<const PCB_DIM_ALIGNED*>( aItem );
 addAnchor( dim->GetCrossbarStart(), CORNER | SNAPPABLE, aItem );
 addAnchor( dim->GetCrossbarEnd(), CORNER | SNAPPABLE, aItem );
 addAnchor( dim->GetStart(), CORNER | SNAPPABLE, aItem );
 addAnchor( dim->GetEnd(), CORNER | SNAPPABLE, aItem );
 }
 
 break;
 
 case PCB_DIM_CENTER_T:
 if( aFrom && aSelectionFilter && !aSelectionFilter->dimensions )
 break;
 
 if( checkVisibility( aItem ) )
 {
 const PCB_DIM_CENTER* dim = static_cast<const PCB_DIM_CENTER*>( aItem );
 addAnchor( dim->GetStart(), CORNER | SNAPPABLE, aItem );
 addAnchor( dim->GetEnd(), CORNER | SNAPPABLE, aItem );
 
 VECTOR2I start( dim->GetStart() );
 VECTOR2I radial( dim->GetEnd() - dim->GetStart() );
 
 for( int i = 0; i < 2; i++ )
 {
 RotatePoint( radial, -ANGLE_90 );
 addAnchor( start + radial, CORNER | SNAPPABLE, aItem );
 }
 }
 
 break;
 
 case PCB_DIM_RADIAL_T:
 if( aFrom && aSelectionFilter && !aSelectionFilter->dimensions )
 break;
 
 if( checkVisibility( aItem ) )
 {
 const PCB_DIM_RADIAL* radialDim = static_cast<const PCB_DIM_RADIAL*>( aItem );
 addAnchor( radialDim->GetStart(), CORNER | SNAPPABLE, aItem );
 addAnchor( radialDim->GetEnd(), CORNER | SNAPPABLE, aItem );
 addAnchor( radialDim->GetKnee(), CORNER | SNAPPABLE, aItem );
 addAnchor( radialDim->GetTextPos(), CORNER | SNAPPABLE, aItem );
 }
 
 break;
 
 case PCB_DIM_LEADER_T:
 if( aFrom && aSelectionFilter && !aSelectionFilter->dimensions )
 break;
 
 if( checkVisibility( aItem ) )
 {
 const PCB_DIM_LEADER* leader = static_cast<const PCB_DIM_LEADER*>( aItem );
 addAnchor( leader->GetStart(), CORNER | SNAPPABLE, aItem );
 addAnchor( leader->GetEnd(), CORNER | SNAPPABLE, aItem );
 addAnchor( leader->GetTextPos(), CORNER | SNAPPABLE, aItem );
 }
 
 break;
 
 case PCB_FIELD_T:
 case PCB_TEXT_T:
 if( aFrom && aSelectionFilter && !aSelectionFilter->text )
 break;
 
 if( checkVisibility( aItem ) )
 addAnchor( aItem->GetPosition(), ORIGIN, aItem );
 
 break;
 
 case PCB_GROUP_T:
 for( BOARD_ITEM* item : static_cast<const PCB_GROUP*>( aItem )->GetItems() )
 {
 if( checkVisibility( item ) )
 computeAnchors( item, aRefPos, aFrom, nullptr );
 }
 
 break;
 
 default:
 break;
 }
}
 
 
PCB_GRID_HELPER::ANCHOR* PCB_GRID_HELPER::nearestAnchor( const VECTOR2I& aPos, int aFlags )
{
 // Do this all in squared distances as we only care about relative distances
 using ecoord = VECTOR2I::extended_type;
 
 ecoord minDist = std::numeric_limits<ecoord>::max();
 std::vector<ANCHOR*> anchorsAtMinDistance;
 
 for( ANCHOR& anchor : m_anchors )
 {
 // There is no need to filter by layers here, as the items are already filtered
 // by layer (if needed) when the anchors are computed.
 if( ( aFlags & anchor.flags ) != aFlags )
 continue;
 
 if( !anchorsAtMinDistance.empty() && anchor.pos == anchorsAtMinDistance.front()->pos )
 {
 // Same distance as the previous best anchor
 anchorsAtMinDistance.push_back( &anchor );
 }
 else
 {
 const double dist = anchor.pos.SquaredDistance( aPos );
 if( dist < minDist )
 {
 // New minimum distance
 minDist = dist;
 anchorsAtMinDistance.clear();
 anchorsAtMinDistance.push_back( &anchor );
 }
 }
 }
 
 // More than one anchor can be at the same distance, for example
 // two lines end-to-end each have the same endpoint anchor.
 // So, check which one has an involved item that's closest to the origin,
 // and use that one (which allows the user to choose which items
 // gets extended - it's the one nearest the cursor)
 ecoord minDistToItem = std::numeric_limits<ecoord>::max();
 ANCHOR* best = nullptr;
 
 // One of the anchors at the minimum distance
 for( ANCHOR* const anchor : anchorsAtMinDistance )
 {
 ecoord distToNearestItem = std::numeric_limits<ecoord>::max();
 for( EDA_ITEM* const item : anchor->items )
 {
 if( !item )
 continue;
 
 std::optional<ecoord> distToThisItem =
 FindSquareDistanceToItem( static_cast<const BOARD_ITEM&>( *item ), aPos );
 
 if( distToThisItem )
 distToNearestItem = std::min( distToNearestItem, *distToThisItem );
 }
 
 // If the item doesn't have any special min-dist handler,
 // just use the distance to the anchor
 distToNearestItem = std::min( distToNearestItem, minDist );
 
 if( distToNearestItem < minDistToItem )
 {
 minDistToItem = distToNearestItem;
 best = anchor;
 }
 }
 
 return best;
}