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) 2018-2021 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 <functional>
#include <board.h>
#include <pcb_dimension.h>
#include <fp_shape.h>
#include <footprint.h>
#include <pad.h>
#include <pcb_group.h>
#include <pcb_track.h>
#include <zone.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 <macros.h>
#include <math/util.h> // for KiROUND
#include <painter.h>
#include <pcbnew_settings.h>
#include <tool/tool_manager.h>
#include <tools/pcb_tool_base.h>
#include <view/view.h>
#include "pcb_grid_helper.h"


PCB_GRID_HELPER::PCB_GRID_HELPER( TOOL_MANAGER* aToolMgr, MAGNETIC_SETTINGS* aMagneticSettings ) :
 GRID_HELPER( aToolMgr ),
 m_magneticSettings( aMagneticSettings )
{
 KIGFX::VIEW* view = m_toolMgr->GetView();
 KIGFX::RENDER_SETTINGS* settings = view->GetPainter()->GetSettings();
 KIGFX::COLOR4D auxItemsColor = settings->GetLayerColor( LAYER_AUX_ITEMS );
 KIGFX::COLOR4D umbilicalColor = settings->GetLayerColor( LAYER_ANCHOR );

 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.SetStyle( KIGFX::ORIGIN_VIEWITEM::CIRCLE_CROSS );
 m_viewSnapPoint.SetColor( auxItemsColor );
 m_viewSnapPoint.SetDrawAtZero( true );
 view->Add( &m_viewSnapPoint );
 view->SetVisible( &m_viewSnapPoint, false );

 m_viewSnapLine.SetStyle( KIGFX::ORIGIN_VIEWITEM::DASH_LINE );
 m_viewSnapLine.SetColor( umbilicalColor );
 m_viewSnapLine.SetDrawAtZero( true );
 view->Add( &m_viewSnapLine );
 view->SetVisible( &m_viewSnapLine, false );
}


VECTOR2I PCB_GRID_HELPER::AlignToSegment( const VECTOR2I& aPoint, const SEG& aSeg )
{
 OPT_VECTOR2I pts[6];

 const int c_gridSnapEpsilon = 2;

 if( !m_enableSnap )
 return aPoint;

 VECTOR2I nearest = Align( aPoint );

 SEG pos_slope( nearest + VECTOR2I( -1, 1 ), nearest + VECTOR2I( 1, -1 ) );
 SEG neg_slope( nearest + VECTOR2I( -1, -1 ), nearest + VECTOR2I( 1, 1 ) );
 int max_i = 2;

 pts[0] = aSeg.A;
 pts[1] = aSeg.B;

 if( !aSeg.ApproxParallel( pos_slope ) )
 pts[max_i++] = aSeg.IntersectLines( pos_slope );

 if( !aSeg.ApproxParallel( neg_slope ) )
 pts[max_i++] = aSeg.IntersectLines( neg_slope );

 int min_d = std::numeric_limits<int>::max();

 for( int i = 0; i < max_i; i++ )
 {
 if( pts[i] && aSeg.Distance( *pts[i] ) <= c_gridSnapEpsilon )
 {
 int d = (*pts[i] - aPoint).EuclideanNorm();

 if( d < min_d )
 {
 min_d = d;
 nearest = *pts[i];
 }
 }
 }

 return nearest;
}


VECTOR2I PCB_GRID_HELPER::AlignToArc( const VECTOR2I& aPoint, const SHAPE_ARC& aArc )
{
 if( !m_enableSnap )
 return aPoint;

 const VECTOR2D gridOffset( GetOrigin() );
 const VECTOR2D gridSize( GetGrid() );

 VECTOR2I nearest( KiROUND( ( aPoint.x - gridOffset.x ) / gridSize.x ) * gridSize.x + gridOffset.x,
 KiROUND( ( aPoint.y - gridOffset.y ) / gridSize.y ) * gridSize.y + gridOffset.y );

 int min_d = std::numeric_limits<int>::max();

 for( auto pt : { aArc.GetP0(), aArc.GetP1() } )
 {
 int d = ( pt - aPoint ).EuclideanNorm();

 if( d < min_d )
 {
 min_d = d;
 nearest = pt;
 }
 else
 break;
 }

 return nearest;
}


VECTOR2I PCB_GRID_HELPER::AlignToNearestPad( const VECTOR2I& aMousePos, PADS& aPads )
{
 clearAnchors();

 for( BOARD_ITEM* item : aPads )
 computeAnchors( item, aMousePos, true );

 double minDist = std::numeric_limits<double>::max();
 ANCHOR* nearestOrigin = nullptr;

 for( ANCHOR& a : m_anchors )
 {
 BOARD_ITEM* item = static_cast<BOARD_ITEM*>( a.item );

 if( ( ORIGIN & a.flags ) != ORIGIN )
 continue;

 if( !item->HitTest( wxPoint( aMousePos.x, aMousePos.y ) ) )
 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 )
{
 clearAnchors();

 for( BOARD_ITEM* item : aItems )
 computeAnchors( item, aMousePos, true );

 double worldScale = m_toolMgr->GetView()->GetGAL()->GetWorldScale();
 double lineSnapMinCornerDistance = 50.0 / worldScale;

 ANCHOR* nearestOutline = nearestAnchor( aMousePos, OUTLINE, LSET::AllLayersMask() );
 ANCHOR* nearestCorner = nearestAnchor( aMousePos, CORNER, LSET::AllLayersMask() );
 ANCHOR* nearestOrigin = nearestAnchor( aMousePos, ORIGIN, LSET::AllLayersMask() );
 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 )
{
 LSET layers;
 std::vector<BOARD_ITEM*> item;

 if( aReferenceItem )
 {
 layers = aReferenceItem->GetLayerSet();
 item.push_back( aReferenceItem );
 }
 else
 {
 layers = LSET::AllLayersMask();
 }

 return BestSnapAnchor( aOrigin, layers, item );
}


VECTOR2I PCB_GRID_HELPER::BestSnapAnchor( const VECTOR2I& aOrigin, const LSET& aLayers,
 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
 double snapScale = snapSize / m_toolMgr->GetView()->GetGAL()->GetWorldScale();
 int snapRange = std::min( KiROUND( snapScale ), GetGrid().x );
 int snapDist = snapRange;

 BOX2I bb( VECTOR2I( aOrigin.x - snapRange / 2, aOrigin.y - snapRange / 2 ),
 VECTOR2I( snapRange, snapRange ) );

 clearAnchors();

 for( BOARD_ITEM* item : queryVisible( bb, aSkip ) )
 computeAnchors( item, aOrigin );

 ANCHOR* nearest = nearestAnchor( aOrigin, SNAPPABLE, aLayers );
 VECTOR2I nearestGrid = Align( aOrigin );

 if( nearest )
 snapDist = nearest->Distance( aOrigin );

 // Existing snap lines need priority over new snaps
 if( m_snapItem && m_enableSnapLine && m_enableSnap )
 {
 bool snapLine = false;
 int x_dist = std::abs( m_viewSnapLine.GetPosition().x - aOrigin.x );
 int y_dist = std::abs( m_viewSnapLine.GetPosition().y - aOrigin.y );

 if( x_dist < snapRange && ( !nearest || snapDist > snapRange ) )
 {
 nearestGrid.x = m_viewSnapLine.GetPosition().x;
 snapLine = true;
 }

 if( y_dist < snapRange && ( !nearest || snapDist > snapRange ) )
 {
 nearestGrid.y = m_viewSnapLine.GetPosition().y;
 snapLine = true;
 }

 if( snapLine && m_skipPoint != VECTOR2I( m_viewSnapLine.GetPosition() ) )
 {
 m_viewSnapLine.SetEndPosition( nearestGrid );

 if( m_toolMgr->GetView()->IsVisible( &m_viewSnapLine ) )
 m_toolMgr->GetView()->Update( &m_viewSnapLine, KIGFX::GEOMETRY );
 else
 m_toolMgr->GetView()->SetVisible( &m_viewSnapLine, true );

 return nearestGrid;
 }
 }

 if( nearest && m_enableSnap )
 {
 if( nearest->Distance( aOrigin ) <= snapRange )
 {
 m_viewSnapPoint.SetPosition( wxPoint( nearest->pos ) );
 m_viewSnapLine.SetPosition( wxPoint( nearest->pos ) );
 m_toolMgr->GetView()->SetVisible( &m_viewSnapLine, false );

 if( m_toolMgr->GetView()->IsVisible( &m_viewSnapPoint ) )
 m_toolMgr->GetView()->Update( &m_viewSnapPoint, KIGFX::GEOMETRY);
 else
 m_toolMgr->GetView()->SetVisible( &m_viewSnapPoint, true );

 m_snapItem = nearest;
 return nearest->pos;
 }
 }

 m_snapItem = nullptr;
 m_toolMgr->GetView()->SetVisible( &m_viewSnapPoint, false );
 m_toolMgr->GetView()->SetVisible( &m_viewSnapLine, false );
 return nearestGrid;
}


BOARD_ITEM* PCB_GRID_HELPER::GetSnapped() const
{
 if( !m_snapItem )
 return nullptr;

 return static_cast<BOARD_ITEM*>( m_snapItem->item );
}


std::set<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;

 KIGFX::VIEW* view = m_toolMgr->GetView();
 RENDER_SETTINGS* settings = view->GetPainter()->GetSettings();
 const std::set<unsigned int>& activeLayers = settings->GetHighContrastLayers();
 bool isHighContrast = settings->GetHighContrast();

 view->Query( aArea, selectedItems );

 for( const KIGFX::VIEW::LAYER_ITEM_PAIR& it : selectedItems )
 {
 BOARD_ITEM* item = static_cast<BOARD_ITEM*>( it.first );

 // If we are in the footprint editor, don't use the footprint itself
 if( static_cast<PCB_TOOL_BASE*>( m_toolMgr->GetCurrentTool() )->IsFootprintEditor()
 && item->Type() == PCB_FOOTPRINT_T )
 {
 continue;
 }

 // The item must be visible and on an active layer
 if( view->IsVisible( item )
 && ( !isHighContrast || activeLayers.count( it.second ) )
 && item->ViewGetLOD( it.second, view ) < view->GetScale() )
 {
 items.insert ( item );
 }
 }

 for( BOARD_ITEM* skipItem : aSkip )
 items.erase( skipItem );

 return items;
}


void PCB_GRID_HELPER::computeAnchors( BOARD_ITEM* aItem, const VECTOR2I& aRefPos, bool aFrom )
{
 KIGFX::VIEW* view = m_toolMgr->GetView();
 RENDER_SETTINGS* settings = view->GetPainter()->GetSettings();
 const std::set<unsigned int>& activeLayers = settings->GetHighContrastLayers();
 bool isHighContrast = settings->GetHighContrast();

 auto handlePadShape =
 [&]( PAD* aPad )
 {
 addAnchor( aPad->GetPosition(), ORIGIN | SNAPPABLE, aPad );

 if( aFrom )
 return;

 const std::shared_ptr<SHAPE> eshape = aPad->GetEffectiveShape( aPad->GetLayer() );

 wxASSERT( eshape->Type() == SH_COMPOUND );
 const std::vector<SHAPE*> shapes =
 static_cast<const SHAPE_COMPOUND*>( eshape.get() )->Shapes();

 for( const SHAPE* shape : shapes )
 {
 switch( shape->Type() )
 {
 case SH_RECT:
 {
 const SHAPE_RECT* rect = static_cast<const SHAPE_RECT*>( shape );
 SHAPE_LINE_CHAIN outline = rect->Outline();

 for( int i = 0; i < outline.SegmentCount(); i++ )
 {
 const SEG& seg = outline.CSegment( i );
 addAnchor( seg.A, OUTLINE | SNAPPABLE, aPad );
 addAnchor( seg.Center(), OUTLINE | SNAPPABLE, aPad );
 }

 break;
 }

 case SH_SEGMENT:
 {
 const SHAPE_SEGMENT* segment = static_cast<const SHAPE_SEGMENT*>( shape );

 int offset = segment->GetWidth() / 2;
 SEG seg = segment->GetSeg();
 VECTOR2I normal = ( seg.B - seg.A ).Resize( offset ).Rotate( -M_PI_2 );

 /*
 * TODO: This creates more snap points than necessary for rounded rect pads
 * because they are built up of overlapping segments. We could fix this if
 * desired by testing these to see if they are "inside" the pad.
 */

 addAnchor( seg.A + normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( seg.A - normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( seg.B + normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( seg.B - normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( seg.Center() + normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( seg.Center() - normal, OUTLINE | SNAPPABLE, aPad );

 normal = normal.Rotate( M_PI_2 );

 addAnchor( seg.A - normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( seg.B + normal, OUTLINE | SNAPPABLE, aPad );
 break;
 }

 case SH_CIRCLE:
 {
 const SHAPE_CIRCLE* circle = static_cast<const SHAPE_CIRCLE*>( shape );

 int r = circle->GetRadius();
 VECTOR2I start = circle->GetCenter();

 addAnchor( start + VECTOR2I( -r, 0 ), OUTLINE | SNAPPABLE, aPad );
 addAnchor( start + VECTOR2I( r, 0 ), OUTLINE | SNAPPABLE, aPad );
 addAnchor( start + VECTOR2I( 0, -r ), OUTLINE | SNAPPABLE, aPad );
 addAnchor( start + VECTOR2I( 0, r ), OUTLINE | SNAPPABLE, aPad );
 break;
 }

 case SH_ARC:
 {
 const SHAPE_ARC* arc = static_cast<const SHAPE_ARC*>( shape );

 addAnchor( arc->GetP0(), OUTLINE | SNAPPABLE, aPad );
 addAnchor( arc->GetP1(), OUTLINE | SNAPPABLE, aPad );
 addAnchor( arc->GetArcMid(), OUTLINE | SNAPPABLE, aPad );
 break;
 }

 case SH_SIMPLE:
 {
 const SHAPE_SIMPLE* poly = static_cast<const SHAPE_SIMPLE*>( shape );

 for( size_t i = 0; i < poly->GetSegmentCount(); i++ )
 {
 const SEG& seg = poly->GetSegment( i );

 addAnchor( seg.A, OUTLINE | SNAPPABLE, aPad );
 addAnchor( seg.Center(), OUTLINE | SNAPPABLE, aPad );

 if( i == poly->GetSegmentCount() - 1 )
 addAnchor( seg.B, OUTLINE | SNAPPABLE, aPad );
 }

 break;
 }

 case SH_POLY_SET:
 case SH_LINE_CHAIN:
 case SH_COMPOUND:
 case SH_POLY_SET_TRIANGLE:
 case SH_NULL:
 default:
 break;
 }
 }
 };

 switch( aItem->Type() )
 {
 case PCB_FOOTPRINT_T:
 {
 FOOTPRINT* footprint = static_cast<FOOTPRINT*>( aItem );

 for( PAD* pad : footprint->Pads() )
 {
 // Getting pads from the footprint requires re-checking that the pad is shown
 if( ( aFrom || m_magneticSettings->pads == MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 && pad->GetBoundingBox().Contains( wxPoint( aRefPos.x, aRefPos.y ) )
 && view->IsVisible( pad )
 && ( !isHighContrast || activeLayers.count( pad->GetLayer() ) )
 && pad->ViewGetLOD( pad->GetLayer(), view ) < view->GetScale() )
 {
 handlePadShape( pad );
 break;
 }
 }

 // if the cursor is not over a pad, then drag the footprint by its origin
 VECTOR2I position = footprint->GetPosition();
 addAnchor( position, ORIGIN | SNAPPABLE, footprint );

 // Add the footprint center point if it is markedly different from the origin
 VECTOR2I center = footprint->GetBoundingBox( false, false ).Centre();
 VECTOR2I grid( GetGrid() );

 if( ( center - position ).SquaredEuclideanNorm() > grid.SquaredEuclideanNorm() )
 addAnchor( center, ORIGIN | SNAPPABLE, footprint );

 break;
 }

 case PCB_PAD_T:
 {
 if( aFrom || m_magneticSettings->pads == MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 {
 PAD* pad = static_cast<PAD*>( aItem );
 handlePadShape( pad );
 }

 break;
 }

 case PCB_FP_SHAPE_T:
 case PCB_SHAPE_T:
 {
 if( !m_magneticSettings->graphics )
 break;

 PCB_SHAPE* shape = static_cast<PCB_SHAPE*>( aItem );
 VECTOR2I start = shape->GetStart();
 VECTOR2I end = shape->GetEnd();

 switch( shape->GetShape() )
 {
 case SHAPE_T::CIRCLE:
 {
 int r = ( start - end ).EuclideanNorm();

 addAnchor( start, ORIGIN | SNAPPABLE, shape );
 addAnchor( start + VECTOR2I( -r, 0 ), OUTLINE | SNAPPABLE, shape );
 addAnchor( start + VECTOR2I( r, 0 ), OUTLINE | SNAPPABLE, shape );
 addAnchor( start + VECTOR2I( 0, -r ), OUTLINE | SNAPPABLE, shape );
 addAnchor( start + VECTOR2I( 0, r ), OUTLINE | SNAPPABLE, shape );
 break;
 }

 case SHAPE_T::ARC:
 addAnchor( shape->GetStart(), CORNER | SNAPPABLE, shape );
 addAnchor( shape->GetEnd(), CORNER | SNAPPABLE, shape );
 addAnchor( shape->GetArcMid(), CORNER | SNAPPABLE, shape );
 addAnchor( shape->GetCenter(), ORIGIN | SNAPPABLE, shape );
 break;

 case SHAPE_T::RECT:
 {
 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 );

 addAnchor( first.A, CORNER | SNAPPABLE, shape );
 addAnchor( first.Center(), CORNER | SNAPPABLE, shape );
 addAnchor( second.A, CORNER | SNAPPABLE, shape );
 addAnchor( second.Center(), CORNER | SNAPPABLE, shape );
 addAnchor( third.A, CORNER | SNAPPABLE, shape );
 addAnchor( third.Center(), CORNER | SNAPPABLE, shape );
 addAnchor( fourth.A, CORNER | SNAPPABLE, shape );
 addAnchor( fourth.Center(), CORNER | SNAPPABLE, shape );
 break;
 }

 case SHAPE_T::SEGMENT:
 addAnchor( start, CORNER | SNAPPABLE, shape );
 addAnchor( end, CORNER | SNAPPABLE, shape );
 addAnchor( shape->GetCenter(), CORNER | SNAPPABLE, shape );
 break;

 case SHAPE_T::POLY:
 {
 SHAPE_LINE_CHAIN lc;
 lc.SetClosed( true );
 std::vector<wxPoint> poly;
 shape->DupPolyPointsList( poly );

 for( const wxPoint& p : poly )
 {
 addAnchor( p, CORNER | SNAPPABLE, shape );
 lc.Append( p );
 }

 addAnchor( lc.NearestPoint( aRefPos ), OUTLINE, aItem );
 break;
 }

 case SHAPE_T::BEZIER:
 addAnchor( start, CORNER | SNAPPABLE, shape );
 addAnchor( end, CORNER | SNAPPABLE, shape );
 KI_FALLTHROUGH;

 default:
 addAnchor( shape->GetPosition(), ORIGIN | SNAPPABLE, shape );
 break;
 }
 break;
 }

 case PCB_TRACE_T:
 case PCB_ARC_T:
 {
 if( aFrom || m_magneticSettings->tracks == MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 {
 PCB_TRACK* track = static_cast<PCB_TRACK*>( aItem );

 addAnchor( track->GetStart(), CORNER | SNAPPABLE, track );
 addAnchor( track->GetEnd(), CORNER | SNAPPABLE, track );
 addAnchor( track->GetCenter(), ORIGIN, track);
 }

 break;
 }

 case PCB_MARKER_T:
 case PCB_TARGET_T:
 addAnchor( aItem->GetPosition(), ORIGIN | CORNER | SNAPPABLE, aItem );
 break;

 case PCB_VIA_T:
 {
 if( aFrom || m_magneticSettings->tracks == MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 addAnchor( aItem->GetPosition(), ORIGIN | CORNER | SNAPPABLE, aItem );

 break;
 }

 case PCB_ZONE_T:
 {
 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, aItem );
 lc.Append( *iter );
 }

 addAnchor( lc.NearestPoint( aRefPos ), OUTLINE, aItem );

 break;
 }

 case PCB_DIM_ALIGNED_T:
 case PCB_DIM_ORTHOGONAL_T:
 {
 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:
 {
 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++ )
 {
 radial = radial.Rotate( DEG2RAD( 90 ) );
 addAnchor( start + radial, CORNER | SNAPPABLE, aItem );
 }

 break;
 }

 case PCB_DIM_LEADER_T:
 {
 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->Text().GetPosition(), CORNER | SNAPPABLE, aItem );
 break;
 }

 case PCB_FP_TEXT_T:
 case PCB_TEXT_T:
 addAnchor( aItem->GetPosition(), ORIGIN, aItem );
 break;

 case PCB_GROUP_T:
 {
 const PCB_GROUP* group = static_cast<const PCB_GROUP*>( aItem );

 for( BOARD_ITEM* item : group->GetItems() )
 computeAnchors( item, aRefPos, aFrom );

 break;
 }

 default:
 break;
 }
}


PCB_GRID_HELPER::ANCHOR* PCB_GRID_HELPER::nearestAnchor( const VECTOR2I& aPos, int aFlags,
 LSET aMatchLayers )
{
 double minDist = std::numeric_limits<double>::max();
 ANCHOR* best = nullptr;

 for( ANCHOR& a : m_anchors )
 {
 BOARD_ITEM* item = static_cast<BOARD_ITEM*>( a.item );

 if( ( aMatchLayers & item->GetLayerSet() ) == 0 )
 continue;

 if( ( aFlags & a.flags ) != aFlags )
 continue;

 double dist = a.Distance( aPos );

 if( dist < minDist )
 {
 minDist = dist;
 best = &a;
 }
 }

 return best;
}