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 <functional>
#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 <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 )
{
 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, 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( aMousePos ) )
 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,
 const SELECTION_FILTER_OPTIONS* aSelectionFilter )
{
 clearAnchors();
 
 for( BOARD_ITEM* item : aItems )
 computeAnchors( item, aMousePos, true, aSelectionFilter );
 
 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
 // see https://gitlab.com/kicad/code/kicad/-/issues/12303
 int snapScale = KiROUND( snapSize / m_toolMgr->GetView()->GetGAL()->GetWorldScale() );
 int snapRange = m_enableGrid ? std::min( snapScale, GetVisibleGrid().x ) : snapScale;
 int snapDist = snapRange;
 
 //Respect limits of coordinates representation
 BOX2I bb;
 bb.SetOrigin( GetClampedCoords<double, int>( VECTOR2D( aOrigin ) - snapRange / 2.0 ) );
 bb.SetEnd( GetClampedCoords<double, int>( VECTOR2D( aOrigin ) + snapRange / 2.0 ) );
 
 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( nearest->pos );
 m_viewSnapLine.SetPosition( 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<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,
 const 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 handlePadShape =
 [&]( PAD* aPad )
 {
 addAnchor( aPad->GetPosition(), ORIGIN | SNAPPABLE, aPad );
 
 if( aFrom )
 return;
 
 switch( aPad->GetShape() )
 {
 case PAD_SHAPE::CIRCLE:
 {
 int r = aPad->GetSizeX() / 2;
 VECTOR2I center = aPad->ShapePos();
 
 addAnchor( center + VECTOR2I( -r, 0 ), OUTLINE | SNAPPABLE, aPad );
 addAnchor( center + VECTOR2I( r, 0 ), OUTLINE | SNAPPABLE, aPad );
 addAnchor( center + VECTOR2I( 0, -r ), OUTLINE | SNAPPABLE, aPad );
 addAnchor( center + VECTOR2I( 0, r ), OUTLINE | SNAPPABLE, aPad );
 break;
 }
 
 case PAD_SHAPE::OVAL:
 {
 VECTOR2I pos = aPad->ShapePos();
 VECTOR2I half_size = aPad->GetSize() / 2;
 int half_width = std::min( half_size.x, half_size.y );
 VECTOR2I half_len( half_size.x - half_width, half_size.y - half_width );
 
 RotatePoint( half_len, aPad->GetOrientation() );
 
 VECTOR2I a( pos - half_len );
 VECTOR2I b( pos + half_len );
 VECTOR2I normal = b - a;
 normal.Resize( half_width );
 RotatePoint( normal, ANGLE_90 );
 
 addAnchor( a + normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( a - normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( b + normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( b - normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( pos + normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( pos - normal, OUTLINE | SNAPPABLE, aPad );
 
 RotatePoint( normal, -ANGLE_90 );
 
 addAnchor( a - normal, OUTLINE | SNAPPABLE, aPad );
 addAnchor( b + normal, OUTLINE | SNAPPABLE, aPad );
 break;
 }
 
 case PAD_SHAPE::RECTANGLE:
 case PAD_SHAPE::TRAPEZOID:
 case PAD_SHAPE::ROUNDRECT:
 case PAD_SHAPE::CHAMFERED_RECT:
 {
 VECTOR2I half_size( aPad->GetSize() / 2 );
 VECTOR2I trap_delta( 0, 0 );
 
 if( aPad->GetShape() == PAD_SHAPE::TRAPEZOID )
 trap_delta = aPad->GetDelta() / 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() );
 
 for( size_t ii = 0; ii < corners.GetSegmentCount(); ++ii )
 {
 const SEG& seg = corners.GetSegment( ii );
 addAnchor( seg.A, OUTLINE | SNAPPABLE, aPad );
 addAnchor( seg.Center(), OUTLINE | SNAPPABLE, aPad );
 
 if( ii == corners.GetSegmentCount() - 1 )
 addAnchor( seg.B, OUTLINE | SNAPPABLE, aPad );
 }
 
 break;
 }
 
 default:
 {
 const std::shared_ptr<SHAPE_POLY_SET>& outline = aPad->GetEffectivePolygon();
 
 if( !outline->IsEmpty() )
 {
 for( const VECTOR2I& pt : outline->Outline( 0 ).CPoints() )
 addAnchor( pt, OUTLINE | SNAPPABLE, aPad );
 }
 
 break;
 }
 }
 };
 
 auto handleShape =
 [&]( PCB_SHAPE* shape )
 {
 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<VECTOR2I> poly;
 shape->DupPolyPointsList( poly );
 
 for( const VECTOR2I& 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;
 }
 };
 
 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( !view->IsVisible( pad ) || !pad->GetBoundingBox().Contains( aRefPos ) )
 continue;
 
 // Getting pads from a footprint requires re-checking that the pads are shown
 bool onActiveLayer = !isHighContrast;
 bool isLODVisible = false;
 
 for( PCB_LAYER_ID layer : pad->GetLayerSet().Seq() )
 {
 if( !onActiveLayer && activeLayers.count( layer ) )
 onActiveLayer = true;
 
 if( !isLODVisible && pad->ViewGetLOD( layer, view ) < view->GetScale() )
 isLODVisible = true;
 
 if( onActiveLayer && isLODVisible )
 {
 handlePadShape( pad );
 break;
 }
 }
 }
 
 if( aFrom && aSelectionFilter && !aSelectionFilter->footprints )
 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 )
 {
 if( aSelectionFilter && !aSelectionFilter->pads )
 break;
 }
 else
 {
 if( m_magneticSettings->pads != MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 break;
 }
 
 handlePadShape( static_cast<PAD*>( aItem ) );
 
 break;
 
 case PCB_TEXTBOX_T:
 if( aFrom )
 {
 if( aSelectionFilter && !aSelectionFilter->text )
 break;
 }
 else
 {
 if( !m_magneticSettings->graphics )
 break;
 }
 
 handleShape( static_cast<PCB_SHAPE*>( aItem ) );
 break;
 
 case PCB_SHAPE_T:
 if( aFrom )
 {
 if( aSelectionFilter && !aSelectionFilter->graphics )
 break;
 }
 else
 {
 if( !m_magneticSettings->graphics )
 break;
 }
 
 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;
 }
 
 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 )
 {
 if( aSelectionFilter && !aSelectionFilter->vias )
 break;
 }
 else
 {
 if( m_magneticSettings->tracks != MAGNETIC_OPTIONS::CAPTURE_ALWAYS )
 break;
 }
 
 addAnchor( aItem->GetPosition(), ORIGIN | CORNER | SNAPPABLE, aItem );
 
 break;
 
 case PCB_ZONE_T:
 {
 if( aFrom && aSelectionFilter && !aSelectionFilter->zones )
 break;
 
 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 );
 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;
 
 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;
 
 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;
 
 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;
 
 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_TEXT_T:
 if( aFrom && aSelectionFilter && !aSelectionFilter->text )
 break;
 
 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;
}