grid_helper.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright The 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, see <https://www.gnu.org/licenses/>.
 */
 
#include "tool/grid_helper.h"
 
#include <array>
#include <functional>
#include <cmath>
#include <limits>
#include <numbers>
 
#include <advanced_config.h>
#include <trace_helpers.h>
#include <wx/log.h>
#include <gal/graphics_abstraction_layer.h>
#include <math/util.h> // for KiROUND
#include <math/vector2d.h>
#include <tool/tool_manager.h>
#include <tool/tools_holder.h>
#include <view/view.h>
#include <settings/app_settings.h>
#include <gal/painter.h>
 
 
GRID_HELPER::GRID_HELPER() :
        m_toolMgr( nullptr ), m_snapManager( m_constructionGeomPreview )
{
    m_maskTypes = ALL;
    m_enableSnap = true;
    m_enableSnapLine = true;
    m_enableGrid = true;
    m_snapItem = std::nullopt;
 
    // Default-constructing the point would park it on the origin and suppress snapping there
    ClearSkipPoint();
 
    m_manualGrid = VECTOR2D( 1, 1 );
    m_manualVisibleGrid = VECTOR2D( 1, 1 );
    m_manualOrigin = VECTOR2I( 0, 0 );
    m_manualGridSnapping = true;
}
 
 
GRID_HELPER::GRID_HELPER( TOOL_MANAGER* aToolMgr, int aConstructionLayer ) :
        GRID_HELPER()
{
    m_toolMgr = aToolMgr;
 
    if( !m_toolMgr )
        return;
 
    KIGFX::VIEW*            view = m_toolMgr->GetView();
    KIGFX::RENDER_SETTINGS* settings = view->GetPainter()->GetSettings();
    KIGFX::COLOR4D          constructionColor = settings->GetLayerColor( aConstructionLayer );
 
    m_constructionGeomPreview.SetColor( constructionColor );
    m_constructionGeomPreview.SetPersistentColor( constructionColor );
 
    view->Add( &m_constructionGeomPreview );
    view->SetVisible( &m_constructionGeomPreview, false );
 
    m_snapManager.SetUpdateCallback(
            [view, this]( bool aAnythingShown )
            {
                const bool currentlyVisible = view->IsVisible( &m_constructionGeomPreview );
 
                if( currentlyVisible && aAnythingShown )
                {
                    view->Update( &m_constructionGeomPreview, KIGFX::GEOMETRY );
                }
                else
                {
                    view->SetVisible( &m_constructionGeomPreview, aAnythingShown );
                }
 
                // Headless tests and benchmarks have a view but no canvas holder.
                if( TOOLS_HOLDER* holder = m_toolMgr->GetToolHolder() )
                    holder->RefreshCanvas();
            } );
 
    // Initialise manual values from view for compatibility
    m_manualGrid = view->GetGAL()->GetGridSize();
    m_manualVisibleGrid = view->GetGAL()->GetVisibleGridSize();
    m_manualOrigin = VECTOR2I( view->GetGAL()->GetGridOrigin() );
    m_manualGridSnapping = view->GetGAL()->GetGridSnapping();
}
 
 
GRID_HELPER::~GRID_HELPER()
{
    if( !m_toolMgr )
        return;
 
    KIGFX::VIEW& view = *m_toolMgr->GetView();
    view.Remove( &m_constructionGeomPreview );
 
    if( m_anchorDebug )
        view.Remove( m_anchorDebug.get() );
}
 
 
KIGFX::ANCHOR_DEBUG* GRID_HELPER::enableAndGetAnchorDebug()
{
    static bool permitted = ADVANCED_CFG::GetCfg().m_EnableSnapAnchorsDebug;
 
    if( !m_toolMgr )
        return nullptr;
 
    if( permitted && !m_anchorDebug )
    {
        KIGFX::VIEW& view = *m_toolMgr->GetView();
        m_anchorDebug = std::make_unique<KIGFX::ANCHOR_DEBUG>();
        view.Add( m_anchorDebug.get() );
        view.SetVisible( m_anchorDebug.get(), true );
    }
 
    return m_anchorDebug.get();
}
 
 
void GRID_HELPER::showConstructionGeometry( bool aShow )
{
    if( m_toolMgr )
        m_toolMgr->GetView()->SetVisible( &m_constructionGeomPreview, aShow );
}
 
 
void GRID_HELPER::SetSnapLineDirections( const std::vector<VECTOR2I>& aDirections )
{
    m_snapManager.GetSnapLineManager().SetDirections( aDirections );
}
 
 
void GRID_HELPER::SetSnapLineOrigin( const VECTOR2I& aOrigin )
{
    m_snapManager.GetSnapLineManager().SetSnapLineOrigin( aOrigin );
}
 
void GRID_HELPER::SetSnapLineEnd( const std::optional<VECTOR2I>& aEnd )
{
    m_snapManager.GetSnapLineManager().SetSnapLineEnd( aEnd );
}
 
void GRID_HELPER::ClearSnapLine()
{
    m_snapManager.GetSnapLineManager().ClearSnapLine();
}
 
 
void GRID_HELPER::applySnapResultGuides( const SNAP_RESULT& aResult )
{
    std::vector<SEG>  dimensionBrackets;
    const SNAP_GUIDE* snapLine = nullptr;
 
    for( const SNAP_GUIDE& guide : aResult.guides )
    {
        if( guide.style == SNAP_GUIDE_STYLE::DIMENSION_BRACKET )
        {
            dimensionBrackets.emplace_back( guide.start, guide.end );
            wxLogTrace( wxT( "KICAD_SNAP_RESOLVER" ), "bracket axis=%c start=(%d,%d) end=(%d,%d)",
                        guide.start.x == guide.end.x ? 'y' : 'x', guide.start.x, guide.start.y, guide.end.x,
                        guide.end.y );
        }
        else if( !snapLine )
        {
            snapLine = &guide;
        }
    }
 
    m_snapManager.SetDimensionBrackets( std::move( dimensionBrackets ) );
 
    if( snapLine )
    {
        SNAP_LINE_MANAGER& manager = m_snapManager.GetSnapLineManager();
        manager.SetSnapLineOrigin( snapLine->start );
        manager.SetSnapLineEnd( snapLine->end );
    }
}
 
 
SNAP_REFERENCE_PREFERENCE GRID_HELPER::classifyReference( const VECTOR2I& aPoint, const BOX2I& aBounds,
                                                          bool aAnchorPoint )
{
    if( aAnchorPoint )
        return { SNAP_REFERENCE_KIND::ANCHOR_POINT, -1, -1 };
 
    const std::array<int, 3> xFeatures = { aBounds.GetLeft(), aBounds.Centre().x, aBounds.GetRight() };
    const std::array<int, 3> yFeatures = { aBounds.GetTop(), aBounds.Centre().y, aBounds.GetBottom() };
    const auto               nearestFeature = []( int aCoordinate, const std::array<int, 3>& aFeatures )
    {
        int best = 0;
 
        for( int index = 1; index < 3; ++index )
        {
            if( std::abs( aCoordinate - aFeatures[index] ) < std::abs( aCoordinate - aFeatures[best] ) )
            {
                best = index;
            }
        }
 
        return best;
    };
 
    return { SNAP_REFERENCE_KIND::BOUNDS_FEATURE, nearestFeature( aPoint.x, xFeatures ),
             nearestFeature( aPoint.y, yFeatures ) };
}
 
 
void GRID_HELPER::setLayoutReference( const VECTOR2I& aPoint, const std::optional<BOX2I>& aBounds, bool aAnchorPoint )
{
    if( aBounds )
        m_layoutReferencePreference = classifyReference( aPoint, *aBounds, aAnchorPoint );
    else
        m_layoutReferencePreference = {};
 
    const char* referenceKind = "none";
 
    if( m_layoutReferencePreference.kind == SNAP_REFERENCE_KIND::BOUNDS_FEATURE )
        referenceKind = "bounds";
    else if( m_layoutReferencePreference.kind == SNAP_REFERENCE_KIND::ANCHOR_POINT )
        referenceKind = "anchor-point";
 
    wxLogTrace( wxT( "KICAD_SNAP_RESOLVER" ), "drag reference kind=%s x-feature=%d y-feature=%d", referenceKind,
                m_layoutReferencePreference.horizontalFeature, m_layoutReferencePreference.verticalFeature );
}
 
 
std::optional<VECTOR2I> GRID_HELPER::SnapToConstructionLines( const VECTOR2I& aPoint, const VECTOR2I& aNearestGrid,
                                                              const VECTOR2D& aGrid, double aSnapRange ) const
{
    const SNAP_LINE_MANAGER& snapLineManager = m_snapManager.GetSnapLineManager();
    const OPT_VECTOR2I&      snapOrigin = snapLineManager.GetSnapLineOrigin();
 
    wxLogTrace( traceSnap, "SnapToConstructionLines: aPoint=(%d, %d), nearestGrid=(%d, %d), snapRange=%.1f", aPoint.x,
                aPoint.y, aNearestGrid.x, aNearestGrid.y, aSnapRange );
 
    if( !snapOrigin || snapLineManager.GetDirections().empty() )
    {
        wxLogTrace( traceSnap, "  No snap origin or no directions, returning nullopt" );
        return std::nullopt;
    }
 
    const VECTOR2I& origin = *snapOrigin;
 
    wxLogTrace( traceSnap, "  snapOrigin=(%d, %d), directions count=%zu",
                origin.x, origin.y, snapLineManager.GetDirections().size() );
 
    const std::vector<VECTOR2I>& directions = snapLineManager.GetDirections();
    const std::optional<int>     activeDirection = snapLineManager.GetActiveDirection();
 
    if( activeDirection )
        wxLogTrace( traceSnap, "  activeDirection=%d", *activeDirection );
 
    const VECTOR2D originVec( origin );
    const VECTOR2D cursorVec( aPoint );
    const VECTOR2D delta = cursorVec - originVec;
 
    std::optional<VECTOR2I> bestPoint;
    double                  bestPerp = std::numeric_limits<double>::max();
    double                  bestDistance = std::numeric_limits<double>::max();
 
    for( size_t ii = 0; ii < directions.size(); ++ii )
    {
        const VECTOR2I& dir = directions[ii];
        VECTOR2D        dirVector( dir );
        double          dirLength = dirVector.EuclideanNorm();
 
        if( dirLength == 0.0 )
        {
            wxLogTrace( traceSnap, "    Direction %zu: zero length, skipping", ii );
            continue;
        }
 
        VECTOR2D dirUnit = dirVector / dirLength;
 
        double    distanceAlong = delta.Dot( dirUnit );
        VECTOR2D  projection = originVec + dirUnit * distanceAlong;
        VECTOR2D  offset = delta - dirUnit * distanceAlong;
        double    perpDistance = offset.EuclideanNorm();
 
        double snapThreshold = aSnapRange;
 
        if( activeDirection && *activeDirection == static_cast<int>( ii ) )
        {
            snapThreshold *= 1.5;
            wxLogTrace( traceSnap, "    Direction %zu: ACTIVE, increased snapThreshold=%.1f", ii, snapThreshold );
        }
 
        wxLogTrace( traceSnap, "    Direction %zu: dir=(%d, %d), perpDist=%.1f, threshold=%.1f",
                    ii, dir.x, dir.y, perpDistance, snapThreshold );
 
        if( perpDistance > snapThreshold )
        {
            wxLogTrace( traceSnap, "      perpDistance > threshold, skipping" );
            continue;
        }
 
        VECTOR2D candidate = projection;
 
        if( canUseGrid() )
        {
            if( dir.x == 0 && dir.y != 0 )
            {
                // Vertical construction line: snap to grid intersection
                candidate.x = origin.x;
                candidate.y = aNearestGrid.y;
                wxLogTrace( traceSnap, "      Vertical snap: candidate=(%d, %d)", (int) candidate.x,
                            (int) candidate.y );
            }
            else if( dir.y == 0 && dir.x != 0 )
            {
                // Horizontal construction line: snap to grid intersection
                candidate.x = aNearestGrid.x;
                candidate.y = origin.y;
                wxLogTrace( traceSnap, "      Horizontal snap: candidate=(%d, %d)", (int) candidate.x,
                            (int) candidate.y );
            }
            else
            {
                // Diagonal construction line: find nearest grid intersection along the line
                // We need to find grid points near the projection point and pick the closest
                // one that lies on the construction line
 
                // Get the grid origin for proper alignment
                VECTOR2D gridOrigin( GetOrigin() );
 
                // Calculate the projection point relative to grid
                VECTOR2D relProjection = projection - gridOrigin;
 
                // Find nearby grid points (check 9 points in a 3x3 grid around the projection)
                std::vector<VECTOR2D> gridPoints;
                for( int dx = -1; dx <= 1; ++dx )
                {
                    for( int dy = -1; dy <= 1; ++dy )
                    {
                        double gridX = std::round( relProjection.x / aGrid.x ) * aGrid.x + dx * aGrid.x;
                        double gridY = std::round( relProjection.y / aGrid.y ) * aGrid.y + dy * aGrid.y;
                        gridPoints.push_back( VECTOR2D( gridX + gridOrigin.x, gridY + gridOrigin.y ) );
                    }
                }
 
                // Find the grid point closest to the construction line
                double   bestGridDist = std::numeric_limits<double>::max();
                VECTOR2D bestGridPt = projection;
 
                for( const VECTOR2D& gridPt : gridPoints )
                {
                    // Calculate perpendicular distance from grid point to construction line
                    VECTOR2D gridDelta = gridPt - originVec;
                    double   gridDistAlong = gridDelta.Dot( dirUnit );
                    VECTOR2D gridProjection = originVec + dirUnit * gridDistAlong;
                    double   gridPerpDist = ( gridPt - gridProjection ).EuclideanNorm();
 
                    // Also consider distance from cursor
                    double distFromCursor = ( gridPt - cursorVec ).EuclideanNorm();
 
                    // Prefer grid points that are close to the line and close to cursor
                    double score = gridPerpDist + distFromCursor * 0.1;
 
                    if( score < bestGridDist )
                    {
                        bestGridDist = score;
                        bestGridPt = gridPt;
                    }
                }
 
                candidate = bestGridPt;
                wxLogTrace( traceSnap, "      Diagonal snap: candidate=(%.1f, %.1f), perpDist=%.1f",
                            candidate.x, candidate.y, bestGridDist );
            }
        }
        else
        {
            wxLogTrace( traceSnap, "      Grid disabled, using projection candidate=(%.1f, %.1f)",
                        candidate.x, candidate.y );
        }
 
        VECTOR2I candidateInt = KiROUND( candidate );
 
        if( candidateInt == m_skipPoint )
        {
            wxLogTrace( traceSnap, "      candidateInt matches m_skipPoint, skipping" );
            continue;
        }
 
        VECTOR2D candidateDelta( candidateInt.x - aPoint.x, candidateInt.y - aPoint.y );
        double    candidateDistance = candidateDelta.EuclideanNorm();
 
        wxLogTrace( traceSnap, "      candidateInt=(%d, %d), candidateDist=%.1f",
                    candidateInt.x, candidateInt.y, candidateDistance );
 
        if( perpDistance < bestPerp
                || ( std::abs( perpDistance - bestPerp ) < 1e-9 && candidateDistance < bestDistance ) )
        {
            wxLogTrace( traceSnap, "      NEW BEST: perpDist=%.1f, candDist=%.1f", perpDistance, candidateDistance );
            bestPerp = perpDistance;
            bestDistance = candidateDistance;
            bestPoint = candidateInt;
        }
    }
 
    if( bestPoint )
    {
        wxLogTrace( traceSnap, "  RETURNING bestPoint=(%d, %d)", bestPoint->x, bestPoint->y );
    }
    else
    {
        wxLogTrace( traceSnap, "  RETURNING nullopt (no valid snap found)" );
    }
 
    return bestPoint;
}
 
 
void GRID_HELPER::updateSnapPoint( const TYPED_POINT2I& aPoint )
{
    if( !m_toolMgr )
        return;
 
    m_viewSnapPoint.SetPosition( aPoint.m_point );
    m_viewSnapPoint.SetSnapTypes( aPoint.m_types );
 
    if( m_toolMgr->GetView()->IsVisible( &m_viewSnapPoint ) )
        m_toolMgr->GetView()->Update( &m_viewSnapPoint, KIGFX::GEOMETRY );
    else
        m_toolMgr->GetView()->SetVisible( &m_viewSnapPoint, true );
}
 
 
VECTOR2I GRID_HELPER::GetGrid() const
{
    VECTOR2D size = m_toolMgr ? m_toolMgr->GetView()->GetGAL()->GetGridSize() : m_manualGrid;
    return VECTOR2I( KiROUND( size.x ), KiROUND( size.y ) );
}
 
 
VECTOR2D GRID_HELPER::GetVisibleGrid() const
{
    return m_toolMgr ? m_toolMgr->GetView()->GetGAL()->GetVisibleGridSize() : m_manualVisibleGrid;
}
 
 
VECTOR2I GRID_HELPER::GetOrigin() const
{
    if( m_toolMgr )
    {
        VECTOR2D origin = m_toolMgr->GetView()->GetGAL()->GetGridOrigin();
        return VECTOR2I( origin );
    }
 
    return m_manualOrigin;
}
 
 
GRID_HELPER_GRIDS GRID_HELPER::GetSelectionGrid( const SELECTION& aSelection ) const
{
    GRID_HELPER_GRIDS grid = GetItemGrid( aSelection.Front() );
 
    // Find the largest grid of all the items and use that
    for( EDA_ITEM* item : aSelection )
    {
        GRID_HELPER_GRIDS itemGrid = GetItemGrid( item );
 
        if( GetGridSize( itemGrid ) > GetGridSize( grid ) )
            grid = itemGrid;
    }
 
    return grid;
}
 
 
VECTOR2D GRID_HELPER::GetGridSize( GRID_HELPER_GRIDS aGrid ) const
{
    return m_toolMgr ? m_toolMgr->GetView()->GetGAL()->GetGridSize() : m_manualGrid;
}
 
 
void GRID_HELPER::SetAuxAxes( bool aEnable, const VECTOR2I& aOrigin )
{
    if( aEnable )
    {
        m_auxAxis = aOrigin;
        m_viewAxis.SetPosition( aOrigin );
        if( m_toolMgr )
            m_toolMgr->GetView()->SetVisible( &m_viewAxis, true );
    }
    else
    {
        m_auxAxis = std::optional<VECTOR2I>();
        if( m_toolMgr )
            m_toolMgr->GetView()->SetVisible( &m_viewAxis, false );
    }
}
 
 
VECTOR2I GRID_HELPER::AlignGrid( const VECTOR2I& aPoint ) const
{
    return computeNearest( aPoint, GetGrid(), GetOrigin() );
}
 
 
VECTOR2I GRID_HELPER::AlignGrid( const VECTOR2I& aPoint, const VECTOR2D& aGrid,
                                 const VECTOR2D& aOffset ) const
{
    // Round the grid size and offset rather than relying on the implicit VECTOR2D->VECTOR2I
    // truncation in computeNearest. Grid sizes that aren't exact in IEEE 754 (e.g., 0.254mm =
    // 10 mil) would otherwise truncate to the wrong integer (253999 instead of 254000),
    // producing positions that aren't true grid multiples.
    return computeNearest( aPoint, KiROUND( aGrid ), KiROUND( aOffset ) );
}
 
 
VECTOR2I GRID_HELPER::computeNearest( const VECTOR2I& aPoint, const VECTOR2I& aGrid,
                                      const VECTOR2I& aOffset ) const
{
    return VECTOR2I( KiROUND( (double) ( aPoint.x - aOffset.x ) / aGrid.x ) * aGrid.x + aOffset.x,
                     KiROUND( (double) ( aPoint.y - aOffset.y ) / aGrid.y ) * aGrid.y + aOffset.y );
}
 
 
VECTOR2I GRID_HELPER::Align( const VECTOR2I& aPoint ) const
{
    return Align( aPoint, GetGrid(), GetOrigin() );
}
 
 
VECTOR2I GRID_HELPER::Align( const VECTOR2I& aPoint, const VECTOR2D& aGrid,
                             const VECTOR2D& aOffset ) const
{
    if( !canUseGrid() )
        return aPoint;
 
    VECTOR2I nearest = AlignGrid( aPoint, aGrid, aOffset );
 
    if( !m_auxAxis )
        return nearest;
 
    if( std::abs( m_auxAxis->x - aPoint.x ) < std::abs( nearest.x - aPoint.x ) )
        nearest.x = m_auxAxis->x;
 
    if( std::abs( m_auxAxis->y - aPoint.y ) < std::abs( nearest.y - aPoint.y ) )
        nearest.y = m_auxAxis->y;
 
    return nearest;
}
 
 
bool GRID_HELPER::canUseGrid() const
{
    return m_enableGrid && ( m_toolMgr ? m_toolMgr->GetView()->GetGAL()->GetGridSnapping()
                                       : m_manualGridSnapping );
}
 
 
std::optional<VECTOR2I> GRID_HELPER::GetSnappedPoint() const
{
    if( m_snapItem )
        return m_snapItem->pos;
 
    return std::nullopt;
}
 
 
GRID_HELPER::SNAP_RANGES GRID_HELPER::computeSnapRanges( bool aClampToVisibleGrid ) const
{
    KIGFX::VIEW* view = m_toolMgr->GetView();
    SNAP_RANGES  ranges;
 
    ranges.scale = view->ToWorld( SNAP_SCREEN_RADIUS );
 
    // GetVisibleGrid().x sometimes exceeds INT_MAX, so the comparison stays in double.
    ranges.range = KiROUND( aClampToVisibleGrid ? std::min( ranges.scale, GetVisibleGrid().x ) : ranges.scale );
 
    const double hysteresisPixels = ADVANCED_CFG::GetCfg().m_SnapHysteresis;
    const int    hysteresisWorld = KiROUND( view->ToWorld( hysteresisPixels ) );
 
    ranges.in = std::max( 0, ranges.range - hysteresisWorld );
    ranges.out = ranges.range + hysteresisWorld;
    ranges.rankingHysteresis = hysteresisPixels / SNAP_SCREEN_RADIUS;
 
    return ranges;
}
 
 
void GRID_HELPER::emitAngleBranchCandidates( std::vector<SNAP_CANDIDATE>& aCandidates, const VECTOR2I& aOrigin,
                                             double aSnapScale ) const
{
    if( !m_angleOrigin || m_angleStepDegrees <= 0.0 || aOrigin == *m_angleOrigin )
        return;
 
    VECTOR2D delta( aOrigin - *m_angleOrigin );
    double   step = m_angleStepDegrees * std::numbers::pi / 180.0;
    double   rawAngle = std::atan2( delta.y, delta.x );
    int      lowerBranch = static_cast<int>( std::floor( rawAngle / step ) );
 
    for( int branch : { lowerBranch, lowerBranch + 1 } )
    {
        double   angle = branch * step;
        VECTOR2D direction( std::cos( angle ), std::sin( angle ) );
        double   residual = std::abs( delta.x * direction.y - delta.y * direction.x ) / aSnapScale;
        aCandidates.push_back( SNAP_CANDIDATE::Line( { SNAP_ID_KIND::ANGLE_BRANCH, {}, 0, branch },
                                                     SNAP_PRIORITY_TIER::ANGLE, SNAP_CANDIDATE_SUBTYPE::ANGLE_BRANCH,
                                                     *m_angleOrigin, direction, residual ) );
    }
}
 
 
SNAP_RESOLVER::TRACE_CALLBACK GRID_HELPER::snapTraceCallback( const SNAP_SOURCE_CONTEXT& aContext ) const
{
    static const wxString traceCategory = wxT( "KICAD_SNAP_RESOLVER" );
    const auto            callback = []( const std::string& aMessage )
    {
        wxLogTrace( traceCategory, "%s", aMessage.c_str() );
    };
 
    if( !wxLog::IsAllowedTraceMask( traceCategory ) )
        return {};
 
    if( !aContext.movingBounds )
    {
        wxLogTrace( traceCategory, "context raw=(%d,%d) reference=none bounds=none", aContext.sourcePoint.x,
                    aContext.sourcePoint.y );
        return callback;
    }
 
    BOX2I projectedBounds = *aContext.movingBounds;
 
    if( aContext.movingReferencePoint )
        projectedBounds.Offset( aContext.sourcePoint - *aContext.movingReferencePoint );
 
    wxLogTrace( traceCategory, "context raw=(%d,%d) reference=(%d,%d) bounds=(%d,%d,%d,%d) projected=(%d,%d,%d,%d)",
                aContext.sourcePoint.x, aContext.sourcePoint.y,
                aContext.movingReferencePoint ? aContext.movingReferencePoint->x : aContext.sourcePoint.x,
                aContext.movingReferencePoint ? aContext.movingReferencePoint->y : aContext.sourcePoint.y,
                aContext.movingBounds->GetLeft(), aContext.movingBounds->GetTop(), aContext.movingBounds->GetRight(),
                aContext.movingBounds->GetBottom(), projectedBounds.GetLeft(), projectedBounds.GetTop(),
                projectedBounds.GetRight(), projectedBounds.GetBottom() );
 
    return callback;
}
 
 
void GRID_HELPER::emitSelfAndGridCandidates( std::vector<SNAP_CANDIDATE>& aCandidates,
                                             const SNAP_SOURCE_CONTEXT& aContext, const VECTOR2I& aOrigin,
                                             const VECTOR2I& aNearestGrid, double aSnapScale, int aSnapRange,
                                             bool aUseGrid ) const
{
    const bool pointEdit = aContext.profile == SNAP_EDITOR_PROFILE::POINT_EDIT && aContext.movingItem;
 
    if( pointEdit && aContext.stationarySourceLeg
        && aContext.stationarySourceLeg->Distance( aOrigin ) <= aSnapRange )
    {
        SNAP_STABLE_ID id = MakeDerivedSnapId( SNAP_ID_KIND::SELF_ENDPOINT, *aContext.movingItem );
        aCandidates.push_back( SNAP_CANDIDATE::Point(
                std::move( id ), SNAP_PRIORITY_TIER::OBJECT, SNAP_CANDIDATE_SUBTYPE::INTRINSIC_ANCHOR,
                *aContext.stationarySourceLeg, aContext.stationarySourceLeg->Distance( aOrigin ) / aSnapScale ) );
    }
 
    if( pointEdit )
    {
        for( size_t i = 0; i < m_stationarySelfPoints.size(); ++i )
        {
            if( m_stationarySelfPoints[i].Distance( aOrigin ) > aSnapRange )
                continue;
 
            SNAP_STABLE_ID id =
                    MakeDerivedSnapId( SNAP_ID_KIND::SELF_POINT, *aContext.movingItem, static_cast<int>( i ) );
            aCandidates.push_back( SNAP_CANDIDATE::Point(
                    std::move( id ), SNAP_PRIORITY_TIER::OBJECT, SNAP_CANDIDATE_SUBTYPE::INTRINSIC_ANCHOR,
                    m_stationarySelfPoints[i], m_stationarySelfPoints[i].Distance( aOrigin ) / aSnapScale ) );
        }
    }
 
    if( aUseGrid )
    {
        aCandidates.push_back( SNAP_CANDIDATE::AxisX( { SNAP_ID_KIND::GRID_X }, SNAP_PRIORITY_TIER::GRID,
                                                      SNAP_CANDIDATE_SUBTYPE::GRID_AXIS, aNearestGrid.x,
                                                      std::abs( aNearestGrid.x - aOrigin.x ) / aSnapScale ) );
        aCandidates.push_back( SNAP_CANDIDATE::AxisY( { SNAP_ID_KIND::GRID_Y }, SNAP_PRIORITY_TIER::GRID,
                                                      SNAP_CANDIDATE_SUBTYPE::GRID_AXIS, aNearestGrid.y,
                                                      std::abs( aNearestGrid.y - aOrigin.y ) / aSnapScale ) );
    }
}
 
 
void GRID_HELPER::retainAcceptedSnaps( const SNAP_RESULT& aResult )
{
    m_stickySnapIds = aResult.accepted;
    m_retainedAngleBranch.reset();
 
    for( const SNAP_STABLE_ID& id : aResult.accepted )
    {
        if( id.kind == SNAP_ID_KIND::ANGLE_BRANCH )
        {
            m_retainedAngleBranch = id;
            break;
        }
    }
}