constraint_edit_tool.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 <tools/constraint_edit_tool.h>
 
#include <algorithm>
#include <cmath>
#include <ranges>
#include <set>
 
#include <bitmaps.h>
#include <collectors.h>
#include <core/kicad_algo.h>
#include <tool/tool_manager.h>
#include <tool/conditional_menu.h>
#include <tool/selection_conditions.h>
#include <tools/pcb_picker_tool.h>
#include <pcb_shape.h>
#include <board.h>
#include <board_commit.h>
#include <footprint.h>
#include <tools/pcb_actions.h>
#include <tools/pcb_selection.h>
#include <tools/pcb_selection_tool.h>
#include <tools/pcb_selection_conditions.h>
#include <tools/constraint_overlay.h>
#include <view/view.h>
#include <view/view_controls.h>
#include <gal/graphics_abstraction_layer.h>
#include <pcb_painter.h>
#include <tool/actions.h>
#include <tool/edit_points.h>
#include <widgets/wx_infobar.h>
#include <widgets/msgpanel.h>
#include <pcb_base_frame.h>
#include <dialogs/dialog_constraint_value.h>
#include <dialogs/dialog_constraint_list.h>
#include <widgets/panel_constraints.h>
#include <pcb_edit_frame.h>
#include <settings/settings_manager.h>
#include <pcbnew_settings.h>
#include <footprint_editor_settings.h>
#include <constraints/pcb_constraint.h>
#include <constraints/constraint_builder.h>
#include <constraints/board_constraint_adapter.h>
 
#include <base_units.h>
#include <geometry/seg.h>
 
 
CONSTRAINT_EDIT_TOOL::CONSTRAINT_EDIT_TOOL() :
        PCB_TOOL_BASE( "pcbnew.ConstraintEditor" ),
        m_selectionTool( nullptr ),
        m_menu( nullptr )
{
}
 
 
void CONSTRAINT_EDIT_TOOL::Reset( RESET_REASON aReason )
{
    // The board (and its view) is being torn down or reloaded; drop the overlay so it does not
    // dangle on a stale view.
    m_overlay.reset();
 
    // Reload may reuse a KIID for a new item
    // Drop cached diagnosis so it never survives stale
    m_diagnoser.Clear();
 
    // Per-type values survive an ordinary redraw or canvas switch
    // Only a model reload clears them
    if( aReason == MODEL_RELOAD || aReason == SUPERMODEL_RELOAD )
    {
        m_lastConstraintValue.clear();
        m_lastConstraintDriving.clear();
    }
 
    // At shutdown the frame/info bar may already be tearing down, so don't touch UI then.
    if( aReason == SHUTDOWN )
        return;
 
    // The overlay is long-lived so hover can reveal constraints at any time; the sticky setting only
    // chooses whether it always shows everything (ALWAYS) or reveals on hover (HOVER).
    if( frame() && board() && getView() )
    {
        m_overlay = std::make_unique<CONSTRAINT_OVERLAY>( board(), getView() );
        m_overlay->SetVisibilityMode( frame()->GetPcbNewSettings()->m_Display.m_ShowConstraints
                                              ? OVERLAY_MODE::ALWAYS
                                              : OVERLAY_MODE::HOVER );
    }
 
    refreshDiagnostics();   // marks the diagnosis dirty and re-renders
}
 
 
int CONSTRAINT_EDIT_TOOL::onSelectionChanged( const TOOL_EVENT& aEvent )
{
    // A real board selection supersedes a badge selection (and keeps Delete unambiguous).  This
    // does not fire for SelectConstraintAt's own ClearSelection, which leaves the board empty.
    if( m_selectionTool && !m_selectionTool->GetSelection().Empty() )
        setSelectedConstraint( nullptr );
 
    // A canvas selection shows all constraints again.
    if( m_overlay && m_overlay->SetIsolated( niluuid ) )
        m_overlay->RefreshSelection();
 
    return 0;
}
 
 
PCB_CONSTRAINT* CONSTRAINT_EDIT_TOOL::hitTestBadge( const VECTOR2I& aPos ) const
{
    if( !m_overlay || !board() )
        return nullptr;
 
    // Hit-test against the exact positions the badges draw at (same LayoutBadges call), so a click
    // and a glyph can never drift apart at any zoom.
    double worldPerPx = CONSTRAINT_OVERLAY::BadgeWorldPerPixel( getView()->GetGAL()->GetWorldScale() );
    double best = CONSTRAINT_OVERLAY::BadgeHitRadius() * worldPerPx;
 
    const std::vector<CONSTRAINT_BADGE>& badges = m_overlay->Badges();
    std::vector<VECTOR2D>                layout = CONSTRAINT_OVERLAY::LayoutBadges( badges, worldPerPx );
    PCB_CONSTRAINT*                      result = nullptr;
 
    for( size_t i = 0; i < badges.size(); ++i )
    {
        double dist = ( layout[i] - VECTOR2D( aPos ) ).EuclideanNorm();
 
        if( dist <= best )
        {
            best = dist;
            result = dynamic_cast<PCB_CONSTRAINT*>( board()->ResolveItem( badges[i].constraint, true ) );
        }
    }
 
    return result;
}
 
 
void CONSTRAINT_EDIT_TOOL::setSelectedConstraint( PCB_CONSTRAINT* aConstraint )
{
    if( !m_overlay )
        return;
 
    if( m_overlay->SetSelected( aConstraint ? aConstraint->m_Uuid : niluuid ) )
        m_overlay->RefreshSelection();
 
    // Highlight members with a brighter thicker shadow
    updateHighlightedConstraintMembers( aConstraint );
 
    if( aConstraint )
    {
        if( PCB_EDIT_FRAME* pcbFrame = dynamic_cast<PCB_EDIT_FRAME*>( frame() ) )
        {
            if( PANEL_CONSTRAINTS* panel = pcbFrame->GetConstraintsPanel() )
                panel->SelectConstraint( aConstraint->m_Uuid );
        }
    }
 
    updateConstraintMsgPanel( aConstraint );
}
 
 
void CONSTRAINT_EDIT_TOOL::updateConstraintMsgPanel( PCB_CONSTRAINT* aConstraint )
{
    if( !frame() )
        return;
 
    if( !aConstraint || !board() )
    {
        // Restore the default board readout (Pads/Vias/Tracks), unless a board selection owns the
        // panel now.
        if( board() && m_selectionTool && m_selectionTool->GetSelection().Empty() )
            frame()->SetMsgPanel( board() );
 
        return;
    }
 
    std::vector<MSG_PANEL_ITEM> items;
 
    items.emplace_back( _( "Constraint" ), ConstraintDisplayLabel( *aConstraint, frame()->GetUserUnits() ) );
 
    wxString members;
 
    for( const CONSTRAINT_MEMBER& member : aConstraint->GetMembers() )
    {
        if( !members.IsEmpty() )
            members += wxT( ", " );
 
        members += ConstraintMemberLabel( board()->ResolveItem( member.m_item, true ), member, frame() );
    }
 
    items.emplace_back( _( "Items" ), members );
 
    const BOARD_CONSTRAINT_DIAGNOSTICS& diag = ensureDiagnosis();
    wxString                            state = _( "OK" );
 
    if( alg::contains( diag.errored, aConstraint->m_Uuid ) )
        state = _( "Error (missing item)" );
    else if( alg::contains( diag.conflicting, aConstraint->m_Uuid ) )
        state = _( "Over-constrained" );
    else if( alg::contains( diag.redundant, aConstraint->m_Uuid ) )
        state = _( "Redundant" );
 
    items.emplace_back( _( "State" ), state );
 
    frame()->SetMsgPanel( items );
}
 
 
bool CONSTRAINT_EDIT_TOOL::SelectConstraintAt( const VECTOR2I& aPos )
{
    PCB_CONSTRAINT* constraint = hitTestBadge( aPos );
 
    if( !constraint )
        return false;
 
    // A constraint is not a board selection; clear it so a following Delete targets the relation.
    m_selectionTool->ClearSelection();
    setSelectedConstraint( constraint );
    return true;
}
 
 
bool CONSTRAINT_EDIT_TOOL::EditConstraintAt( const VECTOR2I& aPos )
{
    PCB_CONSTRAINT* constraint = hitTestBadge( aPos );
 
    if( !constraint )
        return false;
 
    setSelectedConstraint( constraint );
    editConstraint( constraint );
    return true;
}
 
 
bool CONSTRAINT_EDIT_TOOL::ClearConstraintSelection()
{
    bool wasSelected = m_overlay && m_overlay->GetSelected() != niluuid;
    setSelectedConstraint( nullptr );
    return wasSelected;
}
 
 
BOARD_ITEM* CONSTRAINT_EDIT_TOOL::constraintParent() const
{
    if( IsFootprintEditor() && board() )
        return board()->GetFirstFootprint();
 
    return board();
}
 
 
void CONSTRAINT_EDIT_TOOL::refreshDiagnostics()
{
    // Called when the model changed, so the cached diagnosis is stale.  A bare re-render (hover) uses
    // renderConstraintViews() directly and keeps the cache.
    m_diagDirty = true;
    m_hoverCandidates.reset();   // the constrained-shape set may have changed too
    renderConstraintViews();
}
 
 
void CONSTRAINT_EDIT_TOOL::renderConstraintViews()
{
    // The overlay tint/badges, the info bar, and the docked list all read the same board-wide
    // diagnosis; solve it once here and hand the result to each so a model change costs one solve,
    // not one per view.  Refresh the panel only while it is shown so a hidden pane costs nothing.
    PANEL_CONSTRAINTS* panel = nullptr;
 
    if( PCB_EDIT_FRAME* pcbFrame = dynamic_cast<PCB_EDIT_FRAME*>( frame() ) )
        panel = pcbFrame->GetConstraintsPanel();
 
    bool panelShown = panel && panel->IsShownOnScreen();
 
    // With a long-lived overlay, only actually solve when something reads the result: ALWAYS mode, an
    // active hover, or the docked panel.  A HOVER-idle canvas costs nothing.
    bool overlayActive = m_overlay
                         && ( m_overlay->GetVisibilityMode() == OVERLAY_MODE::ALWAYS
                              || m_overlay->GetHoverShape() != niluuid );
 
    if( !overlayActive && !panelShown )
    {
        if( m_overlay )
        {
            m_overlay->SetIsolated( niluuid );   // a panel isolation must not linger while hidden
            m_overlay->Update( {} );             // draw nothing while hidden
        }
 
        // Hidden view computes no fresh diagnosis
        // Drop the shadow sets too rather than leave stale ones under the now hidden items
        updateConstrainedItems( {} );
        updateHighlightedConstraintMembers( nullptr );
 
        return;
    }
 
    applyDiagnostics( ensureDiagnosis() );
}
 
 
const BOARD_CONSTRAINT_DIAGNOSTICS& CONSTRAINT_EDIT_TOOL::ensureDiagnosis()
{
    if( m_diagDirty )
    {
        m_cachedDiag = m_diagnoser.Diagnose( board() );
        m_diagDirty = false;
    }
 
    return m_cachedDiag;
}
 
 
const std::vector<PCB_SHAPE*>& CONSTRAINT_EDIT_TOOL::hoverCandidates()
{
    if( m_hoverCandidates )
        return *m_hoverCandidates;
 
    std::set<KIID>          ids;
    std::vector<PCB_SHAPE*> shapes;
 
    auto collect =
            [&]( const CONSTRAINTS& aConstraints )
            {
                for( PCB_CONSTRAINT* c : aConstraints )
                {
                    for( const CONSTRAINT_MEMBER& m : c->GetMembers() )
                    {
                        if( ids.insert( m.m_item ).second )
                        {
                            if( PCB_SHAPE* shape =
                                        dynamic_cast<PCB_SHAPE*>( board()->ResolveItem( m.m_item, true ) ) )
                            {
                                shapes.push_back( shape );
                            }
                        }
                    }
                }
            };
 
    if( board() )
    {
        collect( board()->Constraints() );
 
        for( FOOTPRINT* footprint : board()->Footprints() )
            collect( footprint->Constraints() );
    }
 
    m_hoverCandidates = std::move( shapes );
    return *m_hoverCandidates;
}
 
 
int CONSTRAINT_EDIT_TOOL::onHoverMotion( const TOOL_EVENT& aEvent )
{
    // Cheapest guards first: only HOVER mode with constraints on the board does any work.  Waiting
    // tools (selection, router, move) already saw this motion before the transition loop reached us,
    // so there is nothing to forward.
    if( !m_overlay || m_overlay->GetVisibilityMode() != OVERLAY_MODE::HOVER || !board()
        || !BoardHasConstraints( board() ) )
    {
        return 0;
    }
 
    VECTOR2I cursor = getViewControls()->GetMousePosition();
    double   tol = getView()->ToWorld( CONSTRAINT_OVERLAY::BadgeHitRadius() );
 
    // Stay sticky while the cursor is still over the current shape or one of its badges, so a badge
    // does not blink out as the pointer moves off the thin outline toward it.
    if( m_overlay->GetHoverShape() != niluuid )
    {
        if( PCB_SHAPE* shape =
                    dynamic_cast<PCB_SHAPE*>( board()->ResolveItem( m_overlay->GetHoverShape(), true ) ) )
        {
            double worldPerPx = CONSTRAINT_OVERLAY::BadgeWorldPerPixel( getView()->GetGAL()->GetWorldScale() );
            std::vector<VECTOR2D> layout = CONSTRAINT_OVERLAY::LayoutBadges( m_overlay->Badges(), worldPerPx );
            double                badgeTol = CONSTRAINT_OVERLAY::BadgeHitRadius() * worldPerPx;
 
            bool overBadge = std::ranges::any_of( layout,
                                          [&]( const VECTOR2D& aPos )
                                          { return ( aPos - VECTOR2D( cursor ) ).EuclideanNorm() <= badgeTol; } );
 
            if( overBadge || shape->HitTest( cursor, KiROUND( tol ) ) )
                return 0;   // keep the current hover
        }
    }
 
    std::optional<KIID> hit = NearestConstrainedShape( hoverCandidates(), cursor, KiROUND( tol ) );
 
    // Only the hover filter changed, not the model, so redraw just the overlay from the cached
    // diagnosis -- the panel (its row selection) and the info bar are left untouched.
    if( m_overlay->SetHoverShape( hit.value_or( niluuid ) ) )
        m_overlay->Update( ensureDiagnosis() );
 
    return 0;
}
 
 
KIGFX::PCB_RENDER_SETTINGS* CONSTRAINT_EDIT_TOOL::pcbRenderSettings() const
{
    if( !getView() || !getView()->GetPainter() )
        return nullptr;
 
    return dynamic_cast<KIGFX::PCB_RENDER_SETTINGS*>( getView()->GetPainter()->GetSettings() );
}
 
 
void CONSTRAINT_EDIT_TOOL::updateConstrainedItems( const BOARD_CONSTRAINT_DIAGNOSTICS& aDiag )
{
    KIGFX::PCB_RENDER_SETTINGS* rs = pcbRenderSettings();
 
    if( !rs )
        return;
 
    std::unordered_set<KIID> constrained;
 
    for( const auto& entry : aDiag.shapeStates )
        constrained.insert( entry.first );
 
    // Shadow is a cached layer so re-cache each item whose constrained state changed
    // Set the new set BEFORE the re-cache so ViewGetLOD reads fresh membership on redraw
    std::unordered_set<KIID> previous = rs->GetConstrainedItems();
    rs->SetConstrainedItems( constrained );
    repaintShadowItems( previous, constrained );
}
 
 
void CONSTRAINT_EDIT_TOOL::updateHighlightedConstraintMembers( PCB_CONSTRAINT* aConstraint )
{
    KIGFX::PCB_RENDER_SETTINGS* rs = pcbRenderSettings();
 
    if( !rs )
        return;
 
    std::unordered_set<KIID> members;
 
    if( aConstraint )
    {
        for( const CONSTRAINT_MEMBER& member : aConstraint->GetMembers() )
            members.insert( member.m_item );
    }
 
    // Re-cache members whose highlight changed so the brighter shadow follows the badge selection
    // Set the new membership before the re-cache so the redraw reads it
    std::unordered_set<KIID> previous = rs->GetHighlightedConstraintMembers();
    rs->SetHighlightedConstraintMembers( members );
    repaintShadowItems( previous, members );
}
 
 
void CONSTRAINT_EDIT_TOOL::repaintShadowItems( const std::unordered_set<KIID>& aOld,
                                               const std::unordered_set<KIID>& aNew )
{
    if( !board() || !getView() )
        return;
 
    // Re-cache only the symmetric difference items rather than the whole board every time
    // ALL forces the regen a shape first cached unconstrained needs before it has shadow geometry
    auto repaint = [&]( const KIID& aId )
    {
        if( BOARD_ITEM* item = board()->ResolveItem( aId, true ) )
            getView()->Update( item, KIGFX::ALL );
    };
 
    for( const KIID& id : aOld )
    {
        if( !aNew.contains( id ) )
            repaint( id );
    }
 
    for( const KIID& id : aNew )
    {
        if( !aOld.contains( id ) )
            repaint( id );
    }
}
 
 
void CONSTRAINT_EDIT_TOOL::applyDiagnostics( const BOARD_CONSTRAINT_DIAGNOSTICS& aDiag )
{
    if( m_overlay )
        m_overlay->Update( aDiag );
 
    // The constraint shadow layer draws only for items in this set a constant time gate at draw time
    updateConstrainedItems( aDiag );
 
    if( PCB_EDIT_FRAME* pcbFrame = dynamic_cast<PCB_EDIT_FRAME*>( frame() ) )
    {
        if( PANEL_CONSTRAINTS* panel = pcbFrame->GetConstraintsPanel(); panel && panel->IsShownOnScreen() )
            panel->RefreshList( aDiag );
    }
}
 
 
void CONSTRAINT_EDIT_TOOL::removeConstraint( PCB_CONSTRAINT* aConstraint )
{
    // Remember the member shapes so their clusters can re-settle once the constraint is gone.
    std::vector<PCB_SHAPE*> members;
 
    for( const CONSTRAINT_MEMBER& member : aConstraint->GetMembers() )
    {
        if( PCB_SHAPE* shape = dynamic_cast<PCB_SHAPE*>( board()->ResolveItem( member.m_item, true ) ) )
            members.push_back( shape );
    }
 
    BOARD_COMMIT commit( this );
    commit.Remove( aConstraint );
    commit.Push( _( "Remove Geometric Constraint" ) );
 
    SolveAfterMove( members );
 
    refreshDiagnostics();
}
 
 
PCB_CONSTRAINT* CONSTRAINT_EDIT_TOOL::resolveConstraint( const KIID& aId ) const
{
    if( !board() || aId == niluuid )
        return nullptr;
 
    return dynamic_cast<PCB_CONSTRAINT*>( board()->ResolveItem( aId, true ) );
}
 
 
void CONSTRAINT_EDIT_TOOL::RemoveConstraintById( const KIID& aId )
{
    if( PCB_CONSTRAINT* constraint = resolveConstraint( aId ) )
        removeConstraint( constraint );
}
 
 
void CONSTRAINT_EDIT_TOOL::editConstraint( PCB_CONSTRAINT* aConstraint )
{
    if( !aConstraint )
        return;
 
    BOARD_COMMIT commit( this );
 
    if( EditConstraintValue( frame(), aConstraint, commit ) )
    {
        // The committed value becomes the remembered default for the next creation of this type
        // matching what the creation dialog stores
        if( aConstraint->HasValue() )
        {
            m_lastConstraintValue[aConstraint->GetConstraintType()] = *aConstraint->GetValue();
            m_lastConstraintDriving[aConstraint->GetConstraintType()] = aConstraint->IsDriving();
        }
 
        refreshDiagnostics();
    }
}
 
 
void CONSTRAINT_EDIT_TOOL::EditConstraintById( const KIID& aId )
{
    PCB_CONSTRAINT* constraint = resolveConstraint( aId );
 
    if( !constraint )
        return;
 
    // A valueless relation has nothing to edit, so locate its members on the canvas instead of
    // ignoring the gesture, matching the modal list's double-click behavior.
    if( !constraint->HasValue() )
    {
        HighlightConstraintMembers( aId, -1 );
        return;
    }
 
    editConstraint( constraint );
}
 
 
void CONSTRAINT_EDIT_TOOL::HighlightConstraintMembers( const KIID& aId, int aMemberIndex )
{
    PCB_CONSTRAINT* constraint = resolveConstraint( aId );
 
    if( !constraint )
        return;
 
    // Selecting the members is a board selection, so drop any badge selection to keep the two
    // selection models mutually exclusive (Delete then targets the highlighted members).
    setSelectedConstraint( nullptr );
    m_selectionTool->ClearSelection();
 
    const std::vector<CONSTRAINT_MEMBER>& members = constraint->GetMembers();
 
    // A click on a blank item cell (index past the members) falls back to highlighting all.
    bool highlightOne = aMemberIndex >= 0 && aMemberIndex < static_cast<int>( members.size() );
 
    auto selectMember = [&]( const CONSTRAINT_MEMBER& aMember )
    {
        if( BOARD_ITEM* item = board()->ResolveItem( aMember.m_item, true ) )
            m_selectionTool->select( item );
    };
 
    if( highlightOne )
        selectMember( members[aMemberIndex] );
    else
        std::ranges::for_each( members, selectMember );
 
    // Zoom to what we just selected so the affected items fill the view.
    if( !m_selectionTool->GetSelection().Empty() )
        m_toolMgr->RunAction( ACTIONS::zoomFitSelection );
 
    // Set this after selecting, which clears the isolate.
    if( m_overlay && m_overlay->SetIsolated( aId ) )
        m_overlay->RefreshSelection();
}
 
 
bool CONSTRAINT_EDIT_TOOL::allMembersLocked( const PCB_CONSTRAINT* aConstraint ) const
{
    if( !board() || !aConstraint || aConstraint->GetMembers().empty() )
        return false;
 
    return std::ranges::all_of( aConstraint->GetMembers(),
                                [&]( const CONSTRAINT_MEMBER& aMember )
                                {
                                    BOARD_ITEM* item = board()->ResolveItem( aMember.m_item, true );
                                    return item && ConstraintItemIsLocked( item );
                                } );
}
 
 
bool CONSTRAINT_EDIT_TOOL::isDuplicateConstraint( const PCB_CONSTRAINT* aConstraint ) const
{
    if( !aConstraint || !board() )
        return false;
 
    auto scan = [&]( const CONSTRAINTS& aList )
    {
        return std::ranges::any_of( aList,
                            [&]( const PCB_CONSTRAINT* aExisting )
                            {
                                return aExisting != aConstraint && ConstraintsAreDuplicate( *aExisting, *aConstraint );
                            } );
    };
 
    if( scan( board()->Constraints() ) )
        return true;
 
    return board()->GetFirstFootprint() && scan( board()->GetFirstFootprint()->Constraints() );
}
 
 
void CONSTRAINT_EDIT_TOOL::finishConstraintCommit( BOARD_COMMIT& aCommit,
                                                   const std::vector<PCB_CONSTRAINT*>& aAdded )
{
    aCommit.Push( _( "Add Geometric Constraint" ) );
 
    // Solving any one constraint pins its first member and pulls the rest of the cluster into place.
    if( !aAdded.empty() )
        solveAddedConstraint( aAdded.front() );
 
    refreshDiagnostics();
 
    if( aAdded.empty() || !frame() )
        return;
 
    // A locked shape is a fixed reference the solver may not move.  If every referenced item is
    // locked there is nothing it can adjust, so the relation is recorded but the geometry cannot
    // snap; tell the user rather than appearing to silently do nothing.  A fix asks for exactly
    // that outcome, so on a locked item it is redundant, not thwarted.
    if( aAdded.front()->GetConstraintType() != PCB_CONSTRAINT_TYPE::FIXED_POSITION
        && allMembersLocked( aAdded.front() ) )
    {
        frame()->ShowInfoBarWarning( _( "All items referenced by this constraint are locked, so the constraint cannot "
                                        "move any geometry." ),
                                     true );
        return;
    }
 
    // In the default configuration (hover overlay idle, panel hidden) nothing else surfaces the
    // diagnosis, so an unsatisfiable new constraint must be called out here or the add appears to
    // succeed silently.  Mirrors the SolveAfterMove() warning for the same condition.
    const BOARD_CONSTRAINT_DIAGNOSTICS& diag = ensureDiagnosis();
 
    for( const PCB_CONSTRAINT* added : aAdded )
    {
        if( alg::contains( diag.conflicting, added->m_Uuid ) )
        {
            frame()->ShowInfoBarWarning( _( "The new geometric constraint conflicts with existing constraints and "
                                            "could not be satisfied." ),
                                         true );
            return;
        }
 
        if( alg::contains( diag.errored, added->m_Uuid ) )
        {
            frame()->ShowInfoBarWarning( _( "The new geometric constraint could not be applied to the referenced "
                                            "items." ),
                                         true );
            return;
        }
    }
}
 
 
bool CONSTRAINT_EDIT_TOOL::TryDeleteSelectedConstraint()
{
    // With no badge selected, fall through to the normal item-delete path.
    if( !m_overlay || m_overlay->GetSelected() == niluuid )
        return false;
 
    PCB_CONSTRAINT* constraint = resolveConstraint( m_overlay->GetSelected() );
 
    setSelectedConstraint( nullptr );
 
    // The selected constraint vanished (undo / panel delete) but the badge selection lingered;
    // consume the Delete so it does not fall through and remove a hovered board item.
    if( !constraint )
        return true;
 
    removeConstraint( constraint );
    return true;
}
 
 
bool CONSTRAINT_EDIT_TOOL::TryEditSelectedConstraint()
{
    // With no badge selected, fall through to the normal properties path.
    if( !m_overlay || m_overlay->GetSelected() == niluuid )
        return false;
 
    PCB_CONSTRAINT* constraint = resolveConstraint( m_overlay->GetSelected() );
 
    // The selected constraint vanished (undo / panel delete) but the badge selection lingered;
    // clear it and fall through instead of consuming the key with no effect.
    if( !constraint )
    {
        setSelectedConstraint( nullptr );
        return false;
    }
 
    // editConstraint only opens a dialog for a valued constraint; others just consume the key.
    editConstraint( constraint );
    return true;
}
 
 
void CONSTRAINT_EDIT_TOOL::solveAddedConstraint( PCB_CONSTRAINT* aConstraint )
{
    // A fix contributes no equation -- it is enforced by dropping its point from the unknowns -- so
    // there is nothing to snap to.  Re-solving anyway would only expose the pinned shape to the
    // cluster's other constraints with its own stay-put pin lifted, which can drift it.
    if( aConstraint->GetConstraintType() == PCB_CONSTRAINT_TYPE::FIXED_POSITION )
        return;
 
    // This solve runs after the add was pushed because SolveCluster gathers the cluster from
    // board->Constraints(), and BOARD_COMMIT only makes the constraint live at Push time.
    // APPEND_UNDO folds the snap into the add so creating a constraint is a single undoable action.
    BOARD_COMMIT            commit( this );
    std::vector<PCB_SHAPE*> modified;
 
    ApplyConstraintImmediately(
            board(), aConstraint, &modified,
            [&]( BOARD_ITEM* aItem )
            {
                commit.Modify( aItem );
            },
            ConstraintReferenceShapes( board(), aConstraint ) );
 
    // Push if the snap moved a shape or re-measured a reference value in this cluster.
    if( !commit.Empty() )
        commit.Push( _( "Apply Geometric Constraint" ), APPEND_UNDO );
}
 
 
void CONSTRAINT_EDIT_TOOL::SolveAfterMove( const std::vector<PCB_SHAPE*>& aShapes )
{
    if( aShapes.empty() || !board() || !BoardHasConstraints( board() ) )
        return;
 
    BOARD_COMMIT            commit( this );
    std::vector<PCB_SHAPE*> modified;
 
    ReSolveShapeClusters( board(), aShapes, &modified,
                          [&]( BOARD_ITEM* aItem )
                          {
                              commit.Modify( aItem );
                          } );
 
    if( !commit.Empty() )
        commit.Push( _( "Apply Geometric Constraint" ), APPEND_UNDO );
 
    DiagnoseAfterMove( aShapes );
}
 
 
void CONSTRAINT_EDIT_TOOL::SolveAfterEdit( const std::vector<PCB_SHAPE*>& aShapes )
{
    if( aShapes.empty() || !board() || !BoardHasConstraints( board() ) )
        return;
 
    BOARD_COMMIT            commit( this );
    std::vector<PCB_SHAPE*> modified;
 
    ReSolveShapeClustersHoldingEdited( board(), aShapes, &modified,
                                       [&]( BOARD_ITEM* aItem )
                                       {
                                           commit.Modify( aItem );
                                       } );
 
    if( !commit.Empty() )
        commit.Push( _( "Apply Geometric Constraint" ), APPEND_UNDO );
 
    DiagnoseAfterMove( aShapes );
}
 
 
void CONSTRAINT_EDIT_TOOL::DiagnoseAfterMove( const std::vector<PCB_SHAPE*>& aShapes )
{
    if( aShapes.empty() || !board() || !BoardHasConstraints( board() ) )
        return;
 
    // Diagnose once and use it for both the views and the warning below, so a transform does not
    // pay for two board-wide solves.  Cache it so a following hover reuses this fresh result.
    m_cachedDiag = m_diagnoser.Diagnose( board() );
    m_diagDirty = false;
    const BOARD_CONSTRAINT_DIAGNOSTICS& diag = m_cachedDiag;
    applyDiagnostics( diag );
 
    // If the edit left a moved shape's constraint unsatisfiable, say so even when the overlay is off.
    bool overConstrained = std::ranges::any_of( aShapes,
            [&]( const PCB_SHAPE* aShape )
            {
                auto it = diag.shapeStates.find( aShape->m_Uuid );
                return it != diag.shapeStates.end() && it->second == CONSTRAINT_STATE::OVER_CONSTRAINED;
            } );
 
    if( overConstrained && frame() )
        frame()->ShowInfoBarWarning( _( "A geometric constraint could not be satisfied by this edit." ), true );
}
 
 
int CONSTRAINT_EDIT_TOOL::ShowConstraints( const TOOL_EVENT& aEvent )
{
    if( !m_overlay && board() && getView() )
        m_overlay = std::make_unique<CONSTRAINT_OVERLAY>( board(), getView() );
 
    if( m_overlay )
    {
        // The action, not a toggle, chooses the mode, so a freshly created overlay can never invert
        // the clicked label.  The overlay object itself stays alive either way.
        bool always = aEvent.IsAction( &PCB_ACTIONS::showConstraints );
        m_overlay->SetVisibilityMode( always ? OVERLAY_MODE::ALWAYS : OVERLAY_MODE::HOVER );
 
        if( !always )
            m_overlay->SetHoverShape( niluuid );   // hover mode starts hidden until a hover
 
        // Remember the choice so it persists across board reloads and sessions.
        if( frame() )
            frame()->GetPcbNewSettings()->m_Display.m_ShowConstraints = always;
    }
 
    refreshDiagnostics();
    return 0;
}
 
 
int CONSTRAINT_EDIT_TOOL::ManageConstraints( const TOOL_EVENT& )
{
    // In the board editor the constraint list is a dockable pane; the footprint editor (which has
    // no such pane) falls back to the modal list dialog.
    if( PCB_EDIT_FRAME* pcbFrame = dynamic_cast<PCB_EDIT_FRAME*>( frame() ) )
    {
        pcbFrame->ToggleConstraintsPanel();
        return 0;
    }
 
    auto highlight =
            [&]( PCB_CONSTRAINT* aConstraint )
            {
                m_selectionTool->ClearSelection();
 
                for( const CONSTRAINT_MEMBER& member : aConstraint->GetMembers() )
                {
                    if( BOARD_ITEM* item = board()->ResolveItem( member.m_item, true ) )
                        m_selectionTool->select( item );
                }
            };
 
    auto remove = [&]( PCB_CONSTRAINT* aConstraint ) { removeConstraint( aConstraint ); };
 
    DIALOG_CONSTRAINT_LIST dlg( frame(), board(), highlight, remove );
    dlg.ShowModal();
 
    return 0;
}
 
 
int CONSTRAINT_EDIT_TOOL::ToggleAutoConstraints( const TOOL_EVENT& )
{
    if( frame()->IsType( FRAME_PCB_EDITOR ) )
    {
        PCBNEW_SETTINGS* cfg = GetAppSettings<PCBNEW_SETTINGS>( "pcbnew" );
        cfg->m_AutoConstraints = !cfg->m_AutoConstraints;
    }
    else
    {
        FOOTPRINT_EDITOR_SETTINGS* cfg = GetAppSettings<FOOTPRINT_EDITOR_SETTINGS>( "fpedit" );
        cfg->m_AutoConstraints = !cfg->m_AutoConstraints;
    }
 
    return 0;
}
 
 
int CONSTRAINT_EDIT_TOOL::refreshOverlay( const TOOL_EVENT& aEvent )
{
    m_diagDirty = true;   // the model changed, so the cached diagnosis is stale
    refreshDiagnostics();
 
    aEvent.PassEvent();
    return 0;
}
 
 
bool CONSTRAINT_EDIT_TOOL::Init()
{
    m_selectionTool = m_toolMgr->GetTool<PCB_SELECTION_TOOL>();
 
    if( !m_selectionTool )
        return false;
 
    using S_C = SELECTION_CONDITIONS;
 
    static const std::vector<KICAD_T> segmentType = { PCB_SHAPE_LOCATE_SEGMENT_T };
 
    auto twoSegments = S_C::Count( 2 ) && S_C::OnlyTypes( segmentType );
    auto oneSegment = S_C::Count( 1 ) && S_C::OnlyTypes( segmentType );
 
    auto kindOf = []( const EDA_ITEM* aItem ) -> SHAPE_T
    {
        if( !aItem || aItem->Type() != PCB_SHAPE_T )
            return SHAPE_T::UNDEFINED;
 
        return static_cast<const PCB_SHAPE*>( aItem )->GetShape();
    };
 
    // A circle or arc has a radius; a closed or arc ellipse adds to that a centre only.
    auto isRadial = []( SHAPE_T aShape )
    {
        return aShape == SHAPE_T::CIRCLE || aShape == SHAPE_T::ARC;
    };
 
    auto isCentered = [isRadial]( SHAPE_T aShape )
    {
        return isRadial( aShape ) || aShape == SHAPE_T::ELLIPSE || aShape == SHAPE_T::ELLIPSE_ARC;
    };
 
    auto oneRadial = [kindOf, isRadial]( const SELECTION& aSel )
    {
        return aSel.Size() == 1 && isRadial( kindOf( aSel[0] ) );
    };
 
    auto oneArc = [kindOf]( const SELECTION& aSel )
    {
        return aSel.Size() == 1 && kindOf( aSel[0] ) == SHAPE_T::ARC;
    };
 
    auto twoRadial = [kindOf, isRadial]( const SELECTION& aSel )
    {
        return aSel.Size() == 2 && isRadial( kindOf( aSel[0] ) ) && isRadial( kindOf( aSel[1] ) );
    };
 
    auto twoCentered = [kindOf, isCentered]( const SELECTION& aSel )
    {
        return aSel.Size() == 2 && isCentered( kindOf( aSel[0] ) ) && isCentered( kindOf( aSel[1] ) );
    };
 
    // Tangent joins a line with a curve, or two circles/arcs.
    auto tangentPair = [kindOf, isCentered, isRadial]( const SELECTION& aSel )
    {
        if( aSel.Size() != 2 )
            return false;
 
        SHAPE_T a = kindOf( aSel[0] );
        SHAPE_T b = kindOf( aSel[1] );
 
        return ( a == SHAPE_T::SEGMENT && isCentered( b ) ) || ( b == SHAPE_T::SEGMENT && isCentered( a ) )
               || ( isRadial( a ) && isRadial( b ) );
    };
 
    // Only offer Remove when something selected actually carries a constraint.
    auto selectionConstrained = [this]( const SELECTION& aSel ) -> bool
    {
        if( aSel.Empty() || !board() )
            return false;
 
        std::set<KIID> ids;
 
        for( EDA_ITEM* item : aSel )
            ids.insert( item->m_Uuid );
 
        auto anyMember = [&]( const CONSTRAINTS& aList )
        {
            return std::ranges::any_of( aList,
                    [&]( const PCB_CONSTRAINT* c )
                    {
                        return std::ranges::any_of( c->GetMembers(),
                                [&]( const CONSTRAINT_MEMBER& m ) { return ids.contains( m.m_item ); } );
                    } );
        };
 
        if( anyMember( board()->Constraints() ) )
            return true;
 
        return IsFootprintEditor() && board()->GetFirstFootprint()
               && anyMember( board()->GetFirstFootprint()->Constraints() );
    };
 
    // One "Constraints" submenu holds every constraint command.  The add-type items are gated by
    // the current selection so only constraints valid for what is selected are offered; the
    // manage/show/remove items are always present.
    m_menu = new CONDITIONAL_MENU( this );
    m_menu->SetIcon( BITMAPS::measurement );
    m_menu->SetUntranslatedTitle( _HKI( "Constraints" ) );
 
    // Gate each selection-based add-type by what it needs; the point-anchored families are authored
    // by clicking and need no prior selection, so they are absent here and default to ShowAlways.
    // The action list itself lives in PCB_ACTIONS::ConstraintAddActions() so the menubar's copy of
    // this submenu cannot drift from it.
    const std::map<const TOOL_ACTION*, SELECTION_CONDITION> gate = {
        { &PCB_ACTIONS::addConstraintParallel,      twoSegments },
        { &PCB_ACTIONS::addConstraintPerpendicular, twoSegments },
        { &PCB_ACTIONS::addConstraintEqualLength,   twoSegments },
        { &PCB_ACTIONS::addConstraintCollinear,     twoSegments },
        { &PCB_ACTIONS::addConstraintAngular,       twoSegments },
        { &PCB_ACTIONS::addConstraintTangent,       tangentPair },
        { &PCB_ACTIONS::addConstraintHorizontal,    oneSegment },
        { &PCB_ACTIONS::addConstraintVertical,      oneSegment },
        { &PCB_ACTIONS::addConstraintFixedLength,   oneSegment },
        { &PCB_ACTIONS::addConstraintConcentric,    twoCentered },
        { &PCB_ACTIONS::addConstraintEqualRadius,   twoRadial },
        { &PCB_ACTIONS::addConstraintFixedRadius,   oneRadial },
        { &PCB_ACTIONS::addConstraintArcAngle,      oneArc },
    };
 
    bool pointGroupSeparated = false;
 
    for( const TOOL_ACTION* action : PCB_ACTIONS::ConstraintAddActions() )
    {
        if( auto it = gate.find( action ); it != gate.end() )
        {
            m_menu->AddItem( *action, it->second );
        }
        else
        {
            if( !pointGroupSeparated )
            {
                m_menu->AddSeparator();
                pointGroupSeparated = true;
            }
 
            m_menu->AddItem( *action, S_C::ShowAlways );
        }
    }
 
    // Show while hidden, Hide while shown, so the label always names what the click will do.
    // "Shown" is the always-on mode; the hover mode reads as hidden and offers the Show action.
    // The ALWAYS/HOVER choice is a tool mode rather than an object visibility, which is why it
    // lives here and not in the Appearance panel's Objects tab.
    auto overlayShown = [this]( const SELECTION& )
    {
        return m_overlay && m_overlay->GetVisibilityMode() == OVERLAY_MODE::ALWAYS;
    };
    auto overlayHidden = [this]( const SELECTION& )
    {
        return !m_overlay || m_overlay->GetVisibilityMode() == OVERLAY_MODE::HOVER;
    };
 
    m_menu->AddSeparator();
    m_menu->AddItem( PCB_ACTIONS::removeConstraints, selectionConstrained );
    m_menu->AddItem( PCB_ACTIONS::showConstraints, overlayHidden );
    m_menu->AddItem( PCB_ACTIONS::hideConstraints, overlayShown );
    m_menu->AddItem( PCB_ACTIONS::manageConstraints,          S_C::ShowAlways );
 
    CONDITIONAL_MENU& selToolMenu = m_selectionTool->GetToolMenu().GetMenu();
    selToolMenu.AddMenu( m_menu, S_C::ShowAlways, 100 );
 
    return true;
}
 
 
int CONSTRAINT_EDIT_TOOL::AddConstraint( const TOOL_EVENT& aEvent )
{
    PCB_CONSTRAINT_TYPE  type = aEvent.Parameter<PCB_CONSTRAINT_TYPE>();
    const PCB_SELECTION& selection = m_selectionTool->GetSelection();
 
    std::vector<BOARD_ITEM*> items;
 
    for( EDA_ITEM* item : selection )
    {
        if( item->IsBOARD_ITEM() )
            items.push_back( static_cast<BOARD_ITEM*>( item ) );
    }
 
    std::unique_ptr<PCB_CONSTRAINT> constraint =
            BuildConstraintFromItems( constraintParent(), type, items );
 
    // A valid selection builds right away (the context-menu path).  Otherwise drop into click-to-pick
    // so the toolbar and hotkeys can author a constraint by clicking the items on the canvas.
    if( !constraint )
    {
        // Switching to click-to-pick silently reads as the tool ignoring the selection, so say what
        // the type wanted.  Only when something was selected: an empty one is the normal toolbar path.
        if( !items.empty() && frame() )
        {
            if( wxString hint = ConstraintSelectionHint( type ); !hint.IsEmpty() )
                frame()->ShowInfoBarWarning( hint );
        }
 
        // Horizontal and vertical also accept two point anchors so levelling a corner needs no segment
        // The linear picker offers both paths
        if( type == PCB_CONSTRAINT_TYPE::HORIZONTAL || type == PCB_CONSTRAINT_TYPE::VERTICAL )
            return pickLinearConstraint( type, aEvent );
 
        return pickShapeConstraint( type, aEvent );
    }
 
    commitConstraint( std::move( constraint ) );
    return 0;
}
 
 
bool CONSTRAINT_EDIT_TOOL::commitConstraint( std::unique_ptr<PCB_CONSTRAINT> aConstraint )
{
    if( !aConstraint )
        return false;
 
    if( isDuplicateConstraint( aConstraint.get() ) )
    {
        if( frame() )
            frame()->ShowInfoBarWarning( _( "An identical geometric constraint already exists." ) );
 
        return false;
    }
 
    // For a dimensional constraint, let the user confirm/override the measured value and choose
    // driving vs reference (issue #2329 step 7).
    if( aConstraint->HasValue() )
    {
        PCB_CONSTRAINT_TYPE type = aConstraint->GetConstraintType();
 
        // Default to the shape measurement unless the user already set a value for this type this session
        // Reuse that so a run of same type constraints keeps one size
        double initial = InitialConstraintValue( type, *aConstraint->GetValue(), m_lastConstraintValue );
 
        bool driving = aConstraint->IsDriving();
 
        if( auto it = m_lastConstraintDriving.find( type ); it != m_lastConstraintDriving.end() )
            driving = it->second;
 
        DIALOG_CONSTRAINT_VALUE dlg( frame(), type, initial, driving );
 
        if( dlg.ShowModal() != wxID_OK )
            return false;
 
        aConstraint->SetValue( dlg.GetConstraintValue() );
        aConstraint->SetDriving( dlg.GetDriving() );
 
        m_lastConstraintValue[type] = dlg.GetConstraintValue();
        m_lastConstraintDriving[type] = dlg.GetDriving();
    }
 
    PCB_CONSTRAINT* added = aConstraint.get();
 
    BOARD_COMMIT commit( this );
    commit.Add( aConstraint.release() );
    finishConstraintCommit( commit, { added } );
 
    return true;
}
 
 
int CONSTRAINT_EDIT_TOOL::pickShapeConstraint( PCB_CONSTRAINT_TYPE aType, const TOOL_EVENT& aEvent )
{
    int  count = 2;
    bool allowCircle = false;
 
    switch( aType )
    {
    case PCB_CONSTRAINT_TYPE::HORIZONTAL:
    case PCB_CONSTRAINT_TYPE::VERTICAL:
    case PCB_CONSTRAINT_TYPE::FIXED_LENGTH:
        count = 1;
        allowCircle = false;
        break;
    case PCB_CONSTRAINT_TYPE::FIXED_RADIUS:
    case PCB_CONSTRAINT_TYPE::ARC_ANGLE:
        count = 1;
        allowCircle = true;
        break;
    case PCB_CONSTRAINT_TYPE::TANGENT:
    case PCB_CONSTRAINT_TYPE::CONCENTRIC:
    case PCB_CONSTRAINT_TYPE::EQUAL_RADIUS:
        count = 2;
        allowCircle = true;
        break;
    default:
        count = 2;
        allowCircle = false;
        break;
    }
 
    PCB_PICKER_TOOL* picker = m_toolMgr->GetTool<PCB_PICKER_TOOL>();
 
    if( !picker )
        return 0;
 
    std::vector<KIID> picked;
    const double      snapTol = pcbIUScale.mmToIU( 1.0 );
 
    Activate();
    picker->SetCursor( KICURSOR::BULLSEYE );
    picker->SetSnapping( true );
    picker->ClearHandlers();
 
    picker->SetClickHandler(
            [&]( const VECTOR2D& aPoint ) -> bool
            {
                VECTOR2I            pos( KiROUND( aPoint.x ), KiROUND( aPoint.y ) );
                std::optional<KIID> target = NearestOutlineShape( board(), pos, snapTol, allowCircle );
 
                if( !target || alg::contains( picked, *target ) )
                    return true; // nothing new snapped, keep picking
 
                picked.push_back( *target );
 
                if( static_cast<int>( picked.size() ) < count )
                {
                    // Clear the preview of the just consumed target
                    // Not advertised until the next motion event re-derives the pick
                    if( m_overlay )
                        m_overlay->ClearPickPreview();
 
                    return true; // need more
                }
 
                std::vector<BOARD_ITEM*> items;
 
                for( const KIID& id : picked )
                {
                    if( BOARD_ITEM* item = board()->ResolveItem( id, true ) )
                        items.push_back( item );
                }
 
                std::unique_ptr<PCB_CONSTRAINT> constraint =
                        BuildConstraintFromItems( constraintParent(), aType, items );
 
                if( !constraint && frame() )
                {
                    frame()->ShowInfoBarWarning( wxString::Format( _( "Cannot form a %s constraint from those items." ),
                                                                   ConstraintTypeLabel( aType ) ) );
                }
 
                commitConstraint( std::move( constraint ) );
                picked.clear();
                return true; // stay active so more can be placed, like the draw tools
            } );
 
    // Outline the element the next pick would take so the target is clear before clicking
    picker->SetMotionHandler(
            [&]( const VECTOR2D& aPoint )
            {
                if( !m_overlay )
                    return;
 
                VECTOR2I            pos( KiROUND( aPoint.x ), KiROUND( aPoint.y ) );
                std::optional<KIID> target = NearestOutlineShape( board(), pos, snapTol, allowCircle );
 
                // Mirror the click handler rejection so an already picked shape is not advertised
                // as eligible for the remaining picks
                if( target && alg::contains( picked, *target ) )
                    target.reset();
 
                m_overlay->SetPickPreview( target.value_or( niluuid ), true, std::nullopt );
            } );
 
    bool done = false;
 
    picker->SetFinalizeHandler(
            [&]( const int& )
            {
                done = true;
            } );
 
    m_toolMgr->RunAction( ACTIONS::pickerTool, &aEvent );
 
    while( !done )
    {
        if( TOOL_EVENT* evt = Wait() )
            evt->SetPassEvent();
        else
            break;
    }
 
    picker->ClearHandlers();
 
    if( m_overlay )
        m_overlay->ClearPickPreview();
 
    return 0;
}
 
 
int CONSTRAINT_EDIT_TOOL::pickLinearConstraint( PCB_CONSTRAINT_TYPE aType, const TOOL_EVENT& aEvent )
{
    PCB_PICKER_TOOL* picker = m_toolMgr->GetTool<PCB_PICKER_TOOL>();
 
    if( !picker )
        return 0;
 
    // Empty until the first pick is a point then holds that point while the second is chosen
    std::vector<CONSTRAINT_MEMBER> members;
    const double                   snapTol = pcbIUScale.mmToIU( 1.0 );
 
    Activate();
    picker->SetCursor( KICURSOR::BULLSEYE );
    picker->SetSnapping( true );
    picker->ClearHandlers();
 
    auto commitPointPair = [&]()
    {
        std::unique_ptr<PCB_CONSTRAINT> constraint =
                std::make_unique<PCB_CONSTRAINT>( constraintParent(), aType );
 
        for( const CONSTRAINT_MEMBER& member : members )
            constraint->AddMember( member.m_item, member.m_anchor, member.m_index );
 
        commitConstraint( std::move( constraint ) );
    };
 
    picker->SetClickHandler(
            [&]( const VECTOR2D& aPoint ) -> bool
            {
                VECTOR2I pos( KiROUND( aPoint.x ), KiROUND( aPoint.y ) );
 
                // A point under the cursor wins over its segment so clicking a corner starts the two point path
                // A segment middle has no anchor and takes the whole segment path
                std::optional<CONSTRAINT_MEMBER> anchor =
                        NearestConstraintAnchor( board(), pos, snapTol, members );
 
                if( anchor )
                {
                    members.push_back( *anchor );
 
                    if( members.size() < 2 )
                    {
                        if( m_overlay )
                            m_overlay->ClearPickPreview();
 
                        return true;   // need the second point
                    }
 
                    commitPointPair();
                    members.clear();
                    return true;   // stay active so more can be placed, like the draw tools
                }
 
                // No anchor snapped before the first point a whole segment authors immediately
                // Once a point is held only a second point completes the pair
                if( members.empty() )
                {
                    if( std::optional<KIID> target = NearestOutlineShape( board(), pos, snapTol, false ) )
                    {
                        std::unique_ptr<PCB_CONSTRAINT> constraint =
                                std::make_unique<PCB_CONSTRAINT>( constraintParent(), aType );
                        constraint->AddMember( *target, CONSTRAINT_ANCHOR::WHOLE );
                        commitConstraint( std::move( constraint ) );
                    }
                }
 
                return true;
            } );
 
    picker->SetMotionHandler(
            [&]( const VECTOR2D& aPoint )
            {
                if( !m_overlay )
                    return;
 
                VECTOR2I pos( KiROUND( aPoint.x ), KiROUND( aPoint.y ) );
 
                // Mirror the click handler so the preview shows exactly what the next click takes.
                if( std::optional<CONSTRAINT_MEMBER> anchor =
                            NearestConstraintAnchor( board(), pos, snapTol, members ) )
                {
                    m_overlay->SetPickPreview( anchor->m_item, false,
                                               ConstraintAnchorPosition( board(), *anchor ) );
                }
                else if( members.empty() )
                {
                    if( std::optional<KIID> target = NearestOutlineShape( board(), pos, snapTol, false ) )
                        m_overlay->SetPickPreview( *target, true, std::nullopt );
                    else
                        m_overlay->ClearPickPreview();
                }
                else
                {
                    m_overlay->ClearPickPreview();
                }
            } );
 
    bool done = false;
 
    picker->SetFinalizeHandler(
            [&]( const int& )
            {
                done = true;
            } );
 
    m_toolMgr->RunAction( ACTIONS::pickerTool, &aEvent );
 
    while( !done )
    {
        if( TOOL_EVENT* evt = Wait() )
            evt->SetPassEvent();
        else
            break;
    }
 
    picker->ClearHandlers();
 
    if( m_overlay )
        m_overlay->ClearPickPreview();
 
    return 0;
}
 
 
int CONSTRAINT_EDIT_TOOL::AddPointConstraint( const TOOL_EVENT& aEvent )
{
    PCB_CONSTRAINT_TYPE type = aEvent.Parameter<PCB_CONSTRAINT_TYPE>();
 
    // In the pick plan, true means click a point anchor and false means click a whole segment.
    std::vector<bool> plan;
 
    switch( type )
    {
    case PCB_CONSTRAINT_TYPE::FIXED_POSITION: plan = { true }; break;
    case PCB_CONSTRAINT_TYPE::COINCIDENT:    plan = { true, true }; break;
    case PCB_CONSTRAINT_TYPE::POINT_ON_LINE:
    case PCB_CONSTRAINT_TYPE::MIDPOINT:      plan = { true, false }; break;
    case PCB_CONSTRAINT_TYPE::SYMMETRIC:     plan = { true, true, false }; break;
    default:                                 return 0;
    }
 
    PCB_PICKER_TOOL* picker = m_toolMgr->GetTool<PCB_PICKER_TOOL>();
 
    if( !picker )
        return 0;
 
    std::vector<CONSTRAINT_MEMBER> members;
    const double                   snapTol = pcbIUScale.mmToIU( 1.0 );
 
    Activate();
    picker->SetCursor( KICURSOR::BULLSEYE );
    picker->SetSnapping( true );
    picker->ClearHandlers();
 
    picker->SetClickHandler(
            [&]( const VECTOR2D& aPoint ) -> bool
            {
                VECTOR2I pos( KiROUND( aPoint.x ), KiROUND( aPoint.y ) );
 
                if( plan[members.size()] )   // wants a point anchor
                {
                    // Exclude already picked handles so the same shape and anchor cannot repeat
                    // while a coincident but distinct endpoint stays reachable
                    std::optional<CONSTRAINT_MEMBER> anchor =
                            NearestConstraintAnchor( board(), pos, snapTol, members );
 
                    if( !anchor )
                        return true;   // nothing snapped; keep picking
 
                    members.push_back( *anchor );
                }
                else // wants a whole shape
                {
                    std::optional<KIID> target =
                            NearestOutlineShape( board(), pos, snapTol, type == PCB_CONSTRAINT_TYPE::POINT_ON_LINE );
 
                    if( !target )
                        return true;
 
                    members.emplace_back( *target, CONSTRAINT_ANCHOR::WHOLE );
                }
 
                if( members.size() < plan.size() )
                {
                    // Clear the preview of the just consumed target
                    // Not advertised until the next motion event re-derives the pick
                    if( m_overlay )
                        m_overlay->ClearPickPreview();
 
                    return true;   // need more picks
                }
 
                std::unique_ptr<PCB_CONSTRAINT> constraint =
                        std::make_unique<PCB_CONSTRAINT>( constraintParent(), type );
 
                for( const CONSTRAINT_MEMBER& member : members )
                    constraint->AddMember( member.m_item, member.m_anchor, member.m_index );
 
                if( isDuplicateConstraint( constraint.get() ) )
                {
                    if( frame() )
                        frame()->ShowInfoBarWarning( _( "An identical geometric constraint already exists." ) );
 
                    return false; // done
                }
 
                PCB_CONSTRAINT* added = constraint.get();
 
                BOARD_COMMIT commit( this );
                commit.Add( constraint.release() );
                finishConstraintCommit( commit, { added } );
 
                return false;   // done
            } );
 
    // Preview the next pick target before the click the point steps also mark the exact anchor
    picker->SetMotionHandler(
            [&]( const VECTOR2D& aPoint )
            {
                if( !m_overlay || members.size() >= plan.size() )
                    return;
 
                VECTOR2I pos( KiROUND( aPoint.x ), KiROUND( aPoint.y ) );
 
                KIID                    element = niluuid;
                bool                    whole = true;
                std::optional<VECTOR2I> anchorPos;
 
                if( plan[members.size()] )   // wants a point anchor
                {
                    if( std::optional<CONSTRAINT_MEMBER> anchor =
                                NearestConstraintAnchor( board(), pos, snapTol, members ) )
                    {
                        element = anchor->m_item;
                        whole = false;
                        anchorPos = ConstraintAnchorPosition( board(), *anchor );
                    }
                }
                else if( std::optional<KIID> target = NearestOutlineShape(
                                 board(), pos, snapTol, type == PCB_CONSTRAINT_TYPE::POINT_ON_LINE ) )
                {
                    element = *target;
                }
 
                m_overlay->SetPickPreview( element, whole, anchorPos );
            } );
 
    bool done = false;
 
    picker->SetFinalizeHandler(
            [&]( const int& aFinalState )
            {
                done = true;
            } );
 
    m_toolMgr->RunAction( ACTIONS::pickerTool, &aEvent );
 
    // RunAction returns before picking ends. Wait so the handlers' captures stay alive.
    while( !done )
    {
        if( TOOL_EVENT* evt = Wait() )
            evt->SetPassEvent();
        else
            break;
    }
 
    picker->ClearHandlers();
 
    if( m_overlay )
        m_overlay->ClearPickPreview();
 
    return 0;
}
 
 
int CONSTRAINT_EDIT_TOOL::RemoveConstraints( const TOOL_EVENT& aEvent )
{
    PCB_SELECTION& selection = m_selectionTool->GetSelection();
    std::set<KIID> selectedIds;
 
    for( EDA_ITEM* item : selection )
        selectedIds.insert( item->m_Uuid );
 
    if( selectedIds.empty() )
        return 0;
 
    BOARD_COMMIT commit( this );
    bool         any = false;
 
    auto removeReferencing =
            [&]( const CONSTRAINTS& aConstraints )
            {
                for( PCB_CONSTRAINT* constraint : aConstraints )
                {
                    bool referenced = std::ranges::any_of( constraint->GetMembers(),
                            [&]( const CONSTRAINT_MEMBER& aMember )
                            { return selectedIds.contains( aMember.m_item ); } );
 
                    if( referenced )
                    {
                        commit.Remove( constraint );
                        any = true;
                    }
                }
            };
 
    if( board() )
    {
        removeReferencing( board()->Constraints() );
 
        if( IsFootprintEditor() && board()->GetFirstFootprint() )
            removeReferencing( board()->GetFirstFootprint()->Constraints() );
    }
 
    if( any )
        commit.Push( _( "Remove Geometric Constraints" ) );
 
    refreshDiagnostics();
 
    return 0;
}
 
 
void CONSTRAINT_EDIT_TOOL::setTransitions()
{
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintParallel.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintPerpendicular.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintEqualLength.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintCollinear.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintAngular.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintTangent.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintHorizontal.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintVertical.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintFixedLength.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintConcentric.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintEqualRadius.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintFixedRadius.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddConstraint, PCB_ACTIONS::addConstraintArcAngle.MakeEvent() );
 
    Go( &CONSTRAINT_EDIT_TOOL::AddPointConstraint, PCB_ACTIONS::addConstraintCoincident.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddPointConstraint, PCB_ACTIONS::addConstraintPointOnLine.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddPointConstraint, PCB_ACTIONS::addConstraintMidpoint.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddPointConstraint, PCB_ACTIONS::addConstraintSymmetric.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::AddPointConstraint, PCB_ACTIONS::addConstraintFixedPosition.MakeEvent() );
 
    Go( &CONSTRAINT_EDIT_TOOL::RemoveConstraints, PCB_ACTIONS::removeConstraints.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::ShowConstraints,   PCB_ACTIONS::showConstraints.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::ShowConstraints, PCB_ACTIONS::hideConstraints.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::ManageConstraints, PCB_ACTIONS::manageConstraints.MakeEvent() );
    Go( &CONSTRAINT_EDIT_TOOL::ToggleAutoConstraints, PCB_ACTIONS::toggleAutoConstraints.MakeEvent() );
 
    // Keep the diagnostics overlay current as the board changes underneath it.  Undo/redo posts its
    // own event (not TA_MODEL_CHANGE), so listen for it too or a restored/removed constraint's badge
    // would not reappear/disappear.
    Go( &CONSTRAINT_EDIT_TOOL::refreshOverlay,    TOOL_EVENT( TC_MESSAGE, TA_MODEL_CHANGE ) );
    Go( &CONSTRAINT_EDIT_TOOL::refreshOverlay, EVENTS::UndoRedoPostEvent );
 
    // Show/refresh the endpoint markers as the selection changes.
    Go( &CONSTRAINT_EDIT_TOOL::onSelectionChanged, EVENTS::SelectedEvent );
    Go( &CONSTRAINT_EDIT_TOOL::onSelectionChanged, EVENTS::UnselectedEvent );
    Go( &CONSTRAINT_EDIT_TOOL::onSelectionChanged, EVENTS::ClearedEvent );
 
    // No other pcbnew tool registers a plain-motion transition (only one transition runs per mouse
    // event), and waiting tools receive motion before this loop, so claiming it here is safe.
    Go( &CONSTRAINT_EDIT_TOOL::onHoverMotion, TOOL_EVENT( TC_MOUSE, TA_MOUSE_MOTION ) );
}