Break a track when placing a via on it.

Fixes: lp:1737349
* https://bugs.launchpad.net/kicad/+bug/1737349

pcbnew/tools/drawing_tool.cpp

@@ -48,6 +48,7 @@
 #include <hotkeys.h>
 #include <painter.h>
 #include <status_popup.h>
+#include "grid_helper.h"
 
 #include <preview_items/arc_assistant.h>
 
@@ -1418,20 +1419,36 @@ int DRAWING_TOOL::DrawVia( const TOOL_EVENT& aEvent )
 {
     struct VIA_PLACER : public INTERACTIVE_PLACER_BASE
     {
+        GRID_HELPER m_gridHelper;
+
+        VIA_PLACER( PCB_EDIT_FRAME* aFrame ) : m_gridHelper( aFrame )
+        {}
+
+        TRACK* findTrack( VIA* aVia )
+        {
+            const LSET lset = aVia->GetLayerSet();
+
+            for( TRACK* track : m_board->Tracks() )
+            {
+                if( !(track->GetLayerSet() & lset ).any() )
+                    continue;
+
+                if( TestSegmentHit( aVia->GetPosition(), track->GetStart(), track->GetEnd(),
+                                    ( track->GetWidth() + aVia->GetWidth() ) / 2 ) )
+                    return track;
+            }
+
+            return nullptr;
+        }
+
         int findStitchedZoneNet( VIA* aVia )
         {
             const auto  pos     = aVia->GetPosition();
             const auto  lset    = aVia->GetLayerSet();
 
-            for( auto tv : m_board->Tracks() ) // fixme: move to BOARD class?
-            {
-                if( tv->HitTest( pos ) && ( tv->GetLayerSet() & lset ).any() )
-                    return -1;
-            }
-
             for( auto mod : m_board->Modules() )
             {
-                for( auto pad : mod->Pads() )
+                for( D_PAD* pad : mod->Pads() )
                 {
                     if( pad->HitTest( pos ) && ( pad->GetLayerSet() & lset ).any() )
                         return -1;
@@ -1470,15 +1487,55 @@ int DRAWING_TOOL::DrawVia( const TOOL_EVENT& aEvent )
             return -1;
         }
 
-        bool PlaceItem( BOARD_ITEM* aItem ) override
+        void SnapItem( BOARD_ITEM *aItem ) override
+        {
+#if 0
+            // If you place a Via on a track but not on its centerline, the current
+            // connectivity algorithm will require us to put a kink in the track when
+            // we break it (so that each of the two segments ends on the via center).
+            // That's not ideal, and is in fact probably worse than forcing snap in
+            // this situation.
+            if( m_frame->Settings().m_magneticTracks == CAPTURE_CURSOR_IN_TRACK_TOOL
+                || m_frame->Settings().m_magneticTracks == CAPTURE_ALWAYS )
+#endif
             {
                 auto    via = static_cast<VIA*>( aItem );
-            int     newNet = findStitchedZoneNet( via );
+                wxPoint pos = via->GetPosition();
+                TRACK*  track = findTrack( via );
+
+                if( track )
+                {
+                    SEG         trackSeg( track->GetStart(), track->GetEnd() );
+                    VECTOR2I    snap = m_gridHelper.AlignToSegment( pos, trackSeg );
+
+                    aItem->SetPosition( wxPoint( snap.x, snap.y ) );
+                }
+            }
+        }
+
+        void PlaceItem( BOARD_ITEM* aItem, BOARD_COMMIT& aCommit ) override
+        {
+            auto    via = static_cast<VIA*>( aItem );
+            int     newNet;
+            TRACK*  track = findTrack( via );
+
+            if( track )
+            {
+                aCommit.Modify( track );
+                TRACK* newTrack = dynamic_cast<TRACK*>( track->Clone() );
+                track->SetEnd( via->GetPosition() );
+                newTrack->SetStart( via->GetPosition() );
+                aCommit.Add( newTrack );
+
+                newNet = track->GetNetCode();
+            }
+            else
+                newNet = findStitchedZoneNet( via );
 
             if( newNet > 0 )
                 via->SetNetCode( newNet );
 
-            return false;
+            aCommit.Add( aItem );
         }
 
         std::unique_ptr<BOARD_ITEM> CreateItem() override
@@ -1550,7 +1607,7 @@ int DRAWING_TOOL::DrawVia( const TOOL_EVENT& aEvent )
         }
     };
 
-    VIA_PLACER placer;
+    VIA_PLACER placer( frame() );
 
     frame()->SetToolID( ID_PCB_DRAW_VIA_BUTT, wxCURSOR_PENCIL, _( "Add vias" ) );
 

pcbnew/tools/pcb_tool.cpp

@@ -131,7 +131,7 @@ void PCB_TOOL::doInteractiveItemPlacement( INTERACTIVE_PLACER_BASE* aPlacer,
                 newItem->ClearFlags();
                 preview.Remove( newItem.get() );
 
-                aPlacer->PlaceItem( newItem.get() );
+                aPlacer->PlaceItem( newItem.get(), commit );
 
                 if( newItem->Type() == PCB_MODULE_T )
                 {
@@ -139,7 +139,7 @@ void PCB_TOOL::doInteractiveItemPlacement( INTERACTIVE_PLACER_BASE* aPlacer,
                     module->RunOnChildren( std::bind( &KIGFX::VIEW_GROUP::Remove, &preview, _1 ) );
                 }
 
-                commit.Add( newItem.release() );
+                newItem.release();
                 commit.Push( aCommitMessage );
 
                 controls()->CaptureCursor( false );
@@ -186,6 +186,7 @@ void PCB_TOOL::doInteractiveItemPlacement( INTERACTIVE_PLACER_BASE* aPlacer,
         {
             // track the cursor
             newItem->SetPosition( wxPoint( cursorPos.x, cursorPos.y ) );
+            aPlacer->SnapItem( newItem.get() );
 
             // Show a preview of the item
             view()->Update( &preview );
@@ -228,3 +229,14 @@ SELECTION& PCB_TOOL::selection()
     auto& selection = selTool->GetSelection();
     return selection;
 }
+
+
+void INTERACTIVE_PLACER_BASE::SnapItem( BOARD_ITEM *aItem )
+{
+    // Base implementation performs no snapping
+}
+
+void INTERACTIVE_PLACER_BASE::PlaceItem( BOARD_ITEM *aItem, BOARD_COMMIT& aCommit )
+{
+    aCommit.Add( aItem );
+}

pcbnew/tools/pcb_tool.h

@@ -52,7 +52,8 @@ class SELECTION;
 struct INTERACTIVE_PLACER_BASE
 {
     virtual std::unique_ptr<BOARD_ITEM> CreateItem() = 0;
-    virtual bool PlaceItem( BOARD_ITEM *aItem ) { return false; }
+    virtual void SnapItem( BOARD_ITEM *aItem );
+    virtual void PlaceItem( BOARD_ITEM *aItem, BOARD_COMMIT& aCommit );
 
     PCB_EDIT_FRAME* m_frame;
     BOARD* m_board;