Solder masks for teardrops on tracks with solder masks.

Also moves teardrops away from the zone UI: they
are now always filled and their borders never
drawn.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/20744

pcbnew/pcb_painter.cpp

@@ -2738,6 +2738,9 @@ void PCB_PAINTER::draw( const ZONE* aZone, int aLayer )
     std::deque<VECTOR2D> corners;
     ZONE_DISPLAY_MODE    displayMode = m_pcbSettings.m_ZoneDisplayMode;
 
+    if( aZone->IsTeardropArea() )
+        displayMode = ZONE_DISPLAY_MODE::SHOW_FILLED;
+
     // Draw the outline
     if( !IsZoneFillLayer( aLayer ) )
     {

pcbnew/teardrop/teardrop.cpp

@@ -73,8 +73,7 @@ ZONE* TEARDROP_MANAGER::createTeardrop( TEARDROP_VARIANT aTeardropVariant,
     teardrop->SetPadConnection( ZONE_CONNECTION::FULL );
     teardrop->SetIsFilled( false );
     teardrop->SetIslandRemovalMode( ISLAND_REMOVAL_MODE::NEVER );
-    teardrop->SetBorderDisplayStyle( ZONE_BORDER_DISPLAY_STYLE::DIAGONAL_FULL,
-                                     pcbIUScale.mmToIU( 0.1 ), true );
+    teardrop->SetBorderDisplayStyle( ZONE_BORDER_DISPLAY_STYLE::INVISIBLE_BORDER, 0, false );
 
     SHAPE_POLY_SET* outline = teardrop->Outline();
     outline->NewOutline();
@@ -94,6 +93,45 @@ ZONE* TEARDROP_MANAGER::createTeardrop( TEARDROP_VARIANT aTeardropVariant,
 }
 
 
+ZONE* TEARDROP_MANAGER::createTeardropMask( TEARDROP_VARIANT aTeardropVariant,
+                                            std::vector<VECTOR2I>& aPoints, PCB_TRACK* aTrack ) const
+{
+    ZONE* teardrop = new ZONE( m_board );
+
+    teardrop->SetTeardropAreaType( aTeardropVariant == TD_TYPE_PADVIA ? TEARDROP_TYPE::TD_VIAPAD
+                                                                      : TEARDROP_TYPE::TD_TRACKEND );
+    teardrop->SetLayer( aTrack->GetLayer() == F_Cu ? F_Mask : B_Mask );
+    teardrop->SetMinThickness( pcbIUScale.mmToIU( 0.0254 ) );  // The minimum zone thickness
+    teardrop->SetIsFilled( false );
+    teardrop->SetIslandRemovalMode( ISLAND_REMOVAL_MODE::NEVER );
+    teardrop->SetBorderDisplayStyle( ZONE_BORDER_DISPLAY_STYLE::INVISIBLE_BORDER, 0, false );
+
+    SHAPE_POLY_SET* outline = teardrop->Outline();
+    outline->NewOutline();
+
+    for( const VECTOR2I& pt: aPoints )
+        outline->Append( pt.x, pt.y );
+
+    if( int expansion = aTrack->GetSolderMaskExpansion() )
+    {
+        // The zone-min-thickness deflate/reinflate is going to round corners, so it's more
+        // efficient to allow acute corners on the solder mask expansion here, and delegate the
+        // rounding to the deflate/reinflate.
+        teardrop->SetMinThickness( std::max( teardrop->GetMinThickness(), expansion ) );
+
+        outline->Inflate( expansion, CORNER_STRATEGY::ALLOW_ACUTE_CORNERS,
+                          m_board->GetDesignSettings().m_MaxError );
+    }
+
+    // Until we know better (ie: pay for a potentially very expensive zone refill), the teardrop
+    // fill is the same as its outline.
+    teardrop->SetFilledPolysList( teardrop->GetLayer(), *teardrop->Outline() );
+    teardrop->SetIsFilled( true );
+
+    return teardrop;
+}
+
+
 void TEARDROP_MANAGER::RemoveTeardrops( BOARD_COMMIT& aCommit,
                                         const std::vector<BOARD_ITEM*>* dirtyPadsAndVias,
                                         const std::set<PCB_TRACK*>* dirtyTracks )
@@ -217,6 +255,13 @@ void TEARDROP_MANAGER::UpdateTeardrops( BOARD_COMMIT& aCommit,
                 m_createdTdList.push_back( new_teardrop );
 
                 aCommit.Added( new_teardrop );
+
+                if( track->HasSolderMask() && ( track->GetLayer() == F_Cu || track->GetLayer() == B_Cu ) )
+                {
+                    ZONE* new_teardrop_mask = createTeardropMask( TD_TYPE_PADVIA, points, track );
+                    m_board->Add( new_teardrop_mask, ADD_MODE::BULK_INSERT );
+                    aCommit.Added( new_teardrop_mask );
+                }
             }
         }
 
@@ -253,6 +298,13 @@ void TEARDROP_MANAGER::UpdateTeardrops( BOARD_COMMIT& aCommit,
                 m_createdTdList.push_back( new_teardrop );
 
                 aCommit.Added( new_teardrop );
+
+                if( track->HasSolderMask() && ( track->GetLayer() == F_Cu || track->GetLayer() == B_Cu ) )
+                {
+                    ZONE* new_teardrop_mask = createTeardropMask( TD_TYPE_PADVIA, points, track );
+                    m_board->Add( new_teardrop_mask, ADD_MODE::BULK_INSERT );
+                    aCommit.Added( new_teardrop_mask );
+                }
             }
         }
     }
@@ -428,6 +480,13 @@ void TEARDROP_MANAGER::AddTeardropsOnTracks( BOARD_COMMIT& aCommit,
                     m_createdTdList.push_back( new_teardrop );
 
                     aCommit.Added( new_teardrop );
+
+                    if( track->HasSolderMask() && ( track->GetLayer() == F_Cu || track->GetLayer() == B_Cu ) )
+                    {
+                        ZONE* new_teardrop_mask = createTeardropMask( TD_TYPE_TRACKEND, points, track );
+                        m_board->Add( new_teardrop_mask, ADD_MODE::BULK_INSERT );
+                        aCommit.Added( new_teardrop_mask );
+                    }
                 }
             }
         }

pcbnew/teardrop/teardrop.h

@@ -205,6 +205,9 @@ private:
     ZONE* createTeardrop( TEARDROP_VARIANT aTeardropVariant,
                           std::vector<VECTOR2I>& aPoints, PCB_TRACK* aTrack ) const;
 
+    ZONE* createTeardropMask( TEARDROP_VARIANT aTeardropVariant,
+                              std::vector<VECTOR2I>& aPoints, PCB_TRACK* aTrack ) const;
+
     /**
      * Set priority of created teardrops. smaller have bigger priority
      */