Forbid drawing self-intersecting polygons.

common/geometry/shape_poly_set.cpp

@@ -387,11 +387,8 @@ bool SHAPE_POLY_SET::GetNeighbourIndexes( int aGlobalIndex, int* aPrevious, int*
 
 bool SHAPE_POLY_SET::IsPolygonSelfIntersecting( int aPolygonIndex )
 {
-    // Get polygon
-    const POLYGON poly = CPolygon( aPolygonIndex );
-
-    SEGMENT_ITERATOR    iterator = IterateSegmentsWithHoles( aPolygonIndex );
-    SEGMENT_ITERATOR    innerIterator;
+    SEGMENT_ITERATOR iterator = IterateSegmentsWithHoles( aPolygonIndex );
+    SEGMENT_ITERATOR innerIterator;
 
     for( iterator = IterateSegmentsWithHoles( aPolygonIndex ); iterator; iterator++ )
     {

common/preview_items/polygon_geom_manager.cpp

@@ -28,7 +28,8 @@
 
 POLYGON_GEOM_MANAGER::POLYGON_GEOM_MANAGER( CLIENT& aClient ):
     m_client( aClient ),
-    m_leaderMode( LEADER_MODE::DIRECT )
+    m_leaderMode( LEADER_MODE::DIRECT ),
+    m_intersectionsAllowed( false )
 {}
 
 
@@ -52,6 +53,17 @@ bool POLYGON_GEOM_MANAGER::AddPoint( const VECTOR2I& aPt )
         m_lockedPoints.Append( aPt );
     }
 
+    // check for self-intersections (line chain needs to be set as closed for proper checks)
+    m_lockedPoints.SetClosed( true );
+    bool selfIntersect = !!m_lockedPoints.SelfIntersecting();
+    m_lockedPoints.SetClosed( false );
+
+    if( !m_intersectionsAllowed && selfIntersect )
+    {
+        m_lockedPoints.Remove( m_lockedPoints.PointCount() - 1 );
+        return false;
+    }
+
     m_client.OnGeometryChange( *this );
     return true;
 }
@@ -117,8 +129,6 @@ void POLYGON_GEOM_MANAGER::Reset()
 void POLYGON_GEOM_MANAGER::updateLeaderPoints( const VECTOR2I& aEndPoint, LEADER_MODE aModifier )
 {
     wxCHECK( m_lockedPoints.PointCount() > 0, /*void*/ );
-    SHAPE_LINE_CHAIN newChain;
-
     const VECTOR2I& lastPt = m_lockedPoints.CLastPoint();
 
     if( m_leaderMode == LEADER_MODE::DEG45 || aModifier == LEADER_MODE::DEG45 )
@@ -129,6 +139,7 @@ void POLYGON_GEOM_MANAGER::updateLeaderPoints( const VECTOR2I& aEndPoint, LEADER
 
         // Can also add chain back to start, but this rearely produces
         // usable result
+        //SHAPE_LINE_CHAIN newChain;
         //DIRECTION_45 directionToStart( aEndPoint - m_lockedPoints.front() );
         //newChain.Append( directionToStart.BuildInitialTrace( aEndPoint, m_lockedPoints.front() ) );
     }

include/preview_items/polygon_geom_manager.h

@@ -95,6 +95,24 @@ public:
      */
     void SetLeaderMode( LEADER_MODE aMode );
 
+    /**
+     * Enables/disables self-intersecting polygons.
+     * @param aEnabled true if self-intersecting polygons are enabled.
+     */
+    void AllowIntersections( bool aEnabled )
+    {
+        m_intersectionsAllowed = true;
+    }
+
+    /**
+     * Checks whether self-intersecting polygons are enabled.
+     * @return true if self-intersecting polygons are enabled.
+     */
+    bool IntersectionsAllowed() const
+    {
+        return m_intersectionsAllowed;
+    }
+
     /**
      * Set the current cursor position
      */
@@ -155,6 +173,9 @@ private:
     ///> The current mode of the leader line
     LEADER_MODE m_leaderMode;
 
+    ///> Flag enabling self-intersecting polygons
+    bool m_intersectionsAllowed;
+
     ///> Point that have been "locked in"
     SHAPE_LINE_CHAIN m_lockedPoints;
 

pcbnew/tools/drawing_tool.cpp

@@ -47,6 +47,7 @@
 #include <bitmaps.h>
 #include <hotkeys.h>
 #include <painter.h>
+#include <status_popup.h>
 
 #include <preview_items/arc_assistant.h>
 
@@ -658,6 +659,7 @@ int DRAWING_TOOL::DrawZoneCutout( const TOOL_EVENT& aEvent )
     return drawZone( false, ZONE_MODE::CUTOUT );
 }
 
+
 int DRAWING_TOOL::DrawGraphicPolygon( const TOOL_EVENT& aEvent )
 {
     SCOPED_DRAW_MODE scopedDrawMode( m_mode, MODE::GRAPHIC_POLYGON );
@@ -1251,6 +1253,7 @@ void DRAWING_TOOL::runPolygonEventLoop( POLYGON_GEOM_MANAGER& polyGeomMgr )
 {
     auto&   controls    = *getViewControls();
     bool    started     = false;
+    STATUS_TEXT_POPUP status( m_frame );
 
     while( OPT_TOOL_EVENT evt = Wait() )
     {
@@ -1296,6 +1299,7 @@ void DRAWING_TOOL::runPolygonEventLoop( POLYGON_GEOM_MANAGER& polyGeomMgr )
                 controls.SetAutoPan( false );
                 controls.CaptureCursor( false );
             }
+
             // adding a corner
             else if( polyGeomMgr.AddPoint( cursorPos ) )
             {
@@ -1306,6 +1310,16 @@ void DRAWING_TOOL::runPolygonEventLoop( POLYGON_GEOM_MANAGER& polyGeomMgr )
                     controls.CaptureCursor( true );
                 }
             }
+            else if( started )
+            {
+                status.SetTextColor( wxColour( 255, 0, 0 ) );
+                status.SetText( _( "Self-intersecting polygons are not allowed" ) );
+                wxPoint p = wxGetMousePosition() + wxPoint( 20, 20 );
+                status.Move( p );
+                status.Popup( m_frame );
+                status.Expire( 1500 );
+            }
+
         }
         else if( evt->IsAction( &deleteLastPoint ) )
         {