pcbnew: Improve zone/polygon selection

Allows selection of polygons and zones by their visible area.  Will only
select polygons/filled areas when they are unobstructed by other
elements in the footprint/pcb.  Also adds a "skip heuristics" modifier
key for clicking (ALT) that allows the full disambiguation list to be
displayed without removing less-likely elements.  This dovetails the
zone/polygon selection as it allows selecting even when areas a fully
overlapped.

Fixes: lp:1753153
* https://bugs.launchpad.net/kicad/+bug/1753153

pcbnew/class_drawsegment.cpp

@@ -643,14 +643,9 @@ bool DRAWSEGMENT::HitTest( const wxPoint& aPosition ) const
     case S_POLYGON:     // not yet handled
         {
             #define MAX_DIST_IN_MM 0.25
-            int distmax = Millimeter2iu( 0.25 );
-            SHAPE_POLY_SET::VERTEX_INDEX dummy;
-            auto poly = m_Poly;
+            int distmax = std::max( m_Width, Millimeter2iu( MAX_DIST_IN_MM ) );
 
-            if( poly.CollideVertex( VECTOR2I( aPosition ), dummy, distmax ) )
-                return true;
-
-            if( poly.CollideEdge( VECTOR2I( aPosition ), dummy, distmax ) )
+            if( m_Poly.Collide( VECTOR2I( aPosition ), distmax ) )
                 return true;
         }
         break;

pcbnew/class_zone.cpp

@@ -653,7 +653,8 @@ void ZONE_CONTAINER::SetCornerRadius( unsigned int aRadius )
 
 bool ZONE_CONTAINER::HitTest( const wxPoint& aPosition ) const
 {
-    return HitTestForCorner( aPosition ) || HitTestForEdge( aPosition );
+    return HitTestForCorner( aPosition ) || HitTestForEdge( aPosition ) ||
+            HitTestFilledArea( aPosition );
 }
 
 

pcbnew/tools/selection_tool.cpp

@@ -195,6 +195,7 @@ SELECTION_TOOL::SELECTION_TOOL() :
         m_additive( false ),
         m_subtractive( false ),
         m_multiple( false ),
+        m_skip_heuristics( false ),
         m_locked( true ),
         m_menu( *this ),
         m_priv( std::make_unique<PRIV>() )
@@ -274,6 +275,10 @@ int SELECTION_TOOL::Main( const TOOL_EVENT& aEvent )
         // This will be ignored if the SHIFT modifier is pressed
         m_subtractive = !m_additive && evt->Modifier( MD_CTRL );
 
+        // Is the user requesting that the selection list include all possible
+        // items without removing less likely selection candidates
+        m_skip_heuristics = !!evt->Modifier( MD_ALT );
+
         // Single click? Select single object
         if( evt->IsClick( BUT_LEFT ) )
         {
@@ -513,12 +518,15 @@ bool SELECTION_TOOL::selectPoint( const VECTOR2I& aWhere, bool aOnDrag,
     }
 
     // Apply some ugly heuristics to avoid disambiguation menus whenever possible
-    guessSelectionCandidates( collector );
-
-    if( collector.GetCount() == 1 )
+    if( !m_skip_heuristics )
     {
-        toggleSelection( collector[0] );
-        return true;
+        guessSelectionCandidates( collector );
+
+        if( collector.GetCount() == 1 )
+        {
+            toggleSelection( collector[0] );
+            return true;
+        }
     }
 
     // Still more than one item.  We're going to have to ask the user.
@@ -2030,6 +2038,30 @@ void SELECTION_TOOL::guessSelectionCandidates( GENERAL_COLLECTOR& aCollector ) c
         }
     }
 
+    int numZones = aCollector.CountType( PCB_ZONE_AREA_T );
+
+    if( numZones > 0 && aCollector.GetCount() > numZones )
+    {
+        for( int i = aCollector.GetCount() - 1; i >= 0; i-- )
+        {
+            if( aCollector[i]->Type() == PCB_ZONE_AREA_T )
+                aCollector.Remove( i );
+        }
+    }
+
+    int numDrawitems = aCollector.CountType( PCB_LINE_T ) +
+            aCollector.CountType( PCB_MODULE_EDGE_T );
+
+    if( numDrawitems > 0 && aCollector.GetCount() > numDrawitems )
+    {
+        for( int i = aCollector.GetCount() - 1; i >= 0; i-- )
+        {
+            auto ds = static_cast<DRAWSEGMENT*>( aCollector[i] );
+            if( ds->GetShape() == S_POLYGON )
+                aCollector.Remove( i );
+        }
+    }
+
     if( aCollector.CountType( PCB_MODULE_TEXT_T ) > 0 )
     {
         for( int i = 0; i < aCollector.GetCount(); ++i )

pcbnew/tools/selection_tool.h

@@ -356,6 +356,9 @@ private:
     /// Flag saying if multiple selection mode is active.
     bool m_multiple;
 
+    /// Flag saying that heuristics should be skipped while choosing selection
+    bool m_skip_heuristics;
+
     /// Can other tools modify locked items.
     bool m_locked;