From 5dd0099119e391c326d6ddb35201e4b9620bf50b Mon Sep 17 00:00:00 2001
From: unknown <pavlina.chris@gmail.com>
Date: Tue, 23 Jun 2015 17:01:34 +0200
Subject: [PATCH] Eeschema: Remove backtracking (overlapping) wires when
 creating new connections.

---
 eeschema/bus-wire-junction.cpp | 51 ++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/eeschema/bus-wire-junction.cpp b/eeschema/bus-wire-junction.cpp
index 62141bd93f..d0c6994e71 100644
--- a/eeschema/bus-wire-junction.cpp
+++ b/eeschema/bus-wire-junction.cpp
@@ -43,6 +43,7 @@
 #include <sch_text.h>
 #include <sch_component.h>
 #include <sch_sheet.h>
+#include <trigo.h>
 
 
 static void AbortCreateNewLine( EDA_DRAW_PANEL* aPanel, wxDC* aDC );
@@ -52,6 +53,53 @@ static DLIST< SCH_ITEM > s_wires;       // when creating a new set of wires,
                                         // stores here the new wires.
 
 
+/**
+ * In a contiguous list of wires, remove wires that backtrack over the previous
+ * wire. Example:
+ *
+ * Wire is added:
+ * ---------------------------------------->
+ *
+ * A second wire backtracks over it:
+ * -------------------<====================>
+ *
+ * RemoveBacktracks is called:
+ * ------------------->
+ */
+static void RemoveBacktracks( DLIST<SCH_ITEM>& aWires )
+{
+    SCH_LINE* last_line = NULL;
+
+    EDA_ITEM* first = aWires.GetFirst();
+    for( EDA_ITEM* p = first; p; )
+    {
+        SCH_LINE *line = dynamic_cast<SCH_LINE*>( p );
+        if( !line )
+        {
+            wxFAIL_MSG( "RemoveBacktracks() requires SCH_LINE items" );
+            break;
+        }
+        p = line->Next();
+
+        if( last_line )
+        {
+            wxASSERT_MSG( last_line->GetEndPoint() == line->GetStartPoint(),
+                    "RemoveBacktracks() requires contiguous lines" );
+            if( IsPointOnSegment( last_line->GetStartPoint(), line->GetStartPoint(),
+                        line->GetEndPoint() ) )
+            {
+                last_line->SetEndPoint( line->GetEndPoint() );
+                delete s_wires.Remove( line );
+            }
+            else
+                last_line = line;
+        }
+        else
+            last_line = line;
+    }
+}
+
+
 /**
  * Mouse capture callback for drawing line segments.
  */
@@ -261,6 +309,9 @@ void SCH_EDIT_FRAME::EndSegment( wxDC* DC )
 
     SaveCopyInUndoList( oldItems, UR_WIRE_IMAGE );
 
+    // Remove segments backtracking over others
+    RemoveBacktracks( s_wires );
+
     // Add the new wires
     screen->Append( s_wires );