From f3c2083018576e48c924aac17e1663729039a1f4 Mon Sep 17 00:00:00 2001
From: Yon Uriarte <yon.uriarte@gmail.com>
Date: Mon, 12 Feb 2024 08:39:11 +0100
Subject: [PATCH] Performance SCH_EDIT_FRAME::SchematicCleanUp

Avoid O(N^2) comparisonis by spatial presorting. If bounding boxes don't
overlap there's no need to run expensive checks.
---
 eeschema/bus-wire-junction.cpp | 42 ++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/eeschema/bus-wire-junction.cpp b/eeschema/bus-wire-junction.cpp
index 8f37b339a8..2faa8830e2 100644
--- a/eeschema/bus-wire-junction.cpp
+++ b/eeschema/bus-wire-junction.cpp
@@ -186,6 +186,28 @@ void SCH_EDIT_FRAME::SchematicCleanUp( SCH_COMMIT* aCommit, SCH_SCREEN* aScreen
             } );
 
 
+    auto minX = []( const SCH_LINE* l )
+                {
+                    return std::min( l->GetStartPoint().x, l->GetEndPoint().x );
+                };
+
+    auto maxX = []( const SCH_LINE* l )
+                {
+                    return std::max( l->GetStartPoint().x, l->GetEndPoint().x );
+                };
+
+    auto minY = []( const SCH_LINE* l )
+                {
+                    return std::min( l->GetStartPoint().y, l->GetEndPoint().y );
+                };
+
+    auto maxY = []( const SCH_LINE* l )
+                {
+                    return std::max( l->GetStartPoint().y, l->GetEndPoint().y );
+                };
+
+    // Would be nice to put lines in a canonical form here by swapping
+    //  start <-> end as needed but I don't know what swapping breaks.
     while( changed )
     {
         changed = false;
@@ -197,6 +219,13 @@ void SCH_EDIT_FRAME::SchematicCleanUp( SCH_COMMIT* aCommit, SCH_SCREEN* aScreen
                 lines.push_back( static_cast<SCH_LINE*>( item ) );
         }
 
+        // Sort by minimum X position
+        std::sort( lines.begin(), lines.end(),
+                   [&]( const SCH_LINE* a, const SCH_LINE* b )
+                   {
+                       return minX( a ) < minX( b );
+                   } );
+
         for( auto it1 = lines.begin(); it1 != lines.end(); ++it1 )
         {
             SCH_LINE* firstLine = *it1;
@@ -210,11 +239,24 @@ void SCH_EDIT_FRAME::SchematicCleanUp( SCH_COMMIT* aCommit, SCH_SCREEN* aScreen
                 continue;
             }
 
+            int  firstRightXEdge = maxX( firstLine );
             auto it2 = it1;
 
             for( ++it2; it2 != lines.end(); ++it2 )
             {
                 SCH_LINE* secondLine = *it2;
+                int       secondLeftXEdge = minX( secondLine );
+
+                // impossible to overlap remaining lines
+                if( secondLeftXEdge > firstRightXEdge )
+                    break;
+
+                // No Y axis overlap
+                if( !( std::max( minY( firstLine ), minY( secondLine ) )
+                       <= std::min( maxY( firstLine ), maxY( secondLine ) ) ) )
+                {
+                    continue;
+                }
 
                 if( secondLine->GetFlags() & STRUCT_DELETED )
                     continue;