From 4dda7d39aba3d8317af5d370578689bbe0b44e52 Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Mon, 5 Jun 2023 18:54:52 +0100
Subject: [PATCH] Tranform diamonds back to rects after rotating to a cardinal
 orientation.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/14828
---
 common/eda_shape.cpp | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/common/eda_shape.cpp b/common/eda_shape.cpp
index 7a357603df..cb9a486194 100644
--- a/common/eda_shape.cpp
+++ b/common/eda_shape.cpp
@@ -262,6 +262,18 @@ void EDA_SHAPE::scale( double aScale )
 
 void EDA_SHAPE::rotate( const VECTOR2I& aRotCentre, const EDA_ANGLE& aAngle )
 {
+    auto horizontal =
+            []( const SEG& seg )
+            {
+                return seg.A.y == seg.B.y;
+            };
+
+    auto vertical =
+            []( const SEG& seg )
+            {
+                return seg.A.x == seg.B.x;
+            };
+
     switch( m_shape )
     {
     case SHAPE_T::SEGMENT:
@@ -297,6 +309,36 @@ void EDA_SHAPE::rotate( const VECTOR2I& aRotCentre, const EDA_ANGLE& aAngle )
 
     case SHAPE_T::POLY:
         m_poly.Rotate( aAngle, aRotCentre );
+
+        // Convert back to rectangle if appropriate
+        if( m_poly.OutlineCount() == 1 && m_poly.Outline( 0 ).SegmentCount() == 4 )
+        {
+            SHAPE_LINE_CHAIN& outline = m_poly.Outline( 0 );
+
+            if( horizontal( outline.Segment( 0 ) )
+                && vertical( outline.Segment( 1 ) )
+                && horizontal( outline.Segment( 2 ) )
+                && vertical( outline.Segment( 3 ) ) )
+            {
+                m_shape = SHAPE_T::RECT;
+                m_start.x = std::min( outline.Segment( 0 ).A.x, outline.Segment( 0 ).B.x );
+                m_start.y = std::min( outline.Segment( 1 ).A.y, outline.Segment( 1 ).B.y );
+                m_end.x = std::max( outline.Segment( 0 ).A.x, outline.Segment( 0 ).B.x );
+                m_end.y = std::max( outline.Segment( 1 ).A.y, outline.Segment( 1 ).B.y );
+            }
+            else if( vertical( outline.Segment( 0 ) )
+                  && horizontal( outline.Segment( 1 ) )
+                  && vertical( outline.Segment( 2 ) )
+                  && horizontal( outline.Segment( 3 ) ) )
+            {
+                m_shape = SHAPE_T::RECT;
+                m_start.x = std::min( outline.Segment( 1 ).A.x, outline.Segment( 1 ).B.x );
+                m_start.y = std::min( outline.Segment( 0 ).A.y, outline.Segment( 0 ).B.y );
+                m_end.x = std::max( outline.Segment( 1 ).A.x, outline.Segment( 1 ).B.x );
+                m_end.y = std::max( outline.Segment( 0 ).A.y, outline.Segment( 0 ).B.y );
+            }
+        }
+
         break;
 
     case SHAPE_T::BEZIER: