From d78f6857c1d7c1306658a50fe7963d7fbaaa452c Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Sat, 1 Nov 2025 19:47:46 +0000
Subject: [PATCH] Export Gerber slots as single-pad-footprints.

(We export round holes as vias, but they don't
allow slots.)

Fixes https://gitlab.com/kicad/code/kicad/-/issues/22057
---
 gerbview/export_to_pcbnew.cpp | 37 ++++++++++++++++++++++++++++++++---
 gerbview/export_to_pcbnew.h   | 27 ++++++++++++++++++++-----
 2 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/gerbview/export_to_pcbnew.cpp b/gerbview/export_to_pcbnew.cpp
index a2bb4b3ca8..f79477dc5a 100644
--- a/gerbview/export_to_pcbnew.cpp
+++ b/gerbview/export_to_pcbnew.cpp
@@ -38,6 +38,7 @@
 #include <wildcards_and_files_ext.h>
 #include "excellon_image.h"
 #include <wx/log.h>
+#include <convert_basic_shapes_to_polygon.h>
 
 
 GBR_TO_PCB_EXPORTER::GBR_TO_PCB_EXPORTER( GERBVIEW_FRAME* aFrame, const wxString& aFileName )
@@ -135,6 +136,9 @@ bool GBR_TO_PCB_EXPORTER::ExportPcb( const int* aLayerLookUpTable, int aCopperLa
     for( const EXPORT_VIA& via : m_vias )
         export_via( via );
 
+    for( const EXPORT_SLOT& slot : m_slots )
+        export_slot( slot );
+
     fprintf( m_fp, ")\n" );
 
     fclose( m_fp );
@@ -295,8 +299,10 @@ void GBR_TO_PCB_EXPORTER::export_non_copper_arc( const GERBER_DRAW_ITEM* aGbrIte
 
 void GBR_TO_PCB_EXPORTER::collect_hole( const GERBER_DRAW_ITEM* aGbrItem )
 {
-    int size = std::min( aGbrItem->m_Size.x, aGbrItem->m_Size.y );
-    m_vias.emplace_back( aGbrItem->m_Start, size + 1, size );
+    if( aGbrItem->m_ShapeType == GBR_SPOT_CIRCLE )
+        m_vias.emplace_back( aGbrItem->m_Start, aGbrItem->m_Size.x + 1, aGbrItem->m_Size.x );
+    else if( aGbrItem->m_ShapeType == GBR_SEGMENT )
+        m_slots.emplace_back( aGbrItem->m_Start, aGbrItem->m_End, aGbrItem->m_Size.x );
 }
 
 
@@ -308,7 +314,7 @@ void GBR_TO_PCB_EXPORTER::export_via( const EXPORT_VIA& aVia )
     via_pos.y = -via_pos.y;
 
     // Layers are Front to Back
-    fprintf( m_fp, " (via (at %s %s) (size %s) (drill %s)",
+    fprintf( m_fp, "\t(via (at %s %s) (size %s) (drill %s)",
              FormatDouble2Str( MapToPcbUnits( via_pos.x ) ).c_str(),
              FormatDouble2Str( MapToPcbUnits( via_pos.y ) ).c_str(),
              FormatDouble2Str( MapToPcbUnits( aVia.m_Size ) ).c_str(),
@@ -320,6 +326,31 @@ void GBR_TO_PCB_EXPORTER::export_via( const EXPORT_VIA& aVia )
 }
 
 
+void GBR_TO_PCB_EXPORTER::export_slot( const EXPORT_SLOT& aSlot )
+{
+    VECTOR2I start = aSlot.m_Start;
+    VECTOR2I end = aSlot.m_End;
+
+    // Reverse Y axis:
+    start.y = -start.y;
+    end.y = -end.y;
+
+    VECTOR2I dir = end - start;
+    int      minorAxis = aSlot.m_Width;
+    int      majorAxis = aSlot.m_Width + dir.EuclideanNorm();
+    VECTOR2I center = ( start + end ) / 2;
+
+    fprintf( m_fp, "\t(footprint \"slot\" (pad 1 thru_hole oval (at %s %s %s) (size %s %s) (drill oval %s %s)))\n",
+             FormatDouble2Str( MapToPcbUnits( center.x ) ).c_str(),
+             FormatDouble2Str( MapToPcbUnits( center.y ) ).c_str(),
+             FormatDouble2Str( EDA_ANGLE( dir ).AsDegrees() ).c_str(),
+             FormatDouble2Str( MapToPcbUnits( majorAxis + 1 ) ).c_str(),
+             FormatDouble2Str( MapToPcbUnits( minorAxis + 1 ) ).c_str(),
+             FormatDouble2Str( MapToPcbUnits( majorAxis ) ).c_str(),
+             FormatDouble2Str( MapToPcbUnits( minorAxis ) ).c_str() );
+}
+
+
 void GBR_TO_PCB_EXPORTER::export_copper_item( const GERBER_DRAW_ITEM* aGbrItem, int aLayer )
 {
     if( aGbrItem->GetLayerPolarity() )
diff --git a/gerbview/export_to_pcbnew.h b/gerbview/export_to_pcbnew.h
index 9323ad88ee..d9f2260216 100644
--- a/gerbview/export_to_pcbnew.h
+++ b/gerbview/export_to_pcbnew.h
@@ -26,6 +26,20 @@
 #include <layer_ids.h>
 
 
+struct EXPORT_SLOT
+{
+    EXPORT_SLOT( const VECTOR2I& aStart, const VECTOR2I& aEnd, int aWidth ) :
+            m_Start( aStart ),
+            m_End( aEnd ),
+            m_Width( aWidth )
+    { }
+
+    VECTOR2I m_Start;
+    VECTOR2I m_End;
+    int      m_Width;
+};
+
+
 struct EXPORT_VIA
 {
     EXPORT_VIA( const VECTOR2I& aPos, int aSize, int aDrill ) :
@@ -80,6 +94,8 @@ private:
      */
     void export_via( const EXPORT_VIA& aVia );
 
+    void export_slot( const EXPORT_SLOT& aSlot );
+
     /**
      * Write a non copper line or arc to the board file.
      *
@@ -188,9 +204,10 @@ private:
     }
 
 private:
-    GERBVIEW_FRAME*         m_gerbview_frame;   // the main gerber frame
-    wxString                m_pcb_file_name;    // BOARD file to write to
-    FILE*                   m_fp;               // the board file
-    int                     m_pcbCopperLayersCount;
-    std::vector<EXPORT_VIA> m_vias;
+    GERBVIEW_FRAME*          m_gerbview_frame;   // the main gerber frame
+    wxString                 m_pcb_file_name;    // BOARD file to write to
+    FILE*                    m_fp;               // the board file
+    int                      m_pcbCopperLayersCount;
+    std::vector<EXPORT_VIA>  m_vias;
+    std::vector<EXPORT_SLOT> m_slots;
 };