Keep colors & visibility with layer objects, not layer number.

Also fixes a bug where the Layers manager would keep getting wider
each time the longest item was moved

Fixes https://gitlab.com/kicad/code/kicad/-/issues/15790

gerbview/gerbview_frame.cpp

@@ -492,7 +492,7 @@ void GERBVIEW_FRAME::ApplyDisplaySettingsToGAL()
 
 int GERBVIEW_FRAME::getNextAvailableLayer() const
 {
-    for( unsigned i = 0; i < ImagesMaxCount(); ++i )
+    for( int i = 0; i < (int) ImagesMaxCount(); ++i )
     {
         const GERBER_FILE_IMAGE* gerber = GetGbrImage( i );
 
@@ -544,10 +544,23 @@ void GERBVIEW_FRAME::SortLayersByX2Attributes()
 }
 
 
-void GERBVIEW_FRAME::RemapLayers( std::unordered_map<int, int> remapping )
+void GERBVIEW_FRAME::RemapLayers( const std::unordered_map<int, int>& remapping )
 {
-    ReFillLayerWidget();
+    std::unordered_map<int, COLOR4D> oldColors;
-    syncLayerBox( true );
+    std::unordered_map<int, bool>    oldVisibility;
+    LSET                             newVisibility;
+
+    for( const std::pair<const int, int>& entry : remapping )
+    {
+        oldColors[ entry.second ] = GetLayerColor( GERBER_DRAW_LAYER( entry.second ) );
+        oldVisibility[ entry.second ] = IsLayerVisible( entry.second );
+    }
+
+    for( const std::pair<const int, int>& entry : remapping )
+    {
+        SetLayerColor( GERBER_DRAW_LAYER( entry.first ), oldColors[ entry.second ] );
+        newVisibility.set( entry.first, oldVisibility[ entry.second ] );
+    }
 
     std::unordered_map<int, int> view_remapping;
 
@@ -558,6 +571,10 @@ void GERBVIEW_FRAME::RemapLayers( std::unordered_map<int, int> remapping )
     }
 
     GetCanvas()->GetView()->ReorderLayerData( view_remapping );
+
+    SetVisibleLayers( newVisibility );
+    ReFillLayerWidget();
+    syncLayerBox( true );
     GetCanvas()->Refresh();
 }
 

gerbview/gerbview_frame.h

@@ -359,7 +359,7 @@ public:
      * @param remapping A map of old layer number -> new layer number mapping.
      *                  Generally sourced from the SortImagesBy* functions.
      */
-    void RemapLayers( std::unordered_map<int, int> remapping );
+    void RemapLayers( const std::unordered_map<int, int>& remapping );
 
     /**
      * Update each layers' differential option. Needed when xor mode changes or the active layer

gerbview/widgets/gerbview_layer_widget.cpp

@@ -318,7 +318,9 @@ void GERBER_LAYER_WIDGET::ReFill()
             SetLayerVisible( layer, visible );
         }
         else
+        {
             AppendLayerRow( LAYER_WIDGET::ROW( msg, layer, color, wxEmptyString, visible, true ) );
+        }
     }
 
     UpdateLayouts();

gerbview/widgets/layer_widget.cpp

@@ -339,7 +339,7 @@ void LAYER_WIDGET::insertLayerRow( int aRow, const ROW& aSpec )
     bmb->Bind( COLOR_SWATCH_CHANGED, &LAYER_WIDGET::OnLayerSwatchChanged, this );
     bmb->SetToolTip( _( "Left double click or middle click for color change, right click for "
                         "menu" ) );
-    m_LayersFlexGridSizer->wxSizer::Insert( index+col, bmb, 0, flags );
+    m_LayersFlexGridSizer->wxSizer::Insert( index+col, bmb, 0, flags | wxRIGHT, 2 );
 
     // column 2 (COLUMN_COLOR_LYR_CB)
     col = COLUMN_COLOR_LYR_CB;
@@ -517,7 +517,7 @@ LAYER_WIDGET::LAYER_WIDGET( wxWindow* aParent, wxWindow* aFocusOwner, wxWindowID
     m_LayerScrolledWindow = new wxScrolledWindow( m_LayerPanel, wxID_ANY, wxDefaultPosition,
                                                   wxDefaultSize, wxNO_BORDER );
     m_LayerScrolledWindow->SetScrollRate( 5, 5 );
-    m_LayersFlexGridSizer = new wxFlexGridSizer( 0, LYR_COLUMN_COUNT, 0, 1 );
+    m_LayersFlexGridSizer = new wxFlexGridSizer( 0, LYR_COLUMN_COUNT, 3, 4 );
     m_LayersFlexGridSizer->SetFlexibleDirection( wxHORIZONTAL );
     m_LayersFlexGridSizer->SetNonFlexibleGrowMode( wxFLEX_GROWMODE_NONE );
 
@@ -542,7 +542,7 @@ LAYER_WIDGET::LAYER_WIDGET( wxWindow* aParent, wxWindow* aFocusOwner, wxWindowID
     m_RenderScrolledWindow = new wxScrolledWindow( m_RenderingPanel, wxID_ANY, wxDefaultPosition,
                                                    wxDefaultSize, wxNO_BORDER );
     m_RenderScrolledWindow->SetScrollRate( 5, 5 );
-    m_RenderFlexGridSizer = new wxFlexGridSizer( 0, RND_COLUMN_COUNT, 0, 1 );
+    m_RenderFlexGridSizer = new wxFlexGridSizer( 0, RND_COLUMN_COUNT, 3, 4 );
     m_RenderFlexGridSizer->SetFlexibleDirection( wxHORIZONTAL );
     m_RenderFlexGridSizer->SetNonFlexibleGrowMode( wxFLEX_GROWMODE_NONE );
 
@@ -583,13 +583,8 @@ wxSize LAYER_WIDGET::GetBestSize() const
     wxArrayInt widths = m_LayersFlexGridSizer->GetColWidths();
     int totWidth = 0;
 
-    if( widths.GetCount() )
+    for( int i = 0; i < LYR_COLUMN_COUNT && i < widths.GetCount(); ++i )
-    {
+        totWidth += widths[i];
-        for( int i = 0; i < LYR_COLUMN_COUNT; ++i )
-        {
-            totWidth += widths[i] + m_LayersFlexGridSizer->GetHGap();
-        }
-    }
 
     // Account for the parent's frame:
     totWidth += 15;
@@ -607,13 +602,8 @@ wxSize LAYER_WIDGET::GetBestSize() const
     widths = m_RenderFlexGridSizer->GetColWidths();
     totWidth = 0;
 
-    if( widths.GetCount() )
+    for( int i = 0; i < RND_COLUMN_COUNT && i < widths.GetCount(); ++i )
-    {
+        totWidth += widths[i];
-        for( int i = 0; i < RND_COLUMN_COUNT; ++i )
-        {
-            totWidth += widths[i] + m_RenderFlexGridSizer->GetHGap();
-        }
-    }
 
     // account for the parent's frame, this one has void space of 10 PLUS a border:
     totWidth += 15;