Speed up pcbnew loading/updating

Rather than detaching and re-attaching the layer panels with the
attendant overhead, we keep each panel intact and only update its
contents.  Since the bindings are the same, this saves substantial time
on pcb loading as well as when closing the board setup dialog

include/widgets/bitmap_toggle.h

@@ -25,7 +25,7 @@
 #ifndef _BITMAP_TOGGLE_H
 #define _BITMAP_TOGGLE_H
 
-#include <wx/bitmap.h>
+#include <wx/statbmp.h>
 #include <wx/panel.h>
 
 #include <gal/color4d.h>
@@ -54,6 +54,16 @@ public:
     ///< Read the checkbox state
     bool GetValue() const { return m_checked; }
 
+    /**
+     * Updates the window ID of this control and its children
+     * @param aId new Window ID to set
+     */
+    void SetWindowID( wxWindowID aId )
+    {
+        SetId( aId );
+        m_bitmap->SetId( aId );
+    }
+
 private:
     bool m_checked;
 

include/widgets/color_swatch.h

@@ -99,6 +99,16 @@ public:
      */
     KIGFX::COLOR4D GetSwatchColor() const;
 
+    /**
+     * Updates the window ID of this control and its children
+     * @param aId new Window ID to set
+     */
+    void SetWindowID( wxWindowID aId )
+    {
+        SetId( aId );
+        m_swatch->SetId( aId );
+    }
+
     /**
      * Prompt for a new colour, using the colour picker dialog.
      *

include/widgets/indicator_icon.h

@@ -24,7 +24,7 @@
 #ifndef ROW_INDICATOR__H_
 #define ROW_INDICATOR__H_
 
-#include <wx/bitmap.h>
+#include <wx/statbmp.h>
 #include <wx/panel.h>
 
 class wxStaticBitmap;
@@ -97,6 +97,16 @@ public:
      */
     ICON_ID GetIndicatorState() const;
 
+    /**
+     * Updates the window ID of this control and its children
+     * @param aId new Window ID to set
+     */
+    void SetWindowID( wxWindowID aId )
+    {
+        SetId( aId );
+        m_bitmap->SetId( aId );
+    }
+
 private:
 
     ///< An class that delivers icons for the indicator (currently just

pcbnew/widgets/appearance_controls.cpp

@@ -1408,10 +1408,6 @@ void APPEARANCE_CONTROLS::rebuildLayers()
     m_windowLayersSizerItem->SetFlag( m_windowLayersSizerItem->GetFlag() & ~wxTOP );
 #endif
 
-    m_layerSettings.clear();
-    m_layerSettingsMap.clear();
-    m_layersOuterSizer->Clear( true );
-
     auto appendLayer =
             [&]( std::unique_ptr<APPEARANCE_SETTING>& aSetting )
             {
@@ -1500,39 +1496,21 @@ void APPEARANCE_CONTROLS::rebuildLayers()
                 label->Bind( wxEVT_RIGHT_DOWN, &APPEARANCE_CONTROLS::rightClickHandler, this );
             };
 
-    // Add right click handling to show the conterxt menu when clicking to the free area in
+    auto updateLayer =
-    // m_windowLayers (below the layer items)
+            [&]( std::unique_ptr<APPEARANCE_SETTING>& aSetting )
-    m_windowLayers->Bind( wxEVT_RIGHT_DOWN, &APPEARANCE_CONTROLS::rightClickHandler, this );
+            {
-
+                int layer = aSetting->id;
-    wxString dsc;
+                aSetting->visible = visible[layer];
-
+                aSetting->ctl_panel->Show();
-    // show all coppers first, with front on top, back on bottom, then technical layers
+                aSetting->ctl_panel->SetId( layer );
-    for( LSEQ cu_stack = enabled.CuStack(); cu_stack; ++cu_stack )
+                aSetting->ctl_indicator->SetWindowID( layer );
-    {
+                aSetting->ctl_color->SetWindowID( layer );
-        PCB_LAYER_ID layer = *cu_stack;
+                aSetting->ctl_color->SetSwatchColor( theme->GetColor( layer ), false );
-
+                aSetting->ctl_visibility->SetWindowID( layer );
-        switch( layer )
+                aSetting->ctl_text->SetLabelText( aSetting->label );
-        {
+                aSetting->ctl_text->SetId( layer );
-            case F_Cu: dsc = _( "Front copper layer" ); break;
+                aSetting->ctl_text->SetToolTip( aSetting->tooltip );
-            case B_Cu: dsc = _( "Back copper layer" );  break;
+            };
-            default:   dsc = _( "Inner copper layer" ); break;
-        }
-
-        m_layerSettings.emplace_back(
-                std::make_unique<APPEARANCE_SETTING>( board->GetLayerName( layer ), layer, dsc ) );
-
-        std::unique_ptr<APPEARANCE_SETTING>& setting = m_layerSettings.back();
-
-        m_layerSettingsMap[layer] = setting.get();
-
-        appendLayer( setting );
-
-        if( m_isFpEditor && LSET::ForbiddenFootprintLayers().test( layer ) )
-        {
-            setting->ctl_text->Disable();
-            setting->ctl_color->SetToolTip( wxEmptyString );
-        }
-    }
 
     // technical layers are shown in this order:
     // Because they are static, wxGetTranslation must be explicitly
@@ -1570,6 +1548,76 @@ void APPEARANCE_CONTROLS::rebuildLayers()
         { User_9,           _( "User defined layer 9" ) },
     };
 
+    // There is a spacer added to the end of the list that we need to remove and re-add
+    // after possibly adding additional layers
+    if( m_layersOuterSizer->GetItemCount() > 0 )
+    {
+        m_layersOuterSizer->Detach( m_layersOuterSizer->GetItemCount() - 1 );
+    }
+    // Otherwise, this is the first time we are updating the control, so we need to attach
+    // the handler
+    else
+    {
+        // Add right click handling to show the context menu when clicking to the free area in
+        // m_windowLayers (below the layer items)
+        m_windowLayers->Bind( wxEVT_RIGHT_DOWN, &APPEARANCE_CONTROLS::rightClickHandler, this );
+    }
+
+    std::size_t total_layers = enabled.CuStack().size();
+
+    for( const auto& entry : non_cu_seq )
+    {
+        if( enabled[entry.layerId] )
+            total_layers++;
+    }
+
+    // Adds layers to the panel until we have enough to hold our total count
+    while( total_layers > m_layerSettings.size() )
+        m_layerSettings.push_back( std::make_unique<APPEARANCE_SETTING>() );
+
+    // We never delete layers from the panel, only hide them.  This saves us
+    // having to recreate the (possibly) later with minimal overhead
+    for( std::size_t ii = total_layers; ii < m_layerSettings.size(); ++ii )
+    {
+        if( m_layerSettings[ii]->ctl_panel )
+            m_layerSettings[ii]->ctl_panel->Show( false );
+    }
+
+    auto layer_it = m_layerSettings.begin();
+
+    // show all coppers first, with front on top, back on bottom, then technical layers
+    for( LSEQ cu_stack = enabled.CuStack(); cu_stack; ++cu_stack, ++layer_it )
+    {
+        PCB_LAYER_ID layer = *cu_stack;
+        wxString dsc;
+
+        switch( layer )
+        {
+            case F_Cu: dsc = _( "Front copper layer" ); break;
+            case B_Cu: dsc = _( "Back copper layer" );  break;
+            default:   dsc = _( "Inner copper layer" ); break;
+        }
+
+        std::unique_ptr<APPEARANCE_SETTING>& setting = *layer_it;
+
+        setting->label = board->GetLayerName( layer );
+        setting->id = layer;
+        setting->tooltip = dsc;
+
+        if( setting->ctl_panel == nullptr )
+            appendLayer( setting );
+        else
+            updateLayer( setting );
+
+        m_layerSettingsMap[layer] = setting.get();
+
+        if( m_isFpEditor && LSET::ForbiddenFootprintLayers().test( layer ) )
+        {
+            setting->ctl_text->Disable();
+            setting->ctl_color->SetToolTip( wxEmptyString );
+        }
+    }
+
     for( const auto& entry : non_cu_seq )
     {
         PCB_LAYER_ID layer = entry.layerId;
@@ -1577,20 +1625,26 @@ void APPEARANCE_CONTROLS::rebuildLayers()
         if( !enabled[layer] )
             continue;
 
-        m_layerSettings.emplace_back( std::make_unique<APPEARANCE_SETTING>(
+        std::unique_ptr<APPEARANCE_SETTING>& setting = *layer_it;
-                board->GetLayerName( layer ), layer, wxGetTranslation( entry.tooltip ) ) );
 
-        std::unique_ptr<APPEARANCE_SETTING>& setting = m_layerSettings.back();
+        setting->label = board->GetLayerName( layer );
+        setting->id = layer;
+        setting->tooltip = entry.tooltip;
+
+        if( setting->ctl_panel == nullptr )
+            appendLayer( setting );
+        else
+            updateLayer( setting );
 
         m_layerSettingsMap[layer] = setting.get();
 
-        appendLayer( setting );
-
         if( m_isFpEditor && LSET::ForbiddenFootprintLayers().test( layer ) )
         {
             setting->ctl_text->Disable();
             setting->ctl_color->SetToolTip( wxEmptyString );
         }
+
+        ++layer_it;
     }
 
     m_layersOuterSizer->AddSpacer( 10 );