Graphical diff for board vs library footprints.

Fixes https://gitlab.com/kicad/code/kicad/issues/13736

common/CMakeLists.txt

@@ -169,10 +169,10 @@ set( COMMON_WIDGET_SRCS
     widgets/bitmap_button.cpp
     widgets/bitmap_toggle.cpp
     widgets/button_row_panel.cpp
-        widgets/wx_collapsible_pane.cpp
     widgets/color_swatch.cpp
     widgets/font_choice.cpp
     widgets/footprint_choice.cpp
+    widgets/footprint_diff_widget.cpp
     widgets/footprint_preview_widget.cpp
     widgets/footprint_select_widget.cpp
     widgets/gal_options_panel.cpp
@@ -206,6 +206,7 @@ set( COMMON_WIDGET_SRCS
     widgets/wx_aui_art_providers.cpp
     widgets/wx_aui_utils.cpp
     widgets/wx_busy_indicator.cpp
+    widgets/wx_collapsible_pane.cpp
     widgets/wx_combobox.cpp
     widgets/wx_ellipsized_static_text.cpp
     widgets/wx_grid.cpp

common/draw_panel_gal.cpp

@@ -2,7 +2,7 @@
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
  * Copyright (C) 2013-2017 CERN
- * Copyright (C) 2013-2021 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2013-2023 KiCad Developers, see AUTHORS.txt for contributors.
  *
  * @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
  * @author Maciej Suminski <maciej.suminski@cern.ch>
@@ -361,7 +361,8 @@ void EDA_DRAW_PANEL_GAL::onSize( wxSizeEvent& aEvent )
     if( m_view )
         bottom = m_view->ToWorld( m_gal->GetScreenPixelSize(), true );
 
-    m_gal->ResizeScreen( clientSize.GetX(), clientSize.GetY() );
+    // Note: ( +1, +1 ) prevents an ugly black line on right and bottom (at least on Mac)
+    m_gal->ResizeScreen( clientSize.GetX() + 1, clientSize.GetY() + 1 );
 
     if( m_view )
     {

common/widgets/footprint_diff_widget.cpp

@@ -0,0 +1,127 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2023 KiCad Developers, see AUTHORS.txt for contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <widgets/footprint_diff_widget.h>
+#include <pcb_painter.h>
+#include <footprint.h>
+#include <settings/settings_manager.h>
+#include <wx/sizer.h>
+#include <wx/stattext.h>
+#include <wx/slider.h>
+
+
+FOOTPRINT_DIFF_WIDGET::FOOTPRINT_DIFF_WIDGET( wxWindow* aParent, KIWAY& aKiway ) :
+        FOOTPRINT_PREVIEW_WIDGET( aParent, aKiway ),
+        m_libraryItem( nullptr ),
+        m_slider( nullptr )
+{
+    wxBoxSizer* bottomSizer = new wxBoxSizer( wxHORIZONTAL );
+
+    wxStaticText* schLabel = new wxStaticText( this, wxID_ANY, _( "Board" ) );
+    wxStaticText* libLabel = new wxStaticText( this, wxID_ANY, _( "Library" ) );
+    m_slider = new wxSlider( this, wxID_ANY, 50, 0, 100 );
+
+    bottomSizer->Add( schLabel, 0, wxLEFT | wxRIGHT | wxBOTTOM | wxALIGN_CENTRE_VERTICAL, 6 );
+    bottomSizer->Add( m_slider, 1, wxLEFT | wxRIGHT | wxALIGN_BOTTOM, 30 );
+    bottomSizer->Add( libLabel, 0, wxLEFT | wxRIGHT | wxBOTTOM | wxALIGN_CENTRE_VERTICAL, 6 );
+
+    m_outerSizer->Add( bottomSizer, 0, wxTOP | wxLEFT | wxRIGHT | wxEXPAND, 10 );
+
+    Layout();
+
+    m_slider->Bind( wxEVT_SCROLL_TOP, &FOOTPRINT_DIFF_WIDGET::onSlider, this );
+   	m_slider->Bind( wxEVT_SCROLL_BOTTOM, &FOOTPRINT_DIFF_WIDGET::onSlider, this );
+   	m_slider->Bind( wxEVT_SCROLL_LINEUP, &FOOTPRINT_DIFF_WIDGET::onSlider, this );
+   	m_slider->Bind( wxEVT_SCROLL_LINEDOWN, &FOOTPRINT_DIFF_WIDGET::onSlider, this );
+   	m_slider->Bind( wxEVT_SCROLL_PAGEUP, &FOOTPRINT_DIFF_WIDGET::onSlider, this );
+   	m_slider->Bind( wxEVT_SCROLL_PAGEDOWN, &FOOTPRINT_DIFF_WIDGET::onSlider, this );
+   	m_slider->Bind( wxEVT_SCROLL_THUMBTRACK, &FOOTPRINT_DIFF_WIDGET::onSlider, this );
+   	m_slider->Bind( wxEVT_SCROLL_THUMBRELEASE, &FOOTPRINT_DIFF_WIDGET::onSlider, this );
+   	m_slider->Bind( wxEVT_SCROLL_CHANGED, &FOOTPRINT_DIFF_WIDGET::onSlider, this );
+}
+
+
+void FOOTPRINT_DIFF_WIDGET::DisplayDiff( FOOTPRINT* aBoardFootprint,
+                                         std::shared_ptr<FOOTPRINT>& aLibFootprint )
+{
+    m_boardItemCopy.reset( static_cast<FOOTPRINT*>( aBoardFootprint->Clone() ) );
+    m_boardItemCopy->ClearSelected();
+    m_boardItemCopy->ClearBrightened();
+
+    m_boardItemCopy->RunOnChildren(
+            [&]( BOARD_ITEM* child )
+            {
+                child->ClearSelected();
+                child->ClearBrightened();
+            } );
+
+    m_boardItemCopy->Move( -m_boardItemCopy->GetPosition() );
+
+    m_libraryItem = aLibFootprint;
+
+    DisplayFootprints( m_boardItemCopy, m_libraryItem );
+
+    wxScrollEvent dummy;
+    onSlider( dummy );
+}
+
+
+void FOOTPRINT_DIFF_WIDGET::onSlider( wxScrollEvent& aEvent )
+{
+    double pct = (double) m_slider->GetValue() / 100.0;
+
+    if( m_boardItemCopy )
+    {
+        double val;
+
+        if( pct < 0.5  )
+            val = 0.0;
+        else
+            val = ( pct - 0.5 ) * 2;
+
+        m_boardItemCopy->SetForceTransparency( val );
+
+        m_boardItemCopy->RunOnChildren(
+                [&]( BOARD_ITEM* child )
+                {
+                    child->SetForceTransparency( val );
+                } );
+    }
+
+    if( m_libraryItem )
+    {
+        double val;
+
+        if( pct > 0.5  )
+            val = 0.0;
+        else
+            val = 1.0 - ( pct * 2 );
+
+        m_libraryItem->SetForceTransparency( val );
+
+        m_libraryItem->RunOnChildren(
+                [&]( BOARD_ITEM* child )
+                {
+                    child->SetForceTransparency( val );
+                } );
+    }
+
+    RefreshAll();
+    aEvent.Skip();
+}

common/widgets/footprint_preview_widget.cpp

@@ -1,7 +1,7 @@
 /*
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
- * Copyright (C) 2017-2021 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2017-2023 KiCad Developers, see AUTHORS.txt for contributors.
  * Copyright (C) 2017 Chris Pavlina <pavlina.chris@gmail.com>
  *
  * This program is free software: you can redistribute it and/or modify it
@@ -112,6 +112,20 @@ void FOOTPRINT_PREVIEW_WIDGET::DisplayFootprint( const LIB_ID& aFPID )
 }
 
 
+void FOOTPRINT_PREVIEW_WIDGET::DisplayFootprints( std::shared_ptr<FOOTPRINT> aFootprintA,
+                                                  std::shared_ptr<FOOTPRINT> aFootprintB )
+{
+    ClearStatus();
+    m_prev_panel->DisplayFootprints( aFootprintA, aFootprintB );
+}
+
+
+void FOOTPRINT_PREVIEW_WIDGET::RefreshAll()
+{
+    m_prev_panel->RefreshAll();
+}
+
+
 FOOTPRINT_PREVIEW_PANEL_BASE* FOOTPRINT_PREVIEW_PANEL_BASE::Create( wxWindow* aParent,
                                                                     KIWAY& aKiway )
 {

eeschema/widgets/symbol_diff_widget.cpp

@@ -39,9 +39,9 @@ SYMBOL_DIFF_WIDGET::SYMBOL_DIFF_WIDGET( wxWindow* aParent,
     wxStaticText* libLabel = new wxStaticText( this, wxID_ANY, _( "Library" ) );
     m_slider = new wxSlider( this, wxID_ANY, 50, 0, 100 );
 
-    bottomSizer->Add( schLabel, 0, wxLEFT | wxRIGHT | wxBOTTOM | wxALIGN_CENTRE_VERTICAL, 8 );
+    bottomSizer->Add( schLabel, 0, wxLEFT | wxRIGHT | wxBOTTOM | wxALIGN_CENTRE_VERTICAL, 6 );
     bottomSizer->Add( m_slider, 1, wxLEFT | wxRIGHT | wxALIGN_BOTTOM, 30 );
-    bottomSizer->Add( libLabel, 0, wxLEFT | wxRIGHT | wxBOTTOM | wxALIGN_CENTRE_VERTICAL, 8 );
+    bottomSizer->Add( libLabel, 0, wxLEFT | wxRIGHT | wxBOTTOM | wxALIGN_CENTRE_VERTICAL, 6 );
 
     m_outerSizer->Add( bottomSizer, 0, wxTOP | wxLEFT | wxRIGHT | wxEXPAND, 10 );
 

eeschema/widgets/symbol_diff_widget.h

@@ -20,9 +20,6 @@
 #ifndef SYMBOL_DIFF_WIDGET_H
 #define SYMBOL_DIFF_WIDGET_H
 
-#include <wx/panel.h>
-#include <kiway.h>
-#include <gal/gal_display_options.h>
 #include <widgets/symbol_preview_widget.h>
 
 
@@ -34,7 +31,8 @@ class SYMBOL_DIFF_WIDGET: public SYMBOL_PREVIEW_WIDGET
 {
 public:
     /**
-     * Construct a symbol diff widget.
+     * Construct a symbol diff widget, consisting on a canvas for displaying a schematic and
+     * a library symbol, and a slider for fading between the two.
      *
      * @param aParent - parent window
      * @param aCanvasType = the type of canvas (GAL_TYPE_OPENGL or GAL_TYPE_CAIRO only)

include/widgets/footprint_diff_widget.h

@@ -0,0 +1,57 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2023 KiCad Developers, see AUTHORS.txt for contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef FOOTPRINT_DIFF_WIDGET_H
+#define FOOTPRINT_DIFF_WIDGET_H
+
+#include <widgets/footprint_preview_widget.h>
+
+
+class FOOTPRINT;
+class wxSlider;
+
+
+class FOOTPRINT_DIFF_WIDGET: public FOOTPRINT_PREVIEW_WIDGET
+{
+public:
+    /**
+     * Construct a footprint diff widget, consisting on a canvas for displaying a board and
+     * a library footprint, and a slider for fading between the two.
+     *
+     * @param aParent - parent window
+     * @param aKiway - an active Kiway instance
+     */
+    FOOTPRINT_DIFF_WIDGET( wxWindow* aParent, KIWAY& aKiway );
+
+    /**
+     * Set the currently displayed symbol.
+     */
+    void DisplayDiff( FOOTPRINT* aBoardFootprint, std::shared_ptr<FOOTPRINT>& aLibFootprint );
+
+private:
+    void onSlider( wxScrollEvent& aEvent );
+
+private:
+    std::shared_ptr<FOOTPRINT> m_boardItemCopy;
+    std::shared_ptr<FOOTPRINT> m_libraryItem;
+    wxSlider*                  m_slider;
+};
+
+
+#endif // FOOTPRINT_DIFF_WIDGET_H

include/widgets/footprint_preview_widget.h

@@ -29,6 +29,7 @@
 #include <gal/color4d.h>
 
 class FOOTPRINT_PREVIEW_PANEL_BASE;
+class FOOTPRINT;
 class KIWAY;
 class wxStaticText;
 class wxSizer;
@@ -74,7 +75,18 @@ public:
      */
     void DisplayFootprint( const LIB_ID& aFPID );
 
-private:
+    /**
+     * Display a pair of footprints.  (Normally used for diff'ing.)
+     */
+    void DisplayFootprints( std::shared_ptr<FOOTPRINT> aFootprintA,
+                            std::shared_ptr<FOOTPRINT> aFootprintB );
+
+    /**
+     * Force the redrawing of all contents.
+     */
+    void RefreshAll();
+
+protected:
     FOOTPRINT_PREVIEW_PANEL_BASE* m_prev_panel;
 
     wxStaticText*                 m_status;
@@ -102,6 +114,17 @@ public:
      */
     virtual bool DisplayFootprint( LIB_ID const& aFPID ) = 0;
 
+    /**
+     * Display a pair of footprints.  (Normally used for diff'ing.)
+     */
+    virtual void DisplayFootprints( std::shared_ptr<FOOTPRINT> aFootprintA,
+                                    std::shared_ptr<FOOTPRINT> aFootprintB ) = 0;
+
+    /**
+     * Force the redrawing of all contents.
+     */
+    virtual void RefreshAll() = 0;
+
     /**
      * Get the underlying wxWindow.
      */

pcbnew/drc/drc_test_provider_library_parity.cpp

@@ -1,7 +1,7 @@
 /*
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
- * Copyright (C) 2021-2022 KiCad Developers.
+ * Copyright (C) 2021-2023 KiCad Developers.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -556,12 +556,12 @@ bool FOOTPRINT::FootprintNeedsUpdate( const FOOTPRINT* aLibFootprint, REPORTER*
             if( padNeedsUpdate( *aIt, *bIt ) )
             {
                 diff = true;
-                REPORT( wxString::Format( _( "%s differs." ), ITEM_DESC( *aIt ) ) );
+                REPORT( wxString::Format( _( "Pad %s differs." ), (*aIt)->GetNumber() ) );
             }
             else if( aReporter && padHasOverrides( *aIt, *bIt ) )
             {
                 diff = true;
-                REPORT( wxString::Format( _( "%s has overrides." ), ITEM_DESC( *aIt ) ) );
+                REPORT( wxString::Format( _( "Pad %s has overrides." ), (*aIt)->GetNumber() ) );
             }
         }
     }

pcbnew/footprint_preview_panel.cpp

@@ -1,7 +1,7 @@
 /*
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
- * Copyright (C) 2016-2020 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2016-2023 KiCad Developers, see AUTHORS.txt for contributors.
  * Copyright (C) 2017 Chris Pavlina <pavlina.chris@gmail.com>
  * Copyright (C) 2016 Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
  *
@@ -72,6 +72,13 @@ FOOTPRINT_PREVIEW_PANEL::~FOOTPRINT_PREVIEW_PANEL( )
         GetView()->Clear();
         m_currentFootprint->SetParent( nullptr );
     }
+
+    if( m_otherFootprint )
+    {
+        GetView()->Remove( m_otherFootprint.get() );
+        GetView()->Clear();
+        m_otherFootprint->SetParent( nullptr );
+    }
 }
 
 
@@ -95,19 +102,7 @@ const COLOR4D& FOOTPRINT_PREVIEW_PANEL::GetForegroundColor() const
 
 void FOOTPRINT_PREVIEW_PANEL::renderFootprint( std::shared_ptr<FOOTPRINT> aFootprint )
 {
-    if( m_currentFootprint )
-    {
-        GetView()->Remove( m_currentFootprint.get() );
-        GetView()->Clear();
-        m_currentFootprint->SetParent( nullptr );
-    }
-
-    m_currentFootprint = aFootprint;
-
-    if( !m_currentFootprint )
-        return;
-
-    m_currentFootprint->SetParent( m_dummyBoard.get() );
+    aFootprint->SetParent( m_dummyBoard.get() );
 
     INSPECTOR_FUNC inspector =
             [&]( EDA_ITEM* descendant, void* aTestData )
@@ -116,20 +111,24 @@ void FOOTPRINT_PREVIEW_PANEL::renderFootprint( std::shared_ptr<FOOTPRINT> aFootp
                 return INSPECT_RESULT::CONTINUE;
             };
 
-    m_currentFootprint->Visit( inspector, nullptr, { PCB_FP_DIM_LEADER_T,
-                                                     PCB_FP_DIM_ORTHOGONAL_T,
-                                                     PCB_FP_DIM_CENTER_T,
-                                                     PCB_FP_DIM_RADIAL_T } );
+    aFootprint->Visit( inspector, nullptr, { PCB_FP_DIM_LEADER_T,
+                                             PCB_FP_DIM_ORTHOGONAL_T,
+                                             PCB_FP_DIM_CENTER_T,
+                                             PCB_FP_DIM_RADIAL_T } );
 
     // Ensure we are not using the high contrast mode to display the selected footprint
     KIGFX::PAINTER* painter = GetView()->GetPainter();
     auto settings = static_cast<KIGFX::PCB_RENDER_SETTINGS*>( painter->GetSettings() );
     settings->m_ContrastModeDisplay = HIGH_CONTRAST_MODE::NORMAL;
 
-    GetView()->Add( m_currentFootprint.get() );
-    GetView()->SetVisible( m_currentFootprint.get(), true );
-    GetView()->Update( m_currentFootprint.get(), KIGFX::ALL );
+    GetView()->Add( aFootprint.get() );
+    GetView()->SetVisible( aFootprint.get(), true );
+    GetView()->Update( aFootprint.get(), KIGFX::ALL );
+}
 
+
+void FOOTPRINT_PREVIEW_PANEL::fitToCurrentFootprint()
+{
     BOX2I bbox = m_currentFootprint->ViewBBox();
     bbox.Merge( m_currentFootprint->Value().ViewBBox() );
     bbox.Merge( m_currentFootprint->Reference().ViewBBox() );
@@ -149,6 +148,13 @@ void FOOTPRINT_PREVIEW_PANEL::renderFootprint( std::shared_ptr<FOOTPRINT> aFootp
 
 bool FOOTPRINT_PREVIEW_PANEL::DisplayFootprint( const LIB_ID& aFPID )
 {
+    if( m_currentFootprint )
+    {
+        GetView()->Remove( m_currentFootprint.get() );
+        GetView()->Clear();
+        m_currentFootprint->SetParent( nullptr );
+    }
+
     FP_LIB_TABLE* fptbl = Prj().PcbFootprintLibs();
 
     try
@@ -166,13 +172,59 @@ bool FOOTPRINT_PREVIEW_PANEL::DisplayFootprint( const LIB_ID& aFPID )
         m_currentFootprint.reset();
     }
 
-    renderFootprint( m_currentFootprint );
+    if( m_currentFootprint )
+    {
+        renderFootprint( m_currentFootprint );
+        fitToCurrentFootprint();
+    }
+
     Refresh();
 
     return m_currentFootprint != nullptr;
 }
 
 
+void FOOTPRINT_PREVIEW_PANEL::DisplayFootprints( std::shared_ptr<FOOTPRINT> aFootprintA,
+                                                 std::shared_ptr<FOOTPRINT> aFootprintB )
+{
+    if( m_currentFootprint )
+    {
+        GetView()->Remove( m_currentFootprint.get() );
+        m_currentFootprint->SetParent( nullptr );
+
+        wxASSERT( m_otherFootprint );
+
+        GetView()->Remove( m_otherFootprint.get() );
+        m_otherFootprint->SetParent( nullptr );
+
+        GetView()->Clear();
+    }
+
+    m_currentFootprint = aFootprintA;
+    m_otherFootprint = aFootprintB;
+
+    if( m_currentFootprint )
+    {
+        wxASSERT( m_otherFootprint );
+
+        renderFootprint( m_currentFootprint );
+        renderFootprint( m_otherFootprint );
+        fitToCurrentFootprint();
+    }
+
+    Show();
+    Layout();
+    RefreshAll();
+}
+
+
+void FOOTPRINT_PREVIEW_PANEL::RefreshAll()
+{
+    GetView()->UpdateAllItems( KIGFX::REPAINT );
+    ForceRefresh();
+}
+
+
 wxWindow* FOOTPRINT_PREVIEW_PANEL::GetWindow()
 {
     return static_cast<wxWindow*>( this );
@@ -213,5 +265,10 @@ FOOTPRINT_PREVIEW_PANEL* FOOTPRINT_PREVIEW_PANEL::New( KIWAY* aKiway, wxWindow*
                                                                  gridCfg.sizes[ gridIdx ] );
     panel->GetGAL()->SetGridSize( VECTOR2D( gridSize, gridSize ) );
 
+    auto painter = static_cast<KIGFX::PCB_PAINTER*>( panel->GetView()->GetPainter() );
+    auto settings = static_cast<KIGFX::PCB_RENDER_SETTINGS*>( painter->GetSettings() );
+    settings->SetHighlight( false );
+    settings->SetNetColorMode( NET_COLOR_MODE::OFF );
+
     return panel;
 }

pcbnew/footprint_preview_panel.h

@@ -1,7 +1,7 @@
 /*
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
- * Copyright (C) 2016-2020 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2016-2023 KiCad Developers, see AUTHORS.txt for contributors.
  * Copyright (C) 2017 Chris Pavlina <pavlina.chris@gmail.com>
  * Copyright (C) 2016 Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
  *
@@ -55,6 +55,8 @@ public:
 
     virtual void SetUserUnits( EDA_UNITS aUnits ) override { m_userUnits = aUnits; }
     virtual bool DisplayFootprint( const LIB_ID& aFPID ) override;
+    virtual void DisplayFootprints( std::shared_ptr<FOOTPRINT> aFootprintA,
+                                    std::shared_ptr<FOOTPRINT> aFootprintB ) override;
 
     virtual const KIGFX::COLOR4D& GetBackgroundColor() const override;
     virtual const KIGFX::COLOR4D& GetForegroundColor() const override;
@@ -62,6 +64,8 @@ public:
     virtual wxWindow* GetWindow() override;
     BOARD* GetBoard() { return m_dummyBoard.get(); }
 
+    virtual void RefreshAll() override;
+
     static FOOTPRINT_PREVIEW_PANEL* New( KIWAY* aKiway, wxWindow* aParent );
 
 private:
@@ -79,11 +83,14 @@ private:
 
     void renderFootprint( std::shared_ptr<FOOTPRINT> aFootprint );
 
+    void fitToCurrentFootprint();
+
 private:
     std::unique_ptr<BOARD>                      m_dummyBoard;
     std::unique_ptr<KIGFX::GAL_DISPLAY_OPTIONS> m_displayOptions;
     EDA_UNITS                                   m_userUnits;
     std::shared_ptr<FOOTPRINT>                  m_currentFootprint;
+    std::shared_ptr<FOOTPRINT>                  m_otherFootprint;
 };
 
 #endif

pcbnew/pcb_painter.cpp

@@ -434,6 +434,9 @@ COLOR4D PCB_RENDER_SETTINGS::GetColor( const VIEW_ITEM* aItem, int aLayer ) cons
     else if( item->Type() == PCB_BITMAP_T )
         color.a *= m_imageOpacity;
 
+    if( item->GetForceTransparency() > 0.0 )
+        color = color.WithAlpha( color.a * ( 1.0 - item->GetForceTransparency() ) );
+
     // No special modifiers enabled
     return color;
 }

pcbnew/tools/board_inspection_tool.cpp

@@ -39,6 +39,7 @@
 #include <pcbnew_settings.h>
 #include <widgets/appearance_controls.h>
 #include <widgets/wx_html_report_box.h>
+#include <widgets/footprint_diff_widget.h>
 #include <drc/drc_item.h>
 #include <pad.h>
 
@@ -1413,9 +1414,15 @@ int BOARD_INSPECTION_TOOL::DiffFootprint( const TOOL_EVENT& aEvent )
             r->Report( wxString::Format( _( "The library no longer contains the item %s." ),
                                          fpName) );
         }
-        else if( !footprint->FootprintNeedsUpdate( libFootprint.get(), r ) )
+        else
         {
-            r->Report( _( "No relevant differences detected." ) );
+            if( !footprint->FootprintNeedsUpdate( libFootprint.get(), r ) )
+                r->Report( _( "No relevant differences detected." ) );
+
+            wxPanel*               panel = m_diffFootprintDialog->AddBlankPage( _( "Visual" ) );
+            FOOTPRINT_DIFF_WIDGET* diff = constructDiffPanel( panel );
+
+            diff->DisplayDiff( footprint, libFootprint );
         }
     }
 
@@ -1428,6 +1435,20 @@ int BOARD_INSPECTION_TOOL::DiffFootprint( const TOOL_EVENT& aEvent )
 }
 
 
+FOOTPRINT_DIFF_WIDGET* BOARD_INSPECTION_TOOL::constructDiffPanel( wxPanel* aParentPanel )
+{
+    wxBoxSizer* sizer = new wxBoxSizer( wxVERTICAL );
+
+    FOOTPRINT_DIFF_WIDGET* diffWidget = new FOOTPRINT_DIFF_WIDGET( aParentPanel, m_frame->Kiway() );
+
+   	sizer->Add( diffWidget, 1, wxEXPAND | wxALL, 5 );
+    aParentPanel->SetSizer( sizer );
+    aParentPanel->Layout();
+
+    return diffWidget;
+}
+
+
 int BOARD_INSPECTION_TOOL::HighlightItem( const TOOL_EVENT& aEvent )
 {
     BOARD_ITEM* item = aEvent.Parameter<BOARD_ITEM*>();

pcbnew/tools/board_inspection_tool.h

@@ -34,6 +34,7 @@
 #include <tools/pcb_tool_base.h>
 
 class CONNECTIVITY_DATA;
+class FOOTPRINT_DIFF_WIDGET;
 
 
 /**
@@ -131,6 +132,8 @@ private:
     void reportHeader( const wxString& aTitle, BOARD_ITEM* a, BOARD_ITEM* b, PCB_LAYER_ID aLayer,
                        REPORTER* r );
 
+    FOOTPRINT_DIFF_WIDGET* constructDiffPanel( wxPanel* aParentPanel );
+
 private:
     PCB_EDIT_FRAME*     m_frame;    // Pointer to the currently used edit frame.