GerbView #2501 - Add mirror display function to GerbView

Adds the ability to flip (mirror) the display, just like "Flip
Board View" does in Pcbnew.

Also added this to vertical toolbar since it's handy to not
have to go into the menu system to flip the display back and
forth.

Fixes issue https://gitlab.com/kicad/code/kicad/-/issues/2501

gerbview/gbr_display_options.h

@@ -46,9 +46,10 @@ public:
     bool    m_DisplayPageLimits;
     bool    m_DisplayNegativeObjects;   ///< Option to draw negative objects in a specific color
     bool    m_IsPrinting;               ///< true when printing a page, false when drawing on screen
-    bool    m_ForceBlackAndWhite;       ///< Option print in blackand white (ont used id draw mode
+    bool    m_ForceBlackAndWhite;       ///< Option print in black and white (not used in draw mode
     bool    m_DiffMode;                 ///< Display layers in diff mode
     bool    m_HighContrastMode;         ///< High contrast mode (dim un-highlighted objects)
+    bool    m_FlipGerberView;           ///< Display as a mirror image
     COLOR4D m_NegativeDrawColor;        ///< The color used to draw negative objects, usually the
                                         ///< background color, but not always, when negative objects
                                         ///< must be visible
@@ -69,6 +70,7 @@ public:
         m_BgDrawColor = COLOR4D::BLACK;
         m_DiffMode = false;
         m_HighContrastMode = false;
+        m_FlipGerberView = false;
     }
 };
 

gerbview/menubar.cpp

@@ -182,6 +182,9 @@ void GERBVIEW_FRAME::ReCreateMenuBar()
     auto contrastModeCondition = [ this ] ( const SELECTION& aSel ) {
         return m_DisplayOptions.m_HighContrastMode;
     };
+    auto flipViewCondition = [this]( const SELECTION& aSel ) {
+        return m_DisplayOptions.m_FlipGerberView;
+    };
 
     // Hide layer manager
     viewMenu->AddCheckItem( ID_TB_OPTIONS_SHOW_LAYERS_MANAGER_VERTICAL_TOOLBAR,
@@ -215,6 +218,7 @@ void GERBVIEW_FRAME::ReCreateMenuBar()
     viewMenu->AddCheckItem( GERBVIEW_ACTIONS::negativeObjectDisplay,   showNegativeObjects );
     viewMenu->AddCheckItem( GERBVIEW_ACTIONS::toggleDiffMode,          diffModeCondition );
     viewMenu->AddCheckItem( ACTIONS::highContrastMode,                 contrastModeCondition );
+    viewMenu->AddCheckItem( GERBVIEW_ACTIONS::flipGerberView,          flipViewCondition );
 
     viewMenu->Resolve();
 

gerbview/toolbars_gerber.cpp

@@ -249,6 +249,7 @@ void GERBVIEW_FRAME::ReCreateOptToolbar()
     m_optionsToolBar->Add( GERBVIEW_ACTIONS::dcodeDisplay,            ACTION_TOOLBAR::TOGGLE );
     m_optionsToolBar->Add( GERBVIEW_ACTIONS::toggleDiffMode,          ACTION_TOOLBAR::TOGGLE );
     m_optionsToolBar->Add( ACTIONS::highContrastMode,                 ACTION_TOOLBAR::TOGGLE );
+    m_optionsToolBar->Add( GERBVIEW_ACTIONS::flipGerberView,          ACTION_TOOLBAR::TOGGLE );
 
     // Tools to show/hide toolbars:
     m_optionsToolBar->AddScaledSeparator( this );
@@ -500,5 +501,6 @@ void GERBVIEW_FRAME::SyncToolbars()
                                                   IsElementVisible( LAYER_DCODES ) );
     m_optionsToolBar->Toggle( GERBVIEW_ACTIONS::toggleDiffMode,m_DisplayOptions.m_DiffMode );
     m_optionsToolBar->Toggle( ACTIONS::highContrastMode,       m_DisplayOptions.m_HighContrastMode );
+    m_optionsToolBar->Toggle( GERBVIEW_ACTIONS::flipGerberView, m_DisplayOptions.m_FlipGerberView );
     m_optionsToolBar->Refresh();
 }

gerbview/tools/gerbview_actions.cpp

@@ -148,6 +148,11 @@ TOOL_ACTION GERBVIEW_ACTIONS::toggleDiffMode( "gerbview.Control.toggleDiffMode",
         _( "Show in Differential Mode" ), _( "Show layers in diff (compare) mode" ),
         gbr_select_mode2_xpm );
 
+TOOL_ACTION GERBVIEW_ACTIONS::flipGerberView( "gerbview.Control.flipGerberView",
+        AS_GLOBAL, 0, "",
+        _( "Flip Gerber View" ), _( "Show as mirror image" ),
+        swap_layer_xpm );
+
 
 // GERBVIEW_SELECTION_TOOL
 //

gerbview/tools/gerbview_actions.h

@@ -63,6 +63,7 @@ public:
     static TOOL_ACTION negativeObjectDisplay;
     static TOOL_ACTION dcodeDisplay;
     static TOOL_ACTION toggleDiffMode;
+    static TOOL_ACTION flipGerberView;
 
     // Layer control
     static TOOL_ACTION layerPrev;

gerbview/tools/gerbview_control.cpp

@@ -28,9 +28,7 @@
 #include "gerbview_selection_tool.h"
 
 
-GERBVIEW_CONTROL::GERBVIEW_CONTROL() :
+GERBVIEW_CONTROL::GERBVIEW_CONTROL() : TOOL_INTERACTIVE( "gerbview.Control" ), m_frame( nullptr )
-    TOOL_INTERACTIVE( "gerbview.Control" ), 
-    m_frame( nullptr )
 {
 }
 
@@ -169,6 +167,14 @@ int GERBVIEW_CONTROL::DisplayControl( const TOOL_EVENT& aEvent )
         options.m_DiffMode = !options.m_DiffMode;
         needs_refresh = true;
     }
+    else if( aEvent.IsAction( &GERBVIEW_ACTIONS::flipGerberView ) )
+    {
+        options.m_FlipGerberView = !options.m_FlipGerberView;
+
+        KIGFX::VIEW* view = m_frame->GetCanvas()->GetView();
+        view->SetMirror( options.m_FlipGerberView, false );
+        needs_refresh = true;
+    }
 
     if( needs_refresh )
         m_frame->UpdateDisplayOptions( options );
@@ -244,6 +250,7 @@ void GERBVIEW_CONTROL::setTransitions()
     Go( &GERBVIEW_CONTROL::DisplayControl,     GERBVIEW_ACTIONS::dcodeDisplay.MakeEvent() );
     Go( &GERBVIEW_CONTROL::DisplayControl,     ACTIONS::highContrastMode.MakeEvent() );
     Go( &GERBVIEW_CONTROL::DisplayControl,     GERBVIEW_ACTIONS::toggleDiffMode.MakeEvent() );
+    Go( &GERBVIEW_CONTROL::DisplayControl,     GERBVIEW_ACTIONS::flipGerberView.MakeEvent() );
 
     Go( &GERBVIEW_CONTROL::UpdateMessagePanel, EVENTS::SelectedEvent );
     Go( &GERBVIEW_CONTROL::UpdateMessagePanel, EVENTS::UnselectedEvent );