Make SELECTION_AREA a generic overlay item

This simplifies the (already simple) SELECTION_AREA class. It is also
moved into KIGFX::PREVIEW and put in the common library, where it can be
reused by other GAL-aware tools (not just in Pcbnew) in future.

common/CMakeLists.txt

@@ -185,6 +185,7 @@ set( COMMON_PAGE_LAYOUT_SRCS
 
 set( COMMON_PREVIEW_ITEMS_SRCS
     preview_items/simple_overlay_item.cpp
+    preview_items/selection_area.cpp
     )
 
 set( COMMON_SRCS

pcbnew/tools/selection_area.cpp → common/preview_items/selection_area.cpp

@@ -22,13 +22,20 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  */
 
-#include "selection_area.h"
-#include <gal/graphics_abstraction_layer.h>
-#include <gal/color4d.h>
+#include <preview_items/selection_area.h>
 
+#include <gal/graphics_abstraction_layer.h>
 #include <view/view.h>
 
-using namespace KIGFX;
+using namespace KIGFX::PREVIEW;
+
+
+SELECTION_AREA::SELECTION_AREA()
+{
+    SetStrokeColor( COLOR4D( 1.0, 1.0, 0.4, 1.0 ) );
+    SetFillColor( COLOR4D( 0.3, 0.3, 0.5, 0.3 ) );
+}
+
 
 const BOX2I SELECTION_AREA::ViewBBox() const
 {
@@ -41,26 +48,8 @@ const BOX2I SELECTION_AREA::ViewBBox() const
 }
 
 
-void SELECTION_AREA::ViewGetLayers( int aLayers[], int& aCount ) const
+void SELECTION_AREA::drawPreviewShape( KIGFX::GAL& aGal ) const
 {
-    aLayers[0] = SelectionLayer;
-    aCount = 1;
+    aGal.DrawRectangle( m_origin, m_end );
 }
 
-
-void SELECTION_AREA::ViewDraw( int aLayer, KIGFX::VIEW* aView ) const
-{
-    auto gal = aView->GetGAL();
-    gal->SetLineWidth( 1.0 );
-    gal->SetStrokeColor( COLOR4D( 1.0, 1.0, 0.4, 1.0 ) );
-    gal->SetFillColor( COLOR4D( 0.3, 0.3, 0.5, 0.3 ) );
-    gal->SetIsStroke( true );
-    gal->SetIsFill( true );
-    gal->DrawRectangle( m_origin, m_end );
-}
-
-
-SELECTION_AREA::SELECTION_AREA() :
-    EDA_ITEM( NOT_USED )    // this item is never added to a BOARD so it needs no type.
-{
-}

pcbnew/tools/selection_area.h → include/preview_items/selection_area.h

@@ -22,63 +22,70 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  */
 
-#ifndef __SELECTION_AREA_H
-#define __SELECTION_AREA_H
+#ifndef PREVIEW_ITEMS_SELECTION_AREA_H
+#define PREVIEW_ITEMS_SELECTION_AREA_H
+
+#include <preview_items/simple_overlay_item.h>
 
-#include <base_struct.h>
-#include <layers_id_colors_and_visibility.h>
-#include <math/box2.h>
 
 namespace KIGFX
 {
 class GAL;
-}
+
+namespace PREVIEW
+{
 
 /**
  * Class SELECTION_AREA
  *
- * Represents a selection area (currently a rectangle) in a VIEW.
+ * Represents a selection area (currently a rectangle) in a VIEW,
+ * drawn corner-to-corner between two points. This is useful when
+ * selecting a rectangular area, for lasso-select or zooming, for
+ * example.
  */
-class SELECTION_AREA : public EDA_ITEM
+class SELECTION_AREA : public SIMPLE_OVERLAY_ITEM
 {
 public:
-    static const int SelectionLayer = ITEM_GAL_LAYER( GP_OVERLAY );
 
     SELECTION_AREA();
-    ~SELECTION_AREA() {};
-
-    virtual const BOX2I ViewBBox() const override;
 
-    void ViewDraw( int aLayer, KIGFX::VIEW* aView ) const override;
-
-    void ViewGetLayers( int aLayers[], int& aCount ) const override;
+    const BOX2I ViewBBox() const override;
 
+    ///> Set the origin of the rectange (the fixed corner)
     void SetOrigin( VECTOR2I aOrigin )
     {
         m_origin = aOrigin;
     }
 
+    /**
+     * Set the current end of the rectangle (the corner that moves
+     * with the cursor.
+     */
     void SetEnd( VECTOR2I aEnd )
     {
         m_end = aEnd;
     }
 
-#if defined(DEBUG)
-    void Show( int x, std::ostream& st ) const override
-    {
-    }
-#endif
-
-    /** Get class name
+    /**
+     * Get class name
      * @return  string "SELECTION_AREA"
      */
-    virtual wxString GetClass() const override
+    wxString GetClass() const override
     {
         return wxT( "SELECTION_AREA" );
     }
 
 private:
+
+    /**
+     * Draw the selection rectangle onto the GAL
+     */
+    void drawPreviewShape( KIGFX::GAL& aGal ) const override;
+
     VECTOR2I m_origin, m_end;
 };
 
-#endif
+} // PREVIEW
+} // KIGFX
+
+#endif // PREVIEW_ITEMS_SELECTION_AREA_H

pcbnew/CMakeLists.txt

@@ -290,7 +290,6 @@ set( PCBNEW_CLASS_SRCS
     class_action_plugin.cpp
 
     tools/selection_tool.cpp
-    tools/selection_area.cpp
     tools/pcb_selection_conditions.cpp
     tools/bright_box.cpp
     tools/edit_points.cpp

pcbnew/tools/selection_tool.cpp

@@ -43,6 +43,7 @@ using namespace std::placeholders;
 #include <class_draw_panel_gal.h>
 #include <view/view_controls.h>
 #include <view/view_group.h>
+#include <preview_items/selection_area.h>
 #include <painter.h>
 #include <bitmaps.h>
 #include <hotkeys.h>
@@ -52,7 +53,6 @@ using namespace std::placeholders;
 #include <ratsnest_data.h>
 
 #include "selection_tool.h"
-#include "selection_area.h"
 #include "bright_box.h"
 #include "pcb_actions.h"
 
@@ -464,7 +464,7 @@ bool SELECTION_TOOL::selectMultiple()
     KIGFX::VIEW* view = getView();
     getViewControls()->SetAutoPan( true );
 
-    SELECTION_AREA area;
+    KIGFX::PREVIEW::SELECTION_AREA area;
     view->Add( &area );
 
     while( OPT_TOOL_EVENT evt = Wait() )

pcbnew/tools/selection_tool.h

@@ -37,7 +37,6 @@
 #include <tool/tool_menu.h>
 
 class PCB_BASE_FRAME;
-class SELECTION_AREA;
 class BOARD_ITEM;
 class GENERAL_COLLECTOR;
 

pcbnew/tools/zoom_tool.cpp

@@ -23,9 +23,9 @@
 #include <view/view_controls.h>
 #include <view/view.h>
 #include <tool/tool_manager.h>
+#include <preview_items/selection_area.h>
 
 #include "zoom_tool.h"
-#include "selection_area.h"
 #include "pcb_actions.h"
 
 
@@ -76,7 +76,7 @@ bool ZOOM_TOOL::selectRegion()
     auto canvas = m_frame->GetGalCanvas();
     getViewControls()->SetAutoPan( true );
 
-    SELECTION_AREA area;
+    KIGFX::PREVIEW::SELECTION_AREA area;
     view->Add( &area );
 
     while( auto evt = Wait() )