Fix and enable optimized grid drawing and other minor changes.

* Fix optimized bitmap grid drawing method.
* Enable optimized grid drawing method on Windows and Linux.
* Create a helper class for resetting and restoring device context scale
  and origin settings for blitting purposes.
* Use wxLogTrace instead of wxLogDebug for coordinate dumping in
  drawpanel.cpp.  See comments for more information on enabling coordinate
  tracing.
* Add flag to allow hiding the drawing cross hair.  Hide cross hair by
  default on OSX.
* Move get cross hair device position code from draw panel object to base
  screen object.
* Remove redundant parent member variable from draw panel object by
  overriding wxWindow::GetParent() method.

common/base_screen.cpp

@@ -423,6 +423,18 @@ wxPoint BASE_SCREEN::GetCursorPosition( bool aOnGrid, wxRealPoint* aGridSize )
 }
 
 
+wxPoint BASE_SCREEN::GetCrossHairScreenPosition() const
+{
+    wxPoint pos = m_Curseur - m_DrawOrg;
+    double scalar = GetScalingFactor();
+
+    pos.x = wxRound( (double) pos.x * scalar );
+    pos.y = wxRound( (double) pos.y * scalar );
+
+    return pos;
+}
+
+
 /* free the undo and the redo lists
  */
 void BASE_SCREEN::ClearUndoRedoList()

common/drawframe.cpp

@@ -727,12 +727,12 @@ void EDA_DRAW_FRAME::LoadSettings()
     bool btmp;
 
     if ( cfg->Read( m_FrameName + ShowGridEntryKeyword, &btmp ) )
-        SetGridVisibility( btmp);
+        SetGridVisibility( btmp );
 
     int itmp;
 
     if( cfg->Read( m_FrameName + GridColorEntryKeyword, &itmp ) )
-        SetGridColor(itmp);
+        SetGridColor( itmp );
 
     cfg->Read( m_FrameName + LastGridSizeId, &m_LastGridSizeId, 0L );
 }

eeschema/find.cpp

@@ -198,7 +198,7 @@ SCH_ITEM* SCH_EDIT_FRAME::FindComponentAndItem( const wxString& component_refere
         wxPoint old_cursor_position    = sheet->LastScreen()->m_Curseur;
         sheet->LastScreen()->m_Curseur = pos;
 
-        curpos = DrawPanel->CursorScreenPosition();
+        curpos = GetScreen()->GetCrossHairScreenPosition();
 
         DrawPanel->GetViewStart( &( GetScreen()->m_StartVisu.x ),
                                  &( GetScreen()->m_StartVisu.y ) );

gerbview/draw_gerber_screen.cpp

@@ -134,7 +134,9 @@ void BOARD::Draw( EDA_DRAW_PANEL* aPanel, wxDC* aDC, int aDrawMode, const wxPoin
         layerBitmap = new wxBitmap( bitmapWidth, bitmapHeight );
         screenBitmap = new wxBitmap( bitmapWidth, bitmapHeight );
         layerDC.SelectObject( *layerBitmap );
+        EDA_Rect tmpRect = aPanel->m_ClipBox;
         aPanel->DoPrepareDC( layerDC );
+        aPanel->m_ClipBox = tmpRect;
         layerDC.SetBackground( bgBrush );
         layerDC.SetBackgroundMode( wxSOLID );
         layerDC.Clear();

include/class_base_screen.h

@@ -244,7 +244,7 @@ public:
      * @return the the current scale used to draw items on screen
      * draw coordinates are user coordinates * GetScalingFactor( )
      */
-    double  GetScalingFactor()
+    double  GetScalingFactor() const
     {
         return (double) m_ZoomScalar / (double) GetZoom();
     }
@@ -365,6 +365,13 @@ public:
      */
     wxPoint GetCursorPosition( bool aOnGrid, wxRealPoint* aGridSize = NULL );
 
+    /**
+     * Function GetCursorScreenPosition
+     * returns the cross hair position in device (display) units.b
+     * @return The current cross hair position.
+     */
+    wxPoint GetCrossHairScreenPosition() const;
+
     /**
      * Function GetNearestGridPosition
      * returns the nearest \a aGridSize location to \a aPosition.

include/kicad_device_context.h

@@ -86,6 +86,55 @@ private:
 };
 
 
+/**
+ * Class EDA_BLIT_NORMALIZER
+ * is a helper class for clearing a device context scale and offset parameters before
+ * performing a Blit operation.
+ * <p>
+ * This class keeps a temporary copy of the scale and offset parameters of a device
+ * context and then restores them when it goes out of scope.
+ * </p>
+ */
+class EDA_BLIT_NORMALIZER
+{
+public:
+    EDA_BLIT_NORMALIZER( wxDC* aDC )
+        : m_dc( aDC )
+    {
+        if( aDC )
+        {
+            aDC->GetUserScale( &m_userScaleX, &m_userScaleY );
+            aDC->GetLogicalOrigin( &m_logicalOriginX, &m_logicalOriginY );
+            aDC->GetDeviceOrigin( &m_deviceOriginX, &m_deviceOriginY );
+            aDC->SetUserScale( 1.0, 1.0 );
+            aDC->SetLogicalOrigin( 0, 0 );
+            aDC->SetDeviceOrigin( 0, 0 );
+        }
+    }
+
+    ~EDA_BLIT_NORMALIZER()
+    {
+        if( m_dc )
+        {
+            m_dc->SetUserScale( m_userScaleX, m_userScaleY );
+            m_dc->SetLogicalOrigin( m_logicalOriginX, m_logicalOriginY );
+            m_dc->SetDeviceOrigin( m_deviceOriginX, m_deviceOriginY );
+        }
+    }
+
+private:
+    wxDC* m_dc;
+    double m_userScaleX;
+    double m_userScaleY;
+    int m_logicalOriginX;
+    int m_logicalOriginY;
+    int m_deviceOriginX;
+    int m_deviceOriginY;
+
+    DECLARE_NO_COPY_CLASS( EDA_BLIT_NORMALIZER )
+};
+
+
 #if USE_WX_GRAPHICS_CONTEXT
     #include <wx/dcgraph.h>
 #endif