adding ContentScaleFactor support to dc - defaulting to 1.0

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74282 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/dc.h

@@ -522,6 +522,8 @@ public:
     // this needs to overidden if the axis is inverted
     virtual void SetAxisOrientation(bool xLeftRight, bool yBottomUp);
     
+    virtual double GetContentScaleFactor() const { return m_contentScaleFactor; }
+
 #ifdef __WXMSW__
     // Native Windows functions using the underlying HDC don't honour GDI+
     // transformations which may be applied to it. Using this function we can
@@ -748,6 +750,8 @@ protected:
 
     int m_signX, m_signY;  // Used by SetAxisOrientation() to invert the axes
     
+    double m_contentScaleFactor; // used by high resolution displays (retina)
+
     // what is a mm on a screen you don't know the size of?
     double       m_mm_to_pix_x,
                  m_mm_to_pix_y;
@@ -830,6 +834,9 @@ public:
     virtual int GetResolution() const
         { return m_pimpl->GetResolution(); }
 
+    double GetContentScaleFactor() const
+        { return m_pimpl->GetContentScaleFactor(); }
+
     // Right-To-Left (RTL) modes
 
     void SetLayoutDirection(wxLayoutDirection dir)

src/common/dcbase.cpp

@@ -338,6 +338,7 @@ wxDCImpl::wxDCImpl( wxDC *owner )
         , m_userScaleX(1.0), m_userScaleY(1.0)
         , m_scaleX(1.0), m_scaleY(1.0)
         , m_signX(1), m_signY(1)
+        , m_contentScaleFactor(1)
         , m_minX(0), m_minY(0), m_maxX(0), m_maxY(0)
         , m_clipX1(0), m_clipY1(0), m_clipX2(0), m_clipY2(0)
         , m_logicalFunction(wxCOPY)