Add FromDIP to wxDC and wxGraphicsContext

Using the same implementation as wxWindow has.

include/wx/dc.h

@@ -539,6 +539,8 @@ public:
 
     virtual double GetContentScaleFactor() const { return m_contentScaleFactor; }
 
+    virtual wxSize FromDIP(const wxSize& sz) const;
+
 #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
@@ -827,6 +829,16 @@ public:
     double GetContentScaleFactor() const
         { return m_pimpl->GetContentScaleFactor(); }
 
+    wxSize FromDIP(const wxSize& sz) const
+        { return m_pimpl->FromDIP(sz); }
+    wxPoint FromDIP(const wxPoint& pt) const
+    {
+        const wxSize sz = FromDIP(wxSize(pt.x, pt.y));
+        return wxPoint(sz.x, sz.y);
+    }
+    int FromDIP(int d) const
+        { return FromDIP(wxSize(d, 0)).x; }
+
     // Right-To-Left (RTL) modes
 
     void SetLayoutDirection(wxLayoutDirection dir)

include/wx/graphics.h

@@ -739,6 +739,17 @@ public:
     // returns the resolution of the graphics context in device points per inch
     virtual void GetDPI( wxDouble* dpiX, wxDouble* dpiY) const;
 
+    wxSize FromDIP(const wxSize& sz) const;
+    wxPoint FromDIP(const wxPoint& pt) const
+    {
+        const wxSize sz = FromDIP(wxSize(pt.x, pt.y));
+        return wxPoint(sz.x, sz.y);
+    }
+    int FromDIP(int d) const
+    {
+        return FromDIP(wxSize(d, 0)).x;
+    }
+
 #if 0
     // sets the current alpha on this context
     virtual void SetAlpha( wxDouble alpha );

src/common/dcbase.cpp

@@ -36,6 +36,8 @@
 #endif
 
 #include "wx/private/textmeasure.h"
+#include "wx/private/rescale.h"
+#include "wx/display.h"
 
 #ifdef __WXMSW__
     #include "wx/msw/dcclient.h"
@@ -604,6 +606,17 @@ void wxDCImpl::SetAxisOrientation( bool xLeftRight, bool yBottomUp )
     ComputeScaleAndOrigin();
 }
 
+wxSize wxDCImpl::FromDIP(const wxSize& sz) const
+{
+#ifdef wxHAS_DPI_INDEPENDENT_PIXELS
+    return sz;
+#else
+    const wxSize dpi = GetPPI();
+    const wxSize baseline = wxDisplay::GetStdPPI();
+    return wxRescaleCoord(sz).From(baseline).To(dpi);
+#endif // wxHAS_DPI_INDEPENDENT_PIXELS
+}
+
 bool wxDCImpl::DoGetPartialTextExtents(const wxString& text, wxArrayInt& widths) const
 {
     wxTextMeasure tm(GetOwner(), &m_font);

src/common/graphcmn.cpp

@@ -34,6 +34,7 @@
 #endif
 
 #include "wx/private/graphics.h"
+#include "wx/private/rescale.h"
 #include "wx/display.h"
 
 //-----------------------------------------------------------------------------
@@ -641,6 +642,18 @@ void wxGraphicsContext::GetDPI( wxDouble* dpiX, wxDouble* dpiY) const
     }
 }
 
+wxSize wxGraphicsContext::FromDIP(const wxSize& sz) const
+{
+#ifdef wxHAS_DPI_INDEPENDENT_PIXELS
+    return sz;
+#else
+    wxRealPoint dpi;
+    GetDPI(&dpi.x, &dpi.y);
+    const wxSize baseline = wxDisplay::GetStdPPI();
+    return wxRescaleCoord(sz).From(baseline).To(wxSize((int)dpi.x, (int)dpi.y));
+#endif // wxHAS_DPI_INDEPENDENT_PIXELS
+}
+
 // sets the pen
 void wxGraphicsContext::SetPen( const wxGraphicsPen& pen )
 {