Add wxNativeFontInfo::GetPointSizeFromLogFontHeight() helper

No real changes, just refactor the code previously present in both
wxNativeFontInfo ctor and SetPixelSize() in a single function and reuse
it in both places.

include/wx/fontutil.h

@@ -118,7 +118,14 @@ public:
     // set the XFLD
     void SetXFontName(const wxString& xFontName);
 #elif defined(__WXMSW__)
-    wxNativeFontInfo(const LOGFONT& lf_);
+    wxNativeFontInfo(const LOGFONT& lf_)
+        : lf(lf_),
+          pointSize(GetPointSizeFromLogFontHeight(lf.lfHeight))
+    {
+    }
+
+    // MSW-specific: get point size from LOGFONT height using the default DPI.
+    static float GetPointSizeFromLogFontHeight(int height);
 
     // MSW-specific: get the height value in pixels using LOGFONT convention
     // (i.e. negative) corresponding to the given size in points and DPI.

src/msw/font.cpp

@@ -402,13 +402,13 @@ void wxFontRefData::Free()
 // wxNativeFontInfo
 // ----------------------------------------------------------------------------
 
-wxNativeFontInfo::wxNativeFontInfo(const LOGFONT& lf_)
-    : lf(lf_)
+/* static */
+float wxNativeFontInfo::GetPointSizeFromLogFontHeight(int height)
 {
     // Determine the size in points using the primary screen DPI as we don't
     // have anything else here.
     const float ppi = ::GetDeviceCaps(ScreenHDC(), LOGPIXELSY);
-    pointSize = 72.0f * abs(lf.lfHeight) / ppi;
+    return 72.0f * abs(height) / ppi;
 }
 
 void wxNativeFontInfo::Init()
@@ -535,8 +535,7 @@ void wxNativeFontInfo::SetPixelSize(const wxSize& pixelSize)
 
     // We don't have the right DPI to use here neither, but we need to update
     // the point size too, so fall back to the default.
-    const float ppi = ::GetDeviceCaps(ScreenHDC(), LOGPIXELSY);
-    pointSize = 72.0f * pixelSize.GetHeight() / ppi;
+    pointSize = GetPointSizeFromLogFontHeight(lf.lfHeight);
 }
 
 void wxNativeFontInfo::SetStyle(wxFontStyle style)