Implement wxFont::GetFaceName() to return the face name being really used.

Since the change of r60391 empty face name was returned for all fonts created
using the standard wxFont constructor (so basically all fonts except for those
created from native font info and the default/normal font which we retrieve
from the system). Use Windows GetOutlineTextMetrics() function to get the real
face name being used independently of the way the font was created.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62675 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/font.cpp

@@ -32,6 +32,7 @@
     #include "wx/app.h"
     #include "wx/log.h"
     #include "wx/encinfo.h"
+    #include "wx/scopeguard.h"
 #endif // WX_PRECOMP
 
 #include "wx/msw/private.h"
@@ -182,7 +183,19 @@ public:
 
     wxString GetFaceName() const
     {
-        return m_nativeFontInfo.GetFaceName();
+        wxString facename = m_nativeFontInfo.GetFaceName();
+        if ( facename.empty() )
+        {
+            facename = GetMSWFaceName();
+            if ( !facename.empty() )
+            {
+                // cache the face name, it shouldn't change unless the family
+                // does and wxNativeFontInfo::SetFamily() resets the face name
+                const_cast<wxFontRefData *>(this)->SetFaceName(facename);
+            }
+        }
+
+        return facename;
     }
 
     wxFontEncoding GetEncoding() const
@@ -291,6 +304,39 @@ protected:
 
     void Init(const wxNativeFontInfo& info, WXHFONT hFont = 0);
 
+    // retrieve the face name really being used by the font: this is used to
+    // get the face name selected by the system when we don't specify it (but
+    // use just the family for example)
+    wxString GetMSWFaceName() const
+    {
+        ScreenHDC hdc;
+        SelectInHDC selectFont(hdc, m_hFont);
+
+        UINT otmSize = GetOutlineTextMetrics(hdc, 0, NULL);
+        if ( !otmSize )
+        {
+            wxLogLastError("GetOutlineTextMetrics(NULL)");
+            return wxString();
+        }
+
+        OUTLINETEXTMETRIC * const
+            otm = static_cast<OUTLINETEXTMETRIC *>(malloc(otmSize));
+        wxON_BLOCK_EXIT1( free, otm );
+
+        otm->otmSize = otmSize;
+        if ( !GetOutlineTextMetrics(hdc, otmSize, otm) )
+        {
+            wxLogLastError("GetOutlineTextMetrics()");
+            return wxString();
+        }
+
+        // in spit of its type, the otmpFaceName field of OUTLINETEXTMETRIC
+        // gives an offset in _bytes_ of the face name from the struct start
+        // while the name itself is an array of TCHARs
+        return reinterpret_cast<wxChar *>(otm) +
+                    wxPtrToUInt(otm->otmpFaceName)/sizeof(wxChar);
+    }
+
     // are we using m_nativeFontInfo.lf.lfHeight for point size or pixel size?
     bool             m_sizeUsingPixels;