tdf#127471 correct EMF/WMF im/export for scaled font

If FontScaling is used, system-dependent data is held at
vcl::Font Width(). Already if not scaled, we have three
definitions: Width is zero, Width is equal to Height (unx)
or - on Windows - Width equals avgFontWidth.
If used it is W!=H where on unx Width equals Height multiplied
with the scale factor. On Windows, this is Width multiplied
with the only there existing avgFontWidth.
Unfortunately that is ex/imported (since ever) undetected
to EMF/WMF thus making EMF/WMF files containing FontScaling
system-dependent - on which system was LO running when
creating the file? The error can be seen when loading such
a EMF/WMF on the vice-versa system, the FontScale is very
ugly and wrong.
Since EMF/WMF *are* Windows-specific formats the Windows-like
definition is the correct one. This change makes all other
systems export that now, and adapt on import to their system-
specific definition (assuming coming from Windows).
As can be seen, the difficulty is that these adaptions are
necessary on non-Windows plattforms, but these do not have
that avgFontWidth available. Thus I made a deep-dive
investigation and multiple experiments to create a as
similar as possible value to apply the needed calculations.
For details and discussion refer to the bug description.

Change-Id: I983fb6d882e2e8fccf9c8460f01509201d8157f9
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111000
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <Armin.Le.Grand@me.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/vcl/inc/impfont.hxx b/vcl/inc/impfont.hxx
index ba1ea3683926..14a2189d3921 100644
--- a/vcl/inc/impfont.hxx
+++ b/vcl/inc/impfont.hxx
@@ -62,7 +62,18 @@ public:
     void                SetWidthType( const FontWidth eWidthType )      { meWidthType = eWidthType; }
     void                SetAlignment( const TextAlign eAlignment )      { meAlign = eAlignment; }
     void                SetCharSet( const rtl_TextEncoding eCharSet )   { meCharSet = eCharSet; }
-    void                SetFontSize( const Size& rSize )         { maAverageFontSize = rSize; }
+    void                SetFontSize( const Size& rSize )
+    {
+#ifndef _WIN32
+        if(rSize.Height() != maAverageFontSize.Height())
+        {
+            // reset evtl. buffered calculated AverageFontSize, it depends
+            // on Font::Height
+            mnCalculatedAverageFontWidth = 0;
+        }
+#endif
+        maAverageFontSize = rSize;
+    }
 
     void                SetSymbolFlag( const bool bSymbolFlag )         { mbSymbolFlag = bSymbolFlag; }
 
@@ -80,6 +91,11 @@ public:
     void                IncreaseQualityBy( int nQualityAmount )         { mnQuality += nQualityAmount; }
     void                DecreaseQualityBy( int nQualityAmount )         { mnQuality -= nQualityAmount; }
 
+#ifndef _WIN32
+    tools::Long         GetCalculatedAverageFontWidth() const           { return mnCalculatedAverageFontWidth; }
+    void                SetCalculatedAverageFontWidth(tools::Long nNew) { mnCalculatedAverageFontWidth = nNew; }
+#endif
+
     bool                operator==( const ImplFont& ) const;
 
 private:
@@ -130,6 +146,9 @@ private:
 
     int                 mnQuality;
 
+#ifndef _WIN32
+    tools::Long         mnCalculatedAverageFontWidth;
+#endif
 };
 
 #endif // INCLUDED_VCL_INC_IMPFONT_HXX