[harfbuzz] Fix text width calculation

GenericSalLayout::GetTextWidth() uses GlyphItem's mnNewWidth when
calculating text width, and though this seems logical (it is after all
the actual with the glyph is contributing to the all over advance
width), it results in shorter width calculation whenever glyph width
adjustment is involved, no idea why!

The #ifdef is there so that the ICU code path is not changed in anyway,
but all of this should be merged into GenericSalLayout when ICU is
gone.

Change-Id: I7cbde1675b78e87c142513eb52a13ee5fdc60617

vcl/generic/glyphs/gcach_layout.cxx

@@ -67,6 +67,40 @@ bool ServerFontLayout::LayoutText( ImplLayoutArgs& rArgs )
 }
 
 // -----------------------------------------------------------------------
+long ServerFontLayout::GetTextWidth() const
+{
+    long nWidth;
+#if ENABLE_HARFBUZZ
+    const char* pUseHarfBuzz = getenv("SAL_USE_HARFBUZZ");
+    if (pUseHarfBuzz) {
+        GlyphVector aGlyphItems = GenericSalLayout::GetGlyphItems();
+
+        if( aGlyphItems.empty() )
+            return 0;
+
+        // initialize the extent
+        long nMinPos = 0;
+        long nMaxPos = 0;
+
+        for( GlyphVector::const_iterator pG = aGlyphItems.begin(), end = aGlyphItems.end(); pG != end ; ++pG )
+        {
+            // update the text extent with the glyph extent
+            long nXPos = pG->maLinearPos.X();
+            if( nMinPos > nXPos )
+                nMinPos = nXPos;
+            nXPos += pG->mnOrigWidth;
+            if( nMaxPos < nXPos )
+                nMaxPos = nXPos;
+        }
+
+        nWidth = nMaxPos - nMinPos;
+    }
+    else
+#endif
+    nWidth = GenericSalLayout::GetTextWidth();
+    return nWidth;
+}
+
 void ServerFontLayout::AdjustLayout( ImplLayoutArgs& rArgs )
 {
     GenericSalLayout::AdjustLayout( rArgs );

vcl/inc/generic/glyphcache.hxx

@@ -324,6 +324,7 @@ public:
     virtual void    AdjustLayout( ImplLayoutArgs& );
     virtual void    ApplyDXArray( ImplLayoutArgs& );
     virtual void    DrawText( SalGraphics& ) const;
+    virtual long    GetTextWidth() const;
     ServerFont&     GetServerFont() const   { return mrServerFont; }
 };
 

vcl/inc/sallayout.hxx

@@ -367,6 +367,8 @@ protected:
 
     bool            GetCharWidths( sal_Int32* pCharWidths ) const;
 
+    GlyphVector     GetGlyphItems() const { return m_GlyphItems; }
+
 private:
     GlyphVector     m_GlyphItems;
     mutable Point   maBasePoint;