[harfbuzz] Fix text width calculation, 3rd try

It turns out storing the width in the layout is not so good idea,
because in some mysterious cases when font fallback is involved we call
GetTextWidth() without calling LayoutText() first, and we return the
width of the previous text run.

It seems all I needed is to pass down the X offset with the glyph item,
and take it into account when calculating the width.

Change-Id: Idbdb6bba00573fb6ca773701757d667e21ac0912

vcl/generic/glyphs/gcach_layout.cxx

@@ -72,17 +72,6 @@ bool ServerFontLayout::LayoutText( ImplLayoutArgs& rArgs )
 }
 
 // -----------------------------------------------------------------------
-long ServerFontLayout::GetTextWidth() const
-{
-    long nWidth;
-    if (bUseHarfBuzz)
-        nWidth = GetWidth();
-    else
-        nWidth = GenericSalLayout::GetTextWidth();
-
-    return nWidth;
-}
-
 void ServerFontLayout::AdjustLayout( ImplLayoutArgs& rArgs )
 {
     GenericSalLayout::AdjustLayout( rArgs );
@@ -524,7 +513,7 @@ bool HbLayoutEngine::layout(ServerFontLayout& rLayout, ImplLayoutArgs& rArgs)
             int32_t nYAdvance = pHbPositions[i].y_advance >> 6;
 
             Point aNewPos = Point(aCurrPos.X() + nXOffset, -(aCurrPos.Y() + nYOffset));
-            const GlyphItem aGI(nCharPos, nGlyphIndex, aNewPos, nGlyphFlags, nXAdvance);
+            const GlyphItem aGI(nCharPos, nGlyphIndex, aNewPos, nGlyphFlags, nXAdvance, nXOffset);
             rLayout.AppendGlyph(aGI);
 
             aCurrPos.X() += nXAdvance;
@@ -533,7 +522,6 @@ bool HbLayoutEngine::layout(ServerFontLayout& rLayout, ImplLayoutArgs& rArgs)
 
         hb_buffer_destroy(pHbBuffer);
     }
-    rLayout.SetWidth(aCurrPos.X());
 
     hb_font_destroy(pHbFont);
 

vcl/inc/generic/glyphcache.hxx

@@ -317,7 +317,6 @@ private:
     SAL_DLLPRIVATE  ServerFontLayout& operator=( const ServerFontLayout& );
 
     bool            bUseHarfBuzz;
-    long            mnTextWidth;
 
 public:
                     ServerFontLayout( ServerFont& );
@@ -325,12 +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; }
-
-    // used by layout engine
-    void            SetWidth( long nWidth ) { mnTextWidth = nWidth; }
-    long            GetWidth() const { return mnTextWidth; }
 };
 
 // =======================================================================

vcl/inc/sallayout.hxx

@@ -310,6 +310,7 @@ struct GlyphItem
     int     mnCharPos;      // index in string
     int     mnOrigWidth;    // original glyph width
     int     mnNewWidth;     // width after adjustments
+    int     mnXOffset;
     sal_GlyphId mnGlyphIndex;
     Point   maLinearPos;    // absolute position of non rotated string
 
@@ -320,9 +321,19 @@ public:
                 long nFlags, int nOrigWidth )
             :   mnFlags(nFlags), mnCharPos(nCharPos),
                 mnOrigWidth(nOrigWidth), mnNewWidth(nOrigWidth),
+                mnXOffset(0),
                 mnGlyphIndex(nGlyphIndex), maLinearPos(rLinearPos)
             {}
 
+            GlyphItem( int nCharPos, sal_GlyphId nGlyphIndex, const Point& rLinearPos,
+                long nFlags, int nOrigWidth, int nXOffset )
+            :   mnFlags(nFlags), mnCharPos(nCharPos),
+                mnOrigWidth(nOrigWidth), mnNewWidth(nOrigWidth),
+                mnXOffset(nXOffset),
+                mnGlyphIndex(nGlyphIndex), maLinearPos(rLinearPos)
+            {}
+
+
     enum{ FALLBACK_MASK=0xFF, IS_IN_CLUSTER=0x100, IS_RTL_GLYPH=0x200, IS_DIACRITIC=0x400 };
 
     bool    IsClusterStart() const  { return ((mnFlags & IS_IN_CLUSTER) == 0); }

vcl/source/gdi/sallayout.cxx

@@ -996,7 +996,7 @@ long GenericSalLayout::GetTextWidth() const
         long nXPos = pG->maLinearPos.X();
         if( nMinPos > nXPos )
             nMinPos = nXPos;
-        nXPos += pG->mnNewWidth;
+        nXPos += pG->mnNewWidth - pG->mnXOffset;
         if( nMaxPos < nXPos )
             nMaxPos = nXPos;
     }