tdf#103871: Set Kashida flag per glyph

When we are shaping mixed script text, the Kashida flag would be set
based on which script come last, which makes no sense of course.

I just left an XXX note yesterday, and I hit the bug today already
in a friend’s document!

Change-Id: Ic996fd886f30f4385185eccd214b5648f7248262

2 files changed, 10 insertions, 11 deletions

diff --git a/vcl/inc/sallayout.hxx b/vcl/inc/sallayout.hxx
index 6f21064f0371..805b3e2569b0 100644
--- a/vcl/inc/sallayout.hxx
+++ b/vcl/inc/sallayout.hxx
@@ -316,12 +316,14 @@ public:
     enum {
         IS_IN_CLUSTER = 0x001,
         IS_RTL_GLYPH  = 0x002,
-        IS_DIACRITIC  = 0x004
+        IS_DIACRITIC  = 0x004,
+        ALLOW_KASHIDA = 0X010
     };
 
     bool    IsClusterStart() const  { return ((mnFlags & IS_IN_CLUSTER) == 0); }
     bool    IsRTLGlyph() const      { return ((mnFlags & IS_RTL_GLYPH) != 0); }
     bool    IsDiacritic() const     { return ((mnFlags & IS_DIACRITIC) != 0); }
+    bool    AllowKashida() const    { return ((mnFlags & ALLOW_KASHIDA) != 0); }
 };
 
 typedef std::list<GlyphItem> GlyphList;
diff --git a/vcl/source/gdi/CommonSalLayout.cxx b/vcl/source/gdi/CommonSalLayout.cxx
index 047f845ba27d..a6536f1bfb77 100644
--- a/vcl/source/gdi/CommonSalLayout.cxx
+++ b/vcl/source/gdi/CommonSalLayout.cxx
@@ -353,7 +353,6 @@ void CommonSalLayout::DrawText(SalGraphics& rSalGraphics) const
 bool CommonSalLayout::LayoutText(ImplLayoutArgs& rArgs)
 {
     hb_face_t* pHbFace = hb_font_get_face(mpHbFont);
-    hb_script_t aHbScript = HB_SCRIPT_INVALID;
 
     int nGlyphCapacity = 2 * (rArgs.mnEndCharPos - rArgs.mnMinCharPos);
     Reserve(nGlyphCapacity);
@@ -462,7 +461,6 @@ bool CommonSalLayout::LayoutText(ImplLayoutArgs& rArgs)
             int nMinRunPos = aSubRun.mnMin;
             int nEndRunPos = aSubRun.mnEnd;
             int nRunLen = nEndRunPos - nMinRunPos;
-            aHbScript = aSubRun.maScript;
 
             OString sLanguage = msLanguage;
             if (sLanguage.isEmpty())
@@ -549,6 +547,12 @@ bool CommonSalLayout::LayoutText(ImplLayoutArgs& rArgs)
                 if (bDiacritic)
                     nGlyphFlags |= GlyphItem::IS_DIACRITIC;
 
+                if ((aSubRun.maScript == HB_SCRIPT_ARABIC) || (aSubRun.maScript == HB_SCRIPT_SYRIAC))
+                {
+                    nGlyphFlags |= GlyphItem::ALLOW_KASHIDA;
+                    rArgs.mnFlags |= SalLayoutFlags::KashidaJustification;
+                }
+
                 DeviceCoordinate nAdvance, nXOffset, nYOffset;
                 if (aSubRun.maDirection == HB_DIRECTION_TTB)
                 {
@@ -583,13 +587,6 @@ bool CommonSalLayout::LayoutText(ImplLayoutArgs& rArgs)
     // XXX: why?
     SortGlyphItems();
 
-    // determine need for kashida justification
-    // XXX: This assumes all the text is in the same script, which is not
-    // guaranteed. The flag should be per glyph.
-    if ((rArgs.mpDXArray || rArgs.mnLayoutWidth)
-    && ((aHbScript == HB_SCRIPT_ARABIC) || (aHbScript == HB_SCRIPT_SYRIAC)))
-        rArgs.mnFlags |= SalLayoutFlags::KashidaJustification;
-
     return true;
 }
 
@@ -675,7 +672,7 @@ void CommonSalLayout::ApplyDXArray(ImplLayoutArgs& rArgs)
         DeviceCoordinate nDiff = pNewCharWidths[nCharPos] - pOldCharWidths[nCharPos];
 
         // nDiff > 1 to ignore rounding errors.
-        if (bKashidaJustify && nDiff > 1)
+        if (bKashidaJustify && m_GlyphItems[i].AllowKashida() && nDiff > 1)
             pKashidas[i] = nDiff;
 
         // Adjust the width of the first glyph belonging to current character.