[harfbuzz] Fix placement of multi-glyph clusters

Calculate the delta based on the whole cluster width no just the first
glyph.

This whole ApplyDXArray() business is completely flawed, it is just
trying to second guess information we already had, and then workaround
all bugs it is introducing.

Change-Id: I5f719d7addcb89c9d5662b48ca7cf55cd388b41e

1 files changed, 16 insertions, 1 deletions

diff --git a/vcl/generic/glyphs/gcach_layout.cxx b/vcl/generic/glyphs/gcach_layout.cxx
index fa04dca995ee..fab66ac23920 100644
--- a/vcl/generic/glyphs/gcach_layout.cxx
+++ b/vcl/generic/glyphs/gcach_layout.cxx
@@ -176,7 +176,22 @@ void ServerFontLayout::ApplyDXArray(ImplLayoutArgs& rArgs)
         long nDelta = 0;
         for (i = 0; i < m_GlyphItems.size(); ++i)
         {
-            nDelta += pNewGlyphWidths[i] - m_GlyphItems[i].mnNewWidth;
+            if (m_GlyphItems[i].IsClusterStart())
+            {
+                // calculate original and adjusted cluster width
+                int nOldClusterWidth = m_GlyphItems[i].mnNewWidth;
+                int nNewClusterWidth = pNewGlyphWidths[i];
+                size_t j;
+                for (j = i; ++j < m_GlyphItems.size(); )
+                {
+                    if (m_GlyphItems[j].IsClusterStart())
+                        break;
+                    if (!m_GlyphItems[j].IsDiacritic()) // #i99367# ignore diacritics
+                        nOldClusterWidth += m_GlyphItems[j].mnNewWidth;
+                    nNewClusterWidth += pNewGlyphWidths[j];
+                }
+                nDelta += nNewClusterWidth - nOldClusterWidth;
+            }
             m_GlyphItems[i].mnNewWidth = pNewGlyphWidths[i];
             m_GlyphItems[i].maLinearPos.X() += nDelta;
         }