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Fix dotted-circle insertion and improve reordering for Indic scripts. #517

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Merged
JimBobSquarePants merged 2 commits into from
Mar 18, 2026
Merged

Fix dotted-circle insertion and improve reordering for Indic scripts. #517

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4e224e4
Fix dotted-circle insertion and improve reordering for Indic scripts.
JimBobSquarePants Mar 18, 2026
5cb248b
Add tests for Indic shaping categories
JimBobSquarePants Mar 18, 2026
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24 changes: 17 additions & 7 deletions src/SixLabors.Fonts/Tables/AdvancedTypographic/Shapers/IndicShaper.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -379,18 +379,19 @@ private void InitialReorder(IGlyphShapingCollection collection, int index, int c

GlyphShapingData current = substitutionCollection[i];
IndicShapingEngineInfo currentInfo = current.IndicShapingEngineInfo!;
glyphs[0] = current.GlyphId;
glyphs[1] = circleId;
glyphs[0] = circleId;
glyphs[1] = current.GlyphId;

substitutionCollection.Replace(i, glyphs, FeatureTags.GlyphCompositionDecomposition);

// Update shaping info for newly inserted data.
GlyphShapingData dotted = substitutionCollection[i + 1];
// The dotted circle is now at position i (inherits original shaping info).
// Update it to be a dotted circle base.
GlyphShapingData dotted = substitutionCollection[i];
dotted.IndicShapingEngineInfo!.Category = Categories.Dotted_Circle;
dotted.IndicShapingEngineInfo.Position = Positions.End;
dotted.IndicShapingEngineInfo.SyllableType = currentInfo.SyllableType;
dotted.IndicShapingEngineInfo.Syllable = currentInfo.Syllable;

// The original mark glyph is now at position i + 1 (copy of original info).
// Its shaping info is already correct from the copy.
end++;
max++;
}
Expand Down Expand Up @@ -705,6 +706,15 @@ private void InitialReorder(IGlyphShapingCollection collection, int index, int c
}
else if (info.Position != Positions.SMVD)
{
// If an MPst follows an SM, update the SM's position to match
// so they move together during reordering.
if (info.Category == Categories.MPst
&& i > start
&& substitutionCollection[i - 1].IndicShapingEngineInfo?.Category == Categories.SM)
{
substitutionCollection[i - 1].IndicShapingEngineInfo!.Position = info.Position;
}

lastPosition = info.Position;
}
}
Expand Down Expand Up @@ -732,7 +742,7 @@ private void InitialReorder(IGlyphShapingCollection collection, int index, int c

last = i;
}
else if ((FlagUnsafe(info.Category) & Flag(Categories.M)) != 0)
else if ((FlagUnsafe(info.Category) & (Flag(Categories.M) | Flag(Categories.MPst))) != 0)
{
last = i;
}
Expand Down
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