/// <summary>Checks if given glyph line at the given position matches given rule.</summary>
/// <returns>
/// either index which corresponds to the last glyph of the matching context inside the glyph line if context matches,
/// or -1 if context doesn't match.
/// </returns>
protected internal virtual int CheckIfContextMatch(GlyphLine line, ContextualSubstRule rule)
{
int j;
OpenTableLookup.GlyphIndexer gidx = new OpenTableLookup.GlyphIndexer();
gidx.line = line;
gidx.idx = line.idx;
//Note, that starting index shall be 1
for (j = 1; j < rule.GetContextLength(); ++j)
{
gidx.NextGlyph(openReader, lookupFlag);
if (gidx.glyph == null || !rule.IsGlyphMatchesInput(gidx.glyph.GetCode(), j))
{
break;
}
}
bool isMatch = j == rule.GetContextLength();
if (isMatch)
{
return(gidx.idx);
}
else
{
return(-1);
}
}
public override bool TransformOne(GlyphLine line)
{
bool changed = false;
int oldLineStart = line.start;
int oldLineEnd = line.end;
int initialLineIndex = line.idx;
foreach (ContextualSubTable subTable in subTables)
{
ContextualSubstRule contextRule = subTable.GetMatchingContextRule(line);
if (contextRule == null)
{
continue;
}
int lineEndBeforeSubstitutions = line.end;
SubstLookupRecord[] substLookupRecords = contextRule.GetSubstLookupRecords();
OpenTableLookup.GlyphIndexer gidx = new OpenTableLookup.GlyphIndexer();
gidx.line = line;
foreach (SubstLookupRecord substRecord in substLookupRecords)
{
// There could be some skipped glyphs inside the context sequence, therefore currently GlyphIndexer and
// nextGlyph method are used to get to the glyph at "substRecord.sequenceIndex" index
gidx.idx = initialLineIndex;
for (int i = 0; i < substRecord.sequenceIndex; ++i)
{
gidx.NextGlyph(openReader, lookupFlag);
}
line.idx = gidx.idx;
OpenTableLookup lookupTable = openReader.GetLookupTable(substRecord.lookupListIndex);
changed = lookupTable.TransformOne(line) || changed;
}
line.idx = line.end;
line.start = oldLineStart;
int lenDelta = lineEndBeforeSubstitutions - line.end;
line.end = oldLineEnd - lenDelta;
return(changed);
}
++line.idx;
return(changed);
}
