public override bool TryUpdatePosition(
FontMetrics fontMetrics,
GPosTable table,
GlyphPositioningCollection collection,
Tag feature,
ushort index,
int count)
{
ushort glyphId = collection[index][0];
if (glyphId == 0)
{
return(false);
}
SkippingGlyphIterator iterator = new(fontMetrics, collection, index, this.LookupFlags);
if (!AdvancedTypographicUtils.MatchCoverageSequence(iterator, this.coverageTables, 0))
{
return(false);
}
return(AdvancedTypographicUtils.ApplyLookupList(
fontMetrics,
table,
feature,
this.LookupFlags,
this.sequenceLookupRecords,
collection,
index,
count));
}
public override bool TryUpdatePosition(
FontMetrics fontMetrics,
GPosTable table,
GlyphPositioningCollection collection,
Tag feature,
ushort index,
int count)
{
ushort glyphId = collection[index][0];
if (glyphId == 0)
{
return(false);
}
if (this.coverageTable.CoverageIndexOf(glyphId) < 0)
{
return(false);
}
int offset = this.classDefinitionTable.ClassIndexOf(glyphId);
if (offset < 0)
{
return(false);
}
ClassSequenceRuleSetTable ruleSetTable = this.sequenceRuleSetTables[offset];
SkippingGlyphIterator iterator = new(fontMetrics, collection, index, this.LookupFlags);
foreach (ClassSequenceRuleTable ruleTable in ruleSetTable.SequenceRuleTables)
{
int remaining = count - 1;
int seqLength = ruleTable.InputSequence.Length;
if (seqLength > remaining)
{
continue;
}
if (!AdvancedTypographicUtils.MatchClassSequence(iterator, 1, ruleTable.InputSequence, this.classDefinitionTable))
{
continue;
}
// It's a match. Perform position update and return true if anything changed.
return(AdvancedTypographicUtils.ApplyLookupList(
fontMetrics,
table,
feature,
this.LookupFlags,
ruleTable.SequenceLookupRecords,
collection,
index,
count));
}
return(false);
}
public override bool TryUpdatePosition(
FontMetrics fontMetrics,
GPosTable table,
GlyphPositioningCollection collection,
Tag feature,
ushort index,
int count)
{
ushort glyphId = collection[index][0];
if (glyphId == 0)
{
return(false);
}
int offset = this.coverageTable.CoverageIndexOf(glyphId);
if (offset <= -1)
{
return(false);
}
// TODO: Check this.
// https://docs.microsoft.com/en-us/typography/opentype/spec/gsub#example-7-contextual-substitution-format-1
SequenceRuleSetTable ruleSetTable = this.seqRuleSetTables[offset];
SkippingGlyphIterator iterator = new(fontMetrics, collection, index, this.LookupFlags);
foreach (SequenceRuleTable ruleTable in ruleSetTable.SequenceRuleTables)
{
int remaining = count - 1;
int seqLength = ruleTable.InputSequence.Length;
if (seqLength > remaining)
{
continue;
}
if (!AdvancedTypographicUtils.MatchSequence(iterator, 1, ruleTable.InputSequence))
{
continue;
}
// It's a match. Perform position update and return true if anything changed.
return(AdvancedTypographicUtils.ApplyLookupList(
fontMetrics,
table,
feature,
this.LookupFlags,
ruleTable.SequenceLookupRecords,
collection,
index,
count));
}
return(false);
}
