public bool TryUpdatePositions(FontMetrics fontMetrics, GlyphPositioningCollection collection, KerningMode kerningMode, out bool kerned)
{
kerned = false;
bool updated = false;
for (ushort i = 0; i < collection.Count; i++)
{
if (!collection.ShouldProcess(fontMetrics, i))
{
continue;
}
ScriptClass current = CodePoint.GetScriptClass(collection.GetGlyphShapingData(i).CodePoint);
BaseShaper shaper = ShaperFactory.Create(current, kerningMode);
ushort index = i;
ushort count = 1;
while (i < collection.Count - 1)
{
// We want to assign the same feature lookups to individual sections of the text rather
// than the text as a whole to ensure that different language shapers do not interfere
// with each other when the text contains multiple languages.
GlyphShapingData nextData = collection.GetGlyphShapingData(i + 1);
ScriptClass next = CodePoint.GetScriptClass(nextData.CodePoint);
if (next is not ScriptClass.Common and not ScriptClass.Unknown and not ScriptClass.Inherited && next != current)
{
break;
}
i++;
count++;
}
if (shaper.MarkZeroingMode == MarkZeroingMode.PreGPos)
{
ZeroMarkAdvances(fontMetrics, collection, index, count);
}
// Assign Substitution features to each glyph.
shaper.AssignFeatures(collection, index, count);
IEnumerable <Tag> stageFeatures = shaper.GetShapingStageFeatures();
SkippingGlyphIterator iterator = new(fontMetrics, collection, index, default);
foreach (Tag stageFeature in stageFeatures)
{
List <(Tag Feature, ushort Index, LookupTable LookupTable)> lookups = this.GetFeatureLookups(in stageFeature, current);
if (lookups.Count == 0)
{
continue;
}
// Apply features in order.
foreach ((Tag Feature, ushort Index, LookupTable LookupTable)featureLookup in lookups)
{
Tag feature = featureLookup.Feature;
iterator.Reset(index, featureLookup.LookupTable.LookupFlags);
while (iterator.Index < index + count)
{
List <TagEntry> glyphFeatures = collection.GetGlyphShapingData(iterator.Index).Features;
if (!HasFeature(glyphFeatures, in feature))
{
iterator.Next();
continue;
}
bool success = featureLookup.LookupTable.TryUpdatePosition(fontMetrics, this, collection, featureLookup.Feature, iterator.Index, count - (iterator.Index - index));
kerned |= success && (feature == KernTag || feature == VKernTag);
updated |= success;
iterator.Next();
}
}
}
if (shaper.MarkZeroingMode == MarkZeroingMode.PostGpos)
{
ZeroMarkAdvances(fontMetrics, collection, index, count);
}
FixCursiveAttachment(collection, index, count);
FixMarkAttachment(collection, index, count);
if (updated)
{
UpdatePositions(fontMetrics, collection, index, count);
}
}
return(updated);
}
public void ApplySubstitution(FontMetrics fontMetrics, GlyphSubstitutionCollection collection, KerningMode kerningMode)
{
for (ushort i = 0; i < collection.Count; i++)
{
// Choose a shaper based on the script.
// This determines which features to apply to which glyphs.
ScriptClass current = CodePoint.GetScriptClass(collection.GetGlyphShapingData(i).CodePoint);
BaseShaper shaper = ShaperFactory.Create(current, kerningMode);
ushort index = i;
ushort count = 1;
while (i < collection.Count - 1)
{
// We want to assign the same feature lookups to individual sections of the text rather
// than the text as a whole to ensure that different language shapers do not interfere
// with each other when the text contains multiple languages.
GlyphShapingData nextData = collection.GetGlyphShapingData(i + 1);
ScriptClass next = CodePoint.GetScriptClass(nextData.CodePoint);
if (next is not ScriptClass.Common and not ScriptClass.Unknown and not ScriptClass.Inherited && next != current)
{
break;
}
i++;
count++;
}
// Assign Substitution features to each glyph.
shaper.AssignFeatures(collection, index, count);
IEnumerable <Tag> stageFeatures = shaper.GetShapingStageFeatures();
int currentCount = collection.Count;
SkippingGlyphIterator iterator = new(fontMetrics, collection, index, default);
foreach (Tag stageFeature in stageFeatures)
{
List <(Tag Feature, ushort Index, LookupTable LookupTable)> lookups = this.GetFeatureLookups(in stageFeature, current);
if (lookups.Count == 0)
{
continue;
}
// Apply features in order.
foreach ((Tag Feature, ushort Index, LookupTable LookupTable)featureLookup in lookups)
{
Tag feature = featureLookup.Feature;
iterator.Reset(index, featureLookup.LookupTable.LookupFlags);
while (iterator.Index < index + count)
{
List <TagEntry> glyphFeatures = collection.GetGlyphShapingData(iterator.Index).Features;
if (!HasFeature(glyphFeatures, in feature))
{
iterator.Next();
continue;
}
featureLookup.LookupTable.TrySubstitution(fontMetrics, this, collection, featureLookup.Feature, iterator.Index, count - (iterator.Index - index));
iterator.Next();
// Account for substitutions changing the length of the collection.
if (collection.Count != currentCount)
{
count = (ushort)(count - (currentCount - collection.Count));
currentCount = collection.Count;
}
}
}
}
}
}