private static bool Match <T>(
int increment,
T[] sequence,
SkippingGlyphIterator iterator,
Func <T, GlyphShapingData, bool> condition,
Span <int> matches)
{
ushort position = iterator.Index;
ushort offset = iterator.Increment(increment);
IGlyphShapingCollection collection = iterator.Collection;
int i = 0;
while (i < sequence.Length && i < MaxContextLength && offset < collection.Count)
{
if (!condition(sequence[i], collection.GetGlyphShapingData(offset)))
{
break;
}
if (matches.Length == MaxContextLength)
{
matches[i] = iterator.Index;
}
i++;
offset = iterator.Next();
}
iterator.Index = position;
return(i == sequence.Length);
}
public SkippingGlyphIterator(FontMetrics fontMetrics, IGlyphShapingCollection collection, ushort index, LookupFlags lookupFlags)
{
this.fontMetrics = fontMetrics;
this.Collection = collection;
this.Index = index;
this.ignoreMarks = (lookupFlags & LookupFlags.IgnoreMarks) != 0;
this.ignoreBaseGlypghs = (lookupFlags & LookupFlags.IgnoreBaseGlypghs) != 0;
this.ignoreLigatures = (lookupFlags & LookupFlags.IgnoreLigatures) != 0;
this.markAttachmentType = 0; // TODO: Lookup HarfBuzz to see how this is assigned.
}
public static bool CheckAllCoverages(
FontMetrics fontMetrics,
LookupFlags lookupFlags,
IGlyphShapingCollection collection,
ushort index,
int count,
CoverageTable[] input,
CoverageTable[] backtrack,
CoverageTable[] lookahead)
{
// Check that there are enough context glyphs.
if (index - backtrack.Length < 0 || input.Length + lookahead.Length > count)
{
return(false);
}
// Check all coverages: if any of them does not match, abort update.
SkippingGlyphIterator iterator = new(fontMetrics, collection, index, lookupFlags);
if (!MatchCoverageSequence(iterator, backtrack, -backtrack.Length))
{
return(false);
}
if (!MatchCoverageSequence(iterator, input, 0))
{
return(false);
}
if (!MatchCoverageSequence(iterator, lookahead, input.Length))
{
return(false);
}
return(true);
}
/// <inheritdoc/>
public override void AssignFeatures(IGlyphShapingCollection collection, int index, int count)
{
this.AddFeature(collection, index, count, CcmpTag);
this.AddFeature(collection, index, count, LoclTag);
this.AddFeature(collection, index, count, IsolTag, false);
this.AddFeature(collection, index, count, FinaTag, false);
this.AddFeature(collection, index, count, Fin2Tag, false);
this.AddFeature(collection, index, count, Fin3Tag, false);
this.AddFeature(collection, index, count, MediTag, false);
this.AddFeature(collection, index, count, Med2Tag, false);
this.AddFeature(collection, index, count, InitTag, false);
this.AddFeature(collection, index, count, MsetTag);
base.AssignFeatures(collection, index, count);
int prev = -1;
int state = 0;
byte[] actions = new byte[count];
// Apply the state machine to map glyphs to features.
for (int i = 0; i < count; i++)
{
GlyphShapingData data = collection.GetGlyphShapingData(i + index);
JoiningClass joiningClass = CodePoint.GetJoiningClass(data.CodePoint);
JoiningType joiningType = joiningClass.JoiningType;
if (joiningType == JoiningType.Transparent)
{
actions[i] = None;
continue;
}
int shapingClassIndex = GetShapingClassIndex(joiningType);
byte[] actionsWithState = StateTable[state, shapingClassIndex];
byte prevAction = actionsWithState[0];
byte curAction = actionsWithState[1];
state = actionsWithState[2];
if (prevAction != None && prev != -1)
{
actions[prev] = prevAction;
}
actions[i] = curAction;
prev = i;
}
// Apply the chosen features to their respective glyphs.
for (int i = 0; i < actions.Length; i++)
{
switch (actions[i])
{
case Fina:
collection.EnableShapingFeature(i + index, FinaTag);
break;
case Fin2:
collection.EnableShapingFeature(i + index, Fin2Tag);
break;
case Fin3:
collection.EnableShapingFeature(i + index, Fin3Tag);
break;
case Isol:
collection.EnableShapingFeature(i + index, IsolTag);
break;
case Init:
collection.EnableShapingFeature(i + index, InitTag);
break;
case Medi:
collection.EnableShapingFeature(i + index, MediTag);
break;
case Med2:
collection.EnableShapingFeature(i + index, Med2Tag);
break;
}
}
}
/// <summary> /// Assigns the substitution features to each glyph within the collection. /// </summary> /// <param name="collection">The glyph shaping collection.</param> /// <param name="index">The zero-based index of the elements to assign.</param> /// <param name="count">The number of elements to assign.</param> public abstract void AssignFeatures(IGlyphShapingCollection collection, int index, int count);
