internal static bool ApplyLookup(
IOpenTypeFont Font, // Font access interface
OpenTypeTags TableTag, // Layout table tag (GSUB or GPOS)
FontTable Table, // Layout table (GSUB or GPOS)
LayoutMetrics Metrics, // LayoutMetrics
LookupTable Lookup, // List definition structure
int CharCount, // Characters count (i.e. Charmap.Length);
UshortList Charmap, // Char to glyph mapping
GlyphInfoList GlyphInfo, // List of GlyphInfo structs
int* Advances, // Glyph adv.widths
LayoutOffset* Offsets, // Glyph offsets
int FirstGlyph, // where to apply it
int AfterLastGlyph, // how long is a context we can use
uint Parameter, // lookup parameter
int nestingLevel, // Contextual lookup nesting level
out int NextGlyph // out: next glyph index
)
{
Debug.Assert(TableTag==OpenTypeTags.GSUB || TableTag==OpenTypeTags.GPOS);
Debug.Assert(FirstGlyph<AfterLastGlyph);
Debug.Assert(AfterLastGlyph<=GlyphInfo.Length);
ushort lookupType = Lookup.LookupType();
ushort lookupFlags = Lookup.LookupFlags();
ushort subtableCount = Lookup.SubTableCount();
bool match=false;
NextGlyph=FirstGlyph+1; //Just to avoid compiler error
// Find first glyph
if (!IsLookupReversal(TableTag,lookupType))
{
FirstGlyph=LayoutEngine.GetNextGlyphInLookup(Font,GlyphInfo,FirstGlyph,
lookupFlags,LayoutEngine.LookForward);
}
else
{
AfterLastGlyph = LayoutEngine.GetNextGlyphInLookup(Font,GlyphInfo,AfterLastGlyph-1,
lookupFlags,LayoutEngine.LookBackward) + 1;
}
if (FirstGlyph>=AfterLastGlyph) return match;
ushort originalLookupType = lookupType; // We need it to recover, if extension lookup updated lookupFormat
for(ushort subtableIndex=0; !match && subtableIndex < subtableCount; subtableIndex++)
{
lookupType = originalLookupType;
int subtableOffset = Lookup.SubtableOffset(Table, subtableIndex);
switch (TableTag)
{
case OpenTypeTags.GSUB:
{
if (lookupType == 7)
{
ExtensionLookupTable extension =
new ExtensionLookupTable(subtableOffset);
lookupType = extension.LookupType(Table);
subtableOffset = extension.LookupSubtableOffset(Table);
}
switch (lookupType)
{
case 1: //SingleSubst
SingleSubstitutionSubtable singleSub =
new SingleSubstitutionSubtable(subtableOffset);
match = singleSub.Apply( Table,
GlyphInfo,
FirstGlyph,
out NextGlyph
);
break;
case 2: //MultipleSubst
MultipleSubstitutionSubtable multipleSub =
new MultipleSubstitutionSubtable(subtableOffset);
match = multipleSub.Apply( Font,
Table,
CharCount,
Charmap,
GlyphInfo,
lookupFlags,
FirstGlyph,
AfterLastGlyph,
out NextGlyph
);
break;
case 3: //AlternateSubst
AlternateSubstitutionSubtable alternateSub =
new AlternateSubstitutionSubtable(subtableOffset);
match = alternateSub.Apply( Table,
GlyphInfo,
Parameter,
FirstGlyph,
out NextGlyph
);
break;
case 4: //Ligature subst
LigatureSubstitutionSubtable ligaSub =
new LigatureSubstitutionSubtable(subtableOffset);
match = ligaSub.Apply( Font,
Table,
CharCount,
Charmap,
GlyphInfo,
lookupFlags,
FirstGlyph,
AfterLastGlyph,
out NextGlyph
);
break;
case 5: //ContextualSubst
ContextSubtable contextSub =
new ContextSubtable(subtableOffset);
match = contextSub.Apply( Font,
TableTag,
Table,
Metrics,
CharCount,
Charmap,
GlyphInfo,
Advances,
Offsets,
lookupFlags,
FirstGlyph,
AfterLastGlyph,
Parameter,
nestingLevel,
out NextGlyph
);
break;
case 6: //ChainingSubst
ChainingSubtable chainingSub =
new ChainingSubtable(subtableOffset);
match = chainingSub.Apply( Font,
TableTag,
Table,
Metrics,
CharCount,
Charmap,
GlyphInfo,
Advances,
Offsets,
lookupFlags,
FirstGlyph,
AfterLastGlyph,
Parameter,
nestingLevel,
out NextGlyph
);
break;
case 7: //Extension lookup
// Ext.Lookup processed earlier. It can't contain another ext.lookups in it.
// Just skip it (do nothing);
NextGlyph = FirstGlyph + 1;
break;
case 8: //ReverseCahiningSubst
ReverseChainingSubtable reverseChainingSub =
new ReverseChainingSubtable(subtableOffset);
match = reverseChainingSub.Apply(
Font,
TableTag,
Table,
Metrics,
CharCount,
Charmap,
GlyphInfo,
Advances,
Offsets,
lookupFlags,
FirstGlyph,
AfterLastGlyph,
Parameter,
out NextGlyph
);
break;
default:
// Unknown format
NextGlyph = FirstGlyph+1;
break;
}
if (match)
{
if (!IsLookupReversal(TableTag,lookupType))
{
UpdateGlyphFlags(Font,GlyphInfo,FirstGlyph,NextGlyph,true,GlyphFlags.Substituted);
}
else
{
UpdateGlyphFlags(Font,GlyphInfo,NextGlyph,AfterLastGlyph,true,GlyphFlags.Substituted);
}
}
break;
}
case OpenTypeTags.GPOS:
{
if (lookupType == 9)
{
ExtensionLookupTable extension =
new ExtensionLookupTable(subtableOffset);
lookupType = extension.LookupType(Table);
subtableOffset = extension.LookupSubtableOffset(Table);
}
switch (lookupType)
{
case 1: //SinglePos
SinglePositioningSubtable singlePos =
new SinglePositioningSubtable(subtableOffset);
match = singlePos.Apply(Table,
Metrics,
GlyphInfo,
Advances,
Offsets,
FirstGlyph,
AfterLastGlyph,
out NextGlyph
);
break;
case 2: //PairPos
PairPositioningSubtable pairPos =
new PairPositioningSubtable(subtableOffset);
match = pairPos.Apply( Font,
Table,
Metrics, // LayoutMetrics
GlyphInfo, // List of GlyphInfo structs
lookupFlags, // Lookup flags for glyph lookups
Advances, // Glyph adv.widths
Offsets, // Glyph offsets
FirstGlyph, // where to apply lookup
AfterLastGlyph, // how long is a context we can use
out NextGlyph // Next glyph to process
);
break;
case 3: // CursivePos
// Under construction
CursivePositioningSubtable cursivePositioningSubtable =
new CursivePositioningSubtable(subtableOffset);
cursivePositioningSubtable.Apply( Font,
Table,
Metrics, // LayoutMetrics
GlyphInfo, // List of GlyphInfo structs
lookupFlags, // Lookup flags for glyph lookups
Advances, // Glyph adv.widths
Offsets, // Glyph offsets
FirstGlyph, // where to apply lookup
AfterLastGlyph, // how long is a context we can use
out NextGlyph // Next glyph to process
);
break;
case 4: //MarkToBasePos
MarkToBasePositioningSubtable markToBasePos =
new MarkToBasePositioningSubtable(subtableOffset);
match = markToBasePos.Apply(Font,
Table,
Metrics, // LayoutMetrics
GlyphInfo, // List of GlyphInfo structs
lookupFlags, // Lookup flags for glyph lookups
Advances, // Glyph adv.widths
Offsets, // Glyph offsets
FirstGlyph, // where to apply lookup
AfterLastGlyph, // how long is a context we can use
out NextGlyph // Next glyph to process
);
break;
case 5: //MarkToLigaturePos
// Under construction
MarkToLigaturePositioningSubtable markToLigaPos =
new MarkToLigaturePositioningSubtable(subtableOffset);
match = markToLigaPos.Apply(
Font,
Table,
Metrics, // LayoutMetrics
GlyphInfo, // List of GlyphInfo structs
lookupFlags, // Lookup flags for glyph lookups
CharCount, // Characters count (i.e. Charmap.Length);
Charmap, // Char to glyph mapping
Advances, // Glyph adv.widths
Offsets, // Glyph offsets
FirstGlyph, // where to apply lookup
AfterLastGlyph, // how long is a context we can use
out NextGlyph // Next glyph to process
);
break;
case 6: //MarkToMarkPos
MarkToMarkPositioningSubtable markToMarkPos =
new MarkToMarkPositioningSubtable(subtableOffset);
match = markToMarkPos.Apply(
Font,
Table,
Metrics, // LayoutMetrics
GlyphInfo, // List of GlyphInfo structs
lookupFlags, // Lookup flags for glyph lookups
Advances, // Glyph adv.widths
Offsets, // Glyph offsets
FirstGlyph, // where to apply lookup
AfterLastGlyph, // how long is a context we can use
out NextGlyph // Next glyph to process
);
break;
case 7: // Contextual
ContextSubtable contextSub =
new ContextSubtable(subtableOffset);
match = contextSub.Apply( Font,
TableTag,
Table,
Metrics,
CharCount,
Charmap,
GlyphInfo,
Advances,
Offsets,
lookupFlags,
FirstGlyph,
AfterLastGlyph,
Parameter,
nestingLevel,
out NextGlyph
);
break;
case 8: // Chaining
ChainingSubtable chainingSub =
new ChainingSubtable(subtableOffset);
match = chainingSub.Apply( Font,
TableTag,
Table,
Metrics,
CharCount,
Charmap,
GlyphInfo,
Advances,
Offsets,
lookupFlags,
FirstGlyph,
AfterLastGlyph,
Parameter,
nestingLevel,
out NextGlyph
);
break;
case 9: //Extension lookup
// Ext.Lookup processed earlier. It can't contain another ext.lookups in it.
// Just skip it (do nothing);
NextGlyph = FirstGlyph + 1;
break;
default:
// Unknown format
NextGlyph = FirstGlyph + 1;
break;
}
if (match)
{
UpdateGlyphFlags(Font,GlyphInfo,FirstGlyph,NextGlyph,false,GlyphFlags.Positioned);
}
break;
}
default:
Debug.Assert(false,"Unknown OpenType layout table!");
break;
}
}
return match;
}