public bool SetComponents(WoffReader reader)
{
uint startOffset = reader.Offset;
bool weHaveInstructions = false;
ushort flags = MORE_COMPONENTS;
while ((flags & MORE_COMPONENTS) > 0)
{
flags = reader.ReadUInt16();
weHaveInstructions |= (flags & WE_HAVE_INSTRUCTIONS) != 0;
ushort argSize = WoffBuffer.SizeOfUShort; // 2-bytes glyph index
if ((flags & ARG_1_AND_2_ARE_WORDS) > 0)
{
argSize += WoffBuffer.SizeOfUShort * 2; // 4-bytes
}
else
{
argSize += WoffBuffer.SizeOfUShort; // 2-bytes
}
if ((flags & WE_HAVE_A_SCALE) > 0)
{
argSize += WoffBuffer.SizeOfUShort; // 2-bytes
}
else if ((flags & WE_HAVE_AN_X_AND_Y_SCALE) > 0)
{
argSize += WoffBuffer.SizeOfUShort * 2; // 4-bytes
}
else if ((flags & WE_HAVE_A_TWO_BY_TWO) > 0)
{
argSize += WoffBuffer.SizeOfUShort * 4; // 8-bytes
}
if (!reader.Skip(argSize))
{
return(false);
}
}
uint endOffset = reader.Offset;
_hasInstructions = weHaveInstructions;
_componentLength = (ushort)(endOffset - startOffset);
_components = reader.ReadByte(_componentLength, startOffset);
Debug.Assert(reader.Offset == endOffset);
return(reader.Offset == endOffset);
}
private bool TransformHmtx()
{
var glyfTable = _woffFont.Tables[_glyfIndex] as WoffTableGlyf;
Debug.Assert(glyfTable != null);
if (glyfTable == null)
{
return(false);
}
if (_hheaIndex == -1 || _hmtxIndex == -1)
{
return(false);
}
var glyphs = glyfTable.Glyphs;
var glyphAdvances = glyfTable.GlyphsAdvances;
var woffDirs = _woffFont.Directories;
var hheaDir = woffDirs[_hheaIndex];
// Get numberOfHMetrics, https://www.microsoft.com/typography/otspec/hhea.htm
var hheaReader = new WoffReader(hheaDir.OrigTable);
// Skip 34 to reach 'hhea' numberOfHMetrics
if (hheaReader.Skip(34) == false)
{
return(false);
}
ushort numOfHMetrics = hheaReader.ReadUInt16();
var reader = new WoffReader(_woffDir.CompTable);
var flags = reader.ReadByte();
// By the specs: When hmtx transform is indicated by the table directory,
// the Flags (bits 0 or 1 or both) must be set.
if ((flags & 0x01) != 1 && (flags & 0x02) != 1)
{
Trace.TraceError("Hmtx Compression Error: When hmtx transform is indicated by the table directory, "
+ "the Flags (bits 0 or 1 or both) must be set.");
return(false);
}
// By the specs: Bits 2-7 are reserved and must be zero.
if ((flags & 0xFC) != 0)
{
Trace.TraceError("Hmtx Compression Error: Bits 2-7 are reserved and must be zero.");
}
int numOfGlyphs = glyphs.Length;
Debug.Assert(glyphAdvances.Length == numOfGlyphs);
// The number of glyphs numGlyphs can be 0, if there is no 'glyf' but cannot then xform 'hmtx'.
Debug.Assert(numOfHMetrics <= numOfGlyphs);
if (numOfHMetrics > numOfGlyphs)
{
return(false);
}
// https://www.microsoft.com/typography/otspec/hmtx.htm
// "...only one entry need be in the array, but that entry is required."
if (numOfHMetrics < 1)
{
return(false);
}
bool hasProportionalLsbs = (flags & 0x01) == 0;
bool hasMonospaceLsbs = (flags & 0x02) == 0;
IList <ushort> advanceWidths = new List <ushort>();
IList <short> lsbs = new List <short>();
for (ushort glyphIndex = 0; glyphIndex < numOfHMetrics; glyphIndex++)
{
advanceWidths.Add(reader.ReadUInt16());
}
for (ushort glyphIndex = 0; glyphIndex < numOfHMetrics; glyphIndex++)
{
if (hasProportionalLsbs)
{
lsbs.Add(reader.ReadInt16());
}
else
{
lsbs.Add(glyphAdvances[glyphIndex]);
}
}
for (ushort glyphIndex = numOfHMetrics; glyphIndex < numOfGlyphs; glyphIndex++)
{
if (hasMonospaceLsbs)
{
lsbs.Add(reader.ReadInt16());
}
else
{
lsbs.Add(glyphAdvances[glyphIndex]);
}
}
return(SerializeHmtx(advanceWidths, lsbs, numOfHMetrics, numOfGlyphs));
}
