public void ChecksumAdjustment(byte[] headersBuffer, uint headerOffset, uint headerLength, uint tablesChecksum = 0)
{
Debug.Assert(_headIndex != -1);
if (_headIndex == -1)
{
return;
}
var headTable = _woffTables[_headIndex] as WoffTableHead;
Debug.Assert(headTable != null);
if (headTable == null)
{
return;
}
// Compute the checksum of the font's header
Debug.Assert(headerLength != 0);
Debug.Assert(headersBuffer != null && headersBuffer.Length != 0);
var headerPadding = (uint)WoffBuffer.CalcPadBytes((int)headerLength, 4);
var buffer = headersBuffer;
if (headerPadding > 0)
{
var paddedLength = headerLength + headerPadding;
buffer = new byte[paddedLength];
Buffer.BlockCopy(headersBuffer, 0, buffer, 0, headersBuffer.Length);
}
uint nLongs = (headerLength + 3) / 4;
uint headerChecksum = 0;
for (uint i = 0; i < nLongs; i += 4)
{
headerChecksum += WoffBuffer.GetUIntBE(buffer, i);
}
// Compute the checksum of the font by summing the checksum of the header and tables
var fontChecksum = headerChecksum;
if (tablesChecksum == 0)
{
tablesChecksum = headerChecksum;
for (ushort i = 0; i < _woffDirs.Count; i++)
{
tablesChecksum += _woffDirs[i].OrigChecksum;
}
}
fontChecksum += headerChecksum;
// Finally, update the 'head' table's checkSumAdjustment.
headTable.CheckSumAdjustment = 0xB1B0AFBA - fontChecksum;
}
public uint CalculateChecksum()
{
Debug.Assert(_origLength != 0);
Debug.Assert(_origTable != null && _origTable.Length != 0);
var padBytesLength = (uint)WoffBuffer.CalcPadBytes((int)_origLength, 4);
if (padBytesLength != 0)
{
_padding = padBytesLength;
}
var origLength = _origLength;
var buffer = _origTable;
if (_padding > 0)
{
origLength = _origLength + _padding;
buffer = new byte[origLength];
Buffer.BlockCopy(_origTable, 0, buffer, 0, _origTable.Length);
}
uint nLongs = (_origLength + 3) / 4;
uint sum = 0;
//for (uint i = 0; i < nLongs; i++)
//{
// sum += WoffBuffer.GetUIntBE(buffer, i * 4);
//}
for (uint i = 0; i < nLongs; i += 4)
{
sum += WoffBuffer.GetUIntBE(buffer, i);
}
return(sum);
}
