/**
* This will read the required data from the stream.
*
* @param ttf The font that is being read.
* @param data The stream to read the data from.
* @ If there is an error reading the data.
*/
public override void Read(TrueTypeFont ttf, TTFDataStream data)
{
HorizontalHeaderTable hHeader = ttf.HorizontalHeader;
if (hHeader == null)
{
throw new IOException("Could not get hhea table");
}
numHMetrics = hHeader.NumberOfHMetrics;
int numGlyphs = ttf.NumberOfGlyphs;
int bytesRead = 0;
advanceWidth = new int[numHMetrics];
leftSideBearing = new short[numHMetrics];
for (int i = 0; i < numHMetrics; i++)
{
advanceWidth[i] = data.ReadUnsignedShort();
leftSideBearing[i] = data.ReadSignedShort();
bytesRead += 4;
}
int numberNonHorizontal = numGlyphs - numHMetrics;
// handle bad fonts with too many hmetrics
if (numberNonHorizontal < 0)
{
numberNonHorizontal = numGlyphs;
}
// make sure that table is never null and correct size, even with bad fonts that have no
// "leftSideBearing" table although they should
nonHorizontalLeftSideBearing = new short[numberNonHorizontal];
if (bytesRead < Length)
{
for (int i = 0; i < numberNonHorizontal; i++)
{
if (bytesRead < Length)
{
nonHorizontalLeftSideBearing[i] = data.ReadSignedShort();
bytesRead += 2;
}
}
}
initialized = true;
}
private byte[] buildHheaTable()
{
using (var bos = new MemoryStream())
using (var output = new BinaryWriter(bos))
{
HorizontalHeaderTable h = ttf.HorizontalHeader;
WriteFixed(output, h.Version);
WriteSInt16(output, h.Ascender);
WriteSInt16(output, h.Descender);
WriteSInt16(output, h.LineGap);
WriteUint16(output, h.AdvanceWidthMax);
WriteSInt16(output, h.MinLeftSideBearing);
WriteSInt16(output, h.MinRightSideBearing);
WriteSInt16(output, h.XMaxExtent);
WriteSInt16(output, h.CaretSlopeRise);
WriteSInt16(output, h.CaretSlopeRun);
WriteSInt16(output, h.Reserved1); // caretOffset
WriteSInt16(output, h.Reserved2);
WriteSInt16(output, h.Reserved3);
WriteSInt16(output, h.Reserved4);
WriteSInt16(output, h.Reserved5);
WriteSInt16(output, h.MetricDataFormat);
// input there a GID >= numberOfHMetrics ? Then keep the last entry of original hmtx table,
// (add if it isn't in our set of GIDs), see also in buildHmtxTable()
int hmetrics = glyphIds.GetViewBetween(0, h.NumberOfHMetrics).Count();
if (glyphIds.LastOrDefault() >= h.NumberOfHMetrics && !glyphIds.Contains(h.NumberOfHMetrics - 1))
{
++hmetrics;
}
WriteUint16(output, hmetrics);
output.Flush();
return(bos.ToArray());
}
}
private byte[] BuildHmtxTable()
{
MemoryStream bos = new MemoryStream();
HorizontalHeaderTable h = ttf.HorizontalHeader;
HorizontalMetricsTable hm = ttf.HorizontalMetrics;
Bytes.Buffer input = ttf.OriginalData;
// more info: https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6hmtx.html
int lastgid = h.NumberOfHMetrics - 1;
// true if lastgid input not in the set: we'll need its width (but not its left side bearing) later
bool needLastGidWidth = false;
if (glyphIds.LastOrDefault() > lastgid && !glyphIds.Contains(lastgid))
{
needLastGidWidth = true;
}
try
{
long isResult = input.Skip(hm.Offset);
if (isResult.CompareTo(hm.Offset) != 0)
{
Debug.WriteLine($"debug: Tried skipping {hm.Offset} bytes but only {isResult} bytes skipped");
}
long lastOffset = 0;
foreach (int glyphId in glyphIds)
{
// offset in original file
long offset;
if (glyphId <= lastgid)
{
// copy width and lsb
offset = glyphId * 4L;
lastOffset = CopyBytes(input, bos, offset, lastOffset, 4);
}
else
{
if (needLastGidWidth)
{
// one time only: copy width from lastgid, whose width applies
// to all later glyphs
needLastGidWidth = false;
offset = lastgid * 4L;
lastOffset = CopyBytes(input, bos, offset, lastOffset, 2);
// then go on with lsb from actual glyph (lsb are individual even in monotype fonts)
}
// copy lsb only, as we are beyond numOfHMetrics
offset = h.NumberOfHMetrics * 4L + (glyphId - h.NumberOfHMetrics) * 2L;
lastOffset = CopyBytes(input, bos, offset, lastOffset, 2);
}
}
return(bos.ToArray());
}
finally
{
input.Dispose();
}
}
private TTFTable ReadTableDirectory(TrueTypeFont font, TTFDataStream raf)
{
TTFTable table;
string tag = raf.ReadString(4);
switch (tag)
{
case CmapTable.TAG:
table = new CmapTable(font);
break;
case GlyphTable.TAG:
table = new GlyphTable(font);
break;
case HeaderTable.TAG:
table = new HeaderTable(font);
break;
case HorizontalHeaderTable.TAG:
table = new HorizontalHeaderTable(font);
break;
case HorizontalMetricsTable.TAG:
table = new HorizontalMetricsTable(font);
break;
case IndexToLocationTable.TAG:
table = new IndexToLocationTable(font);
break;
case MaximumProfileTable.TAG:
table = new MaximumProfileTable(font);
break;
case NamingTable.TAG:
table = new NamingTable(font);
break;
case OS2WindowsMetricsTable.TAG:
table = new OS2WindowsMetricsTable(font);
break;
case PostScriptTable.TAG:
table = new PostScriptTable(font);
break;
case DigitalSignatureTable.TAG:
table = new DigitalSignatureTable(font);
break;
case KerningTable.TAG:
table = new KerningTable(font);
break;
case VerticalHeaderTable.TAG:
table = new VerticalHeaderTable(font);
break;
case VerticalMetricsTable.TAG:
table = new VerticalMetricsTable(font);
break;
case VerticalOriginTable.TAG:
table = new VerticalOriginTable(font);
break;
case GlyphSubstitutionTable.TAG:
table = new GlyphSubstitutionTable(font);
break;
default:
table = ReadTable(font, tag);
break;
}
table.Tag = tag;
table.CheckSum = raf.ReadUnsignedInt();
table.Offset = raf.ReadUnsignedInt();
table.Length = raf.ReadUnsignedInt();
// skip tables with zero length (except glyf)
if (table.Length == 0 && !tag.Equals(GlyphTable.TAG, StringComparison.Ordinal))
{
return(null);
}
return(table);
}
/**
* Parse all tables and check if all needed tables are present.
*
* @param font the TrueTypeFont instance holding the parsed data.
* @ If there is an error parsing the TrueType font.
*/
private void ParseTables(TrueTypeFont font)
{
foreach (TTFTable table in font.Tables)
{
if (!table.Initialized)
{
font.ReadTable(table);
}
}
bool isPostScript = AllowCFF && font.TableMap.ContainsKey(CFFTable.TAG);
HeaderTable head = font.Header;
if (head == null)
{
throw new IOException("head is mandatory");
}
HorizontalHeaderTable hh = font.HorizontalHeader;
if (hh == null)
{
throw new IOException("hhead is mandatory");
}
MaximumProfileTable maxp = font.MaximumProfile;
if (maxp == null)
{
throw new IOException("maxp is mandatory");
}
PostScriptTable post = font.PostScript;
if (post == null && !isEmbedded)
{
// in an embedded font this table is optional
throw new IOException("post is mandatory");
}
if (!isPostScript)
{
IndexToLocationTable loc = font.IndexToLocation;
if (loc == null)
{
throw new IOException("loca is mandatory");
}
if (font.Glyph == null)
{
throw new IOException("glyf is mandatory");
}
}
if (font.Naming == null && !isEmbedded)
{
throw new IOException("name is mandatory");
}
if (font.HorizontalMetrics == null)
{
throw new IOException("hmtx is mandatory");
}
if (!isEmbedded && font.Cmap == null)
{
throw new IOException("cmap is mandatory");
}
}
