/**
* <summary>Loads the font data.</summary>
*/
private void Load(
)
{
Metrics = new FontMetrics();
// 1. Offset Table.
FontData.Seek(0);
// Get the outline format!
this.OutlineFormat = GetOutlineFormat(FontData.ReadInt());
// Get the number of tables!
int tableCount = FontData.ReadUnsignedShort();
tableOffsets = new Dictionary <string, int>(tableCount);
// 2. Table Directory.
// Skip to the beginning of the table directory!
FontData.Skip(6);
// Collecting the table offsets...
for (
int index = 0;
index < tableCount;
index++
)
{
// Get the table tag!
String tag = ReadAsciiString(4);
// Skip to the table offset!
FontData.Skip(4);
// Get the table offset!
int offset = FontData.ReadInt();
// Collect the table offset!
tableOffsets[tag] = offset;
// Skip to the next entry!
FontData.Skip(4);
}
FontName = Load_GetName(NameID_FontPostscriptName);
Load_Tables();
Load_CMap();
Load_GlyphWidths();
Load_GlyphKerning();
}
/**
* <summary>Gets whether the given data represents a valid Open Font.</summary>
*/
public static bool IsOpenFont(
bytes::IInputStream fontData
)
{
long position = fontData.Position;
fontData.Position = 0;
try
{ GetOutlineFormat(fontData.ReadInt()); }
catch (NotSupportedException)
{ return(false); }
finally
{ fontData.Position = position; }
return(true);
}
/**
* <summary>Gets whether the given data represents a valid Open Font.</summary>
*/
public static bool IsOpenFont(
bytes::IInputStream fontData
)
{
long position = fontData.Position;
try
{
fontData.Position = 0;
GetOutlineFormat(fontData.ReadInt()); // NOTE: An exception is expected to be thrown in case of wrong file format.
return(true);
}
catch
{ return(false); }
finally
{ fontData.Position = position; }
}
/**
* <summary>Gets whether the given data represents a valid Open Font.</summary>
*/
public static bool IsOpenFont(bytes::IInputStream fontData)
{
long position = fontData.Position;
fontData.Seek(0);
try
{
switch (fontData.ReadInt())
{
case (0x00010000): // TrueType (standard/Windows).
case (0x74727565): // TrueType (legacy/Apple).
case (0x4F54544F): // CFF (Type 1).
return(true);
default:
return(false);
}
}
finally
{ fontData.Seek(position); }
}
/**
* <summary>Loads the character to glyph index mapping table.</summary>
*/
private void LoadCMap(
)
{
/*
* NOTE: A 'cmap' table may contain one or more subtables that represent multiple encodings
* intended for use on different platforms (such as Mac OS and Windows).
* Each subtable is identified by the two numbers, such as (3,1), that represent a combination
* of a platform ID and a platform-specific encoding ID, respectively.
* A symbolic font (used to display glyphs that do not use standard encodings, i.e. neither
* MacRomanEncoding nor WinAnsiEncoding) program's "cmap" table should contain a (1,0) subtable.
* It may also contain a (3,0) subtable; if present, this subtable should map from character
* codes in the range 0xF000 to 0xF0FF by prepending the single-byte codes in the (1,0) subtable
* with 0xF0 and mapping to the corresponding glyph descriptions.
*/
// Character To Glyph Index Mapping Table ('cmap' table).
// Retrieve the location info!
int tableOffset;
if (!tableOffsets.TryGetValue("cmap", out tableOffset))
{
throw new ParseException("'cmap' table does NOT exist.");
}
int cmap10Offset = 0;
int cmap31Offset = 0;
// Header.
// Go to the number of tables!
FontData.Seek(tableOffset + 2);
int tableCount = FontData.ReadUnsignedShort();
// Encoding records.
for (
int tableIndex = 0;
tableIndex < tableCount;
tableIndex++
)
{
// Platform ID.
int platformID = FontData.ReadUnsignedShort();
// Encoding ID.
int encodingID = FontData.ReadUnsignedShort();
// Subtable offset.
int offset = FontData.ReadInt();
switch (platformID)
{
case PlatformID_Macintosh:
switch (encodingID)
{
case 0: // Symbolic font.
cmap10Offset = offset;
break;
}
break;
case PlatformID_Microsoft:
switch (encodingID)
{
case 0: // Symbolic font.
break;
case 1: // Nonsymbolic font.
cmap31Offset = offset;
break;
}
break;
}
}
/*
* NOTE: Symbolic fonts use specific (non-standard, i.e. neither Unicode nor
* platform-standard) font encodings.
*/
if (cmap31Offset > 0) // Nonsymbolic.
{
Metrics.IsCustomEncoding = false;
// Go to the beginning of the subtable!
FontData.Seek(tableOffset + cmap31Offset);
}
else if (cmap10Offset > 0) // Symbolic.
{
Metrics.IsCustomEncoding = true;
// Go to the beginning of the subtable!
FontData.Seek(tableOffset + cmap10Offset);
}
else
{
throw new ParseException("CMAP table unavailable.");
}
int format;
format = FontData.ReadUnsignedShort();
// Which cmap table format?
switch (format)
{
case 0: // Byte encoding table.
LoadCMapFormat0();
break;
case 4: // Segment mapping to delta values.
LoadCMapFormat4();
break;
case 6: // Trimmed table mapping.
LoadCMapFormat6();
break;
default:
throw new ParseException("Cmap table format " + format + " NOT supported.");
}
}