Class TtfLocaTable

Parsed OpenType "loca" table (index to location). Maps glyph indices to their byte offsets within the "glyf" table.

Inheritance

object

TtfTableBase

TtfLocaTable

Inherited Members

TtfTableBase.Tag

TtfTableBase.RawBytes

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: DRIT.Drawing.Font.Ttf.Tables

Assembly: DRIT.Drawing.dll

Syntax

public sealed class TtfLocaTable : TtfTableBase

Remarks

The table stores numGlyphs + 1 offsets so the length of any glyph's data can be derived as loca[i+1] − loca[i]. A zero-length entry means the glyph has no outline (e.g. the space character).

Format is controlled by head.indexToLocFormat:

• 0 (short): 16-bit values, each multiplied by 2 to get the byte offset.
• 1 (long): 32-bit values used as-is.

Ref: OpenType spec §5.2.5.

Fields

TableTag

The table tag for the loca table.

Declaration

public const string TableTag = "loca"

Field Value

Type	Description
string

Remarks

The table stores numGlyphs + 1 offsets so the length of any glyph's data can be derived as loca[i+1] − loca[i]. A zero-length entry means the glyph has no outline (e.g. the space character).

Format is controlled by head.indexToLocFormat:

• 0 (short): 16-bit values, each multiplied by 2 to get the byte offset.
• 1 (long): 32-bit values used as-is.

Ref: OpenType spec §5.2.5.

Properties

GlyphCount

Total number of glyph entries (excluding the sentinel).

Declaration

public int GlyphCount { get; }

Property Value

Type	Description
int

Remarks

The table stores numGlyphs + 1 offsets so the length of any glyph's data can be derived as loca[i+1] − loca[i]. A zero-length entry means the glyph has no outline (e.g. the space character).

Format is controlled by head.indexToLocFormat:

• 0 (short): 16-bit values, each multiplied by 2 to get the byte offset.
• 1 (long): 32-bit values used as-is.

Ref: OpenType spec §5.2.5.

IndexToLocFormat

The indexToLocFormat value from the "head" table: 0 = short format, 1 = long format.

Declaration

public short IndexToLocFormat { get; }

Property Value

Type	Description
short

Remarks

The table stores numGlyphs + 1 offsets so the length of any glyph's data can be derived as loca[i+1] − loca[i]. A zero-length entry means the glyph has no outline (e.g. the space character).

Format is controlled by head.indexToLocFormat:

• 0 (short): 16-bit values, each multiplied by 2 to get the byte offset.
• 1 (long): 32-bit values used as-is.

Ref: OpenType spec §5.2.5.

Methods

GetGlyphLength(int)

Returns the byte length of the glyph data for glyphIndex. A return value of 0 indicates a glyph with no outline (e.g. space).

Declaration

public uint GetGlyphLength(int glyphIndex)

Parameters

Type	Name	Description
int	glyphIndex

Returns

Type	Description
uint

Remarks

The table stores numGlyphs + 1 offsets so the length of any glyph's data can be derived as loca[i+1] − loca[i]. A zero-length entry means the glyph has no outline (e.g. the space character).

Format is controlled by head.indexToLocFormat:

• 0 (short): 16-bit values, each multiplied by 2 to get the byte offset.
• 1 (long): 32-bit values used as-is.

Ref: OpenType spec §5.2.5.

GetGlyphOffset(int)

Returns the absolute byte offset of glyph glyphIndex within the "glyf" table data. Returns 0 for out-of-range indices.

Declaration

public uint GetGlyphOffset(int glyphIndex)

Parameters

Type	Name	Description
int	glyphIndex

Returns

Type	Description
uint

Remarks

The table stores numGlyphs + 1 offsets so the length of any glyph's data can be derived as loca[i+1] − loca[i]. A zero-length entry means the glyph has no outline (e.g. the space character).

Format is controlled by head.indexToLocFormat:

• 0 (short): 16-bit values, each multiplied by 2 to get the byte offset.
• 1 (long): 32-bit values used as-is.

Ref: OpenType spec §5.2.5.

Parse(byte[], short, ushort)

Parses the "loca" table from its raw bytes.

Declaration

public static TtfLocaTable Parse(byte[] rawBytes, short indexToLocFormat, ushort numGlyphs)

Parameters

Type	Name	Description
byte[]	rawBytes	Raw table data.
short	indexToLocFormat	Value from IndexToLocFormat: 0 = short (×2), 1 = long.
ushort	numGlyphs	Total glyph count from NumGlyphs. The table will contain numGlyphs + 1 offset entries.

Returns

Type	Description
TtfLocaTable

Remarks

The table stores numGlyphs + 1 offsets so the length of any glyph's data can be derived as loca[i+1] − loca[i]. A zero-length entry means the glyph has no outline (e.g. the space character).

Format is controlled by head.indexToLocFormat:

• 0 (short): 16-bit values, each multiplied by 2 to get the byte offset.
• 1 (long): 32-bit values used as-is.

Ref: OpenType spec §5.2.5.