GDEF Table Examples

The rest of this chapter describes examples of all the GDEF table formats. All the examples reflect unique parameters described below, but the samples provide a useful reference for building tables specific to other situations.

The examples have three columns showing hex data, source, and comments.

Example 1: GDEF Header

Example 1 shows a GDEF Header definition with offsets to each of the main tables in GDEF.

Example 1

Hex Data	Source	Comments
	GDEFHeader
	TheGDEFHeader	;GDEFHeader table definition
00010000	0x00010000	;Version
000A	GlyphClassDefTable	;offset to GlyphClassDef table
0026	AttachListTable	;offset to AttachList table
0040	LigCaretListTable	;offset to LigCaretList table

Example 2: GlyphClassDef Table

The GlyphClassDef table in Example 2 specifies a glyph for the each of the glyph classes predefined in the GlyphClassDef Enumeration List.

Example 2

Hex Data	Source	Comments
	ClassDefFormat2
	GlyphClassDefTable	;ClassDef table definition
0002	2	;ClassFormat
0004	4	;ClassRangeCount
		;ClassRangeRecord[0]
0024	iGlyphID	;Start
0024	iGlyphID	;End
0001	1	;Class
		; 1 = simple glyphs
		;ClassRangeRecord[1]
009F	ffiLigGlyphID	;Start
009F	ffiLigGlyphID	;End
0002	2	;Class
		; 2 = ligature glyphs
		;ClassRangeRecord[2]
0058	umlautAccentGlyphID	;Start
0058	umlautAccentGlyphID	;End
0003	3	;Class
		; 3 = mark glyphs
		;ClassRangeRecord[3]
018F	CurvedTailComponentGlyphID	;Start
018F	CurvedTailComponentGlyphID	;End
0004	4	;Class
		; 4 = component glyphs

Example 3: AttachList Table

In Example 3, the AttachList table enumerates the attachment points defined for two glyphs. The GlyphCoverage table identifies the glyphs: "a" and "e." For each covered glyph, an AttachPoint table specifies the attachment point count and point indices: one point for the "a" glyph and two for the "e" glyph.

Example 3

Hex Data	Source	Comments
	AttachList
	AttachListTable	;AttachList table definition
0012	GlyphCoverage	;offset to Coverage table
0002	2	;GlyphCount
0008	aAttachPoint	;AttachPoint[0]
000C	eAttachPoint	;AttachPoint[1]

	AttachPoint
	aAttachPoint	;AttachPoint table definition
0001	1	;PointCount
0012	18	;PointIndex[0]

	AttachPoint
	eAttachPoint	;AttachPoint table definition
0002	2	;PointCount
000E	14	;PointIndex[0]
0017	23	;PointIndex[1]


	CoverageFormat1
	GlyphCoverage	;Coverage table definition
0001	1	;CoverageFormat
0002	2	;GlyphCount
001C	aGlyphID	;GlyphArray[0]
0020	eGlyphID	;GlyphArray[1]

Example 4: LigCaretList Table, LigGlyph Table and CaretValueFormat1 Table

Example 4 defines a list of ligature carets. The LigCoverage table lists all the ligature glyphs that define caret positions. In this example, two ligatures are covered, "ffi" and "fi." For each covered glyph, a LigGlyph table specifies the number of carets for the ligature and their coordinate values. The "fi" ligature defines one caret, positioned between the "f" and "i" components; the "ffi" ligature defines two, one positioned between the two "f" components and the other positioned between the "f" and "i." The CaretValue tables shown here use Format1, where values are specified in design units only.

Example 4

Hex Data	Source	Comments
	LigCaretList
	LigCaretListTable	;LigCaretList table definition
0008	LigCoverage	;offset to Coverage table
0002	2	;LigGlyphCount
0010	fiLigGlyph	;offset to LigGlyph table[0]
0014	ffiLigGlyph	;offset to LigGlyph table[1]

	CoverageFormat1
	LigCoverage	;Coverage table definition
0001	1	;CoverageFormat
0002	2	;GlyphCount
009F	ffiLigGlyphID	;GlyphArray[0]
00A5	fiLigGlyphID	;GlyphArray[1]

	LigGlyph
	fiLigGlyph	;LigGlyph table definition
0001	1	;CaretCount
		; equals the number of
		; components - 1
000E	CaretFI	;CaretValue[0]

	LigGlyph
	ffiLigGlyph	;LigGlyph table definition
0002	2	;CaretCount
		; equals the number of
		; components - 1
0006	CaretFFI1	;CaretValue[0]
000E	CaretFFI2	;CaretValue[1]

	CaretValueFormat1
	CaretFI	;CaretValue table definition
0001	1	;CaretValueFormat
		; design units only
025B	603	;Coordinate
		; X or Y value

	CaretValueFormat1
	CaretFFI1	;CaretValue table definition
0001	1	;CaretValueFormat
		; design units only
025B	603	;Coordinate
		; X or Y value

	CaretValueFormat1
	CaretFFI2	;CaretValue table definition
0001	1	;CaretValueFormat
		; design units only
04B6	1206	;Coordinate
		; X or Y value

Example 5: CaretValueFormat2 Table

Example 5 shows a CaretValueFormat2 table that specifies a ligature caret coordinate in terms of a contour point index on a specific glyph. The final position of the caret depends on the location of the contour point on the glyph after hinting.

Example 5

Hex Data	Source	Comments
	CaretValueFormat2
	Caret1	;CaretValue table definition
0002	2	;CaretValueFormat
		; contour point
000D	13	;CaretValuePoint
		; contour point index

Example 6: CaretValueFormat3 Table

In Example 6, the CaretValueFormat3 table defines a caret position in design units, but includes a Device table to adjust the X or Y coordinate for the point size and resolution of the output font. Here, the Device table specifies pixel adjustments for font sizes from 12 ppem to 17 ppem.

Example 6

Hex Data	Source	Comments
	CaretValueFormat3
	Caret3	;CaretValue table definition
0003	3	;CaretValueFormat
		; design units plus Device table
04B6	1206	;Coordinate
		; X or Y value, design units
0006	CaretDevice	;offset to Device table

	DeviceTableFormat2
	CaretDevice	;Device Table definition
000C	12	;StartSize
0011	17	;EndSize
0002	2	;DeltaFormat
	1	; increase 12ppm by 1 pixel
	1	; increase 13ppm by 1 pixel
	1	; increase 14ppm by 1 pixel
1111	1	; increase 15ppm by 1 pixel
	2	; increase 16ppm by 1 pixel
2200	2	; increase 17ppm by 1 pixel