Font Definition Header

This structure defines the format or the character definition records that follow it:

typedef struct_FONTDEFINITIONHEADER {
        ULONG        ulIdentity;
        ULONG        ulSize;
        SHORT        fsFontdef;
        SHORT        fsChardef;
        SHORT        usCellSize;
        SHORT        xCellWidth;
        SHORT        yCellHeight;
        SHORT        xCellIncrement;
        SHORT        xCellA;
        SHORT        xCellB;
        SHORT        xCellC;
        SHORT        pCellBaseOffset;
} FONTDEFINITIONHEADER;
typedef FONTDEFINITIONHEADER FAR *PFONTDEFINITIONHEADER;

Where:

ulIdentity

4 bytes.

Must be equal to 2.

ulSize
4 bytes.

Size of this structure in bytes.

fsFontdef
2 bytes of flags.

Indicates which fields are present in the font definition data in the header.

Type 1

Bit 0

1 = width defined in header
Bit 1
1 = height defined in header
Bit 2
1 = char increment same as width, so that it is defined for the whole font
Bit 3
0 = a-space not defined
Bit 4
0 = b-space not defined
Bit 5
0 = c-space not defined
Bit 6
1 = base offset same for all characters.
Type 2

Bit 0

0 = width for each character unique
Bit 1
1 = height defined in header
Bit 2
0 = char increment same as width, so that it is unique for each character
Bit 3
0 = a-space not defined
Bit 4
0 = b-space not defined
Bit 5
0 = c-space not defined
Bit 6
1 = base offset same for all characters.
Type 3

Bit 0

0 = width for each character unique
Bit 1
1 = height defined in header
Bit 2
0 = char increment same as width, so that it is unique
Bit 3
0 = a-space not defined
Bit 4
0 = b-space not defined
Bit 5
0 = c-space not defined
Bit 6
1 = base offset same for all characters.
FsChardef
2 bytes of flags.

Indicates which fields are present on a per character basis.

Type 1

Bit 0

1 = width defined for each character (performance op)
Bit 1
0 = height is in header
Bit 2
0 = char increment is in header
Bit 3
0 = a-space not defined
Bit 4
0 = b-space not defined
Bit 5
0 = c-space not defined
Bit 6
0 = base offset defined in header
Bit 7
1 = offset to glyph defined.
Type 2

Bit 0

1 = width defined for each character
Bit 1
0 = height is in header
Bit 2
0 = char increment same as width
Bit 3
0 = a-space not defined
Bit 4
0 = b-space not defined
Bit 5
0 = c-space not defined
Bit 6
0 = base offset defined in header
Bit 7
1 = offset to glyph defined.
Type 3

Bit 0

1 = width not defined, use a, b, c
Bit 1
0 = height is in header
Bit 2
0 = char increment same as width
Bit 3
1 = a-space defined
Bit 4
1 = b-space defined
Bit 5
1 = c-space defined
Bit 6
0 = base offset defined in header
Bit 7
1 = offset to glyph defined.
usCellSize
2-byte integer.

Indicates the length in bytes of each character definition record (the per character data).

Type 1

6 bytes
Type 2
6 bytes
Type 3
10 bytes.
xCellWidth
2-byte integer

The width of the characters, in pels for image fonts, and relative units for outline fonts.

Type 1

Width of the characters
Type 2
Zero
Type 3
Zero.
yCellHeight
2-byte integer.

The height of the characters, in pels for image fonts, and relative units for outline fonts.

Type 1

Height of the characters
Type 2
Height of the characters
Type 3
Height of the characters.
xCellIncrement
2-byte integer.

The distance along the character baseline required to step from one character to the next (when forming a character string).

Type 1

Width of the characters
Type 2
Zero
Type 3
Zero.
xCellA
2-byte signed integer.

The width of the space before a character in the inline direction (the a-space).

Type 1

Zero
Type 2
Zero
Type 3
a-space for all characters.
xCellB
2-byte integer.

The width of a character (inline direction). The b-space.

Type 1

Zero
Type 2
Zero
Type 3
b-space for all characters.
xCellC
2-byte signed integer.

The width of the space after a character in the inline direction (the c-space).

Type 1

Zero
Type 2
Zero
Type 3
c-space for all characters.
pCellBaseOffset
2-byte signed integer.

The position of the top of a character definition relative to the baseline in the direction perpendicular to the baseline.

Type 1

Baseline offset for all characters
Type 2
Baseline offset for all characters
Type 3
Baseline offset for all characters.
Character Definition Record
xCellSize bytes per record.

The following fields may or may not be present, according to the font character definition fields flags. If a field is present, it is present for each character and the value applies to that character only.

There are usLastChar+2 such records for raster fonts. The final one is for the null character.

• Character Definition Offset: 4-byte integer.

  The offset into the Font File at which the character definition begins.

  Data for a single character raster or vector should not span two segments; that is, if a character is too big to fit into a segment it should be put in the next segment.

  This field should be set to zero if the character being defined is a blank character.

• Character Cell Width: 2-byte integer.

  The width of the character definition in pels.

• Character Cell Height: 2-byte integer.

  The height of the character definition in pels.

• Character Increment: 2-byte integer.

  The length along the character baseline required to step from this character to the next (when forming a character string).

• Character a-space: 2-byte signed integer.

  The width of the space before the character in the inline direction.

• Character b-space: 2-byte integer.

  The width of the character shape (inline direction).

• Character c-space: 2-byte signed integer.

  The width of the space after the character in the inline direction.

• Character Baseline Offset: 2-byte signed integer.

  The position of the top of a character definition relative to the baseline in the direction perpendicular to the baseline.

Note: Type 1 fonts have offset/width pairs (like type 2); however, the usCellSize and xCellIncrement are nonzero. In the fsType field of the font metrics, the proportional-space flag, bit 0, is set.

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