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Microsoft Windows font files contain the font glyph information the
graphics-device interface (GDI) or a graphics driver needs to draw text on a
given device. The font-file format supports both raster and vector fonts.
Also, Windows extended the font file format for Windows 3.x to increase the
maximum size of a font file beyond 64K bytes.
 
This topic does not describe the format of Microsoft TrueType font files.
 
Font Files
 
Font files consist of a font header, a character-width table, and the glyph
data. The font header has the following format:
 
typedef struct tagFONTFILEHEADER {
    short dfVersion;
    long  dfSize;
    char  dfCopyright[60];
    FONTINFO dffi;
} FONTFILEHEADER;
 
The dfVersion member specifies the version of Windows for which the font was
designed. For example, for fonts designed for Windows 3.1, this member is
set to 0x30A. The dfSize member specifies the size in bytes of the entire
font file and the dfCopyright member contains the font designer's
null-terminated copyright string. The rest of the FONTFILEHEADER structure
is identical to the FONTINFO structure.
 
The character-width table for the font file immediately follows the
FONTFILEHEADER structure. The format of the table depends on the font-file
version and whether the font contains raster or vector glyphs. For more
information about the character-width table formats, see the FONTINFO
structure in Chapter 12, "Graphics-Driver Types and Structures."
 
The glyph data usually follows the character-width table. However, the
dfBitsOffset member in the FONTINFO structure always specifies the offset
from the beginning of the file to the start of the data. The data represents
either raster or vector glyphs. The following sections describe these
formats in detail.
 
Raster Glyphs
 
A raster-font file contains individual bitmaps for each glyph in the file.
Each glyph bitmap is stored as a contiguous set of bytes. The first byte
contains the first eight bits of the first scan line (that is, the top line
of the character). The second byte contains the first eight bits of the
second scan line. This continues until what amounts to a first "column" is
completely defined.
 
The following byte contains the next eight bits of the first scan line,
padded with zeros on the right if necessary (and so on, down through the
second "column"). If the glyph is quite narrow, each scan line is covered by
one byte, with bits set to zero as necessary for padding. If the glyph is
very wide, a third or even fourth set of bytes can be present.
 
All bitmaps must be stored contiguously and arranged in ascending order,
that is, the bitmap for the first character is first and the last character
is last.
 
The following example shows the the bytes that form a 12 x 14 pixel
character.
 
00 06 09 10 20 20 20 3F 20 20 20 00 00 00   /* first column */
00 00 00 80 40 40 40 C0 40 40 40 00 00 00   /* second column */
 
Notice that in the second set of bytes, the second digit corresponds to the
thirteenth through sixteenth pixels on the right side of the character.
Since the character is only 12 bits wide, these bits should always be zero.
 
The resulting character looks like this:
 
 ............
 .....**.....
 ....*..*....
 ...*....*...
 ..*......*..
 ..*......*..
 ..*......*..
 ..********..
 ..*......*..
 ..*......*..
 ..*......*..
 ............
 ............
 ............
 
Vector Glyphs
 
A vector-font file contains a series of vectors for each glyph in the file.
Each vector is a signed coordinate pair specifying the amount to move the
pen relative to the current position. The size of each coordinate depends on
the size of the font. If either the dfPixHeight or dfMaxWidth members in the
FONTINFO structure is greater than 128, the coordinates are stored as 2-byte
quantities; otherwise, they are stored as 1-byte quantities.
 
Each coordinate pair may be preceded by a value indicating whether the pen's
tip should be lifted before moving. The tip-up value depends on the size of
the coordinates. For 1-byte coordinates, the value is -128 (0x80) and for
2-byte coordinates, the value is -32768 (0x8000).
 
To draw the a vector glyph, a device moves the pen to the character cell
origin. The origin is assumed to be at the upper-left corner of the
character cell. The device moves the pen to new positions as specified by
each vector. Positive coordinates move the pen down and to the right;
negative coordinates up and to the left. If the tip-up value is given, the
tip stays up for the subsequent coordinate pair only. The number of vectors
for a glyph depends on the glyph. The number of bytes in the vector series
is equal to the difference between the offsets from the character-width
table for the given character and the next character.
 
The following series of vectors draws an exclamation point:
 
-128,   /* pen tip up */
 5,   4,
-1,   2,
 1,  12,
 1, -12,
-1,  -2,
-128,   /* pen tip up */
 0,   2,
 0,   6,
-128,   /* pen tip up */
 0,  11,
-1,   1,
 1,   1,
 1,  -1,
-1,  -1
 
If the character is drawn in a 10 x 24 character cell, the resulting
character looks like this:
 
 ..........
 ..........
 ..........
 ....*.....
 ....*.....
 ...***....
 ...***....
 ...***....
 ...***....
 ...***....
 ...***....
 ...***....
 ....*.....
 ....*.....
 ....*.....
 ....*.....
 ....*.....
 ....*.....
 ..........
 ..........
 ..........
 ..........
 ....*.....
 ...*.*....
 ....*.....
 
 
                                      ♦