ID Number: Q10837
2.00 3.00
WINDOWS
Summary:
The following discussion on Windows fonts describes how they are
defined and why they are necessary.
More Information:
How Default Fonts Are Assigned
------------------------------
At the API level, Windows version 3.0 defines six stock fonts. Each of
these fonts has a logical description. At Windows 3.0 boot time, GDI
constructs the logical description of these fonts in the following
manner:
1. During its initialization, GDI calls an internal function,
InitFonts(), which is responsible for physically loading three
basic fonts. Under a typical Windows 3.0 installation, the names of
the font files for these fonts are listed in the [boot] section of
the SYSTEM.INI file. For example, this section (in part) resembles
the following:
fixedfon.fon=vgafix.fon
oemfonts.fon=vgaoem.fon
fonts.fon=vgasys.fon
The system font is loaded first. GDI first checks the WIN.INI file
in the [windows] section for the key name SystemFont=<file>, where
<file> is a name of a bitmap font (such as HELV.FON). If GDI finds
this keyname, it will attempt to load the specified file as the
system font. Changing this value is one method the user can use to
customize the system font.
If GDI does not find this key name, it attempts to load the system
font from a file called FONTS.FON using the GDI function
AddFontResource. Notice that on typical installations of Windows
3.0, there is no file called FONTS.FON. AddFontResource calls
LoadLibrary to load the specified file. If the file is not found,
LoadLibrary will search the SYSTEM.INI file (in the [boot] section)
for a redirection of the file. As shown above, the [boot] section
of SYSTEM.INI for a VGA system contains the following:
fonts.fon=vgasys.fon
This line indicates that the system font should be loaded from the
file VGASYS.FON, which resides in the system directory.
2. Once the system font is physically loaded, GDI attempts to load a
fixed-pitch font. GDI examines the [boot] section of the SYSTEM.INI
file and extracts the filename from the fixedfon.fon= field. If no
file is specified, the system font (loaded in step 1) is
substituted for the system fixed-pitch font.
3. Next, the terminal font is loaded. GDI attempts to load the file
OEMFONTS.FON (via AddFontResource). This file may be redirected in
the same manner as the system font in step 1.
4. Later during its initialization, GDI gets the module handle of
DISPLAY. Using the module handle, it does a FindResource() on the
resource string "fonts", which is an array of three LOGFONT
structures that have been defined by the display driver
manufacturer. This is the resource that is included in the display
driver's .RC file with the line:
fonts oembin PRELOAD fonts.bin
Once this resource is found, GDI steps through the array of
LOGFONTS and calls CreateFontIndirect to create the stock font
objects:
OEM_FIXED_FONT
ANSI_FIXED_FONT
ANSI_VAR_FONT
These logical font definitions can be thought of as recommendations
for a particular display by the display driver.
In general, these logical font descriptions will map to one of the
physical fonts loaded initially by GDI.
However, when an application selects one of these stock fonts, the
font mapper selects the closest matching font from a list of
available physical fonts in the system. This list contains the
initial system fonts that were loaded by GDI, in addition to other
fonts that may have been loaded at a later time. Therefore, there
is no guarantee that a given stock font will necessarily map to one
of the three initial fonts loaded by GDI.
5. Once these three stock fonts have been defined, GDI defines the
stock font SYSTEM_FONT. GDI does this by opening the system font
file loaded in step 1 and builds a logical font structure that
exactly matches the physical characteristics of the physical font.
This is to ensure that the font mapper will select this physical
font when the SYSTEM_FONT stock font is requested.
6. Finally, the logical description of the device default font
(DEVICE_DEFAULT_FONT) is defined. This font is defined to be the
same as the SYSTEM_FONT.
Why These Fonts Are Necessary
-----------------------------
There are two reasons for having these six stock fonts. One reason is
to provide an OEM font that displays well at 10 pitch on the machine.
This font is also used to determine the height of dialog boxes. The
second reason is to provide ANSI fonts that are based on proposed
standards (device-independent) and match Microsoft's virtual-key
definitions.
Please note that all of these fonts are required. The display driver
must include the three logical fonts (described above) or GDI will not
initialize properly.